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Diseases » Mental retardation » Glossary
 

Glossary for Mental retardation

  • $14q+ syndrome$: A rare chromosomal disorder involving duplication of genetic material from the long arm (q) of chromosome 14 resulting in various abnormalities.
  • $18p minus syndrome$: A rare chromosomal disorder where a portion of chromosome 18 is missing which is characterized by mental and growth deficiencies, drooping upper eyelid and prominent ears. The type and severity of symptoms is determined by the amount of genetic material that is missing.
  • $1q deletion$: A rare chromosomal disorder where part of the long arm (q) of chromosome 1 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • $2-Hydroxyglutaricaciduria$: A rare metabolic disorder characterized by high levels of a certain chemical (2-Hydroxyglutaric) which causes a serious progressive neurological disease and damage to the brain. The features of this disorder are variable and some cases are milder than others.
  • $2p21 deletion syndrome$: This syndrome is a more severe form hypotonia-cystinuria syndrome as a larger portion of genetic material from chromosome 2p21 is deleted. It is characterized by infant seizures, reduced muscle tone, developmental delay, lactic acidosis and unusual facial appearance.
  • $2q deletion$: A rare chromosomal disorder where part of the long arm (q) of chromosome 2 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • $3-methylglutaconic aciduria, type 1$: A recessively inherited metabolic disorder characterized by methylglutaconic acid in the urine.
  • $3-methylglutaconic aciduria, type 4$: A rare genetic disorder where the body's cells are unable to make sufficient energy resulting in an accumulation in the body of 3-methylglutaconic acid. Type 4 is characterized by symptoms which overlap type 1 and 3.
  • $3C syndrome$: A rare disorder characterized by cardiac malformations, cerebellar hypoplasia and cranial dysmorphism which gives the disease it's name.
  • $3q deletion$: A rare chromosomal disorder where part of the long arm (q) of chromosome 3 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • $46,XX chromosome 7 deletion p13$: A chromosomal disorder where a small portion of chromosome 7 is deleted which results in a range of abnormalities.
  • $47 XYY syndrome$: A genetic condition where males have an extra Y chromosome in each of their cells. Normally male cells have one X and one Y chromosome. This is not usually an inherited condition but a defect that occurs during cell division. Often the condition is asymptomatic.
  • $47,XXX syndrome$: A genetic condition where females have an extra X chromosome in each of their cells. Normally female cells have two X chromosomes. This is not usually an inherited condition but a defect that occurs during cell division. Often the condition is asymptomatic.
  • $49,XXXXX syndrome$: A rare chromosomal disorder that affects only females and involves body cells having five copies of the X chromosome instead of the normal two.
  • $6-pyruvoyl-tetrahydropterin synthase deficiency$: A rare genetic disorder where insufficient levels of tetrahydropterin leads to a build up of phenylalanine in the blood which can cause toxic side effects such as nerve damage or even brain damage. The condition does not usually cause any significant symptoms.
  • ADHD: Attention Deficit Hyperactivity Disorder (ADHD) is a mental and behavioral disorder characterized by behavioral problems such as hyperactivity, inattention, concentration difficulty, and other mental symptoms. Typically, ADHD and associated hyperactivity is known as a childhood disorder, although ADD/ADHD in adults is known to be under-diagnosed. It is distinguished from Attention Deficit Disorder (ADD) which has a reduced focus on hyperactivity type symptoms.
  • ATR-X syndrome: A rare X-linked disorder that affects males and is characterized by mental retardation and alpha thalassemia.
  • ATR16: A rare disorder characterized by alpha thalassemia and mental retardation.
  • Absence of septum pellucidum and septo-optic dysplasia: A rare birth defect where a thin membrane in the middle of the brain is missing. This brain abnormality is never present on it's own but is a characteristic of septo-optic dysplasia where the patient also has optic disk abnormalities and pituitary deficiencies.
  • Absence of septum pellucidum with porencephalia syndrome: A rare syndrome present at birth and characterized by the absence of the thin membrane in the middle of the brain (septum pellucidum) as well as abnormal cavities in the brain (porencephaly). The syndrome also involves other structural brain abnormalities.
  • Absent corpus callosum - cataract - immunodeficiency: A rare syndrome characterized by immunodeficiency, cleft lip or palate, cataract, reduced pigmentation and brain abnormalities.
  • Absent patellae - scrotal hypoplasia - renal anomalies - facial dysmorphism - mental retardation: A rare syndrome characterized by absent kneecaps, underdeveloped scrotum, kidney anomalies, unusual facial appearance and mental retardation.
  • Acanthocytosis: A rare disorder where most of the red blood cells are abnormal with spiny projections due to lipid abnormalities. The blood abnormality is seen in conditions such as abetalipoproteinemia, severe liver disease and severe malnutrition. Symptoms and prognosis depend on the underlying disorder.
  • Acidemia, methylmalonic: An inborn error of metabolism where amino acids in the body aren't metabolized properly resulting in high levels of the acid throughout the body.
  • Acrocallosal Syndrome (Schinzel Type): A rare condition characterized by absence of portion of the brain (corpus callosum), mental deficiency, duplicated toes, mental deficiency and other abnormalities.
  • Acrocephalopolydactyly II: A rare genetic disorder characterized by head, hand and genital anomalies as well as mental retardation.
  • Acrocephaly - pulmonary stenosis - mental retardation: A rare syndrome characterized by a pointy skull, narrowed pulmonary valve and mental retardation.
  • Acrofacial dysostosis Catania form: One of a group of disorders characterized by defective limb and facial development. The Catania form is very rare.
  • Acrofrontofacionasal dysostosis syndrome: A very rare syndrome characterized by abnormalities of the bones of the skeleton as well as mental retardation. Various facial, eye and urogenital anomalies are also present.
  • Acromesomelic dysplasia Hunter Thompson type: A rare genetic syndrome characterized by various severe developmental abnormalities of the skeletal bones.
  • Acropectorovertebral dysplasia: A rare inherited genetic disorder characterized by abnormalities involving the fingers, toes, palate and chest bones.
  • Adducted thumb syndrome recessive form: A rare recessively inherited disorder characterized mainly by a small head, arthrogryposis (joint contractures), cleft palate and various other abnormalities.
  • Adducted thumbs Dundar type: A rare disorder characterized by a thumb abnormality as well as mental retardation, foot defects and other anomalies.
  • Adenylosuccinate lyase deficiency: A rare inherited disorder characterized by a deficiency of the enzyme called adenlyosuccinate lyase which generally results in psychomotor retardation and autistic behavior.
  • Adrenoleukodystrophy: A rare disorder which has characteristic symptoms of Addison disease (adrenocortical insufficiency) and Schilder disease (cerebral sclerosis). Bronze skin, brain sclerosis and demyelination are the main symptoms.
  • Agenesis of the corpus callosum - mental retardation - coloboma - micrognathia: A rare inherited disorder characterized by mental retardation, coloboma, small jaw and a brain anomaly.
  • Agyria-pachygyria type 1: Abnormal brain development where the brain fails to develop normally during the fetal stage.
  • Aicardi syndrome: A rare genetic disorder where the structure connecting the two halves of the brain fails to develop which results in seizures and eye abnormalities .
  • Aicardi-Goutieres syndrome: A rare inherited progressive disease that affects the brain and immune system.
  • Akesson syndrome: A very rare syndrome characterized by excessive skin folds and furrows on the scalp, mental retardation the failure of the thyroid to develop.
  • Al Gazali Aziz Salem syndrome: A rare syndrome characterized mainly by heart disease, short stature and a webbed neck.
  • Al Gazali Sabrinathan Nair syndrome: A very rare syndrome characterized by bone and eye problems, seizures and mental retardation.
  • Albers-Schonberg disease - malignant recessive form: A rare disorder characterized primarily by increased bone density as old bone is not resorbed and replaced with new bone - is also known as marble bone disease. The malignant infantile form is the most severe form of this disorder and death usually occurs in the first decade of life.
  • Albright's hereditary osteodystrophy: A rare genetic disorder where the body fails to recognize and respond to the parathyroid hormone. The parathyroid hormone is involved in controlling the blood levels of calcium and phosphate.
  • Aldred syndrome: A rare disorder characterized by the presence of mental retardation and retinitis pigmentosa the starts earlier than normal. Female carriers tend to have only vision symptoms without mental retardation.
  • Alexander Syndrome: Brain myelin disorder causing mental degeneration.
  • Allan-Herndon-Dudley Syndrome: A very rare inherited disorder characterized primarilty by mental retardation.
  • Alopecia mental retardation syndrome: A rare syndrome characterized primarily by a lack of hair and mental retardation.
  • Alopecia, epilepsy, oligophrenia syndrome of Moynahan: A rare condition characterized by alopecia, epilepsy, mental retardation and a small head.
  • Alopecia, epilepsy, pyorrhea, mental subnormality: A rare syndrome characterized by alopecia, epilepsy, mental retardation and pus-producing gum and tooth inflammations.
  • Alopecia, mental retardation and neurological problems: A rare, newly described syndrome characterized by baldness, mental retardation and neurological problems.
  • Alopecia-contractures-dwarfism-mental retardation: A rare syndrome characterized primarily by mental retardation, short stature, lack of hair and contractures.
  • Alpers Syndrome: A rare syndrome characterized by liver disease, seizures and progressive, episodic psychomotor retardation.
  • Alpha-ketoglutarate dehydrogenase deficiency: A metabolic disorder characterized by a deficiency of Alpha-ketoglutarate dehydrogenase which results in high levels of oxoglutaric acid in the urine as well as other severe symptoms.
  • Alpha-mannosidosis type II: A rare inherited metabolic disorder involving a deficiency of an enzyme (alpha-mannosidosase) which results in the accumulation of certain chemicals in the body which leads to progressive damage. This form of the condition is less severe than type I (infantile form).
  • Alport Syndrome: A rare hereditary disorder involving the progressive deterioration of parts of the kidney resulting in chronic kidney disease.
  • Alport syndrome - mental retardation - midface hypoplasia - elliptocytosis: A rare syndrome characterized by the association of Alport syndrome, mental retardation, underdeveloped midface and a blood abnormality (elliptocytosis). Alport syndrome is an inherited condition involving progressive kidney damage and hearing loss.
  • Aminoacidopathies: Any of a group of inborn errors of metabolism which results in the build up in the body of one or more amino acids in the blood and/or urine. The range and severity of symptoms is hugely variable.
  • Ampola syndrome: A rare genetic disease characterized primarily by mental retardation, facial anomalies, short stature, seizures and finger and toe abnormalities.
  • Amyloidosis of gingiva and conjunctiva mental retardation: A rare disorder characterized by mental retardation and abnormal amyloid deposits in the gums and conjunctiva of the eye.
  • Angelman syndrome: A rare genetic disorder characterized by a puppet-like gait, fits of laughter and characteristic facial features.
  • Angiokeratoma - mental retardation - coarse face: A rare inherited genetic syndrome characterized by mental retardation, coarse facial features and capillary hemangiomas.
  • Aniridia - ptosis - mental retardation - obesity, familial: A rare familial disorder characterized by eye abnormalities, mental retardation and obesity.
  • Aniridia - mental retardation syndrome: A very rare syndrome characterized by mental retardation and absent irises.
  • Aniridia - renal agenesis - psychomotor retardation: A rare genetic disorder characterized by missing irises of the eye, kidney developmental problems and mental retardation.
  • Aniridia III: A genetic disorder where part or all of the iris of one or both eyes is missing. The iris is the colored part of the eye. There are four forms of the disease: AN-1, AN-II, AN-III and AN-IV. AN-III is associated with mental retardation.
  • Aniridia cerebellar ataxia mental deficiency: A rare inherited disorder characterized by a partial absence of the iris, mental retardation and impaired coordination of voluntary movements.
  • Anophthalmia - hand and foot defects - mental retardation: A rare syndrome characterized mainly by mental retardation, hand and foot defects and absent eyes.
  • Anophthalmia - heart and pulmonary anomalies - intellectual deficit: A rare disorder characterized by absent eyes, heart and lung anomalies and mental retardation.
  • Anophthalmia - hypyothalamo-pituitary insufficiency: A rare syndrome characterized mainly by small or absent eyes and malformations of the hypothalamus and pituitary gland.
  • Anophthalmos with limb anomalies: A rare disorder characterized by absent eyes
  • Ansell-Bywaters-Elderking syndrome: A rare familial syndrome characterized mainly by mental retardation, rash, eye inflammation and joint disease.
  • Aortic arch anomaly with peculiar facies and mental retardation: A very rare syndrome characterized by mental retardation, characteristic facial anomalies and abnormal position of the aorta.
  • Apert syndrome: A rare condition characterized by abnormalities in the appearance of the face and head as well as finger and toe abnormalities. The bones of the skull fuse together too early which prevents it from growing normally. Various toes and fingers may be fused together.
  • Arachnodactyly - ataxia - cataract - aminoaciduria - mental retardation: A rare syndrome characterized mainly by congenital cataracts, ataxia, mental retardation, abnormal amino acid metabolism and long, thin fingers.
  • Arachnodactyly - mental retardation - dysmorphism: A very rare syndrome characterized by mental retardation, unusual facial features and long, thin fingers and toes.
  • Arakawa syndrome 1: An inherited metabolic disorder where an enzyme deficiency (glutamate formiminotrransferase) causes mental and physical retardation and degeneration of brain tissue.
  • Arginase deficiency: A very rare urea cycle disorder caused by a deficiency of the enzyme (arginase) needed to convert ammonia to the urea which can then be removed in the urine. The condition leads to excess build-up of ammonia in the body which is toxic to the nervous system.
  • Argininosuccinase lyase deficiency, neonatal: A rare inherited urea cycle disorder caused by lack of enzymes (argininosuccinase lyase) needed to turn ammonia into urea resulting in excess ammonia in the body. The neonatal form of the condition can result in death or severe complications if not treated early enough.
  • Arima syndrome: A rare disorder characterized mainly by eye and brain abnormalities.
  • Arnold-Chiari malformation type 4: Arnold-Chiari malformation is a rare malformation where the base of the brain enters into the upper spinal canal. Type 4 actually involves a lack of development of a portion of the base of the brain (cerebellum). The prognosis is very poor with death often occurring during infancy.
  • Arthritis - short stature - deafness: A very rare syndrome characterized by arthritis, short stature, deafness and numerous other abnormalities.
  • Arthrogryposis IUGR thoracic dystrophy: A very rare syndrome characterized by congenital joint contractures, intrauterine growth retardation (IUGR) and ribcage abnormalities.
  • Arthrogryposis multiplex congenita, distal, X-linked: A rare condition characterized by the presence of contractures at birth as well as various other anomalies. The condition is X-linked.
  • Arthrogryposis, congenital - myopathic seizures: A rare syndrome characterized by mental retardation and muscle problems.
  • Aspartylglucosaminuria: Glycoprotein metabolism disorder characterized by lack of aspartylglucosaminuridase.
  • Aspartylglycosaminuria: A very rare genetic disorder caused by a deficiency of a glycoprotein enzyme (aspartylglucosaminidase).
  • Ataxia - apraxia - mental retardation, X-linked: A rare X-linked syndrome characterized mainly by ataxia, apraxia and mental retardation. The symptoms are generally nonprogressive.
  • Ataxia deafness reardon type: A rare syndrome observed in a Kuwati family characterized by ataxia, deafness and mental retardation.
  • Ataxia tapetoretinal degeneration: Conditions involving incoordination and an eye anomaly.
  • Athabaskan brainstem dysgenesis: A rare neurological disorder caused by abnormal brainstem development and function.
  • Atkin-Flatiz syndrome: A rare, X-linked syndrome characterized mainly by mental retardation and facial anomalies.
  • Aughton syndrome: A very rare syndrome characterized primarily by small eyes, cleft palate, mental retardation and dextrocardia (heart located on right side of chest instead of left).
  • Aural atresia - multiple congenital anomalies - mental retardation: A rare syndrome characterized by a number of malformations as well as mental retardation.
  • Autism: Childhood mental condition with social and communication difficulties.
  • Baller-Gerold Syndrome:
  • Bamforth syndrome: A rare syndrome characterized mainly by the association of an abnormal opening in the roof of the mouth and reduced thyroid functioning.
  • Bangstad syndrome: A rare disorder characterized by diabetes, goiter, insufficient hormone production by the gonads and progressive ataxia.
  • Baraitser burn fixen syndrome: A rare syndrome characterized mainly by skeletal abnormalities, a skin disorder and an expressionless face.
  • Baraitser-Rodeck-Garner syndrome: A very rare syndrome characterized primarily by mental retardation, premature fusion of skull bones, kidney anomalies, seizures and facial anomalies.
  • Baraitser-Winter syndrome: A rare syndrome characterized by a structural eye defect, droopy eyelids and mental retardation.
  • Bardet-Biedl Syndrome: A rare genetic disorder characterized by mental retardation, obesity, polydactyly and retinal pigmentation as well as other abnormalities.
  • Bartsocas Papa syndrome: A rare condition characterized by webbing of skin as well as various other physical and mental abnormalities.
  • Bartter Syndrome: A rare genetic disorder of kidney metabolism characterized by reduced blood acidity and low potassium levels.
  • Bartter's syndrome, antenatal type 1: A rare genetic kidney disorder that causes hypokalemia. A defect in the NKCC2 gene impairs the functioning of the Na-Cl cotransporter and leads to electrolyte imbalance. The rate of death is high prior to diagnosis.
  • Bartters syndrome, antenatal , type 2: A rare genetic kidney disorder that causes hypokalemia. A defect in the ROMK gene impairs the ATP-regulated potassium channel functioning and leads to electrolyte imbalance.
  • Battaglia Neri syndrome: A very rare syndrome characterized by mental retardation, small head, epilepsy, coarse facial features and skeletal anomalies. Only two reported cases of this syndrome.
  • Bd syndrome: A very rare syndrome characterized mainly by the association of mental retardation, small eyes and a movement disorder.
  • Behavioral symptoms: Symptoms of personal behavior.
  • Behr syndrome: A rare inherited neurological condition characterized by spastic paraplegia and sometimes optic atrophy.
  • Bellini-Chiumello-Rinoldi syndrome: A very rare syndrome characterized primarily by mental retardation, short stature and unusual shaped ends of long bones.
  • Benjamin syndrome: A rare disorder characterized mainly by anemia, bone abnormalities and mental and growth retardation.
  • Bentham-Driessen-Hanveld syndrome: A rare syndrome characterized mainly by the association of undescended testes, long thin fingers and mental retardation.
  • Berlin Breakage syndrome: A very rare syndrome characterized mainly by a small head, reduced immunity and increased risk of cancer. The features of this condition are virtually indistinguishable from the Nigmegen Breakage syndrome.
  • Beta-mannosidosis: A very rare type of inherited glycoprotein storage disease where deficiency of an enzyme called beta-mannosidase results in a build-up of certain sugars (oligosaccharides) which can harm the body.
  • Beta-ureidopropionase deficiency: A metabolic disorder where the deficiency of an enzyme (Beta-ureidopropionase) results mainly in neurological abnormalities such as mental retardation. The symptoms are variable however.
  • Biemond syndrome type 2: A rare inherited condition characterized by mental retardation, obesity, polydactyly and underdeveloped genitals.
  • Bird-headed dwarfism, Montreal type: A rare condition characterized by dwarfism and a characteristic beak-shaped nose.
  • Blepharophimosis - ptosis - syndactyly - mental retardation: A rare genetic disorder characterized by eye anomalies, webbed fingers and mental retardation.
  • Blepharophimosis syndrome Ohdo type: An extremely rare syndrome characterized primarily by mental retardation and eye anomalies. Only a handful of cases have been reported.
  • Bobble-head doll syndrome: A rare condition where a child's head bobs up and down continuously due to either fluid on the brain or a large cyst in the third ventricle of the brain.
  • Bone dysplasia - corpus callosum agenesis: A very rare syndrome characterized mainly by abnormal brain development and bone growth abnormalities.
  • Bonneman-Meinecke-Reich syndrome: A very rare syndrome characterized by calcium deposits in the brain tissue, deficiency of growth hormones and degeneration of the part of the eye called the retina.
  • Borjeson-Forssman-Lehmann Syndrome:
  • Boscherini-Galasso-Manca-Bitti syndrome: A rare syndrome characterized by a range of abnormalities including mental retardation, growth hormone deficiency, congenital heart defect and facial abnormalities.
  • Brachioskeletogenital syndrome: A rare syndrome characterized by
  • Brachydactyly - dwarfism - mental retardation: A very rare syndrome characterized by short fingers, very short stature and mental retardation.
  • Brachydactyly - mesomelia - mental retardation - heart defects: A rare genetic disorder characterized by mental retardation, heart defects, short digits and short limbs.
  • Brachydactyly, mesomelia, mental retardation, aortic dilation, mitral valve prolapse and characteristic face: A rare syndrome characterized by short digits, short limbs, mental retardation, aortic dilation, mitral valve prolapse and a characteristic face.
  • Branchio-Oculo-Facial Syndrome: A rare genetic disorder characterized by branchial defects, lacrimal duct obstruction and pseudocleft of upper lip.
  • Branchio-skeleto-genital syndrome: A rare inherited disorder characterized by mental retardation, jaw anomalies, cleft palate, sunken chest and other abnormalities.
  • Bullous dystrophy, macular type: A rare condition characterized by loss of scalp hair, increased skin pigmentation, small head, mental retardation, short stature and blisters. The blisters do not form necessarily on skin that has suffered trauma but occurs spontaneously.
  • Buntinx-Lormans-Martin syndrome: A very rare syndrome characterized mainly by eye anomalies and fusion of the forearm bones.
  • Buttiens-Fryns syndrome: A rare genetic disorder characterized by a small jaw, small mouth and defects involving the hands and feet.
  • C Syndrome: A rare inherited disorder characterized by a triangular-shaped head, facial anomalies, joint contractures and loose skin.
  • CACH syndrome: A rare syndrome characterized mainly by childhood ataxia and reduced myelination of the cerebral nerves. Motor and mental development in the first few years of life is normal with progressive neurodegeneration occurring between 2 and 5 years of age. Fever and trauma to the head can speed up disease progression.
  • CAHMR syndrome: A rare genetic disorder characterized mainly by excessive body hair (especially on the back, shoulders and sides of the face), cataracts and mental retardation.
  • CAMFAK syndrome: A rare syndrome characterized by cataracts, small head, failure to thrive and spinal curvature.
  • CCFDN: A rare, recessively inherited syndrome characterized by cataracts during infancy, unusual facial appearance and neuropathy.
  • CHARGE Syndrome: A rare disorder characterized by choanal atresia, coloboma, ear and genital abnormalities and congenital heart defects.
  • COACH syndrome: A very rare syndrome characterized by ataxia, gaps or holes in various eye structures, mental retardation, liver fibrosis and brain abnormalities.
  • Camera-Marugo-Cohen syndrome: A rare syndrome characterized mainly by mental retardation, muscle weakness, obesity and an asymmetrical body.
  • Camptodactyly, tall stature, and hearing loss syndrome: A rare syndrome characterized mainly by camptodactyly, tall stature and hearing loss. The hearing loss starts at birth or during infancy and progresses during childhood resulting in mild to severe hearing impairment.
  • Canavan disease: Rare genetic degenerative brain disease in infants.
  • Cantu Sanchez-Corona Fragoso syndrome: A rare syndrome characterized mainly by severe mental retardation, dwarfism and delayed puberty.
  • Cantu syndrome: A rare syndrome characterized by mental retardation, short stature, large skull, heart anomaly and various other abnormalities.
  • Carbamoyl-phosphate synthase 1 deficiency: A very rare inherited urea cycle disorder where the lack of the enzyme carbamoyl phosphate synthetase prevents ammonia from being turned into urea and being excreted in the urine. Excess ammonia builds up in the body which can cause serious complications or even death if left untreated.
  • Cardiocranial syndrome: A rare syndrome characterized mainly by heart and skull abnormalities.
  • Cardiofaciocutaneous Syndrome: A rare genetic disorder characterized by short stature, congenital heart defects skin anomalies and frontal bossing.
  • Cataract dental syndrome: A very rare inherited condition mainly involving eye abnormalities but also various other physical abnormalities. The type and severity of symptoms is variable.
  • Caudal appendage - deafness: A very rare syndrome characterized mainly by deafness, finger bone abnormalities and a spinal extension giving a tail-like appearance (caudal appendage).
  • Cayler syndrome: A very rare disorder involving heart defects and abnormalities involving the lower lip muscle.
  • Cerebellar ataxia, autosomal recessive: A group of rare, recessively inherited neurological disorders caused by abnormalities in the cerebellum and spinal cord. In some cases other parts of the body may be affected.
  • Cerebellar hypoplasia: A rare brain disorder where a part of the brain (cerebellum) fails to develop fully. The cerebellum is the part of the brain that controls balance and movement.
  • Cerebellar hypoplasia - tapetoretinal degeneration: A rare disorder character where a part of the brain (cerebellum) is underdeveloped and a nonprogressive eye disorder involving the retinal pigments. The cerebellum is the part of the brain that controls balance and movement.
  • Cerebellum agenesis - hydrocephaly: A rare brain disorder which manifests as reduced muscle tone, ataxia, cataracts and mental retardation.
  • Cerebro oculo genital syndrome: A very rare syndrome characterized mainly by brain, eye and genital abnormalities.
  • Cerebro oculo skeleto renal syndrome: A very rare syndrome characterized mainly by brain, eye, skeletal and kidney abnormalities.
  • Cerebro-facio-thoracic dysplasia: A very rare syndrome characterized by mental retardation, spinal and rib defects and facial anomalies.
  • Cerebro-oculo-nasal syndrome: A rare syndrome characterized mainly by eye, nose and brain malformations.
  • Cerebrocostomandibular Syndrome: A rare genetic disorder characterized by a very small jaw, abnormal rib development and a small thorax as well as other abnormalities.
  • Cerebrorenodigital syndrome: A rare group of syndromes characterized mainly by brain, kidney, finger and toe abnormalities.
  • Cerebrotendinous Xanthomatosus: A rare syndrome where a genetic mutation results in a metabolic disorders caused by a deficiency of sterol 27-hydroxylase deficiency. The condition causes progressive neurological dysfunction, cataracts and premature atherosclerosis. Deposits of cholesterol and cholestanol can be found in any part of the body including the brain. The rate of progression and severity of symptoms varying amongst patients. The degree of neurological involvement is also variable.
  • Ceroid lipofuscinosis, neuronal 1, infantile: A rare inherited biochemical disorder involving the progressive accumulation of certain chemicals (lipopigments) in body tissues due to deficiency of an enzyme (palmitoyl-protein thioesterase) needed to process it.
  • Ceroid lipofuscinosis, neuronal 10: A rare metabolic disorder that affects the nerve cells of the body and is characterized by the deposits of lipopigments (lipofuscin). Type 10 involves a deficiency of cathepsin D and involves an initial period of normal development with neurodegenerative symptoms starting during the early school years.
  • Ceroid lipofuscinosis, neuronal 3, Juvenile: A progressive genetic disorder where defective lipid metabolism that causes blindness, neurological deterioration, dementia leading to total incapication within years and death within 10-15 years.
  • Ceroid lipofuscinosis, neuronal 5: A rare metabolic disorder that affects the nerve cells of the body and is characterized by the deposits of lipopigments (lipofuscin). Type 5 is distinguished from other types by the origin of the genetic defect.
  • Charcot-Marie-Tooth disease, X-linked recessive, 4: CMT is an inherited neurological disease characterized by the gradual degeneration of nerves which starts in the hands and feet and results in progressive numbness, muscle weakness and loss of function. Type 4X is an inherited defect of the X chromosome and affects males to a greater degree than females and also involves mental retardation and deafness.
  • Child abuse: Physical, sexual, emotional abuse or neglect of child.
  • Childhood disintegrative disorder: A rare disorder where a period of normal development (a couple of years) is followed by delays in the development of motor, social and language skills. Previously acquired skills are lost.
  • Chitayat-Moore-Del Bigio syndrome: A rare birth disorder characterized mainly by brain abnormalities, large head and facial anomalies.
  • Chitty Hall Baraitser syndrome: A very rare syndrome characterized by short stature (due to abnormal development of ends of thigh bones), deafness, blocked tear ducts and thing bone abnormalities.
  • Chitty-Hall-Webb syndrome: A very rare syndrome characterized mainly by fractures, bowed shin bones, abnormal forearm bone (radius) and reduced bone mass.
  • Chondrodysplasia punctata with steroid sulfatase deficiency: A genetic skeletal and skin disorder involving a deficiency of steroid sulfatase. The skin condition is characterized by large brownish scales which can occur almost anywhere on the skin and can be disfiguring. The face, scalp, palms and soles are usually not involved. The skeletal disorder involves abnormal bone calcification near the joints also results in shortened limbs.
  • Chondrodysplasia punctata, non rhizomelic type: A group of inherited disorder affecting the skeleton, skin, eyes and mental function. The disorders are characterized mainly by stippled epiphyses (abnormal calcification near joints) during infancy. The non-rhizomelic forms tend to be milder, with minimal or no upper limb shortening. The Joints in the ends of the arms and legs tend to be more affected. Some of the specific disorders in this group are Conradi-Hunermann disease, Happle's chondrodysplasia and brachytelephalagnic chondrodysplasia punctata. The range of symptoms and severity may vary between disorders.
  • Chorioretinopathy dominant form - microcephaly: A rare inherited disorder characterized by a small head, mental retardation and a degenerative eye condition.
  • Choroideremia: A rare, inherited, progressive eye disease that causes degeneration of the retina and blindness. The disease usually only affects males.
  • Choroido cerebral calcification syndrome infantile form: A rare syndrome characterized by abnormal calcification in part of the brain and mental retardation.
  • Christian-Demyer-Franken syndrome: A rare syndrome characterized mainly by mental retardation and skeletal abnormalities.
  • Chromosome 1, 1p36 deletion syndrome: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as heart problems, mental retardation, developmental delay, facial dysmorphism and short stature. The symptoms are variable depending on the exact location of chromosomal deletion.
  • Chromosome 1, deletion q21 q25: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as retarded fetal growth, osteoporosis, facial anomalies and hearing loss.
  • Chromosome 1, monosomy 1p22 p13: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as mental retardation, short stature, hearing loss and hand defects.
  • Chromosome 1, monosomy 1p31 p22: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as mental retardation, missing teeth and small eyes and jaw.
  • Chromosome 1, monosomy 1p32: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as mental retardation, clubfoot an umbilical hernia.
  • Chromosome 1, monosomy 1p34 p32: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as mental retardation, fingernail anomalies and testicular problems.
  • Chromosome 1, monosomy 1q25 q32: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as digital defects, facial dysmorphism, retarded growth, mental retardation and spasticity.
  • Chromosome 1, monosomy 1q4: A rare chromosomal disorder where deletion of a portion of chromosome 1 causes various abnormalities such as facial dysmorphism, retarded fetal growth, seizures, mental retardation, testicular problems and kidney defects.
  • Chromosome 1, trisomy 1q32 qter: A rare chromosomal disorder where duplication of a portion of chromosome 1 causes various abnormalities such as retarded fetal growth, facial anomalies, mental retardation, stillbirth, heart defects and finger and toe abnormalities.
  • Chromosome 1, trisomy 1q42 qter: A rare chromosomal disorder where duplication of a portion of chromosome 1 causes various abnormalities such as clubfoot, poor muscle tone, neurological dysfunction, short stature, mental retardation and narrowing of the pulmonary arteries and valves.
  • Chromosome 10 ring syndrome: A rare chromosomal disorder where genetic material from one or both ends of chromosome 10 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 10p deletion syndrome: A rare chromosomal disorder where there is a deletion of the short arm (p) of chromosome 10 resulting in variable abnormalities.
  • Chromosome 10p duplication/10q deletion syndrome: A rare chromosomal disorder where a section of the short arm (p) of chromosome 10 is duplicated and a section of the long arm (q) of chromosome 10 is deleted resulting in various abnormalities.
  • Chromosome 11q duplication syndrome: A rare chromosomal disorder where there are three copies of the long arm (q) of chromosome 11 rather than the normal two resulting in various abnormalities. The type and severity of symptoms depend on the amount and location of genetic material duplicated.
  • Chromosome 11q partial deletion: A rare chromosomal disorder where a portion of chromosome 11 is missing and is characterized by trigonencephaly, heart defects and a large, carp-shaped mouth.
  • Chromosome 12 ring syndrome: A rare chromosomal disorder where genetic material from one or both ends of chromosome 12 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 12 trisomy: A rare chromosomal disorder where there are three copies of chromosome 12 rather than the normal two resulting in various abnormalities.
  • Chromosome 12p deletion syndrome: A rare chromosomal disorder where there is a deletion of the short arm (p) of chromosome 12 resulting in various abnormalities.
  • Chromosome 12p tetrasomy syndrome: A rare chromosomal disorder where there are four copies of the short arm (p) of chromosome 12 rather than the normal two resulting in various abnormalities.
  • Chromosome 12q duplication syndrome: A rare chromosomal disorder where there are three copies of the long arm (q) of chromosome 12 rather than the normal two resulting in various abnormalities. In most cases, death occurs during infancy.
  • Chromosome 13 trisomy syndrome: A rare chromosomal disorder where there are three copies of chromosome 13 rather than the normal two resulting in various abnormalities. Most die within months and there are few survivors after 10 years.
  • Chromosome 13p duplication: A rare chromosomal disorder where duplication of a portion of chromosome 13 causes various abnormalities such as mental retardation, short stature, facial dysmorphism, delayed puberty and heart defects.
  • Chromosome 13q deletion syndrome: A rare chromosomal disorder where the long arm (q) of chromosome 13 is deleted resulting in various physical, neurological and developmental abnormalities. The type and severity of symptoms is determined by the amount and location of the deleted genetic material.
  • Chromosome 13q duplication syndrome: A rare chromosomal disorder where the long arm (q) of chromosome 13 is duplicated resulting in various physical, neurological and developmental abnormalities.
  • Chromosome 14 Ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 14 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing. The disorder is characterized by growth and mental retardation and characteristic facial features.
  • Chromosome 14 trisomy syndrome: A rare chromosomal disorder involving duplication of genetic material from chromosome 14 resulting in various abnormalities.
  • Chromosome 14 uniparental disomy syndrome: A rare chromosomal disorder where two homologues are obtained from one parent.
  • Chromosome 14q deletion syndrome: A rare chromosomal disorder involving deletion of genetic material from the long arm (q) of chromosome 14 resulting in various abnormalities.
  • Chromosome 14q, proximal duplication: A rare chromosomal disorder where duplication of a portion of chromosome 14 causes various abnormalities such as facial dysmorphism, limb abnormalities, mental retardation and short stature.
  • Chromosome 14q, terminal deletion: A very rare syndrome caused by a deletion of a part of the material on chromosome 14 and resulting in various abnormalities such as mental retardation and short fingers.
  • Chromosome 14q, terminal duplication: A very rare syndrome caused by a duplication of a part of the material on chromosome 14 and resulting in various abnormalities such as retarded growth, hearing loss and mental retardation.
  • Chromosome 15 Ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 15 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 15 inverted duplication: A rare chromosomal disorder involving an duplicated section of chromosome 15 which is reversed end-to-end resulting in various abnormalities.
  • Chromosome 15 trisomy: A rare chromosomal disorder involving an extra copy of genetic material from chromosome 15.
  • Chromosome 15, distal trisomy 15q: A very rare chromosomal disorder where the end part of the long arm (q) of chromosome 15 occurs three times in each cell instead of two. Symptoms and severity depend on the size of the chromosomal portion that is duplicated.
  • Chromosome 15q duplication syndrome: A rare chromosomal disorder involving an extra copy of genetic material from the long arm of chromosome 15. The type and severity of symptoms are determined by the amount and location of the duplicated genetic material.
  • Chromosome 15q tetrasomy syndrome: A rare chromosomal disorder where there are four copies of a portion of the long arm of chromosome 15 instead of the normal two resulting in various abnormalities.
  • Chromosome 15q triplication syndrome: A rare chromosomal disorder where there are three copies of a part of the long arm of chromosome 15 resulting in various anomalies.
  • Chromosome 15q, deletion: A rare chromosomal disorder involving deletion of genetic material from the long arm of chromosome 15.
  • Chromosome 15q, partial deletion: A rare chromosomal disorder involving deletion of genetic material from the long arm of chromosome 15. The type and severity of symptoms are determined by the amount and location of the deleted genetic material.
  • Chromosome 15q13.3 microdeletion syndrome: A genetic disorder characterized by the deletion of a small portion of genetic material at the chromosomal location of 15q13.3. A rare syndrome characterized mainly by seizures, mental retardation, and slightly unusual facial features.
  • Chromosome 16p, partial duplication: A rare chromosomal disorder involving an extra copy of genetic material from the short arm of chromosome 16. The type and severity of symptoms are determined by the amount and location of the duplicated genetic material.
  • Chromosome 16q, partial deletion: A rare chromosomal disorder involving deletion of genetic material from the long arm of chromosome 17. The type and severity of symptoms are determined by the amount and location of the lost genetic material.
  • Chromosome 17 ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 17 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 17 trisomy mosaicism: A rare chromosomal disorder where there are three copies of chromosome 17 in some of the body's cells. The type of symptoms and severity is determined by the number of cells that have the three copies. Some cases have no obvious symptoms.
  • Chromosome 17, deletion 17q23 q24: A rare chromosomal disorder involving deletion of genetic material from the long arm of chromosome 17. The type and severity of symptoms are determined by the amount and location of the lost genetic material.
  • Chromosome 17p, partial deletion: A rare chromosomal disorder involving deletion of genetic material from the short arm of chromosome 17. The type and severity of symptoms are determined by the amount and location of the lost genetic material.
  • Chromosome 17p, partial duplication: A rare chromosomal disorder involving an extra copy of genetic material from the short arm of chromosome 17. The type and severity of symptoms are determined by the amount and location of the duplicated genetic material.
  • Chromosome 17q, partial duplication: A rare chromosomal disorder involving an extra copy of genetic material from the long arm of chromosome 17. The type and severity of symptoms are determined by the amount and location of the duplicated genetic material.
  • Chromosome 18 Ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 18 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 18 deletion syndrome: A rare chromosomal disorder where a portion of chromosome 18 is missing.
  • Chromosome 18, Tetrasomy 18p: A rare chromosomal disorder where there are four copies of short arm of chromosome 18 instead of the normal two which results in various genital, kidney, digital, head and face abnormalities.
  • Chromosome 18, deletion 18q23: A very rare syndrome caused by a deletion of a part of the material on chromosome 18 and resulting in various abnormalities such as retarded growth, hearing loss and mental retardation. The abnormalities vary from patient to patient.
  • Chromosome 18, trisomy 18q: A rare chromosomal disorder involving an extra copy of genetic material from the long arm of chromosome 18. The type and severity of symptoms are determined by the amount and location of the duplicated genetic material.
  • Chromosome 18q, partial deletion: A rare chromosomal disorder involving deletion of genetic material from the long arm of chromosome 18. The type and severity of symptoms are determined by the amount and location of the lost genetic material.
  • Chromosome 19 ring syndrome: A rare chromosomal disorder where genetic material from one or both ends of chromosome 19 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 19q, partial duplication: A rare chromosomal disorder where the long arm of chromosome is triplicated. The type and severity of symptoms is determined by the size of the duplicated genetic portion.
  • Chromosome 1p deletion syndrome: A rare chromosomal disorder where part or all of the short arm (p) of chromosome 1 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • Chromosome 1p duplication syndrome: A rare chromosomal disorder where a portion of the short arm (p) of chromosome 1 is duplicated so there is three copies of it rather than the normal two.
  • Chromosome 1q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 1 which results in various abnormalities depending on the size and location of the portion of duplicated genetic material.
  • Chromosome 2 trisomy syndrome: A rare chromosomal disorder where there are three copies of chromosome 2 instead of the normal two.
  • Chromosome 2, monosomy 2p22: A rare chromosomal disorder where deletion of a portion of chromosome 2 causes various abnormalities such as deafness, intestinal problems, mental retardation and speech defects.
  • Chromosome 2, monosomy 2pter p24: A very rare chromosomal disorder where a portion of chromosome 2 is deleted resulting in a range of birth defects and abnormalities.
  • Chromosome 2, monosomy 2q37: A very rare chromosomal disorder where a part of the long arm of chromosome 2 is missing which results in various birth defects and abnormalities. The features of the disorder are determined by the exact size and location of the deletion.
  • Chromosome 20 ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 20 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 20p deletion syndrome: A rare chromosomal disorder where the short arm (p) of chromosome 20 is deleted resulting in various abnormalities.
  • Chromosome 21 Ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 21 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 21 monosomy: A rare chromosomal disorder where there is only one copy of chromosome 21 instead of the normal two leading to various abnormalities.
  • Chromosome 21, tetrasomy 21q: A rare chromosomal disorder where there is four copies of the long arm of chromosome 21 instead of the normal two which results in various physical and mental anomalies.
  • Chromosome 21q deletion syndrome: A rare chromosomal disorder where the long arm of chromosome 21 is deleted resulting in craniofacial, skeletal and other abnormalities as well as mental retardation.
  • Chromosome 21q, partial deletion: A rare chromosomal disorder where a portion of the long arm of chromosome 21 is deleted.
  • Chromosome 22 Ring: A rare chromosomal disorder where genetic material from one or both ends of chromosome 22 is missing and the two broken ends have rejoined to form a ring. The resulting type and severity of symptoms is determined by the amount and location of genetic material missing.
  • Chromosome 22 monosomy syndrome: A rare chromosomal disorder where there is only one copy of chromosome 22 in the body cells instead of two which results in various physical and mental abnormalities.
  • Chromosome 22 suprenumerary marker: A rare chromosomal disorder involving structural abnormalities of chromosome 22 and are more prevalent in children born to older mothers.
  • Chromosome 22 trisomy mosaic: A rare chromosomal disorder where three copies of chromosome 22 are present in some of the body's cells instead of the normal two. Severity of symptoms is determined by how many cells have the extra chromosomal material.
  • Chromosome 22q deletion: The absence of a portion of chromosome 22. The absence of this genetic material may produce a great range of effects, some minor and some serious, depending on how much of the material is missing and what the location of the missing portion. Chromosome 22 is one of the 23 pairs of chromosomes that all humans have.
  • Chromosome 22q deletion syndrome: A rare chromosomal disorder where the long arm of chromosome 22 is deleted resulting in various abnormalities.
  • Chromosome 22q duplication syndrome: A rare chromosomal disorder where the long arm of chromosome 22 is duplicated.
  • Chromosome 2p deletion syndrome: A rare chromosomal disorder where part or all of the short arm (p) of chromosome 2 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • Chromosome 2p duplication syndrome: A rare chromosomal disorder where a portion of the short arm (p) of chromosome 2 is duplicated so there is three copies of it rather than the normal two.
  • Chromosome 2q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 2 which results in various abnormalities depending on the size and location of the portion of duplicated genetic material.
  • Chromosome 3, Trisomy 3q2: A rare chromosomal disorder involving the duplication of a portion of the long arm of chromosome 3. The symptoms are determined by the size and exact location of the duplicated portion.
  • Chromosome 3, monosomy 3p25: A rare chromosomal disorder characterized by mental retardation, short stature, deafness, extra digits, facial anomalies and various other abnormalities.
  • Chromosome 3, trisomy 3p: A rare chromosomal disorder where a portion of the short arm (p) of chromosome 3 is duplicated so there is three copies of it rather than the normal two.
  • Chromosome 3, trisomy 3q13 2 q25: A rare chromosomal disorder characterized by various abnormalities including hearing loss, mental retardation, short stature, obesity and uterine and facial anomalies.
  • Chromosome 3q29 microduplication syndrome: A rare chromosomal disorder where a small portion of chromosome 3 is duplicated. The main features are mental retardation and some minor facial anomalies.
  • Chromosome 4 ring syndrome: A rare chromosomal disorder where the ends of chromosome 4 have been deleted and the two broken ends have rejoined to form a ring shape resulting in a range of symptoms determined by the size and location of the genetic deletion.
  • Chromosome 4, Monosomy 4q: A rare chromosomal disorder where a portion of the long arm (q) of chromosome 4 is missing resulting in various abnormalities.
  • Chromosome 4, Monosomy Distal 4q: A rare chromosomal disorder involving a deletion of the end portion of the long arm of chromosome 4. The symptoms are determined by the size and exact location of the deleted portion.
  • Chromosome 4, monosomy 4p14 p16: A rare chromosomal disorder characterized by various abnormalities including muscle problems, tall stature, mental retardation and hand and facial anomalies.
  • Chromosome 4, partial trisomy distal 4q: A rare chromosomal disorder involving the duplication of the end portion of the long arm of chromosome 4. The symptoms are determined by the size and exact location of the duplicated portion.
  • Chromosome 4p deletion syndrome: A rare chromosomal disorder where part or all of the short arm (p) of chromosome 4 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • Chromosome 4q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 4 which results in various abnormalities depending on the size and location of the portion of duplicated genetic material.
  • Chromosome 5, trisomy 5pter p13 3: A rare chromosomal disorder characterized by cortico-adrenal hypoplasia, mental retardation, seizures and a blood abnormality.
  • Chromosome 5p duplication syndrome: A rare chromosomal disorder where there are three copies of all or part of the short arm (p) of chromosome 5 rather than the normal two. The type and severity of symptoms is determined by the location and size of the genetic material duplicated.
  • Chromosome 5p tetrasomy syndrome: A rare chromosomal disorder where there are four copies of the short arm (p) of chromosome 5 rather than the normal two copies.
  • Chromosome 5q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 5 which results in various abnormalities depending on the size and location of the portion of duplicated genetic material.
  • Chromosome 6 ring syndrome: A rare chromosomal disorder where the ends of chromosome 6 have been deleted and the two broken ends have rejoined to form a ring shape resulting in a range of symptoms determined by the size of the genetic deletion.
  • Chromosome 6, monosomy 6p23: A very rare chromosomal disorder characterized by various abnormalities including mental retardation, facial, finger and toe anomalies as well as heart, skeletal and neurological problems.
  • Chromosome 6, monosomy 6q1: A rare chromosomal disorder involving the deletion of a portion of the long arm of chromosome 6.
  • Chromosome 6p deletion syndrome: A rare chromosomal disorder where part or all of the short arm (p) of chromosome 6 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • Chromosome 6q deletion syndrome: A rare chromosomal disorder where a part of the long arm (q) of chromosome 6 is deleted resulting in various abnormalities depending on the location and length of missing genetic material.
  • Chromosome 6q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 6 which results in various abnormalities depending on the size and location of the portion of duplicated genetic material.
  • Chromosome 7 ring syndrome: A rare chromosomal disorder where the ends of chromosome 7 have been deleted and the two broken ends have rejoined to form a ring shape resulting in a range of symptoms determined by the size of the genetic deletion.
  • Chromosome 7, monosomy 7q21: A rare chromosomal disorder characterized by mental retardation, short stature, facial anomalies and muscle and distal limb abnormalities.
  • Chromosome 7, monosomy 7q3: A very rare chromosomal disorder involving a deletion of material from chromosome 7 at a location known as q3 which results in a wide range of abnormalities.
  • Chromosome 7, trisomy 7p13 p12 2: A rare chromosomal disorder where duplication of a portion of chromosome 7 causes various abnormalities such as short stature and mental retardation.
  • Chromosome 7p deletion syndrome: A rare chromosomal disorder where part or all of the short arm (p) of chromosome 7 is deleted resulting in various abnormalities which are determined by the size of the deleted portion.
  • Chromosome 7p duplication syndrome: A rare chromosomal disorder where there are three copies of all or part of the short arm (p) of chromosome 7 rather than the normal two. The type and severity of symptoms is determined by the location and size of the genetic material duplicated.
  • Chromosome 7q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 7 which results in various abnormalities depending on the size and location of the portion of duplicated genetic material.
  • Chromosome 8 recombinant syndrome: A rare recombinant chromosomal disorder involving chromosome 8 which results in various abnormalities.
  • Chromosome 8 ring: A rare chromosomal disorder involving chromosome 8 which causes various abnormalities such as mental retardation, ureter anomalies, finger defects and facial dysmorphism.
  • Chromosome 8 trisomy syndrome: A rare chromosomal disorder where there are three copies of chromosome 8 rather than the normal two which results in various abnormalities.
  • Chromosome 8, Monosomy 8p2: A rare chromosomal disorder involving the deletion of a portion of the short arm of chromosome 8. The symptoms are determined by the size and exact location of the duplicated portion.
  • Chromosome 8p deletion syndrome: A rare chromosomal disorder involving deletion of the short arm (p) of chromosome 8 resulting in various abnormalities.
  • Chromosome 8p duplication syndrome: A rare chromosomal disorder where the short arm (p) of chromosome 8 is duplicated resulting in three copies instead of two. The type and severity of symptoms depends on the location and length of genetic material duplicated.
  • Chromosome 8p inverted duplication syndrome: A rare chromosomal disorder involving the inverted duplication of the short arm (p) of chromosome 8 resulting in three copies of the genetic material instead of the normal two. The type and severity of symptoms is determined by the location and size of the duplication.
  • Chromosome 8p mosaic tetrasomy: A rare chromosomal disorder where a part of the short arm of chromosome 8 is repeated four times in some of the body's cells instead of the normal two resulting in various abnormalities.
  • Chromosome 8q deletion syndrome: A rare chromosomal disorder where a part of the long arm (q) of chromosome 8 is deleted resulting in various abnormalities depending on the location and length of missing genetic material.
  • Chromosome 8q duplication syndrome: A rare chromosomal disorder where the long arm (q) of chromosome 8 is duplicated resulting in variable abnormalities depending on the location and length of genetic material deleted.
  • Chromosome 9 trisomy syndrome: A rare chromosomal disorder where there are three copies of chromosome 9 in the body's cells instead of the normal two resulting in various abnormalities.
  • Chromosome 9, monosomy 9p: A rare chromosomal disorder where a portion of the short arm (p) of chromosome 9 is missing resulting in various abnormalities.
  • Chromosome 9, trisomy 9q32: A rare chromosomal disorder where duplication of a portion of chromosome 9 causes various abnormalities such as short stature and mental retardation and facial anomalies.
  • Chromosome 9p tetrasomy syndrome: A rare chromosomal disorder where there is four copies of the short arm of chromosome 9 instead of the normal two resulting in various abnormalities.
  • Chromosome 9q deletion syndrome: A rare chromosomal disorder where the long arm (q) of chromosome 9 is deleted resulting in variable symptoms.
  • Chromosome 9q duplication syndrome: A rare chromosomal disorder involving duplication of the long arm (q) of chromosome 9 resulting in various abnormalities.
  • Chromosome 9q duplication/chromosome 9p deletion syndrome: A rare chromosomal disorder where part of the long arm (q) of chromosome 9 is duplicated and part of the short arm (p) is deleted resulting in various abnormalities. These chromosomal abnormality occurs in only some of the body's cells (mosaicism).
  • Chromosome diploid-triploid mosaicism syndrome: A rare chromosomal disorder involving chromosomal duplication, triplication and mosaicism.
  • Chylomicron Retention Disease: A condition characterized by the retention of chylomicrons
  • Chylomicron retention disease with Marinesco-Sjogren syndrome: A rare condition characterized by abnormal lipid metabolism, vitamin E deficiency, incoordination and short stature.
  • Clark-Baraitser syndrome: A very rare syndrome characterized mainly by tallness, large head, mental retardation and various facial anomalies.
  • Classic galactosemia: Rare serious genetic defect in galactose metabolism.
  • Cleft lip - palate - abnormal thumbs - microcephaly: A very rare syndrome characterized by a small head, thumb abnormalities and a cleft lip and palate.
  • Cleft lip - palate - mental retardation - corneal opacity: A very rare syndrome characterized mainly by mental retardation, cleft lip and palate and cloudy corneas.
  • Cleft palate - cardiac defect - genital anomalies - ectrodactyly: A very rare syndrome characterized by variable symptoms including cleft palate, heart defects, genital anomalies and hand and foot malformations.
  • Cleft palate - short stature - vertebral anomalies: A very rare syndrome characterized by a cleft palate, short stature and abnormalities of the vertebrae in the spine.
  • Coats Disease: A rare condition where a small group of dilated blood vessels (telangiectasia) form in the retina of one eye and can result in retinal detachment. It is believed to be a more severe form of Leber military aneurysm.
  • Cockayne syndrome: A rare genetic disorder characterized by a senile-like appearance, hearing and vision impairment and sun sensitive skin.
  • Coenzyme Q 10 (CoQ10), deficiency: A rare inherited disorder characterized by the deficiency of Coenzyme Q 10. The range and severity of symptoms is variable.
  • Coffin syndrome 1: A rare inherited syndrome characterized mainly by spasticity, seizures, congenital heart defects, short stature and delayed mental and motor development.
  • Coffin-Lowry syndrome: A rare genetic disorder characterized by down slanting space between eyelids, bulbous nose, soft hands and tapering fingers.
  • Coffin-Siris Syndrome: A rare genetic disorder characterized by underdeveloped or absent fifth finger and toenails and coarse facial features.
  • Cohen Syndrome: A rare genetic disorder characterized by reduced muscle tone, obesity and prominent front teeth.
  • Cohen-Hayden syndrome: A very rare syndrome characterized mainly by mental retardation, eye defect and various growth abnormalities of the bone, skin and head.
  • Collins-Sakati syndrome: A very rare syndrome characterized mainly by a short, broad toe and a large head.
  • Coloboma chorioretinal cerebellar vermis aplasia: A very rare syndrome characterized by an eye anomaly (gap in eye structures such as choroids and retina) and abnormal development of the midline structure of the brain (cerebellar vermis aplasia).
  • Coloboma uveal with cleft lip palate and mental retardation: A very rare syndrome characterized by a cleft lip and palate, mental retardation and a gap or hole in the iris or uvea of the eye (iris or uveal coloboma).
  • Coloboma, cleft lip/palate and mental retardation syndrome: A very rare syndrome characterized by a cleft lip and palate, mental retardation and a gap or hole in the iris or uvea of the eye (iris or uveal coloboma).
  • Colobomatous microphthalmia - heart disease - hearing loss: A very rare syndrome characterized by small eyes, heart disease and hearing loss.
  • Colpocephaly: A rare brain malformation that is present at birth. The cavities present at the back of the brain are larger than normal as the brain tissue has failed to develop normally to fill some of the space. Severity of symptoms are variable depending on the degree of abnormality.
  • Communication disorders: Various disorders limiting the ability to communicate (including developmental communication disorders)
  • Congenital Disorders of Glycosylation: Congenital disorders of glycosylation is a group of disorders involving abnormally synthesis of N-linked oligosaccharides. There is a long chain of events involved in the synthesis and defects may occur with any of the compounds or enzymes involved in the process. Progressive impairment and regression of skills often occurs after a period of normal development following birth.
  • Congenital Toxoplasmosis: Fetal infection with toxoplasmosis.
  • Congenital disorder of glycosylation type 1A: A very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type 1A involves a phosphomannomutase enzyme defect and affects most body systems especially the nervous system and liver function.
  • Congenital disorder of glycosylation type 1F: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type IF is caused by a defect on chromosome 17p13.1-p12 and involves a defect on the MPDU1 gene.
  • Congenital disorder of glycosylation type 1I: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type Ii is caused by a defect on chromosome 9q22 and involves a defect on the ALG2 gene.
  • Congenital disorder of glycosylation type 1K: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type Ik is caused by a defect on chromosome 16p13.3 and involves a defect in the gene for beta-1,4-mannosyltransferase. The disorder is generally fatal within a year or two of birth.
  • Congenital disorder of glycosylation type 1L: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type Il is caused by a defect on chromosome 11q23 and involves a defect in the ALG9 gene.
  • Congenital disorder of glycosylation type 2A: A very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type 2A has a GlcNAc transferase 2 enzyme defect.
  • Congenital disorder of glycosylation type 2C: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type 2c is caused by a defect on chromosome 11p11.2 and involves a defect in the gene for GDP-fucose transporter.
  • Congenital disorder of glycosylation type 2D: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type 2d is caused by a defect on chromosome 9p13 and involves a defect in the gene for beta-1,4-galactosyltransferase.
  • Congenital disorder of glycosylation type 2E: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type 2e is caused by a defect on chromosome 16p and involves a defect in the gene for oligomeric complex-7.
  • Congenital disorder of glycosylation type 2G: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type IIg is caused by a defect on chromosome 17q25.1 and involves a defect on the COG1 gene.
  • Congenital disorder of glycosylation type IIH: Congenital disorders of glycosylation is a group of very rare inherited metabolic disorder where defective carbohydrate compounds are attached to glycoproteins and thus impairing glycoprotein function. Type IIh is caused by a defect on chromosome 16q22.1 and involves a defect on the COG8 gene.
  • Congenital disorder of glycosylation type X - Bombay blood group phenotype: A rare inherited disorder characterized by abnormal neutrophil functioning which reduces the body's immunity. The abnormal neutrophils are unable to be transported to sites of infection due to their inability to adhere to certain blood vessel components which would normally lead them to the infection site. Infections may be life-threatening as the body is unable to destroy bacteria effectively. Type 2 LAD is where neutrophils can't adhere to necessary blood vessel components due to the absence of proteins on the blood vessel walls needed to bind and guide the neutrophils to the infection site.
  • Congenital heart disease - radio ulnar synostosis - mental retardation: A very rare syndrome characterized mainly by heart disease at birth, fusion of forearm bones and mental retardation.
  • Congenital heart disease radio ulnar synostos mental retardation: A very rare syndrome characterized mainly by the presence of mental retardation, congenital heart disease and fusion of the forearm bones.
  • Congenital heart disease, ptosis, hypodontia, craniosynostosis: A rare birth syndrome characterized by heart disease, droopy eyelids, missing teeth and premature fusion of skull bones.
  • Congenital hypoparathyroidism, seizures, growth and mental retardation and unusual facies: A rare syndrome characterized mainly by growth and mental retardation, seizures, unusual facial appearance and congenital hypoparathyroidism.
  • Congenital hypothyroidism: A congenital deficiency of thyroid hormone due to complete or partial failure of the thyroid gland.
  • Congenital myotonic dystrophy: A form of muscular dystrophy which is usually apparent at birth or within a few years. and affects the skeletal muscles, heart conduction, smooth muscle, eyes and the central nervous system. The range of severity varies from asymptomatic to fetal death.
  • Corneal cerebellar syndrome: A very rare syndrome involving eye problems and progressive motor control problems such as ataxia and weakness on one side of the body.
  • Corneal dystrophy - ichthyosis - microcephaly - mental retardation: A very rare syndrome characterized by vision loss, scaly skin, small head and mental retardation.
  • Cornelia de Lange Syndrome: A very rare disorder involving delayed physical development and various malformations involving the head, face and limbs. The severity of symptoms is variable.
  • Cornelia de Lange syndrome 2: A very rare disorder involving delayed physical development and various malformations involving the head, face and limbs. Type 2 is not as severe as type 1 with some of the abnormalities not presenting until later in life or absent altogether. The range and severity of symptoms is variable.
  • Cornelia de Lange syndrome 3: A very rare disorder involving delayed physical development and various malformations involving the head, face and limbs. Type 3 is a very mild form of the disorder and is typified by mildly unusual facial appearance and no skeletal or limb malformations.
  • Corpus callosum agenesis: A very rare congenital abnormality where part or all of the fibers that connect the two halves of the brain (corpus callosum) are missing.
  • Corpus callosum agenesis - double urinary collecting system: A very rare syndrome characterized mainly by abnormal development of the structure separating the two halves of the brain as well as duplicated ureters that collect the urine from the kidney and deliver it to the bladder.
  • Corpus callosum agenesis-neuropathy: A rare genetic disorder involving mental retardation, progressive neuropathy and absence of the fibers that connect the two halves of the brain together.
  • Corpus callosum dysgenesis X-linked recessive: Partial or complete lack of development of the structure that divides two sides of the brain (corpus callosum). As the condition is X-linked, it only occurs in males.
  • Cortada Koussef Matsumoto syndrome: A rare syndrome characterized by various skeletal abnormalities, small head and mental retardation.
  • Cortada-Kousseff-Matsumoto syndrome: A rare syndrome characterized by various skeletal abnormalities, small head and mental retardation.
  • Cortical dysplasia - focal epilepsy syndrome: Abnormal development of the brain cortex which results in focal epilepsy and progressive neurological deterioration once the epilepsy starts in early childhood.
  • Costello syndrome: A rare genetic disorder characterized by papillomas which may become malignant.
  • Cowden's syndrome: A rare hereditary condition characterized by multiple noncancerous nodules called hamartomas. Sufferers also face an increased risk of particular cancers.
  • Craniodiaphyseal dysplasia: A very rare bone disorder where excess calcium is deposited mainly in the skull bones which can result in compression of various nerves in the skull and even the brain.
  • Craniodigital syndrome - mental retardation: A very rare syndrome characterized by webbed fingers and toes, mental retardation and skull and facial anomalies.
  • Craniofacial dyssynostosis: A very rare syndrome characterized primarily by the premature fusion of certain skull bones which gives the head an abnormal shape and also causes unusual facial features.
  • Craniosynostosis: A defect involving the fusion of one or more bones in the skull before it has finished growing which affects the head size and shape and can affect the growth of the brain. The defect is often associated with other conditions. Symptoms are determined by which skull bones are prematurely fused.
  • Craniosynostosis - alopecia - brain defect: A very rare syndrome characterized mainly by a malformed skull, lack of hair and a brain defect.
  • Craniosynostosis mental retardation clefting syndrome: A rare disorder characterized by premature fusion of the skull bones (craniosynostosis), mental retardation a cleft lip and/or palate.
  • Craniosynostosis radial aplasia syndrome: A rare genetic disorder characterized by premature closing of skull bones, growth deficiency and anal, limb and urogenital craniofacial abnormalities.
  • Craniosynostosis, sagittal, with Dandy-Walker malformation and hydrocephalus: A very rare disorder characterized primarily by the premature fusion of skull bones (sagittal), the Dandy-Walker malformation and a buildup of fluid in the brain (hydrocephalus). The Dandy-Walker malformation is where a cyst develops in the back of the brain and interferes with the movement of fluid through the brain resulting in an accumulation of fluid.
  • Craniotelencephalic dysplasia: A very rare syndrome characterized primarily by premature fusion of various skull bones and abnormal brain development.
  • Creatine deficiency, X-linked: A rare inherited disorder characterized mainly by mental retardation, seizures, short stature and facial anomalies. The disorder is caused by the absence of a compound needed to transport creatine and thus creatine levels may be normal or high, but the body is unable to utilize it.
  • Cretinism athyreotic: A rare form of congenital hypothyroidism that causes mental and physical growth retardation in infants or children. Prompt thyroid hormone therapy is essential in order to prevent progressive neurological and motor deterioration.
  • Crome syndrome: A very rare disorder characterized by various abnormalities including mental retardation, epilepsy and eye and kidney problems.
  • Cryptorchidism - arachnodactyly - mental retardation: A very rare syndrome characterized mainly by undescended testes, long thin fingers and mental retardation.
  • Cutis verticis gyrata mental deficiency: A rare inherited disorder characterized by mental retardation, seizures and eye and movement problems.
  • Cystic fibrosis - gastritis - megaloblastic anaemia: A rare syndrome characterized mainly by cystic fibrosis, metaloblastic anemia, mental retardation and gastritis due to helicobacter pylori.
  • D ercole syndrome: A very rare syndrome characterized mainly by short stature, small head and heart defects.
  • Dandy-Walker - facial hemangioma: A very rare syndrome characterized mainly by a brain malformation (Dandy-Walker) and a hemangioma on the face (mass of dilated blood vessels).
  • Dandy-Walker malformation with mental retardation, macrocephaly, myopia, and brachytelephalangy: A very rare syndrome characterized mainly by mental retardation, large head, short fingers, nearsightedness and brain abnormalities (Dandy-Walker type).
  • Davis syndrome: A very rare condition where short-limbed dwarfism is associated with immunodeficiency.
  • Davis-Lafer syndrome: A very rare syndrome characterized mainly by mental retardation and unusual facial features.
  • De Barsy Syndrome: A rare inherited disorder characterized by loose, inelastic skin, involuntary limb movements, cloudy corneas and other abnormalities.
  • De Lange 1: A rare disorder involving a variety of congenital abnormalities including retarded growth, behavioral problems, characteristic facial features and upper limb abnormalities.
  • Deafness - epiphyseal dysplasia - short stature: A very rare syndrome characterized by short stature (due to abnormal development of ends of thigh bones), deafness, blocked tear ducts and thing bone abnormalities.
  • Deafness - hypospadias - metacarpal and metatarsal synostosis: A very rare syndrome characterized mainly by deafness, penis abnormalities and bone anomalies in the foot and hands.
  • Deafness - skeletal dysplasia - lip granuloma: A very rare syndrome characterized mainly by deafness, skeletal abnormalities, mental retardation and full lips.
  • Deafness, congenital onychodystrophy, recessive form: A very rare inherited disorder involving deafness (D), onychodystrophy (O - nail malformation), osteodystrophy (O - bone malformation) and mental retardation (R).
  • Deafness-mental retardation, Martin-Probst type: A rare disorder characterized mainly by deafness and mental retardation.
  • Deal-Barratt-Dillon syndrome: A very rare syndrome characterized mainly by scaly skin, jaundice, diarrhea and Fanconi syndrome (bone marrow fails to make sufficient new blood cells).
  • Deletion 10q: A rare disorder caused by the deletion of a portion of chromosome 10q. The range and severity of symptoms is determined by the size of the portion that is deleted.
  • Deletion 2q24: A genetic disorder characterized by the deletion of a portion of the long arm of chromosome 2.
  • Deletion 6q16 q21: A rare chromosomal disorder characterized primarily by facial anomalies, mental retardation and a short head.
  • Delta-1-pyrroline 5-carboxylate synthetase deficiency: A rare syndrome caused by an enzyme deficiency (Delta-1-pyrroline 5-carboxylate synthetase).
  • Delta-1-pyrroline-5-carboxylate dehydrogenase deficiency: A rare metabolic abnormality involving a deficiency of a particular enzyme (Delta-1-pyrroline-5-carboxylate dehydrogenase) which affects amino acid metabolism and causes mental retardation and convulsions.
  • Dementia: Various mental impairment conditions.
  • Dennis cohen syndrome: A rare syndrome characterized mainly by unusual facial appearance, mental retardation, short stature and sparse hair.
  • Dentatorubral Pallidoluysian Atrophy: A condition caused by an abnormality of the DNA sequence on chromosome 12
  • Dentinogenesis imperfecta - short stature - hearing loss - mental retardation: A rare syndrome characterized by teeth anomalies (dentinogenesis imperfecta), short stature, hearing loss and mental retardation.
  • Denys-Corbeel syndrome: A rare familial syndrome characterized by short stature, mental retardation and kidney problems.
  • Dermatoleukodystrophy: A very rare progressive brain disease associated with thick wrinkled skin. Only two reported cases with both dying within three years of birth.
  • Desbuquois syndrome: A rare condition characterized by short-limbed dwarfism, characteristic facial features and skeletal abnormalities.
  • Developmental delay - hypotonia extremities hypertrophy: A very rare syndrome characterized mainly by poor muscle tone, developmental delay.
  • Diaphragmatic hernia - exomphalos - corpus callosum agenesis: A very rare syndrome characterized mainly by a diaphragmatic hernia (defect in the diaphragm that allows some of the abdominal organs to move into the chest cavity), brain development abnormalities and deafness.
  • Dibasic aminoaciduria 2: A rare condition where protein intolerance occurs as a result of a defect in the transport of dibasic amino acids through the intestines and kidneys. The amino acids (component of protein) can't be broken down properly and used by the body so it builds up and causes damage.
  • Dibasic aminoaciduria type 1: A rare disorder where the kidney excretes excessive amounts of certain amino acids (lysine, ornithine and arginine.
  • Digitorenocerebral syndrome: A very rare syndrome characterized by numerous abnormalities involving the brain, kidneys, fingers, toes, nails and face as well as mental retardation and vision impairment.
  • Dihydropyrimidine dehydrogenase deficiency: A metabolic error where a deficiency of an enzyme called dihydropyrimidine dehydrogenase prevents the normal metabolism of certain proteins. High levels of certain proteins are excreted in the urine. The enzyme is also needed the breakdown a chemotherapy drug called 5-flurouracil and its absence can result in a severe toxicity reaction.
  • Diomedi-Bernardi-Placidi syndrome: A very rare syndrome characterized mainly by epilepsy, mental retardation and progressive leg weakness and spasticity.
  • Dobrow syndrome: A very rare syndrome characterized mainly by abnormal webbing inside the mouth, short stature, eye problems, mental retardation and small head, jaw, eyes and mouth.
  • Double cortex syndrome: A rare brain development disorder which causes mental retardation and epilepsy. An extra layer of nerves develops under the brain cortex.
  • Dowling-Degos disease: A rare condition characterized by progressive enlargement of pigmented areas that occur on areas of creased or folded skin such as armpits, groin, breasts and limbs.
  • Down Syndrome: A chromosome syndrome causing physical effects and mental retardation.
  • Duane anomaly - mental retardation: A very rare syndrome characterized mainly by mental retardation and eye movement problems (Duane anomaly).
  • Dubowitz Syndrome: A rare genetic and developmental disorder characterized by infantile eczema, small stature, microcephaly and peculiar facial features.
  • Dwarfism - tall vertebrae: A rare form of dwarfism characterized by short stature as well as unusually tall vertebrae and hip deformities.
  • Dysequilibrium syndrome: A very rare syndrome characterized mainly by mental retardation and nonprogressive incoordination.
  • Dysharmonic skeletal maturation - muscular fiber disproportion: A very rare syndrome characterized mainly by abnormal bone development and muscle problems.
  • Dysmorphism - abnormal vocalization - mental retardation: A very rare syndrome characterized mainly by mental retardation, facial abnormalities and an abnormal voice.
  • Dysmorphism - cleft palate - loose skin: A very rare syndrome characterized mainly by facial abnormalities, an opening in the roof of the mouth and loose skin.
  • Dysosteosclerosis: A rare inherited condition characterized by bone development abnormalities (excessive hardening of bone and flattened vertebrae), characteristic facial features. Excessive bone growth at the base of the skull can damage the optic nerves and affect vision.
  • EEC syndrome: A rare genetic disorder characterized by absence of fingers and toes, ectodermal dysplasia and cleft lip or cleft palate.
  • Ectodermal dysplasia - mental retardation - CNS malformation: A rare syndrome characterized mainly by mental retardation, central nervous system disorders and skin, hair and nail abnormalities.
  • Ectodermal dysplasia - mental retardation - central nervous system malformation: A rare syndrome characterized by severe mental retardation, hypothyroidism, abnormal brain development and hair, teeth and nail abnormalities.
  • Ectodermal dysplasia - neurosensory deafness: A rare syndrome characterized by nerve deafness, abnormally bent fifth fingers, ectodermal dysplasia and scoliosis.
  • Ectodermal dysplasia mental retardation syndactyly: A rare syndrome characterized by mental retardation, webbed fingers and hair, nail and teeth abnormalities.
  • Ectodermal dysplasia, Berlin type: A rare syndrome characterized mainly by the absence of many or all teeth, a lack of hair, mental retardation and skin abnormalities.
  • Ectodermal dysplasia, Margarita type: A rare genetic disorder characterized by mental retardation, webbed digits, cleft lip, cleft palate, sparse hair, reduced sweating and teeth abnormalities. Progressive loss of scalp hair usually results in baldness by adulthood.
  • Ectopia lentis, isolated: A rare syndrome characterized by dislocation of eye lenses which often occurred at birth.
  • Edinburgh malformation syndrome: A rare syndrome characterized mental and physical retardation, infant death and various other abnormalities.
  • Edwards Syndrome: A rare inherited genetic disorder where a portion of chromosome 18 is duplicated. Most affected individuals die during the fetal stage and surviving infants have serious defects and tend to live for only a short while.
  • Ehlers-Danlos syndrome type IX: A rare genetic connective tissue disorder involving a defective copper metabolism and characterized by mildly hyperextensible skin, lax joints, bladder problems and chronic diarrhea.
  • Ehlers-Danlos syndrome, Beasley Cohen type: A rare condition where mental retardation, deafness and cataracts are associated with a connective tissue disorder called Ehlers-Danlos syndrome.
  • Ehlers-Danlos syndrome, X-linked: A rare developmental brain abnormality. Type 1 is caused by a defect on chromosome Xq28.
  • Ehlers-Danlos syndrome, classic type: A rare genetic connective tissue disorder characterized by hypermobile joints, joint dislocations and skin hyperextensibility and fragility - a combination of ED types I and II.
  • Ehlers-Danlos syndrome, progeroid form: A connective tissue disorder caused by an enzyme (xylosylprotein 4-beta-galactosyl transferase) deficiency.
  • Ehlers-Danlos syndrome, progeroid form 2: A rare genetic connective tissue disorder characterized by hypermobile joints, fragile skin, mental retardation and short stature.
  • Emerinopathy: A rare, progressive muscle disease that starts during childhood and involves muscle weakness and wasting.
  • Emery-Dreifuss muscular dystrophy, X-linked: A muscle wasting disorder mainly involving the muscles in the arms, legs, face, neck, spine and heart. Symptoms generally only occur in males but female carriers may have some symptoms.
  • Encephalo cranio cutaneous lipomatosis: A rare genetic disorder characterized by craniofacial lipomas, cerebral atrophy and patches of alopecia.
  • Encephalocele anterior: Protrusion of a portion of the brain tissue through a skull defect in the anterior portion of the skull. The severity of symptoms depends on the exact location and size of the deformity.
  • Encephalocele frontal: Protrusion of a portion of the frontal brain tissue through a skull defect. The severity of symptoms depends on the exact location and size of the deformity.
  • Encephaloceles: Improper protrusions of parts of the meninges and brain.
  • Encephalopathy due to sulphite oxidase deficiency: An inborn error of metabolism where an enzyme (sulphite oxidase) deficiency results in encephalopathy. Symptoms usually start at birth.
  • Endomyocardial fibroelastosis: A rare heart malformation involving an abnormal thickening of the part of the heart muscle called the endocardium which affects the heart's function. Death is common in infancy and during early childhood.
  • Engelhard-Yatziv syndrome: A rare syndrome characterized mainly by droopy eyelids, small head and finger and toe abnormalities.
  • Epidermal nevus - vitamin D resistant rickets: A rare syndrome characterized mainly by the presence of birth marks on the skin, bone abnormalities and mental retardation.
  • Epidermolysis bullosa, late-onset, localized junctional, with mental retardation: A rare genetic disorder characterized by mental retardation, hair and nail disorders, absence of teeth and areas fragile skin that blisters easily.
  • Epilepsy - mental deterioration, Finnish type: A rare disorder that occurs predominantly in people of Finnish origin and is characterized by the association of epilepsy with mental retardation.
  • Epilepsy - microcephaly - skeletal dysplasia: A rare syndrome characterized by epilepsy, a small head and skeletal abnormalities.
  • Epilepsy - telangiectasia: A rare syndrome characterized by the association of epilepsy with telangiectasias on the conjunctiva of the eyelids.
  • Epilepsy, progressive myoclonic 3: A genetic disorder involving the early onset of progressive myoclonic epilepsy. The infant develops normally for the first year or so of life and the seizures start usually before the age of two. Once the seizures start, neurological degeneration begins.
  • Epileptic encephalopathy, early infantile, 1: A genetic form of epilepsy which is severe and starts during infancy. This form of the condition is caused by a defect on the ARX gene.
  • Epiphyseal dysplasia - hearing loss - dysmorphism: A rare syndrome characterized mainly by hearing loss, unusual face and bone development abnormalities.
  • Euhidrotic ectodermal dysplasia: A rare syndrome characterized mainly by tooth, hair and facial abnormalities.
  • Facial asymetry - temporal seizures: A rare condition characterized mainly by seizures that originate from the temporal lobe of the brain.
  • Facial dysmorphism - shawl scrotum - joint laxity syndrome: A very rare syndrome characterized mainly by loose joints, facial anomalies and a shawl scrotum.
  • Faciocardiorenal syndrome: A rare syndrome characterized by a variety of abnormalities such as kidney anomaly, mental retardation, unusual facial features, heart problems and joint problems. Infant death or stillbirth may occur in some cases.
  • Fahr's Syndrome: A rare neurologic disorder where calcium is deposited in various parts of the brain resulting in progressive loss of motor and mental function.
  • Familial band heterotopia: A rare inherited disorder where a part of the brain tissue is misplaced during development. More specifically, a layer of brain tissue is abnormally located in the white matter.
  • Familial hypertryptophanemia: A rare genetic metabolic disorder characterized by high levels of tryptophan in the blood. The disorder tends to run in families (familial).
  • Familial porencephaly: A very rare developmental abnormality that tends to run in families and is characterized by a localized accumulation of cerebrospinal fluid in the brain. The severity of symptoms is determined by the size and location of the brain abnormality.
  • Fanconi syndrome: Fanconi syndrome that occurs secondary to the accumulation of crystals of light-chain immunoglobulin molecules in the kidney tubules which affects their functioning.
  • Fanconi-Turler syndrome: A rare syndrome characterized mainly by mental retardation, ataxia and uncoordinated eye movements due to degeneration of parts of the brain.
  • Fanconi-ichthyosis-dysmorphism: A very rare syndrome characterized by scaly skin (ichthyosis), anemia, muscle anomalies and various other abnormalities. All six reported cases died within 6 months.
  • Farber's disease: A rare inherited biochemical disorder involving the deficiency of an enzyme called ceramidase resulting in the harmful accumulation of certain chemicals in the body which causes damage and inflammation.
  • Fenton-Wilkinson-Toselano syndrome: A rare syndrome characterized mainly by ataxia, light sensitivity and short stature.
  • Fetal alcohol syndrome: A pattern of mental and physical birth defects caused by excessive alcohol use during pregnancy. The range and severity of the symptoms may vary greatly.
  • Fetal brain disruption sequence: A very rare syndrome characterized by skull and brain abnormalities.
  • Fibromatosis gingival - hypertrichosis: A rare disorder characterized by excessive growth of body hair and enlarged gums.
  • Filippi Syndrome: A very rare disorder involving finger and toe abnormalities, a small head, characteristic face and physical and mental retardation.
  • Fine-Lubinsky syndrome: A very rare syndrome characterized mainly by a short head, deafness, cataracts and mental retardation.
  • Fitzsimmons-McLachlan-Gilbert syndrome: A very rare syndrome characterized mainly by mental retardation paraplegia and thickened coarse skin on palms and soles.
  • Floating Harbor Syndrome: A rare genetic disorder characterized by growth deficiency, typical facial appearance and speech delay.
  • Focal cortical dysplasia type II: Abnormal development of the brain cortex which results in severe, untreatable seizures which occur several times a day.
  • Focal cortical dysplasia type IIA: Abnormal development of the brain cortex which results in severe, untreatable seizures which occur several times a day. Type IIA is distinguished by the lack of balloon cells wheras type IIB has balloon cells present. Balloon cells are abnormal cells in the brain tissue.
  • Focal dermal hypoplasia: A rare genetic disorder characterized by bone, skin, teeth and pigmentation abnormalities as well as asymmetry of the face, trunk ant extremities.
  • Fountain Syndrome: A very rare inherited disorder involving mental retardation, sensorineural deafness, skeletal defects, coarse facial features and full lips.
  • Fragile-X Syndrome: A rare inherited characterized by various physical anomalies as well as mental retardation. The symptoms are milder in females.
  • Franceschini-Vardeu-Guala syndrome: A very rare disorder characterized by premature puberty, lower lip pits and Kabuki syndrome. Kabuki syndrome is a mental retardation syndrome which also involves a range of physical abnormalities.
  • Franek-Bocker-Kahlen syndrome: A rare syndrome characterized mainly by a small head, brain defect, spasticity and high sodium level.
  • Frank-Ter Haar syndrome: A rare genetic bone disorder characterized by skeletal abnormalities, enlarged corneas and characteristic facial abnormalities.
  • Free sialic Acid storage disease: A rare inherited biochemical disorder characterized by the accumulation of sialic acid in the tissues and excretion of sialic acid in the urine. There are mild and severe forms of the condition - the severe form result in death before birth or within a few years of birth.
  • Freire-Maia odontotrichomelic syndrome: A rare syndrome characterized by tooth, hair and limb abnormalities.
  • Fried syndrome: A rare syndrome characterized mainly by mental retardation, buildup of fluid inside the skull and an unusual facial appearance. The disorder is inherted in a X-linked manner.
  • Froehlich syndrome: A rare condition where an endocrine abnormality (caused by such things as a pituitary tumor or damage to the hypothalamus) affects hormone levels which results in a variety of symptoms.
  • Frontometaphyseal dysplasia: A rare genetic disorder characterized by craniofacial abnormalities, skeletal abnormalities, hearing problems and wasting of arm and leg muscles.
  • Fryns Syndrome: A rare genetic disorder characterized by diaphragmatic abnormalities, coarse face and abnormal growth or development of ends of fingers and toes.
  • Fryns macrocephaly: A rare syndrome characterized by a large head, seizures, spasticity, weakness and unusual facial appearance.
  • Fryns-Aftimos syndrome: A rare syndrome characterized mainly by abnormal brain development, epilepsy, mental retardation and unusual facial appearance.
  • Fryns-Smeets-Thiry syndrome: A rare syndrome characterized by short stature, mental retardation, small head, skeletal anomalies and various other abnormalities.
  • Fucosidosis: A rare progressive biochemical disorder involving deficiency of an enzyme (alpha-fucosidase) which results in accumulation of certain chemicals (glycosphingolipids) in the central nervous system and other body tissues.
  • Fukuyama type muscular dystrophy: A rare inherited muscle wasting disease occurring predominantly in Japan and characterized by mental retardation and muscle weakness from infancy.
  • GM2-gangliosidosis, AB variant: A very rare inherited disorder where the brain and spinal cord nerve cells (central nervous system) are progressively destroyed.
  • GOMBO syndrome: A rare syndrome characterized by retarded growth, eye abnormalities, short fingers and mental deficiency (oligophrenia).
  • Galactosemia I: A rare inherited disorder where deficiency of a particular enzyme (galactose-1-phosphate uridyl transferase) prevents the metabolism of galactose which is a sugar component of milk. Ranges from milk intolerance in mild cases to death in severe untreated cases.
  • Galloway syndrome: A rare genetic disorder primarily involving physical and developmental abnormalities.
  • Galloway-Mowat Syndrome: A condition which is characterized by microcephaly, hiatal hernia and nephrotic syndrome
  • Gangliosidosis GM1 type 3: A rare biochemical disorder involving a deficiency of an enzyme (beta-galactosidase A) which results in the accumulation of harmful chemicals (GM1 gangliosides) in the central nervous system and other body tissues. Type III involves a lesser degree of accumulation than type II or I.
  • Gardner-Morrisson-Abbot syndrome: A rare syndrome characterized by thrombocytopenia and various other abnormalities present at birth.
  • Garret-Tripp syndrome: A rare syndrome characterized mainly by extra digits, a lack of hair and scaly skin on the scalp, face and neck.
  • Generalized lipodystrophy with mental retardation, deafness, short stature and slender bones: A recessively inherited disorder characterized by short stature, mental retardation, deafness, slender bones and degeneration of the body's fat tissue.
  • Genital anomaly - cardiomyopathy: A rare syndrome characterized by the association of heart disease with genital abnormalities.
  • Giacomini disease: A rare inherited disorder characterized mainly by a small head and usually associated with mental retardation and various eye defects.
  • Giant axonal neuropathy: A rare genetic disorder characterized by incoordination, vision problems and dementia caused by abnormalities of a nerve cell component.
  • Global developmental delay - osteopenia - ectodermal defect: A rare syndrome characterized by developmental delay, osteopenia and skin anomalies.
  • Glomerulonephritis - sparse hair - telangiectases: A rare syndrome characterized by sparse hair, kidney disease and enlarged skin blood vessels (telangiectasia).
  • Glucose transport defect, blood-brain barrier: A rare metabolic disorder involving a deficiency of a molecule needed to transport glucose (GLUT1). The glucose is unable to be transported from the blood and into the brain and cerebrospinal fluid. Sugar transport to the brain is essential for normal development. The blood sugar level remains normal. Fasting exacerbates symptoms which can very in severity depending on the degree of deficiency.
  • Glucosephosphate isomerase deficiency: A rare inherited condition where a lack of the enzyme glucosephosphate isomerase causes red blood cells to be destroyed prematurely (hemolytic anemia).
  • Glutamate decarboxylase deficiency: A rare disorder of amino acid metabolism characterized by a deficiency of the enzyme called glutamate decarboxylase which causes seizures that will only respond to pyridoxine (vitamin B6).
  • Glutathione synthetase deficiency, severe: An inborn error of metabolism where insufficient glutathione is produced. Glutathione is an antioxidant which helps destroy unstable molecules that can cause damage to cells and helps develop certain cell components. The condition is due to insufficient glutathione synthetase enzyme. The condition may range from mild, resulting in excessive destruction of red blood cells, to severe which includes neurological symptoms.
  • Glycine encephalopathy, atypical mild form: A rare disorder of amino acid metabolism where glycine are unable to be metabolized properly due to defects in the glycine cleavage system. The atypical mild form tends to be quite mild and can be difficult to diagnose due to the nonspecific symptoms.
  • Glycine encephalopathy, classical neonatal early-onset form: A rare disorder of amino acid metabolism where glycine are unable to be metabolized properly due to defects in the glycine cleavage system. The early onset classical neonatal form usually starts after a period of normal development during the first 6 months of life.
  • Glycine encephalopathy, classical neonatal form: A rare disorder of amino acid metabolism where glycine are unable to be metabolized properly due to defects in the glycine cleavage system.
  • Glycogen storage disease type 2B: A rare inherited biochemical disorder involving the harmful accumulation of certain chemicals (glycogen) in body tissues due to the deficiency of an enzyme (?-glucosidase or acid maltase) needed to break it down. Type IIB usually starts during childhood.
  • Glycogen storage disease type 6A, due to phosphorylase kinase deficiency: A rare, generally mild form of inherited glycogen storage disease where a deficiency of phosphorylase kinase leads to hypoglycemia and accumulation of glycogen in the liver. Phosphorylase kinase deficiency can cause glycogen storage disease type VIa and/or IX.
  • Glycogenosis type 2: A rare inherited biochemical disorder involving the harmful accumulation of certain chemicals (glycogen) in body tissues due to the deficiency of an enzyme (?-glucosidase or acid maltase) needed to break it down. The severity of the condition is variable and onset may occur during infancy, childhood or adulthood.
  • Gms syndrome: A rare syndrome characterized by mental retardation, short stature and an eye abnormality.
  • Goldberg syndrome: A rare lysosomal storage disorder characterized by an enzyme deficiency (neuraminidase and beta-galactosidase) which results in a build-up of glycoproteins in the urine. There are three main subtypes: infantile, juvenile and adult forms. The early infantile form is the most severe and often results in death during infancy.
  • Goldblatt-Wallis syndrome: A very rare syndrome characterized by mental retardation and an abnormal
  • Gonadal dysgenesis XY type associated anomalies: A very rare syndrome characterized mainly by
  • Greig Cephalopolysyndactyly Syndrome: A rare genetic disorder characterized by premature closing of skull bones and craniofacial abnormalities, finger and toe abnormalities.
  • Grix-Blankenship-Peterson syndrome: A very rare syndrome characterized mainly by mental retardation, bone defects and head and face abnormalities.
  • Growth and mental retardation, mandibulofacial dysostosis, microcephaly, and cleft palate: A rare syndrome characterized mainly by mental retardation, retarded growth, small head, cleft palate and facial abnormalities.
  • Growth delay - mental retardation - mandibulofacial dysostosis - microcephaly - cleft palate: A rare syndrome characterized by delayed growth, mental retardation, small head, cleft palate and facial and jaw anomaly.
  • Growth delay due to insulin-like growth factor I deficiency: A rare disorder where the deficiency of a growth factor (IGF-1) causes growth delay, deafness and mental retardation.
  • Growth retardation mental retardation phalangeal hypoplasia: A rare syndrome characterized mainly by retarded growth, mental retardation and underdeveloped digits.
  • Gurrieri-Sammito-Bellussi syndrome: A rare syndrome characterized by epilepsy, short stature and skeletal abnormalities.
  • Haas-Robinson syndrome: A rare, recessively inherited disorder involving defective copper metabolism within the body which causes symptoms such as mental retardation, seizures and poor muscle tone.
  • Hair defect with photosensitivity and mental retardation: A very rare syndrome characterized mainly by mental retardation, sensitivity to light and sparse, fragile hair
  • Halal Setton Wang syndrome: A very rare syndrome characterized mainly by eye, teeth, nail and skin abnormalities.
  • Hallervorden-Spatz disease: Nerve disorder causing movement problems.
  • Hanhart syndrome type IV: A rare disorder where a genetic error of amino acid metabolism results in thickened skin on palms and soles, skin lumps, mental retardation and finger, toe, eye, hair and teeth abnormalities.
  • Harrod Doman Keele syndrome: A very rare syndrome characterized mainly by skull, facial, genital, finger and toe abnormalities.
  • Haspeslagh Fryns Muelenaere syndrome: A very rare syndrome characterized mainly by short stature, underdeveloped genitals and various skull and facial anomalies.
  • Hemi 3 syndrome: A very rare syndrome where parts of the body undergo excessive growth give the body an asymmetrical appearance.
  • Hemimegalencephaly: A very rare disorder where one side of the brain is bigger than the other.
  • Hemiplegic migraine, familial type 2: A rare inherited form of migraine that characteristically causes temporary paralysis on one side of the body and involves the presence of an aura. A migraine episode may be triggered by minimal trauma to the head. The severity of the disorder is variable with some patients experiencing problems for days. Triggers include tiredness, heat, stress and head injury.
  • Hereditary methemoglobinemia, recessive, type II: A rare inherited blood disorder where the hemoglobin (the oxygen-carrying part of red blood cells) can't bind with oxygen which impairs the oxygen supply to parts of the body, especially during exertion when more oxygen is needed by the body. The type II form of Gibson syndrome is more severe than type I and is characterized by cyanosis as well as neurological problems, mental deficiency and various other anomalies. Type I has enzyme deficiency (cytochrome B5 reductase) only in the red blood cells whereas in Type II the enzyme deficiency occurs in other body cells as well as red blood cells.
  • Hereditary nodular heterotopia: A rare inherited disorder where a part of the brain tissue is misplaced during development. More specifically, nodules of brain tissue is in various parts of the brain.
  • Herpes, Neonatal: Neonatal herpes is the infection of a newborn with the herpes virus within the first six weeks of life. The virus may be transmitted from the mother to the baby while it is still in the uterus or during delivery. The risk of transmitting the virus is highest if genital herpes is contracted during the late stages of the pregnancy. A mother with long standing or recurring herpes infection usually has sufficient antibodies to the virus to prevent the infant becoming infected. Neonatal herpes can also be contracted when an infant comes into contact with an infected person e.g. being kissed by and adult with cold sores. A cesarean birth may be advised for mothers who have active genital lesions.
  • Herpes, Neonatal - Central Nervous System Infection: Central nervous system herpes infection in neonates is a herpes infection of the central nervous system (brain, spinal cord) that develops in infants within the first six weeks of life. The virus may be transmitted from the mother to the baby while it is still in the uterus or during delivery. The risk of transmitting the virus is highest if genital herpes is contracted during the late stages of the pregnancy. A mother with long standing or recurring herpes infection usually has sufficient antibodies to the virus to prevent the infant becoming infected. Neonatal herpes can also be contracted when an infant comes into contact with an infected person e.g. being kissed by and adult with cold sores. A cesarean birth may be advised for mothers who have active genital lesions. Central nervous system infection will occur in nearly three quarters of infants with a herpes infection.
  • Herpes, Neonatal - Disseminated: Disseminated neonatal herpes is a widespread infection of a newborn with the herpes virus within the first six weeks of life. The virus may be transmitted from the mother to the baby while it is still in the uterus or during delivery. The risk of transmitting the virus is highest if genital herpes is contracted during the late stages of the pregnancy. A mother with long standing or recurring herpes infection usually has sufficient antibodies to the virus to prevent the infant becoming infected. Neonatal herpes can also be contracted when an infant comes into contact with an infected person e.g. being kissed by and adult with cold sores. A cesarean birth may be advised for mothers who have active genital lesions. Brain infection will occur in over half of infants with the disseminated form.
  • Herrmann-Opitz craniosynostosi: A very rare syndrome characterized mainly by mental retardation, skeletal abnormalities and an unusual facial appearance.
  • Hersh-Podruch-Weisskopk syndrome: A very rare syndrome characterized mainly by progressive retinal damage, mental retardation and deafness.
  • Histidinemia: A metabolic disorder where there is a deficiency of the histidase enzyme which is needed to metabolise the amino acid called histidine. Histidine levels then buildup of histidine in the blood and urine.
  • Histidinuria, renal tubular defect: A very rare syndrome where a kidney defect causes high levels of histidine in the urine.
  • Holoprosencephaly: A rare disorder where abnormalities of the fetal forebrain development lead to various birth defects.
  • Holoprosencephaly deletion 2p: A very rare syndrome characterized mainly by the failure of the brain to separate into two lobes, facial deformities and various other anomalies.
  • Homocarnosinosis: A very rare metabolic disorder where a deficiency of homocarnosinase causes a harmful buildup of homcarnosine. Symptoms include mental retardation, retinal pigmentation and spastic diplegia.
  • Homocystinuria: A rare inherited metabolic disorder involving the amino acid methionine and resulting in a harmful accumulation of homocysteine in the body.
  • Homocystinuria due to defect in methylation (cbl g): An inherited organic acid disorder where an enzyme deficiency (methionine synthase) impairs the body's ability to break down certain proteins consumed in the diet. This results in a buildup of methylmalonic acid and homocystine which results in harmful affects. It is a form of vitamin B12 deficiency.
  • Homocystinuria due to defect in methylation cbl e: An inherited organic acid disorder where an enzyme deficiency (methionine synthase reductase) impairs the body's ability to break down certain proteins consumed in the diet. This results in a buildup of methylmalonic acid and homocystine which results in harmful affects. It is a form of vitamin B12 deficiency.
  • Hooft disease: A rare disorder characterized by mental and physical retardation, red rash and low blood lipid level.
  • Hordnes-Engebretsen-Knudtson syndrome: A very rare syndrome characterized by an abnormal skull shape, mental retardation, abnormally placed anus and narrowed pulmonary valve
  • Hornova-Dlurosova syndrome: A rare disorder characterized by mental retardation and amyloid (abnormal protein) deposits in the eyelids and gums.
  • Howard-Young syndrome: A very rare syndrome characterized mainly by a small head, facial cleft and an extra big toe.
  • Hoyeraal-Hreidarsson syndrome: A very rare syndrome characterized mainly by retarded growth, a small head, anemia, immunodeficiency and an underdeveloped brain (cerebellum).
  • Hunter-Carpenter-Macdonald syndrome: A very rare syndrome characterized by various abnormalities including small head, facial anomalies, mental retardation and hair, skin and nail anomalies. Fetal exposure to alcohol is believed to be a factor in the syndrome.
  • Hunter-Fraser syndrome: A rare inherited syndrome characterized mainly by mental retardation and facial and skeletal abnormalities.
  • Hunter-Macpherson syndrome: A very rare disorder characterized by the association of mental retardation and abnormal bone hardening.
  • Hunter-McAlpine syndrome: A very rare dominantly inherited syndrome characterized mainly by premature fusion of skull bones, mental retardation, small mouth, short stature and finger and toe anomalies.
  • Hyde-Forster-Mccarthy-Berry syndrome: A very rare syndrome characterized mainly by mental retardation and an abnormal skull shape.
  • Hydranencephaly: A very rare condition where fluid replaces a portion of the brain.
  • Hydrocephalus: A rare condition where the normal flow of cerebrospinal fluid is impaired by dilated brain ventricles which causes the fluid to accumulate in the skull and hence result in increased brain pressure.
  • Hydrocephalus due to congenital stenosis of aqueduct of sylvius: A very rare disorder where there is a buildup of cerebrospinal fluid inside the skull due to a narrow canal that connects the third and fourth ventricles of the brain.
  • Hydroxykynureninuria: A rare genetic disorder where a deficiency of the enzyme kynureninase (a vitamin B6) causes physical and mental problems. The deficiency can also occur in an acquired form which tends to be less severe.
  • Hyperimidodipeptiduria: A very rare genetic disorder characterized by an excessive level of imidodipeptides in the urine due to a deficiency of the enzyme prolidase.
  • Hypermethioninemia due to S-adenosylhomocysteine hydrolase deficiency: A rare disorder involving an enzyme deficiency which results in increased methionine levels in the blood. The condition manifests as psychomotor delay and severe muscle disease.
  • Hyperornithinemia-hyperammonemia-homocitrullinuria syndrome: A very rare inherited metabolic disorder where ammonia builds up in the body due to a defect in the transport of ornithine which prevents ammonia being converted to urea and being excreted through the urine. The severity of the condition is variable.
  • Hyperprolinemia type 2: A rare metabolic abnormality involving a deficiency of a particular enzyme (Delta-1-pyrroline-5-carboxylate dehydrogenase) which affects amino acid metabolism and causes mental retardation and convulsions.
  • Hypertrichosis brachydactyly obesity and mental retardation: A very rare disorder characterized mainly by excessive hair growth, short digits, obesity and mental retardation
  • Hypertrichosis, hyperkeratosis, mental retardation, and distinctive facial features: A very rare disorder characterized by thickened skin, mental retardation, increased body hair and a characteristic face.
  • Hypertrichotic osteochondrodysplasia: A rare syndrome characterized by mental retardation, short stature, large skull, heart anomaly and various other abnormalities.
  • Hypobetalipoproteinaemia - ataxia - hearing loss: A rare disorder characterized by the association of low blood betalipoprotein level, ataxia and hearing loss.
  • Hypochondroplasia: A rare genetic disorder characterized by short stature which becomes more obvious during and after childhood.
  • Hypogonadism - mitral valve prolapse - mental retardation: A very rare syndrome characterized mainly by a heart disorder, hypogonadism and mental retardation.
  • Hypomandibular faciocranial dysostosis: A very rare syndrome characterized mainly by very underdeveloped upper and lower jaw as well as a very small, absent or small tongue.
  • Hypomelanosis of Ito: A rare genetic neurocutaneous disorder characterized by unusual patterns of depigmented skin and associated disorders such as seizures, psychomotor retardation and eye abnormalities.
  • Hypomyelination - congenital cataract: A rare syndrome characterized by the association of congenital cataract with progressive neurological impairment due to progressive demyelination.
  • Hypomyelination and congenital cataract: An inherited disorder characterized by congenital cataract and progressive neurological impairment due to reduced myelination of nerves.
  • Hypoparathyroidism - short stature - mental retardation: A very rare syndrome characterized mainly by low parathyroid hormone level, short stature and mental retardation.
  • Hypoparathyroidism familial isolated: A rare familial condition involving low levels of parathyroid hormone which upsets the body's ability to regulate calcium and phosphate. The severity of symptoms is determined by the how low the parathyroid hormone level is.
  • Hypothyroidism - cleft palate: A rare syndrome characterized mainly by the association of an abnormal opening in the roof of the mouth and reduced thyroid functioning.
  • Hypothyroidism due to iodide transport defect: Low thyroid hormone levels in infants due to abnormal iodide transport in the body caused by a genetic defect. The severity of the condition varies depending on the extent of the defect and the length of time taken to diagnose the condition. Symptoms tend to become worse, the longer the condition is undiagnosed.
  • Hypothyroidism postaxial polydactyly mental retardation: A very rare syndrome characterized by abnormally low thyroid levels, extra digits, mental retardation and unusually facial appearance.
  • I cell disease: A rare inherited biochemical disorder characterized by the harmful accumulation of chemicals (glycoproteins and glycoplipids) due to the deficiency of an enzyme (UDP-N-acetylglucosamine-I-phosphotransferase).
  • IBIDS syndrome: A rare inherited skin disorder characterized by red, dry, scaly skin (I - ichthyosis), brittle hair (B), impaired physical and mental development (I), decreased fertility (D) and short stature (S). It is the same as PIBIDS syndrome but doesn't involve photosensitivity.
  • ICF syndrome: A very rare, recessively inherited syndrome characterized mainly by a weak immune system and facial anomalies.
  • Ichthyosis - alopecia - eclabion - ectropion - mental retardation: A very rare syndrome characterized mainly by scaly skin, hair loss, mental retardation and outwardly turned eyelids and lips.
  • Ichthyosis - deafness - mental retardation - skeletal anomaly: A rare disorder characterized by deafness, mental retardation, scaly skin and skeletal anomalies.
  • Ichthyosis - mental retardation, Devriendt type: A very rare syndrome characterized mainly by dry, rough, scaly skin and mental retardation.
  • Ichthyosis mental retardation asymptomatic spasticity: A rare syndrome characterized mainly by mental retardation, spasticity and dry scaly skin.
  • Ichthyosis mental retardation dwarfism renal impairment: A rare genetic condition characterized by dwarfism, mental retardation, kidney dysfunction and ichthyosis (skin disorder characterized by fish-like scales).
  • Idaho syndrome: A very rare syndrome characterized by a variety of abnormalities including clubfoot, mental retardation, finger abnormalities and a congenital heart defect.
  • Idiopathic basal ganglia calcification, childhood onset: A rare disorder involving the buildup of calcium deposits in various parts of the brain. It manifests as degeneration of the nervous system.
  • Illum syndrome: A very rare disorder characterized by a distinctive "whistling face" and contractures in multiple joints.
  • Immunodeficiency with short limb dwarfism: A very rare condition where short-limbed dwarfism is associated with immunodeficiency.
  • Inborn amino acid metabolism disorder: A group of inherited disorders where the body is not able to metabolize amino acids consumed in the diet. Amino acids are a part of carbohydrates, fats and proteins and are metabolized in order to provide energy or to make other needed compounds. There are many steps involved in metabolism and the severity can be greatly variable depending on the exact nature of the disorder.
  • Inborn urea cycle disorder: A genetic disorder involving a deficiency of one of the enzymes needed in the urea cycle. The urea cycle is the process of removing ammonia from blood stream by converting it to urea and excreting it via urine. A build-up of ammonia in the blood is toxic to the body and can cause serious brain damage. The progressively severe symptoms usually become obvious within the first few weeks of birth. Nevertheless, mild or partial enzyme deficiencies may cause little or no symptoms or symptoms that don't start until later in life.
  • Incontinentia Pigmenti: A rare genetic skin pigmentation disorder characterized by eye, teeth, bone, nail and hair malformations as well as central nervous abnormalities and mental deficiency.
  • Infant Cytomegalic virus: A serious CMV viral infection in newborns.
  • Infantile Spasms: Seizure condition in infants.
  • Infantile axonal neuropathy: A very rare form of progressive nerve damage that starts early in life. The central nervous system is also usually involved.
  • Infantile multisystem inflammatory disease: A rare autoinflammatory disease characterized by fever, rash, arthritic changes, eye problems and chronic meningitis.
  • Infantile spasms - broad thumbs: A very rare syndrome characterized mainly by spasms during infancy and broad thumbs.
  • Intellectual deficit - multiple anomalies: A very rare syndrome characterized mainly by mental retardation and multiple birth abnormalities such as heart defects, undescended testes, curved spine and distinctive facial appearance.
  • Intellectual impairment: The impairment of ones cognition
  • Intrauterine infections: Infection of the fetus while still inside the womb. The type and severity of symptoms is determined by the type of infection and at what stage of pregnancy it occurs. Some cases are mild enough to be asymptomatic and others are severe enough to cause a miscarriage.
  • Iris coloboma, macrocephaly, agenesis of the corpus callosum, brachydactyly and mental retardation: A rare syndrome characterized mainly by a small head, brain anomaly, short digits, mental retardation and an eye defect.
  • Ischiadic hypoplasia - renal dysfunction - immunodeficiency: A rare disorder characterized by abnormal kidney function, immunodeficiency and an underdeveloped
  • Jackson-Weiss Syndrome: A rare inherited disorder involving bone abnormalities such as fusion of upper foot bones and premature fusion of skull bones which prevents the skull from growing normally. Symptoms can range from mild to severe.
  • Jacobsen syndrome: A very rare chromosomal disorder involving the absence of a portion of chromosome 11q. The range and severity of symptoms is determined by the size of the portion that is deleted.
  • Jaffer-Beighton syndrome: A rare inherited syndrome characterized by loose joints, slipped vertebrae and long, thin fingers.
  • Jeune syndrome: A rare genetic disorder characterized by short limbs, underdeveloped iliac wings and a narrow rigid thoracic cage that often results in asphyxiation.
  • Johanson-Blizzard Syndrome: A rare genetic disorder involving a range of abnormalities including a characteristic beak-like small nose, hypothyroidism and deafness.
  • Jorgenson-Lenz syndrome: A very rare syndrome characterized mainly by
  • Joubert Syndrome: A rare neurological disorder where there is a defect in the part of the brain that controls coordination and balance.
  • Juberg-Hayward syndrome: A rare hereditary disorder characterized by a growth hormone deficiency as well as mouth and limb abnormalities.
  • Jung-Wolff-Back-Stahl syndrome: A very rare syndrome characterized mainly by brain abnormalities, mental retardation and facial and skull anomalies.
  • KBG Syndrome: A very rare genetic disorder involving short stature, mental retardation, abnormal development of various bones.
  • Kalam-Hafeez syndrome: A rare disorder characterized by low parathyroid levels in infants, retarded growth, mental retardation, dysmorphic features and seizures.
  • Kaler-Garrity-Stern syndrome: A very rare syndrome characterized mainly by osteopenia, mental retardation and sparse hair.
  • Karandikar-Maria-Kamble syndrome: A very rare syndrome characterized mainly by cataracts, mental retardation and genitourinary tract abnormalities and
  • Katsantoni-Papadakou-Lagoyanni syndrome: A very rare syndrome characterized mainly by mental retardation and hair abnormalities.
  • Kennerknecht-Sorgo-Oberhoffer syndrome: A very rare syndrome characterized mainly by absent gonads and an underdeveloped right side of the heart.
  • Kennerknecht-Vogel syndrome: A very rare syndrome characterized mainly by absent gonads, mental retardation, short stature, retarded bone age and heart abnormalities.
  • Kifafa seizure disorder: A rare form of seizure involving head nodding prior to the seizure and often associated with neurological symptoms and Parkinson-like symptoms.
  • Kleeblattschaedel syndrome: A very rare syndrome characterized mainly by a head the is somewhat cloverleaf shaped.
  • Klinefelter syndrome: A genetic condition where males have at least one extra X chromosome or extra copies of both the X and Y chromosomes in each cell. Normally male cells contain one X and one Y chromosome in each cell. The condition is not inherited but is a result of problems during cell division. Klinefelter syndrome variants is a more severe form of the condition as it involves more than one extra X or X and Y chromosome in each cell.
  • Koone-Rizzo-Elias syndrome: A rare congenital disorder characterized by mental retardation, spasticity and dry, scaly skin.
  • Kosztolanyi syndrome: A very rare syndrome characterized mainly by severely retarded development, long thin fingers, mental retardation and skull and facial abnormalities.
  • Kramer-Pollnow disease: A neurological condition where young children develop hyperactivity followed by mental retardation, reduced speech efficiency and anxiety.
  • Krause syndrome: A syndrome involving the abnormal development of the eye and cerebral portion of the brain. It most often occurs in premature infants or an infant from a multiple birth. It is believed to possibly result from intercurrent infections in the mother, placental abnormalities and hemorrhages that occur during the second trimester of the pregnancy.
  • Krause-Kivlin syndrome: A rare genetic disorder characterized by short limb dwarfism, mental retardation and Peters anomaly.
  • Kurczynski-Casperson syndrome: A very rare syndrome characterized mainly by premature fusion of skull bones, abnormal ears and webbing of the last two toes.
  • Lactic acidosis congenital infantile: A rare congenital condition where an infant has high levels of lactic acid in the blood causing metabolic acidosis.
  • Landau-Kleffner Syndrome: A neurological disorder which results in aphasia, epileptic seizures and inability to recognize sounds.
  • Lathosterolosis: A very rare disorder where an enzyme (sterol C5-desaturase) deficiency prevents the normal synthesis of cholesterol in the body. The deficiency causes various malformations, mental retardation and liver disease.
  • Laurence-Moon Syndrome: A rare inherited disorder characterized by vision loss, impaired hormone production, mental retardation and spastic paraplegia.
  • Lead poisoning: A type of heavy metal poisoning caused by excessive exposure to lead.
  • Learning disabilities: Various developmental problems impairing learning or schooling.
  • Leigh syndrome: A rare, progressive, neurological disorder characterized by the degeneration of the brain and impaired function of various body organs. The condition is caused by a systemic deficiency of the cytochrome C oxidase enzyme.
  • Leigh syndrome, French Canadian type: A rare, progressive, inherited metabolic disorder where a deficiency of the enzyme cytochrome C oxidase affects skeletal muscles, connective tissue, brain and liver.
  • Lennox-Gastaut Syndrome: A form of epilepsy that occurs mostly in preschool-aged children and is characterized mainly by absences.
  • Lenz Microphthalmia Syndrome: A condition which is characterized by an abnormally small eye
  • Leprechaunism: A very rare genetic disorder characterized by insulin resistance which leads to growth delay and endocrine system abnormalities.
  • Lesch-Nyhan syndrome: Inherited biochemical disorder of purine metabolism caused by the virtual absence of an enzyme called hypoxanthine-guanine phosphoribosyltransferase or HPRT.
  • Leschke-Ullmann syndrome: A rare genetic disorder characterized by patches of skin pigmentation, physical and mental retardation, dwarfism, sexual dysfunction and muscle problems.
  • Leukomalacia: Softening or destruction of the white matter of the brain. Brain tissue that surrounds fluid-filled parts of the brain (ventricles) is destroyed. It tends to occur mainly in premature or newborn babies who have been deprived of oxygen or have poor blood flow to parts of the brain. Intrauterine infections and premature membrane rupture tend to predispose infants to this condition. This type of brain destruction can cause cerebral palsy. Severity of symptoms varies according to the degree of injury to the brain.
  • Levic-Stefanovic-Nikolic syndrome: A very rare inherited syndrome characterized mainly by mental retardation, ophthalmoplegia and a fissured tongue.
  • Lindsay-Burn syndrome: A very rare syndrome characterized mainly by mental retardation, psychosis and enlarged testes.
  • Lindstrom syndrome: A rare disorder characterized by mental retardation, facial anomalies, short stature and seizures.
  • Lipidosis with triglyceride storage disease: A very disorder involving abnormal storage of fat (triglycerides in parts of the body). The condition causes blood abnormalities as well as skin, eye and hearing problems.
  • Lipoamide dehydrogenase deficiency: A very rare enzyme deficiency (dihydrolipoamide dehydrogenase) which can cause lactic acidosis. The age of onset and symptoms are variable.
  • Lipoid proteinosis of Urbach and Wiethe: A rare congenital lipoid storage disease where lipids, carbohydrates and proteins are deposited onto blood vessel walls and other tissues.
  • Lissencephaly - immunodeficiency: A very rare syndrome characterized mainly by abnormal brain development and a poor immune system.
  • Lissencephaly 3: A rare brain malformation where the surface of the brain is smoother than normal. The brain abnormality causes symptoms such as mental retardation and seizures. The severity of the disorder is variable and is caused by a genetic defect on chromosome 12q12-q14.
  • Lissencephaly syndrome type 1: A very rare form of the brain formation disorder called lissencephaly where the brain surface is abnormally smooth rather than convoluted resulting in mental retardation. Physical malformations are also present.
  • Lissencephaly type 1, due to LIS 1 anomalies: A rare brain malformation where the surface of the brain is smoother than normal. Type 1 is caused by a defect on the LIS1 gene on chromosome 17p13.3. The severity of the symptoms are variable depending on the severity of the brain abnormality. Miller-Dieker syndrome is a subtype of this condition.
  • Lissencephaly with cerebellar hypoplasia: Abnormal brain development characterized by an abnormally smooth brain surface and an underdeveloped cerebellum. The severity of the disorder is variable but often involves seizures and mental retardation.
  • Lissencephaly, X linked - agenesis of the corpus callosum - genital anomalies: A rare brain malformation where the surface of the brain is smoother than normal. Absent corpus callosum and genital anomalies are also associated. The severity of the disorder is variable.
  • Lissencephaly, X-linked 2: A rare brain malformation where the surface of the brain is smoother than normal. Genital anomalies are also associated. The severity of the disorder is variable.
  • Lissencephaly, type 1, X-linked: Abnormal brain development characterized by an abnormally smooth brain. This form of the disorder is inherited in a X-linked manner (defect on the DCX gene) and the corpus callosum fails to develop. Males tend to be affected more severely than females.
  • Loeys-Dietz syndrome: A very rare syndrome characterized mainly by a bulge in the aorta (aneurysm), wide set eyes, cleft palate, divided uvula and twisted arteries.
  • Lopes-Marques de Faria syndrome: A very rare syndrome characterized mainly by decreased hair and mental retardation.
  • Low birth weight - dwarfism - dysgammaglobulinemia: A very rare syndrome characterized mainly by low birth weight, short stature and a immune system abnormality.
  • Lowe Syndrome: An X linked condition characterized by vitamin D deficiency and causing an oculocerebrorenal syndrome
  • Lowe oculocerebrorenal syndrome: A rare inherited metabolic disorder characterized primarily by eye and bone abnormalities, mental retardation and kidney problems.
  • Lowry-Maclean syndrome: A very rare syndrome characterized mainly by mental retardation, retarded growth, glaucoma, congenital heart defects and premature fusion of skull bones.
  • Lowry-Wood syndrome: A rare syndrome characterized by a small head, rapid involuntary eye movements (nystagmus) and abnormal development of the ends of long bones where growth occurs.
  • Lujan-Fryns syndrome: A rare genetic disorder characterized by mental retardation and marfanoid habitus (features of Marfan's syndrome).
  • Lundberg II syndrome: A rare syndrome involving cataracts, reduced hormone production by ovaries or testes and myopathy which mainly involves the facial and muscles close to the trunk.
  • Lymphangiectasies and lymphedema Hennekam type: A rare disorder characterized by buildup of lymphatic fluid in the limbs, face and genitals, seizures and mental and growth retardation.
  • MASA Syndrome: A very rare inherited disorders characterized by mental retardation (M), aphasia (A), shuffling walk (S) and adducted thumbs (A). The symptoms are variable from case to case but mental retardation is a consistent feature.
  • MELAS: A mitochondrial disorder characterized by stroke-like episodes, headaches, vomiting and other neurological symptoms.
  • MOMO syndrome: A very rare syndrome characterized mainly by a large size and weight at birth, a large head and eye abnormalities.
  • MORM syndrome: A rare syndrome characterized by mental retardation, truncal obesity, small penis and an eye disorder.
  • MRXS9: A type of mental retardation syndrome characterized mainly by mental retardation, short stature, small head and strabismus. The genetic defect that causes the syndrome is located on chromosome Xq12-q21.31. As the disorder originates from a defect on the X chromosome, only males suffer the full effect of the disorder whereas female carriers are asymptomatic or suffer learning disabilities.
  • MacDermot-Winter syndrome: A very rare syndrome characterized mainly by a small head, underdeveloped genitalia and a protrusion of the area between the eyes (glabella).
  • Macrocephaly - mental retardation - facial dysmorphism: A rare syndrome characterized mainly by a large head, mental retardation and an unusual facial appearance.
  • Macrocephaly mesodermal hamartoma spectrum: A rare syndrome characterized mainly by a large head and multiple lipomas and hemangiomas. The severity of the disorder is variable.
  • Macrogyria, pseudobulbar palsy and mental retardation: A very rare syndrome characterized mainly by abnormal brain development which results in mild mental retardation, epilepsy, developmental delay and pseudobulbar palsy which affects speech, chewing and swallowing functions.
  • Macules, hereditary, congenital hypopigmented and hyperpigmented: A rare inherited genetic disorder involving small flat areas increased and decreased skin pigmentation.
  • Malformations in neuronal migration: A rare disorder where the brain fails to develop normally - usually the cerebral cortex is involved. Various parts of the brain can be affected to various degrees depending on what stage of development the defect occurs. Mental retardation is one of the most common symptoms associated with brain malformations.
  • Malpuech facial clefting syndrome: A very rare syndrome characterized by mental and physical retardation, wide set eyes, genital abnormalities and a characteristic facial cleft.
  • Mannosidosis, alpha B lysosomal: A rare inherited metabolic disorder involving a deficiency of an enzyme (alpha-mannosidosase) which results in the accumulation of certain chemicals in the body which leads to progressive damage.
  • Maple syrup urine disease: A very rare inherited metabolic disorder involving abnormal metabolism of branched chain amino acids (leucine, isoleucine and valine) and resulting in severe illness which generally leads to death if not treated. Other milder variants of the disease do exist and tend to occur as late as childhood. Even mild form can result in mental and physical retardation if untreated.
  • Marden-Walker Syndrome: A rare genetic disorder characterized by blepharophimosis, joint contractures and fixed facial expression.
  • Marfanoid - mental retardation syndrome autosomal: A very rare syndrome characterized mainly by psychomotor retardation, a flat face and some symptoms of Marfan syndrome (long arms and legs, tall stature, reduced skin fat and poor muscle tone).
  • Marinesco-Sjogren syndrome: A group of recessively inherited disorder characterized mainly by incoordination due to a brain anomaly.
  • Marinesco-Sjogren-like syndrome (MSLS): A very rare disorder characterized by cataracts (during childhood), mental retardation, muscle weakness and brain degeneration. The disorder is very similar to another syndrome called Marinesco-Sjogren syndrome.
  • Maroteaux-Fonfria syndrome: A rare congenital disorder characterized by extra little fingers and extra big toes as well as the normal features associated with Apert syndrome.
  • Martsolf syndrome: A rare inherited condition characterized by mental retardation, cataracts, small head and hypogonadism (reduced production of hormones by ovaries or testes).
  • Massa-Casaer-Ceulemans syndrome: A very rare syndrome characterized mainly by abnormal brain development (lissencephaly - smooth brain) and multiple joint contractures at birth.
  • Mastocytosis, cutaneous, with short stature, conductive hearing loss and microtia: A very rare syndrome characterized mainly by short stature, abnormal skin pigmentation, small ears and hearing impairment.
  • Maternally Inherited Leigh Syndrome: A rare condition where Leigh syndrome is inherited from the mother. Leigh syndrome is characterized by degeneration of the brain and impaired function of various organs.
  • Matsoukas syndrome: An extremely rare condition characterized by mental retardation, eye problems, facial anomalies and joint problems.
  • Matsoukas-Liarikos-Giannika syndrome: A very rare syndrome characterized mainly by mental retardation, short stature and eye and joint abnormalities.
  • McDonough syndrome: A very rare syndrome characterized mainly by mental retardation and multiple birth abnormalities such as heart defects, undescended testes, curved spine and distinctive facial appearance.
  • McDowall syndrome: A very rare syndrome characterized mainly by mental retardation and excessive skin folds and furrows on the scalp.
  • Medrano-Roldan syndrome: A very rare syndrome characterized mainly by mental retardation, reduced muscle tone and increased skin pigmentation.
  • Megalencephalic leukoencephalopathy with subcortical cysts: A very rare syndrome characterized mainly by a progressive brain destruction that causes mental retardation and incoordination that starts early in life.
  • Megalencephaly: Abnormally large brain.
  • Megalencephaly - polymicrogyria - post-axial polydactyly - hydrocephalus: A rare syndrome characterized mainly by brain abnormalities, extra digits and a excess fluid inside the skull.
  • Megalocornea mental retardation syndrome: A very rare genetic disorder characterized by reduced muscle tone from birth, mental retardation to varying degrees and eye abnormalities. The type and severity of symptoms is variable
  • Megarbane syndrome: A very rare disorder characterized by short stature, loose joints, hernias, facial abnormalities and severe psychomotor retardation.
  • Meinecke syndrome: A very rare syndrome characterized mainly by mental retardation and short broad thumbs.
  • Meleda Disease: A very rare inherited skin disorder primarily involving dry thick skin patches that develop on the palms of hands and soles of feet. The type and severity of symptoms is variable.
  • Meningitis: Dangerous infection of the membranes surrounding the brain.
  • Meningococcal disease: Dangerous bacterial infection causing meningitis or bacteremia.
  • Meningoencephalocele: A very rare developmental disorder where a part of the membrane that covers the brain and or part of the brain itself protrudes through an abnormal opening in the skull. The condition may be asymptomatic or if the defect is large, severe neurological abnormalities may result.
  • Mental Retardation, X-Linked: A group of inherited disorder characterized by mental retardation. The disorders are inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms. The mental retardation may occur on its own (nonsyndromic) or be associated with other abnormalities (syndromic). The severity of the mental retardation may vary between and even within disorders.
  • Mental illness: Any psychological syndrome
  • Mental retardation - anophthalmia - craniosynostosis: A very rare syndrome characterized mainly by mental retardation, absent eyes and premature fusion of skull bones.
  • Mental retardation - arachnodactyly - hypotonia - telangiectasia: A very rare syndrome characterized mainly by mental retardation, short fingers, reduced muscle tone and spider veins (telangiectasia).
  • Mental retardation - blepharophimosis - obesity - web neck: A very rare syndrome characterized mainly by mental retardation, eye abnormalities, obesity and a webbed neck.
  • Mental retardation - coloboma - slimness: A very rare syndrome characterized mainly by mental retardation, retinal coloboma and a slim build.
  • Mental retardation - contractural arachnodactyly: A rare disorder characterized mainly by the association of mental retardation with long thin fingers which were permanently flexed.
  • Mental retardation - epilepsy: A very rare syndrome characterized by the association of mental retardation with epilepsy.
  • Mental retardation - epilepsy - bulbous nose: A very rare syndrome characterized mainly by mental retardation, epilepsy and a bulbous nose. The condition has been reported in only two families.
  • Mental retardation - epilepsy, X-linked: A rare inherited disorder characterized by the association of mental retardation with epilepsy. The disorders are inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation - epileptic seizures - hypogonadism - hypogenitalism -microcephaly - obesity: A very rare syndrome characterized mainly by mental deficiency, epilepsy, small head, small genitals and obesity. Death occurs within the first two years of life.
  • Mental retardation - gynecomastia - obesity, X-linked: A very rare X-linked syndrome characterized mainly by the associated of mental retardation, enlarged male breasts and obesity.
  • Mental retardation - hip luxation - G6PD variant: A very rare syndrome characterized mainly by mental retardation, partially dislocated hips and an enzyme defect (G6PD).
  • Mental retardation - hypocupremia - hypobetalipoproteinemia: A very rare syndrome characterized mainly by mental retardation, low blood copper levels and low betalipoprotein levels in the blood.
  • Mental retardation - hypotonic facies syndrome, X-linked, 1: A group of rare syndromes characterized by severe mental retardation, unusual facial appearance and other variable abnormalities.
  • Mental retardation - macrocephaly - coarse facies - hypotonia: A very rare syndrome characterized mainly by mental retardation, large head, coarse face and reduced muscle tone.
  • Mental retardation - microcephaly - phalangeal - facial abnormalities: A very rare syndrome characterized mainly by mental retardation, small head, facial and bone abnormalities in the fingers and toes.
  • Mental retardation - multiple nevi: A rare disorder characterized mainly by the association of mental retardation with multiple nevi (permanent skin mark) on the skin.
  • Mental retardation - myopathy - short stature - endocrine defect: A very rare syndrome characterized mainly by mental retardation, muscle disease, short stature and endocrine defects.
  • Mental retardation - nasal hypoplasia - obesity - genital hypoplasia: A rare disorder characterized mainly by the association of mental retardation with obesity and underdeveloped genitals and nose.
  • Mental retardation - osteosclerosis: A rare disorder characterized mainly by the association of mental retardation with an abnormal hardening of the bone.
  • Mental retardation - short stature - absent phalanges: A very rare, recessively inherited syndrome characterized mainly by mental retardation, short stature and missing finger bones.
  • Mental retardation - short stature - cleft palate - unusual facies: A very rare syndrome characterized mainly by short stature, mental retardation, cleft palate and facial anomalies.
  • Mental retardation - short stature - deafness - genital: A very rare syndrome characterized mainly by mental retardation, short stature, deafness and genital abnormalities.
  • Mental retardation - short stature - hand contractures - genital anomalies: A very rare syndrome characterized mainly by mental retardation, short stature, hand contractures and genital abnormalities.
  • Mental retardation - short stature - heart and skeletal anomalies: A very rare syndrome characterized mainly by mental retardation, short stature and heart and skeletal anomalies.
  • Mental retardation - short stature - scoliosis: A very rare syndrome characterized mainly by mental retardation, short stature and scoliosis.
  • Mental retardation - short stature - unusual facies: A very rare syndrome characterized mainly by mental retardation, short stature and an unusual facial appearance.
  • Mental retardation - short stature, Bombay phenotype: A very rare syndrome characterized mainly by mental retardation, short stature and a blood abnormality.
  • Mental retardation - skeletal dysplasia - abducens palsy: A very rare syndrome characterized mainly by mental retardation, skeletal abnormalities and weakness of an eye muscle.
  • Mental retardation - spasticity - ectrodactyly: A very rare syndrome characterized mainly by mental retardation, spasticity and a cleft hand. In the reported case, the parents came from the same bloodline.
  • Mental retardation X-linked dysmorphism: A very rare syndrome characterized mainly by mental retardation, partially dislocated knees and teeth and facial abnormalities.
  • Mental retardation X-linked syndromic 7: A very rare syndrome characterized mainly by mental retardation, obesity, hypogonadism and tapered fingers.
  • Mental retardation X-linked, South African type: A very rare syndrome characterized mainly by mental retardation, mutism, facial anomalies, epilepsy and weak eye muscles. Males tended to have severe mental retardation whereas female carriers had mild or no mental retardation.
  • Mental retardation progressive spasticity, X-linked: A very rare syndrome characterized mainly by mental retardation and progressive spasticity and seizures. The disorder is X-linked and hence only affects males.
  • Mental retardation syndrome, Belgian type: A rare form of mental retardation reported in a Belgian family.
  • Mental retardation, Buenos Aires type: A very rare syndrome characterized mainly by mental retardation, physical retardation, unusual facial appearance and heart and kidney defects.
  • Mental retardation, Mietens-Weber type: A very rare genetic condition characterized by mental retardation, corneal opacity, nystagmus, elbow contractures and dwarfism.
  • Mental retardation, Smith-Fineman-Myers type: A rare inherited disorder characterized mainly by mental retardation and low facial muscle tone.
  • Mental retardation, X linked - precocious puberty - obesity: A rare disorder characterized by mental retardation, premature puberty and obesity. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - acromegaly - hyperactivity: A rare syndrome characterized mainly by mental retardation, hyperactivity and enlarged hands, feet and testes.
  • Mental retardation, X-linked - borderline MAOA metabolism anomaly: A very rare syndrome characterized mainly by mental retardation and lower than normal levels of monoamine oxidase A (MAOA) activity. Low levels of MAOA have been implicated with increased behavioral problems such as violence and impulsiveness.
  • Mental retardation, X-linked - choreoathesis - abnormal behavior: A rare X-linked disorder characterized by mental retardation, abnormal behavior and a movement disorder. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - corpus callosum agenesis - spastic quadriparesis: A rare disorder characterized by mental retardation, abnormal development of a part of the brain called the corpus callosum and spastic quadriparesis. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - cubitus valgus - typical face: A rare disorder characterized by mental retardation, unusual facial appearance and a turned out elbow (cubitus valgus). The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - dystonia - dysarthria: A very rare X-linked disorder characterized by the association of mental retardation with dystonia (movement disorder) and dysarthria (speech disorder).
  • Mental retardation, X-linked - epilepsy - progressive joint contractures - typical face: A rare disorder characterized by mental retardation, epilepsy, unusual facial appearance and slowly-progressive joint contractures. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - gynecomastia - obesity: A rare disorder characterized by mental retardation, obesity, enlarged male breasts, speech problems and other anomalies. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - hypogonadism - ichthyosis - obesity - short stature: A rare X-linked disorder characterized by mental retardation, obesity, short stature, hypogonadism and a skin disorder. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - hypotonia - facial dysmorphism - aggressive behavior: A rare X-linked disorder characterized by mental retardation, reduced muscle tone, aggressive behavior and unusual facial appearance. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked - hypotonic face: A group of syndromes characterized mainly by mental retardation and reduced tone in the facial muscles. Various other abnormalities may be present.
  • Mental retardation, X-linked - macrocephaly - macro-orchidism: A rare disorder characterized by mental retardation, enlarged testes and a large head. Not all patients will exhibit all of these symptoms.
  • Mental retardation, X-linked recessive - macrocephaly - ciliary dysfunction: A rare disorder characterized by mental retardation, large head and dysfunctional cilia. The cilia are tiny hairs that line the breathing airways and act to remove unwanted substances from building up and causing infection. The disorder is X-linked and hence only males exhibit the symptoms.
  • Mental retardation, X-linked syndromic 12: A syndromic form of mental retardation which also involves mutism, retarded growth, seizures and frequent infections. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms. The genetic defect is located on chromosome Xp11.
  • Mental retardation, X-linked syndromic 14: A syndromic form of mental retardation which also involves variable features including poorly muscled build and facial anomalies. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms. The genetic defect is located on chromosome Xq25-q26.
  • Mental retardation, X-linked with brachydactyly and macroglossia: A syndromic form of mental retardation which also involves short digits and an enlarged tongue. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, 1: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.3-q21.1. Female carriers may suffer some mental deficiency.
  • Mental retardation, X-linked, 12: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.
  • Mental retardation, X-linked, 14: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.3-q13.3.
  • Mental retardation, X-linked, 16: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the MECP2 gene on chromosome Xq28. Females tended to be affected as well as males although to a lesser degree.
  • Mental retardation, X-linked, 17: A rare form of non-syndromic mental retardation inherited in a X-linked manner. It occurs as a result the duplication of a small portion of genetic material on chromosome Xp11.22. Females tended to be affected as well as males although to a lesser degree.
  • Mental retardation, X-linked, 2: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp22.3. Mental retardation was mild to moderate.
  • Mental retardation, X-linked, 20: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq11-q21.
  • Mental retardation, X-linked, 21: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the IL1RAPL1 gene on chromosome Xp22.1-p21.3. Female carriers may also suffer from some mental deficiency.
  • Mental retardation, X-linked, 23: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq23-q24.
  • Mental retardation, X-linked, 29: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp22.3-p21.3.
  • Mental retardation, X-linked, 3: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the RABGDIA gene on chromosome Xq28. Female carriers may be asymptomatic or suffer varying degrees of mental retardation.
  • Mental retardation, X-linked, 30: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the p21-activated kinase-3 gene on chromosome Xq21.3-q24. Female carriers were generally asymptomatic.
  • Mental retardation, X-linked, 36: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the ARX gene on chromosome Xp22.1-p21.1. Female carriers may present with varying degrees of mental retardation as well.
  • Mental retardation, X-linked, 42: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq26. The mental retardation ranged from mild to moderate in males whereas female carriers were asymptomatic.
  • Mental retardation, X-linked, 43: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the ARX gene on chromosome Xp22.31-p21.2. Female carriers may present with varying degrees of mental retardation as well.
  • Mental retardation, X-linked, 45: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the zinc finger protein-81 gene on chromosome Xp22.1-p11.
  • Mental retardation, X-linked, 46: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the Rho guanine nucleotide exchange factor-6 gene on chromosome Xq26. Female carriers tend to be normal.
  • Mental retardation, X-linked, 49: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp22.3.
  • Mental retardation, X-linked, 50: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.3-p11.21.
  • Mental retardation, X-linked, 52: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.21-q22.33. Mental retardation tends to be profound in childhood and doesn't progress.
  • Mental retardation, X-linked, 53: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq22.2-q26.
  • Mental retardation, X-linked, 54: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the ARX gene on chromosome Xp22.1-p21.3. Female carriers may present with varying degrees of mental retardation as well.
  • Mental retardation, X-linked, 59: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the sigma-2 subunit of the adaptor protein-1 gene on chromosome Xp22. Mental retardation ranged from mild to severe.
  • Mental retardation, X-linked, 63: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the FACL4 gene on chromosome Xq22.3. Female carriers may be asymptomatic or suffer varying degrees of mental retardation.
  • Mental retardation, X-linked, 72: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq28.
  • Mental retardation, X-linked, 73: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp22.2.
  • Mental retardation, X-linked, 77: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq12-q21.3. Mental retardation tends to be moderate to severe.
  • Mental retardation, X-linked, 78: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.4-p11.23. The mental retardation tended to be from moderate to severe in males and mild to severe in female carriers.
  • Mental retardation, X-linked, 81: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.2-q12.
  • Mental retardation, X-linked, 82: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xq24-q25.
  • Mental retardation, X-linked, 84: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect on chromosome Xp11.3-q22.3.
  • Mental retardation, X-linked, 9: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the FTSJ1 gene on chromosome Xp11.23.
  • Mental retardation, X-linked, 91: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the ZDHHC15 gene on chromosome Xq13.3.
  • Mental retardation, X-linked, 93: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the BRWD3 gene. Female carriers may also suffer from some mental deficiency.
  • Mental retardation, X-linked, 94: A rare form of mental retardation inherited in a X-linked manner. It occurs as a result of a defect in the GRIA3 gene on chromosome Xq25-q26.
  • Mental retardation, X-linked, Armfield type: A rare disorder characterized by mental retardation, seizures, short stature, small hands and small feet. The disorder is X-linked and hence only males exhibit the symptoms. The genetic defect occurs on chromosome Xq28.
  • Mental retardation, X-linked, Brooks type: A rare syndrome characterized by mental retardation, unusual facial appearance and retarded growth.
  • Mental retardation, X-linked, Brunner type: A very rare disorder where a deficiency of monoamine oxidase A causesmild mental retardation and behavioral problems.
  • Mental retardation, X-linked, Cabezas type: A rare X-linked disorder characterized by mental retardation, muscle wasting, short stature and other problems. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Cantagrel type: A rare X-linked disorder characterized by mental retardation, reduced infant muscle tone, developmental delay and other problems. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Pai type: A rare X-linked disorder characterized by mental retardation and a slightly unusual facial appearance. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Raynaud type: A rare disorder characterized by mental retardation, growth hormone deficiency, short stature, small head and a peculiar face. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Reish type: A rare disorder characterized by mental retardation, brain anomalies, skeletal malformations, intestinal problems, eye and ear anomalies, cleft palate and kidney abnormalities. Some infants with the disorder die soon after birth due to breathing problems. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Seemanova type: A rare X-linked disorder characterized by mental retardation, retarded growth and small genitals. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Shrimpton type: A rare X-linked disorder characterized by mental retardation, small head, strabismus and short stature. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Stevenson type: A rare disorder characterized by mental retardation, reduced muscle tone and other anomalies. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Stoll type: A rare disorder characterized by mental retardation, short stature and unusual facial appearance. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Turner type: A rare disorder characterized by mental retardation which is severe in males and moderate in females. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, Vitale type: A rare disorder characterized by mental retardation and facial and skeletal anomalies. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms. The genetic defect occurs on chromosome Xq24.
  • Mental retardation, X-linked, Zorick type: A rare disorder characterized by mental retardation and muscle disease. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, X-linked, nonspecific: Mental retardation that is not associated with any other physical, mental or neurological abnormality. In X-linked disorders, generally males are more severely affected and the female carriers are often asymptomatic or have only mild symptoms.
  • Mental retardation, X-linked, syndromic 11: A rare form of mental retardation inherited in a X-linked manner. It is also associated with an unusual facial appearance and results from a defect on chromosome Xq26-q27. Female carriers tended to have some degree of facial dysmorphism but no mental retardation.
  • Mental retardation, X-linked, syndromic, due to JARID1C mutation: A rare disorder characterized by mental retardation, spasticity and other variable features. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms. The disorder is caused by a defect on the JARID1C gene on chromosome Xp11.22-p11.21.
  • Mental retardation, X-linked, with cerebellar hypoplasia and distinctive facial appearance: A very rare syndrome characterized by moderate to severe mental retardation, unusual facial appearance and an underdeveloped brain.
  • Mental retardation, X-linked, with isolated growth hormone deficiency: A rare disorder characterized by severe mental retardation and growth hormone deficiency. The disorder is inherited in a X-linked manner which means that only males display the full range of symptoms whereas female carriers may have mild or no symptoms.
  • Mental retardation, autosomal recessive, 1: A rare form of recessively inherited mental retardation caused by a defect on chromosome 4q25-q26.
  • Mental retardation, autosomal recessive, 10: A rare form of recessively inherited mental retardation caused by a defect on chromosome 16p12-q12. The mental retardation tends to be moderate.
  • Mental retardation, autosomal recessive, 11: A rare form of recessively inherited mental retardation caused by a defect on chromosome 19q13.2-q13.3.
  • Mental retardation, autosomal recessive, 2: A rare form of recessively inherited mental retardation caused by a defect on chromosome 3p26.2.
  • Mental retardation, autosomal recessive, 3: A rare form of recessively inherited mental retardation caused by a defect on chromosome 19p13.12.
  • Mental retardation, autosomal recessive, 4: A rare form of recessively inherited mental retardation caused by a defect on chromosome 1p21.1-p13.3.
  • Mental retardation, autosomal recessive, 5: A rare form of recessively inherited mental retardation caused by a defect on chromosome 5p15-p14. The mental retardation tends to be moderate to severe.
  • Mental retardation, autosomal recessive, 6: A rare form of recessively inherited mental retardation caused by a defect on chromosome 6q16-q21.
  • Mental retardation, autosomal recessive, 7: A rare form of recessively inherited mental retardation caused by a defect on chromosome 8p12. The mental retardation tends to be moderate.
  • Mental retardation, autosomal recessive, 8: A rare form of recessively inherited mental retardation caused by a defect on chromosome 10q22. The mental retardation tends to be mild to moderate.
  • Mental retardation, autosomal recessive, 9: A rare form of recessively inherited mental retardation caused by a defect on chromosome 14q11.2-q12. The mental retardation tends to be mild.
  • Mental retardation, keratoconus, febrile seizures, and sinoatrial block: A rare disorder characterized by mental retardation, seizures with fever, an eye disorder and a heart anomaly. The heart condition requires a pacemaker in some cases.
  • Mental retardation, macrocephaly, short stature and craniofacial dysmorphism: A very rare syndrome characterized by mental retardation, short stature, a large head and facial abnormalities.
  • Mental retardation, non-syndromic, autosomal recessive: A group of recessively inherited forms of mental retardation. The various forms are differentiated by the origin of the genetic defect.
  • Mental retardation, unexplained: Mental retardation that has no obvious cause.
  • Mental retardation-polydactyly-uncombable hair: A very rare syndrome characterized mainly by mental retardation, extra fingers and uncombable hair.
  • Mesomelia radial hypoplasia bifid thumb unusual facies: A rare syndrome characterized mainly by skeletal abnormalities, dwarfism and hair, nail, skin and teeth abnormalities.
  • Metabolic disorders: Disorders that affect the metabolic system in human
  • Metaphyseal dysostosis mental retardation conductive deafness: A rare, recessively inherited disorder characterized by mental retardation, deafness and skeletal abnormalities.
  • Methionine malabsorption syndrome: A rare inherited disorder characterized by impaired absorption of methionine and other amino acids. The methioning that is not absorbed is converted by an intestinal bacteria into an acid which gives the urine a distinctive odor. The urine smells like that of a building used to dry hops.
  • Methylcobalamin deficiency, cbl E complementation type: An inherited organic acid disorder where an enzyme deficiency (cbl E) impairs the body's ability to break down cobalamin in the diet. This results in a buildup of homocystine which results in harmful affects.
  • Methylene tetrahydrofolate reductase deficiency: A inborn error of metabolism where an inherited deficiency of methylene tetrahydrofolate reductase causes symptoms of ranging severity - from asymptomatic to severe neurological degeneration and premature death.
  • Methylmalonic acidemia - homocystinuria: A rare inborn error of metabolism which results in impaired vitamin B12 metabolism. There are a number of forms of this condition with variable severity.
  • Methylmalonicaciduria with homocystinuria, cobalamin F: An inherited organic acid disorder where an enzyme deficiency (cbl F) impairs the body's ability to break down certain proteins (methionine, threonine, isoleucine and valine) consumed in the diet. This results in a buildup of methylmalonic acid and homocystine which results in harmful affects.
  • Methylmalonicaciduria, vitamin B12 unresponsive, mut -: A metabolic disorder whose severity is somewhat variable with the degree of neurological involvement ranging from severe mental retardation to mild developmental delay. Some patients have no neurological involvement. The condition involves abnormal metabolism of vitamin B12 which doesn't respond to treatment using vitamin B12 administration. This disorder is less severe than the mut (0) form.
  • Michelin tyre baby syndrome: A rare birth malformation characterized by excessive folded skin and characteristic skin lesions (lipomatous nevus).
  • Mickleson syndrome: A very rare syndrome characterized mainly by mental retardation and facial and skull anomalies.
  • Micro syndrome: A rare, recessively inherited disorder characterized by intellectual impairment, small head, various eye problems, small genitals and abnormal brain development.
  • Microbrachycephaly - ptosis - cleft lip: A very rare syndrome characterized mainly by a small, short head, droopy eyelids and a cleft lip.
  • Microcephalic primordial dwarfism, Toriello type: A very rare syndrome characterized mainly by dwarfism, mental retardation and other anomalies.
  • Microcephaly: Small head circumference
  • Microcephaly - deafness syndrome: A very rare syndrome characterized mainly by a small head and deafness.
  • Microcephaly - glomerulonephritis - Marfanoid habitus: A very rare syndrome characterized mainly by a small head, kidney disorder and a and a tall, slight build.
  • Microcephaly - hypergonadotropic hypogonadism - short stature: A very rare syndrome characterized mainly by a small head, short stature and hypogonadism.
  • Microcephaly - mental retardation - retinopathy: A very rare syndrome characterized mainly by a small head, mental retardation and retinal disease.
  • Microcephaly - mental retardation - spasticity - epilepsy: A very rare disorder characterized by an abnormally small head, mental retardation, spasticity and epilepsy.
  • Microcephaly - mesobrachyphalangy - tracheoesophageal fistula syndrome: A very rare syndrome characterized by an abnormally small head, short fingers and an abnormal opening between the trachea and esophagus.
  • Microcephaly - microphthalmos - blindness: A very rare syndrome characterized mainly by a small head, small eyes and blindness.
  • Microcephaly - pontocerebellar hypoplasia - dyskinesia: A rare, recessively inherited disorder characterized by an abnormally small brain and brainstem which manifests as a small head and mental retardation. The brain progressively degenerates.
  • Microcephaly - seizures - mental retardation - heart disorders: A very rare syndrome characterized mainly by a small head, seizures, mental retardation and heart disorders.
  • Microcephaly - sparse hair - mental retardation - seizures: A very rare disorder characterized by an abnormally small head, sparse hair, mental retardation and seizures.
  • Microcephaly nonsyndromal: An abnormally small head that is not associated with any other genetic defect.
  • Microcephaly with spastic quadriplegia: A very rare disorder characterized by an abnormally small head and quadriplegia.
  • Microcephaly, holoprosencephaly, and intrauterine growth retardation: A rare syndrome involving a small head, retarded fetal growth and holoprosencephaly (brain malformation where the two halves of the brain fail to separate).
  • Microcephaly, primary autosomal recessive: A rare, recessively inherited condition characterized by a small head. The 6 forms of this condition differ with respect to the origin of the genetic defect involved. The size of the brain often reduces in size with age with many cases resulting in death before the age of 30 years.
  • Microcephaly, primary autosomal recessive, 1: A rare, recessively inherited condition characterized by a small head. The genetic defect involved in type 1 occurs on chromosome 8p.
  • Microcephaly, primary autosomal recessive, 2: A rare, recessively inherited condition characterized by a small head. The genetic defect involved in type 2 occurs on chromosome 19q13.1-13.2.
  • Microcephaly, primary autosomal recessive, 3: A rare, recessively inherited condition characterized by a small head. The genetic defect involved in type 3 occurs on chromosome 9q34.
  • Microcephaly, primary autosomal recessive, 4: A rare, recessively inherited condition characterized by a small head. The genetic defect involved in type 4 occurs on chromosome 15q15-q21.
  • Microcephaly, primary autosomal recessive, 5: A rare, recessively inherited condition characterized by a small head. The genetic defect involved in type 5 occurs on chromosome 1q31.
  • Microcephaly, primary autosomal recessive, 6: A rare, recessively inherited condition characterized by a small head. The genetic defect involved in type 6 occurs on chromosome 13q12.2.
  • Microdeletion 3q29: A rare chromosomal disorder where a small portion of chromosome 3 is missing. The main features of the syndrome are mental retardation and slightly unusual facial appearance.
  • Microencephaly: Small brain. The condition is often characterized by a small head and neurological problems. The type and severity of symptoms are variable.
  • Microgastria short stature diabetes: A rare syndrome characterized by a very small stomach, diabetes and a growth hormone deficiency.
  • Microphthalmia - ankyloblepharon - mental retardation: A rare syndrome characterized mainly by small eyes, mental retardation and fusion of the edges of the eyelids.
  • Microphthalmia - camptodactyly - mental retardation: A very rare disorder characterized by the association of small eyes, mental retardation and permanently flexed fingers.
  • Microphthalmia and mental deficiency: A very rare syndrome characterized mainly by small eyes and mental deficiency.
  • Microphthalmia syndromic, type 10: A rare inherited syndrome characterized mainly by small eyes and wasting of brain tissue.
  • Microphthalmia syndromic, type 4: A rare syndrome characterized mainly by small or absent eyes, mental retardation and the partial fusion of the eyelid margins (ankyloblepharon).
  • Microphthalmia syndromic, type 8: A rare syndrome characterized by small eyes, small head, missing toes and protruding jaw.
  • Microphthalmia, syndromic 7: A rare genetic disorder characterized by eye and skin abnormalities involving irregular red streaks of skin on the head and neck.
  • Midface hypoplasia, corneal clouding, subvalvular aortic stenosis and mental and somatic retardation: A rare syndrome characterized mainly by an underdeveloped midface, corneal clouding, mental and somatic retardation and narrowed aorta.
  • Mietens syndrome: A rare condition characterized by short stature, short forearms, dislocated radius, strabismus and mental retardation.
  • Miles-Carpenter X-linked mental retardation syndrome: A rare genetic syndrome characterized by mental retardation, contractures at birth and low fingertip arches.
  • Miller-Dieker syndrome: A rare genetic disorder characterized by a smooth brain surface. The condition occurs because of deletion of genetic material from the short arm of chromosome 17 ath a particular location (17p13.3).
  • Mitochondrial encephalomyopathy - aminoacidopathy: A very rare syndrome characterized mainly by muscle and brain disease and an amino acid disorder.
  • Mobius syndrome: Type of facial paralysis.
  • Mohr syndrome: A rare genetic disorder characterized by oral frenula, oral clefts, underdeveloped nose flapss and finger abnormalities.
  • Mohr-Tranebjaerg syndrome: A very rare syndrome characterized mainly by nerve degeneration. Deafness usually occurs early in life.
  • Monoamine oxidase A deficiency: A very rare syndrome characterized mainly low levels of monoamine oxidase A (MAOA) activity. Low levels of MAOA have been implicated with increased behavioral problems such as violence and impulsiveness.
  • Monosomy 8q12 21: A very rare chromosomal disorder where a portion of chromosome 8q is missing. The main symptoms include eye, ear and kidney abnormalities as well as mental retardation.
  • Monosomy 8q21 q22: A very rare chromosomal disorder where a portion of chromosome 8q is missing resulting in various abnormalities.
  • Montefiore syndrome: A very rare syndrome characterized mainly by skull, facial, heart and digital abnormalities.
  • Mowat-Wilson syndrome: A very rare syndrome characterized mainly by mental retardation, a small head, characteristic facial appearance and various other abnormalities.
  • Mucolipidoses: A group of inherited metabolic disorders involving the accumulation of carbohydrates (glycosaminoglycans) and lipids within the tissues of the body due to a deficiencies or abnormal action of various lysosomal enzymes. This abnormal accumulation of carbohydrates and lipids within cells causes them to be damaged which often results in symptoms such as mental retardation and skeletal deformities. Symptoms may become apparent at birth or during childhood or adolescence. Premature death can occur in severe cases. There is a vast array of symptoms that can occur depending on the specific disorder involved.
  • Mucolipidosis III: A rare metabolic disorder where deficiency of a particular enzyme leads to the buildup of mucopolysaccharides and mucolipids in the body which is harmful to the body and leads to premature death.
  • Mucolipidosis IV: A condition which is characterized by the accumulation of both glycoaminoglycans and lipids in tissues
  • Mucolipidosis type 4: A rare inherited biochemical disorder involving the harmful accumulation of certain chemicals (ganglioside and mucopolysaccharide) in body tissues due to the deficiency of an enzyme needed to process it.
  • Mucopolysaccharidoses: A lysosomal storage disorder that is caused by a deficiency of the ability to metabolise glycosaminoglycans
  • Mucopolysaccharidosis VII: Disorder of mucopolysaccharide metabolism.
  • Mucopolysaccharidosis type 2 Hunter syndrome- severe form: A rare inherited biochemical disorder characterized by the accumulation of mucopolysaccharides (glycosaminoglycans) in various body tissues due to insufficient amounts of the enzyme (iduronidate 2-sulfatase) needed to break it down.
  • Mucopolysaccharidosis type 7 Sly syndrome: A rare inherited biochemical disorder characterized by the accumulation of mucopolysaccharides (glycosaminoglycans) in various body tissues due to insufficient amounts of the enzyme (beta-glucuronidase) needed to break it down.
  • Mucopolysaccharidosis type I Hurler syndrome: A rare inherited biochemical disorder characterized by the accumulation of mucopolysaccharides (glycosaminoglycans) in various body tissues due to insufficient amounts of the enzyme (?-L-diuronidase) needed to break it down. There are three main sub-types of the disorder: Hurler - severe form, Scheie - mild form and Hurler/Scheie form which is intermediate.
  • Muller-Barth-Menger syndrome: A rare disorder characterized by brain malformations, seizures, excessive hairiness and overlapping fingers.
  • Multifocal heterotopia: A rare inherited disorder where a part of the brain tissue is misplaced during development. More specifically, brain tissue is abnormally located in multiple locations within the brain.
  • Multiple carboxylase deficiency, propionic acidemia: A disorder of fat metabolism where the body is unable to convert fat to energy due to the lack of a number of enzymes (carboxylases). Sufferers need to eat regularly to prevent symptoms. Symptoms are determined by the size and exact location of the tumor.
  • Multiple congenital anomalies - mental retardation - growth failure and cleft lip/ palate: A very rare syndrome characterized mainly by mental retardation, growth failure, cleft lip, cleft palate and various other abnormalities.
  • Multiple pterygium syndrome: A very rare disorder characterized by webbing of various parts of the body, contractures, short stature, fusion of neck vertebrae and facial anomalies.
  • Multiple synostosis syndrome: A rare genetic disorder characterized by multiple bone fusions involving the face, limbs and middle ear.
  • Muscle phosphoglycerate kinase deficiency: An inherited genetic muscle disease where an enzyme deficiency (phosphoglycerate kinase) affects the normal processes that convert carbohydrates from food into energy.
  • Muscle-eye-brain syndrome: A genetic disease characterized by muscle weakness, congenital brain abnormalities and eye problems as well as other defects.
  • Muscular dystrophy - white matter spongiosis: A very rare syndrome characterized mainly by muscle problems, seizures and mental retardation.
  • Muscular dystrophy, Duchenne and Becker type: An inherited l disorder characterized by progressive muscle weakness. The disorder is caused by a genetic anomaly and results in insufficient quantities of or ineffective dystrophin which is needed for normal muscle functioning. The disorder is expressed in males but females can be carriers.
  • Muscular dystrophy, congenital, type 1C: A recessively inherited muscle disease characterized by muscle weakness and wasting from infancy. Sufferers are generally unable to achieve the ability to walk unaided.
  • Muscular dystrophy, limb-girdle - mental retardation: A rare disorder where muscle weakness and wasting starts in the proximal muscles (upper limbs, shoulders and hips). The condition is caused by a deficiency of alpha-dystroglycan in the muscles.
  • Muscular dystrophy, limb-girdle, autosomal recessive, type 2K: An autosomal recessive form of limb-girdle muscular dystrophy where muscle weakness and atrophy is caused by mutations in the gene for O-mannosyltransferase-1.
  • Myhre Syndrome: A very rare inherited disorder characterized by retarded growth, mental retardation, bone abnormalities and distinctive facial features.
  • Myhre-Ruvalcaba-Graham syndrome: A rare disorder characterized by mental retardation, retarded growth before and after birth, early-onset deafness and facial anomalies as well as other problems.
  • Myopathy - growth and mental retardation - hypospadias: A very rare syndrome characterized mainly by muscle disease, retarded growth, mental retardation and abnormally placed urethral opening.
  • Myopathy and diabetes mellitus: A very rare syndrome characterized mainly by muscle disease and diabetes mellitus. The condition was highly variable with respect to the severity, range and onset of symptoms.
  • Myopathy with lactic acidosis and sideroblastic anemia: A rare disorder of the bone marrow and skeletal muscles which manifests as muscle disease and anemia. Progressive intolerance to exercise usually starts during childhood with anemia occurring around adolescence.
  • Myotonic Dystrophy: An inherited disorder characterized by progressive muscle weakness and wasting as well as eye defects, heart abnormalities and other anomalies. The severity of the condition is greatly variable. There are two type of myotonic dystrophy with type 1 being more severe than type 2.
  • N-acetyl glutamate synthetase deficiency: A rare inherited urea cycle disorder where a lack of a certain enzyme (N-acetyl glutamate synthetase) results in accumulation of ammonia in the blood as it can't be broken down and removed through the urine.
  • Nakajo syndrome: A very rare syndrome characterized mainly by
  • Nakajo-Nishimura syndrome: A rare disorder involving muscle degeneration, loss of skin fat and impaired immune functioning.
  • Narrow oral fissure - short stature - cone-shaped epiphyses: A very rare syndrome characterized mainly by narrow mouth opening, short stature and abnormal bone development.
  • Neonatal ALD: Progressive form of ALD in newborns.
  • Nephroblastomatosis - fetal ascites - macrosomia - wilms tumor: A rare condition characterized by kidney abnormalities, macroxomia, endocrine pancreas abnormalities, large fetus and mental retardation.
  • Nephroblastomatosis, fetal ascites, macrosomia and Wilms tumor: A rare condition characterized by kidney abnormalities, macroxomia, endocrine pancreas abnormalities, large fetus and mental retardation.
  • Nephrogenic diabetes insipidus: A rare inherited condition where the kidneys can't concentrate the urine sufficiently which results in excessive urination and thirst. The condition occurs because the kidneys are unable to respond to the antidiuretic hormone.
  • Neuraminidase deficiency: A rare inherited disorder involving an enzyme (neuraminidase and beta-galactosidase) deficiency which results in a build up of glycoproteins (sialyloligosaccharides) in the urine.
  • Neuroaxonal dystrophy - renal tubular acidosis: A very rare syndrome characterized mainly by muscle and kidney abnormalities.
  • Neurodegenerative syndrome, X-linked, Bertini type: A very rare neurodegenerative disorder characterized mainly by reduced muscle tone, ataxia, recurring bronchopulmonary infections and psychomotor deficit. The disorder is X-linked and thus only males suffer the full extent of the symptoms whereas female carriers may be asymptomatic or have only mild symptoms.
  • Neurodegenerative syndrome, X-linked, Hamel type: A very rare neurodegenerative disorder characterized mainly by mental retardation, blindness, convulsions, spasticity and early death. The disorder is X-linked and thus only males suffer the full extent of the symptoms whereas female carriers may be asymptomatic or have only mild symptoms.
  • Neurofaciodigitorenal syndrome: A very rare syndrome characterized mainly by
  • Neurofibromatosis-Noonan syndrome: A rare disorder where the patients has symptoms of neurofibromatosis (nerve tumors) and Noonan syndrome (short stature, bleeding problems, heart defect, unusual facial features, skeletal anomalies, webbed neck).
  • Neuronal Migration Disorders: Group of disorders caused by abnormal growth of nerves in the brain and head.
  • Neuropathy motor sensory type 2 deafness mental retardation: An inherited neurological disease characterized by the gradual degeneration of nerves which starts in the hands and feet and results in progressive numbness, muscle weakness and loss of function. Deafness and mental retardation are also involved.
  • Nguyen syndrome: A rare disorder characterized by low blood cholesterol, mental retardation and various congenital anomalies.
  • Nicolaides-Baraitser syndrome: A very rare syndrome characterized mainly by short stature, reduced hair, short fingers, epilepsy and abnormal bone development.
  • Niemann-Pick disease: A rare inherited biochemical disorder involving the deficiency of an enzyme (acid sphingomyelinase) needed to break down certain lipids which results in an accumulation of these lipids in the body.
  • Night blindness - skeletal anomalies - unusual facies: A very rare syndrome characterized mainly by night blindness, a distinctive face and skeletal abnormalities.
  • Nijmegen Breakage Syndrome: A very rare syndrome characterized mainly by a small head, reduced immunity and increased risk of cancer.
  • Nivelon-Nivelon-Mabille syndrome: A very rare syndrome characterized mainly by severe dwarfism, abnormal bone development and central nervous system and eye problems.
  • Non-lissencephalic cortical dysplasia: A brain development abnormality characterized by the development of small brain convolutions that generally cause mental retardation. Symptoms depend on the location and extent of the abnormality.
  • Noonan Syndrome: A rare genetic disorder characterized by a webbed neck, chest deformity, undescended testes and pulmonic stenosis.
  • Noonan syndrome 3: A genetic condition characterized by short stature, distinctive facial characteristics, learning difficulties, congenital heart conditions and various other anomalies.
  • OFD syndrome type 8: A rare genetic disorder characterized by oral frenula, oral clefts, underdeveloped nose flapss and finger abnormalities.
  • OFD syndrome type IX: A rare genetic disorder characterized by oral frenula, oral clefts, underdeveloped nose flapss and finger and retinal abnormalities.
  • Obesity, hypothyroidism, craniosynostosis, cardial hypertrophy, colitis and intellectual deficiency: A rare syndrome characterized by a variety of features including obesity, hypothyroidism, premature fusion of skull bones, enlarged heart, colitis and mental retardation. The two reported cases both involved the development of HELLP syndrome during the mother's pregnancy.
  • Oculocerebral hypopigmentation syndrome, type Preus: A very rare syndrome characterized mainly by eye, brain and pigmentation abnormalities.
  • Oculocerebral syndrome with hypopigmentation: A rare inherited disorder involving lack of pigmentation and eye and brain defects caused by central nervous system abnormalities.
  • Oculocutaneous tyrosinemia: A rare condition where a deficiency of a liver enzyme (tyrosinase aminotransferase) causes tyrosine levels in the blood to increase and result in eye problems, mental retardation and horny skin lesions.
  • Oculodental syndrome: A familial disorder characterized by corneal dystrophy, enlarged gums and missing teeth
  • Oculopalatocerebral syndrome: A rare inherited syndrome characterized mainly by short stature, small head, mental retardation, cleft palate and eye problems.
  • Oculopalatoskeletal syndrome: A very rare syndrome characterized mainly by eye, mouth palate and skeletal abnormalities.
  • Ohtahara Syndrome: A very rare syndrome characterized mainly by epilepsy that starts within a month of birth.
  • Oliver syndrome: An extremely rare condition characterized by extra fingers and/or toes and mental retardation.
  • Onychodystrophy - deafness: A very rare inherited disorder involving deafness (D), onychodystrophy (O - nail malformation), osteodystrophy (O - bone malformation) and mental retardation (R).
  • Onychotrichodysplasia and neutropenia: A very rare syndrome characterized mainly by nail, hair and blood abnormalities.
  • Oppositional Defiant Disorder: A behavioral problem that occurs in children and involves persistent disobedience, defiance and hostility towards authority figures. The behavioral problem is greater than the normal pattern of child misbehaviors. The severity of the problem affects the child's ability to perform satisfactorily in home, school and community environments.
  • Opthalmo acromelic syndrome: A very rare syndrome characterized mainly by missing eyes and limb anomalies.
  • Opthalmoplegia - mental retardation - lingua scrotalis: A very rare syndrome characterized mainly by weak or paralyzed eye muscles, mental retardation and a fissured tongue.
  • Opthalmoplegia progressive external scoliosis: A rare disorder characterized by progressive weakening of external eye muscles and scoliosis.
  • Optic atrophy 2: An early onset form of progressive optic nerve dysfunction which results in impaired vision. Neurological symptoms are usually present and vision loss progresses very slowly. The disorder is caused by a genetic defect (Xp11.4-p11.21).
  • Oral facial digital syndrome, type 4: A rare inherited disorder characterized by facial, digital and oral abnormalities. Type IV is differentiated from the other types by the presence of severe shinbone deformity.
  • Ornithine transcarbamylase (OTC) Deficiency: A rare metabolic disorder where a deficiency of the enzyme ornithine transcarbamylase means that nitrogen isn't removed from the body and builds up in the blood in the form of ammonia.
  • Orofaciodigital syndrome type1: A rare genetic disorder characterized by variable malformations of the face, digits and inside the mouth. Type 1 is distinguished from the other types of this condition by the presence of polycystic kidneys and a X-linked dominant inheritance.
  • Orotic aciduria hereditary: A rare metabolic disorder where an inherited enzyme deficiency (lack of orotidylic pyrophosphorylase and orotidylic decarboxylase or a lack of orotidylic decarboxylase only) impairs the body's ability to break down orotic acid which then builds up in the body and causes damage.
  • Oroticaciduria 1: A rare metabolic disorder where deficiency of two enzymes (orotidylic pyrophosphorylase and orotidylic decarboxylase) which impairs the body's ability to break down orotic acid which then builds up in the body where it can cause damage.
  • Orotidylic decarboxylase deficiency: A rare metabolic disorder where deficiency of an enzyme (orotidylic decarboxylase) which impairs the body's ability to break down orotic acid which then builds up in the body where it can cause damage.
  • Osteochondrodysplatic dwarfism - deafness - retinitis pigmentosa: A rare syndrome characterized by extreme dwarfism, deafness, progressive scoliosis and retinal pigment anomalies.
  • Osteopetrosis - renal tubular acidosis: A rare disorder where increased bone density is caused by carbonic anhydrase II deficiency.
  • Osteopetrosis lethal: A severe, lethal form of the brittle bone condition called osteopetrosis.
  • Osteopetrosis with renal tubular acidosis: A rare disorder where increased bone density is caused by carbonic anhydrase II deficiency.
  • Osteoporosis - macrocephaly - mental retardation - blindness: A very rare syndrome characterized mainly by mental retardation, osteoporosis, blindness and a large head.
  • Osteoporosis-pseudoglioma syndrome: A rare genetic disorder characterized by early onset of osteoporosis (during childhood) and loss of vision resulting from retinal detachment due to a retinal pseudoglioma (inflammatory eye condition).
  • Oto-palato-digital syndrome, type 2: A rare genetic disorder characterized by head, face, mouth and bone abnormalities.
  • Otospondylomegaepiphyseal dysplasia: A rare genetic disorder where abnormal bone growth causes hearing loss, skeletal abnormalities and characteristic facial features.
  • Ovarioleukodystrophy: A rare syndrome characterized by ovarian failure and degeneration of the brain white matter which causes mental and motor problems.
  • PIBIDS syndrome: A rare inherited skin disorder characterized by photosensitivity (P), red, dry, scaly skin (I - ichthyosis), brittle hair (B), impaired physical and mental development (I), decreased fertility (D) and short stature (S). It is the same as IBIDS syndrome but involves photosensitivity.
  • Pachygyria - mental retardation - seizures: A very rare syndrome characterized by mental retardation and seizures caused by abnormal structural brain development called pachygyria.
  • Pachygyria, frontotemporal: A recessively inherited disorder characterized by abnormal brain development (pachygyria), mental retardation and various other abnormalities.
  • Paris-Trousseau thrombocytopenia: A very rare syndrome characterized mainly by bleeding problems, mental retardation, heart malformations and facial abnormalities.
  • Partial lissencephaly: A rare birth defect where the a part of the brain's surface is abnormally smooth. Severity of symptoms is determined by the extent of the defect.
  • Partington X-linked mental retardation syndrome: A rare genetic syndrome involving mental retardation, abnormal movements, seizures and ataxia. The syndrome is inherited in a X-linked manner which means that females are carriers but only males display the symptoms.
  • Passos-Bueno syndrome: A very rare syndrome characterized by mental retardation, reduced muscle tone, incontinence, muscle wasting and inability to walk or speak.
  • Patau syndrome: A condition characterised by autosomal trisomy
  • Patella hypoplasia - mental retardation: A very rare genetic disorder characterized by the association of knee problems and mental retardation.
  • Patterson pseudoleprechaunism syndrome: A very rare disorder characterized by excessive pigmentation, looks skin, unusual face, several mental retardation and bone abnormalities.
  • Patterson-Stevenson syndrome: A very rare syndrome characterized mainly by a missing fingers giving the hand a split appearance as well as jaw and face abnormalities.
  • Pectus excavatum macrocephaly dysplastic nails: A rare syndrome characterized mainly by a sunken chest, large head and abnormal nails.
  • Pericardium absent - mental retardation - short stature: A very rare syndrome characterized by mental retardation, short stature and an absent pericardium which is the fluid-filled sac surrounding the heart.
  • Periodic hyperlysinemia: A rare genetic disorder where the body lacks enzymes to metabolize lysine which then causes a harmful builds up of lysine and ammonia in the body.
  • Perisylvian syndrome: A very rare nerve disorder characterized by weakness or paralysis of face, jaw tongue and throat muscles. Other symptoms include seizures, delayed development and mental retardation.
  • Periventricular laminar heterotopia: A rare inherited disorder where a part of the brain tissue is misplaced during development. More specifically, brain tissue is abnormally located in the lining of the brain ventricles.
  • Pervasive developmental disorders: Group of developmental disorders often recognized before 3 years of age.
  • Petit-Fryns syndrome: A very rare syndrome characterized mainly by mental retardation, short stature and degeneration or loss of calcium in bones of the hands and feet.
  • Pfeiffer syndrome Type 3: A rare genetic disorder characterized by premature joining of certain skull bones during development which has an impact on the shape of the head and face. Features include craniofacial abnormalities, cardiovascular malformations and early death is common.
  • Pfeiffer-Mayer syndrome: A very rare syndrome characterized mainly by mental retardation, colobomata and an extra thumb.
  • Pfeiffer-Tietze-Welte syndrome: A very rare disorder characterized by mental retardation, split hand and premature fusion of the sagittal skull bones.
  • Phenobarbital antenatal infection: Fetal exposure to a drug called Phenobarbital which can be used as an anticonvulsant, sedative or hypnotic drug. The range of symptoms depends on the dosage and duration of the drug taking during pregnancy.
  • Phenylketonuria: A metabolic disorder where there is a deficiency of the enzyme phenylalanine hydroxylase which leads to a harmful buildup of the phenylalanine in the body. Normally the phenylalanine is converted into tyrosine. The severity of the symptoms can range from severe enough to cause mental retardation to mild enough not to require treatment. Severity is determined by the level of impairment of enzyme activity of phenylalanine hydroxylase.
  • Phenylketonuria type 2: A genetic condition where phenylalanine (component of protein) is unable to be broken down due to an enzyme (phenylalanine hydroxylase) deficiency which leads to a harmful build up of the compound. The condition is characterized by neurological symptoms as well as the presence of increased levels of phenylalanine in the blood.
  • Phillips-Griffiths syndrome: A rare syndrome characterized mainly by an eye defect called a coloboma and variable skeletal abnormalities.
  • Phosphoglycerate kinase 1 deficiency: An inherited genetic muscle disease where an enzyme deficiency (phosphoglycerate kinase) affects the normal processes that convert carbohydrates from food into energy.
  • Phosphoribosylpyrophosphate synthetase deficiency: A rare disorder where an enzyme (Phosphoribosylpyrophosphate synthetase) deficiency causes mental retardation and hypouricemia.
  • Phosphoribosylpyrophosphate synthetase superactivity: A rare X-linked metabolic disorder caused by the excessive activity of a particular enzyme (Phosphoribosylpyrophosphate synthetase). The main manifestations are increased production of uric acid and purine nucleotide.
  • Pili torti - developmental delay - neurological abnormalities: A very rare syndrome characterized mainly by developmental delay, twisted hair shafts and neurological symptoms.
  • Pilo dento ungular dysplasia - microcephaly: A very rare syndrome characterized mainly by hair, tooth and nail abnormalities as well as a small head.
  • Pilotto syndrome: A very rare syndrome characterized mainly by congenital heart disease, cleft lip and palate, scoliosis, short stature and mental retardation.
  • Pitt-Hopkins syndrome: A very rare syndrome characterized mainly by mental retardation with periods of overbreathing and apnea.
  • Pitt-Rogers-Danks syndrome: A rare genetic condition characterized by reduced fetal growth, mental retardation and distinctive facial features.
  • Piussan-Lenaert-Mathieu syndrome: A rare disorder characterized by mental retardation, a stiff thumb and shortness or absence of middle bones of fingers and toes (brachydactyly type A1).
  • Plum syndrome: A very rare syndrome characterized mainly by eye, brain and bone abnormalities.
  • Poikilodermatomyositis - mental retardation: A very rare syndrome characterized mainly by mental retardation , muscle inflammation and weakness and pigmentation abnormalities.
  • Polymicrogyria - turricephaly - hypogenitalism: A very rare syndrome characterized mainly by abnormal brain structure (polymicrogyria), cone shaped head and underdeveloped genitalia.
  • Polyneuropathy - mental retardation - acromicria - premature menopause: A very rare syndrome characterized mainly by premature menopause, sensory impairment, mental retardation and small, delicate facial bones.
  • Pontocerebellar hypoplasia with infantile spinal muscular atrophy: A rare, recessively inherited disorder characterized by an abnormally small brain and brainstem which manifests as a small head and mental retardation. The disorder is lethal with death usually occurring within the first year. The brain progressively degenerates.
  • Porencephaly: A central nervous system disorder involving cysts in the brain cortex caused by stroke, infection or genetic anomaly.
  • Porencephaly - cerebellar hypoplasia - malformations: A very rare syndrome characterized mainly by abnormal brain development and internal malformations.
  • Potocki-Shaffer syndrome: A very rare syndrome caused by the absence of a portion of chromosome 11p and characterized mainly by bone growths, enlarged fontanel and parietal foramina.
  • Powell-Chandra-Saal syndrome: A very rare syndrome characterized mainly by webbed joints and heart, vertebral, ear and radial defects.
  • Prader-Willi syndrome: A rare genetic disorder characterized by reduced muscle tone, obesity and small hands and feet.
  • Primerose syndrome: A very rare syndrome characterized mainly by mental retardation, cataracts, muscle disease and calcified ear cartilage. The muscle wasting starts in the lower legs and eventually involves the small hand muscles.
  • Progeria: A rare fatal genetic disorder characterized by extremely premature aging.
  • Progeria short stature pigmented nevi: A very rare inherited disorder characterized by premature aging, short stature, and immune system deficiency. The type and severity of symptoms is variable.
  • Prolidase deficiency: A rare metabolic disorder where an enzyme (prolidase) deficiency impairs the breakdown of certain proteins which causes a harmful buildup in the body. The type and severity of symptoms are variable and may include skin disorders, retarded motor development, impaired cognitive development, frequent infections and skeletal abnormalities.
  • Proteus Syndrome: A rare genetic disorder characterized by overgrowth of bones, fatty tissues and skin in various parts of the body.
  • Proud-Levine-Carpenter syndrome: A very rare syndrome characterized mainly by abnormal brain development, a small head and genital abnormalities.
  • Proximal 19q trisomy: A rare, newly described chromosomal syndrome characterized mainly by morbid obesity and mental retardation.
  • Pseudo-torch syndrome: A rare genetic syndrome characterized by a small head, eye disease and brain abnormalities. The symptoms are often very similar to another disorder caused by certain infections during pregnancy.
  • Pseudoadrenoleukodystrophy: A rare disorder where an enzyme deficiency (Acyl-CoA Oxidase) results in symptoms such as seizures, apnea, delayed psychomotor retardation and neurological deterioration.
  • Pseudoaminopterin syndrome: A very rare condtion characterized by mental and physical retardation, skull abnormalities and skeletal defects. The symptoms observed are similar to those caused by aminopterin which was once used to induce abortions but in the pseudo form there is no evidence of exposure to aminopterin.
  • Pseudohypoparathyroidism: An inherited disorder where the body is unable to respond to the parathyroid hormone even though there are normal levels of it. Impaired bone growth is the main feature of this disorder.
  • Pseudoprogeria syndrome: A very rare syndrome characterized mainly by absent eyelashes and eyebrows as well a mental retardation.
  • Psychiatric disorders: Any condition that affects ones mind
  • Psychological disorders: Any condition that affects ones mind
  • Pterygia - mental retardation - facial dysmorphism: A very rare syndrome characterized mainly by mental retardation, unusual facial features and joint webbing.
  • Pterygium colli - mental retardation - digital anomalies: A very rare syndrome characterized mainly by mental retardation, webbed neck and finger abnormalities.
  • Ptosis - coloboma - mental retardation: A very rare syndrome characterized mainly by droopy eyelids, coloboma and mental retardation.
  • Ptosis - coloboma - trigonocephaly: A very rare syndrome characterized mainly by droopy eyelids, coloboma and triogoncephaly as well as other variable features.
  • Purine nucleoside phosphorylase (PNP) deficiency: A condition which is characterized by a deficiency of purine nucleoside phosphorylate
  • Purine nucleoside phosphorylase deficiency: A very rare genetic disease involving an enzyme (purine nucleoside phosphorylase - PNP) deficiency which causes a buildup of toxic metabolic products which in turn impairs the development of T-cells (part of the body's immune system). The condition is characterized primarily by frequent infections and various neurological symptoms.
  • Pyromania: Compulsive arson and fire starting behavior disorder
  • Pyruvate dehydrogenase deficiency: An inherited carbohydrate metabolism disorder where a deficiency of pyruvate dehydrogenase results in metabolic acidosis and mental retardation as well as other neurological symptoms. The condition may be mild or severe. The condition is exacerbated by eating high carbohydrate meals and stress.
  • Pyruvate dehydrogenase phosphatase deficiency: A genetic disease involving an enzyme deficiency which causes exercise intolerance and mild developmental delay. Symptoms are variable.
  • Quattrin mcpherson syndrome: A rare syndrome characterized mainly by a large mouth, developmental delay and an unusual facial appearance.
  • Radioulnar synostosis mental retardation hypotonia: A very rare syndrome involving mental retardation, reduced muscle tone and fusion of the forearm bones.
  • Rajab-Spranger syndrome: A rare syndrome characterized mainly by a skin fat disorder, mental retardation and deafnes.
  • Ramon Syndrome: A rare genetic condition characterized by cherubism, enlarged gums, epilepsy, mental deficiency and excessive body hair (hypertrichosis).
  • Ramos-ArroyoClark syndrome: A very rare genetic disorder characterized distinctive facial features, ductus arteriosus, mental retardation and vision problems.
  • Rasmussen subacute encephalitis: A very rare progressive brain disease possibly caused by immune system problems. Symptoms become progressively worse and then the condition often stabilizes with a long life possible despite permanent neurological damage.
  • Rasmussen's Encephalitis: Rare possibly-autoimmune brain condition.
  • Rayner-Lampert-Rennert syndrome: A rare syndrome characterized mainly by ichthyosis (dry, scaly skin), mental retardation, dwarfism and kidney disease.
  • Reardon-Wilson-Cavanagh syndrome: A rare genetic syndrome characterized by progressive ataxia, deafness and mental retardation.
  • Reese-Ellsworth syndrome: A rare disorder characterized by iridogoniodysgenesis (underdeveloped iris and fluid channels in the eye) as well as mental retardation, cleft palate, syndactyly and muscle disease.
  • Renpenning syndrome 1: A very rare genetic disorder that affects males and is characterized mainly by mental retardation and facial anomalies.
  • Retinis pigmentosa - deafness - hypogenitalism: A very rare syndrome characterized mainly by progressive retinal damage, deafness and genital anomalies.
  • Retinitis pigmentosa - mental retardation - deafness: A very rare syndrome characterized mainly by progressive retinal damage, mental retardation and deafness.
  • Retinitis pigmentosa, deafness, mental retardation, hypogonadism: A rare genetic disorder characterized by mental retardation, reduced hormone production by the testes or ovaries, deafness and vision problems.
  • Retinopathy pigmentary mental retardation: A rare genetic condition characterized by degeneration of retinal pigments, cataracts, small head and mental retardation.
  • Rett-like syndrome: A very rare syndrome characterized mainly by
  • Rhizomelic chondrodysplasia punctata, type 1: A rare genetic disorder involving abnormal development of bones which causes abnormal calcification of bones near the joints. The genetic defect is located on chromosome 6q22-q24.
  • Rhizomelic chondrodysplasia punctata, type 3: A rare genetic disorder involving abnormal development of bones due to a particular enzyme deficiency (alkyldihydroxyacetonephosphate synthase). The bones have abnormal calcification of bones near the joints. The genetic defect is located on chromosome 2q31.
  • Rhizomelic syndrome: A very rare syndrome characterized mainly by short upper arm and thigh bones. Death frequently occurs in early childhood.
  • Rhombencephalosynapsis: Abnormal development of the brain where the vermis of the cerebellum is partially or totally absent and the cerebellar hemispheres are joined together. The type and severity of symptoms depends on the severity of the abnormality - symptoms can range from mild ataxia to cerebral palsy and mental retardation. The condition is usually associated with various other abnormalities or syndromes.
  • Richards-Rundle syndrome: A very rare syndrome characterized mainly by mental retardation, ataxia, deafness and ketoaciduria.
  • Richieri Costa Guion Almeida Cohen syndrome: A very rare syndrome characterized mainly by premature fusion of skull bones, facial anomalies and various other abnormalities.
  • Richieri Costa Guion-Almeida syndrome: A very rare syndrome characterized mainly by mental retardation, short stature, cleft lip/palate and eye anomalies.
  • Richieri-Costa Da Silva syndrome: A very rare syndrome characterized mainly by mental retardation, skeletal anomalies and delayed muscle relaxation.
  • Rickets: A rare condition where a lack of Vitamin D results in bone disease as it is essential for the process of bone calcification.
  • Rieger Syndrome: A rare genetic disorder characterized by underdeveloped or absent teeth and craniofacial and eye abnormalities.
  • Ring D2 chromosome: A rare chromosomal disorder where a portion of chromosome 2 is deleted and the two ends rejoin to form a ring. The condition results in the absence of thumbs, mental and physical retardation, toe and head abnormalities and distinctive facial features.
  • Roberts Pseudothalidomide Syndrome:
  • Roberts syndrome: A very rare genetic disorder involving a range of physical abnormalities.
  • Rodrigues blindness: A rare disorder characterized by severe eye malformations, short stature and hair and dental anomalies.
  • Roifman syndrome: A rare syndrome characterized by abnormal bone growth, immune deficiency and an eye disorder.
  • Rommen-Mueller-Sybert syndrome: A very rare syndrome characterized mainly by heart defects, short stature and craniofacial anomalies.
  • Rubella congenital syndrome: The transplacental infection of a fetus with rubella
  • Rubinstein-Taybi Syndrome: A rare congenital disorder characterized by very small stature, broad thumbs and toes, slanted palpebral fissures and hypoplastic maxilla.
  • Rubinstein-Taybi like syndrome: A condition characterized by numerous congenital abnormalities including small head, unusual facial features, short stature, broad thumb and big toe and mental retardation.
  • Ruvalcaba syndrome: A very rare disorder characterized by short stature, skeletal abnormalities, mental retardation and distinctive facial features.
  • Ruzicka-Goerz-Anton syndrome: A rare genetic syndrome characterized by rough scaly skin, deafness, mental retardation and skeletal anomalies.
  • SCARF syndrome: A rare syndrome characterized mainly by skeletal abnormalities, loose skin, premature fusion of skull bones, ambiguous genitalia, psychomotor retardation and facial abnormalities.
  • SIBIDS syndrome: A rare disorder characterized mainly by sulfur-deficient brittle hair as well as osteosclerosis.
  • SSADH deficiency (succinic semialdehyde dehydrogenase deficiency): A rare inherited metabolic disorder where an enzyme deficiency (succinic semialdehyde dehydrogenase) prevents the normal metabolism of gamma-aminobutyric acid.
  • Sabin-Feldman syndrome: A rare inherited disorder characterized by damage to brain tissue, chorioretinopathy (fluid build up under the retina) and mental retardation. The symptoms of this condition are similar to those of the parasitic infection called toxoplasmosis.
  • Saul-Wilkes-Stevenson syndrome: A very rare syndrome characterized mainly by muscle problems, abnormal skin pigmentation, movement disorder, mental retardation and scoliosis.
  • Say-Barber-Miller syndrome: A very rare syndrome characterized mainly by immune system problems and a small head.
  • Say-Carpenter syndrome: A very rare syndrome characterized mainly by wide set eyes, abnormally placed urethral opening in males and abnormal bone development.
  • Say-Field-Coldwell syndrome: A very rare syndrome characterized mainly by fingerlike thumbs and a dislocated kneecap.
  • Say-Meyer syndrome: A very rare syndrome characterized mainly by short stature, developmental delay and trigonocephaly (premature fusion of skull bones giving the forehead a triangular shape).
  • Schaap-Taylor-Baraitser syndrome: A very rare syndrome characterized mainly by deafness, cataracts and a deficiency of sex hormone production.
  • Schaefer-Stein-Oshman syndrome: A rare disorder where excessive growth and abnormal hardening affects the head and facial bones.
  • Schimke, X-linked, mental retardation syndrome: A very rare syndrome characterized by mental retardation, abnormal involuntary movements and retarded growth.
  • Schindler disease, type 3: Schindler disease is a rare congenital metabolic disorder involving a deficiency of a particular enzyme (alpha-N-acetylgalactosaminidase) which results in a buildup of glycoproteins in the body. The condition originates from a genetic mutation and is an inherited disorder. There are three main types of this condition, each with varying severity. Type 3 is an intermediate form and is between type 1 and 2 with respect to severity.
  • Schizencephaly: A very rare disorder where the brain fails to develop normally and slits or clefts form in the brain. They type and severity of symptoms is determined by the degree of abnormality.
  • Schizophrenia - mental retardation - deafness - retinitis: A very rare syndrome characterized mainly by mental retardation, deafness, retinitis and schizophrenia.
  • Schofer beetz bohl syndrome: A rare syndrome characterized mainly by brain calcification, mental retardation, short stature, diabetes insipidus and unusual facial appearance.
  • Scholte syndrome: A very rare syndrome characterized mainly by premature balding, dislocated kneecap, hypogonadism and small hands and feet.
  • Sclerosing bone dysplasia - mental retardation: A rare disorder characterized by abnormal hardening (sclerosis) of the bone and mental retardation.
  • Scott Craniodigital Syndrome: A condition which is characterized by deformities of the cranium and fingers
  • Scott syndrome: A very rare inherited syndrome characterized by head and digital abnormalities as well as mental retardation.
  • Seckel syndrome: A rare condition characterized by fetal and postnatal growth retardation, mental retardation and characteristic facial features.
  • Seckel syndrome 1: Seckel syndrome is a rare inherited disorder mainly involving retarded growth, mental retardation, small head and a facial appearance resembling a bird. It is often referred to as bird-headed dwarfism. There are three subtypes of the disorder. Additional variable symptoms may also occur.
  • Seckel syndrome 2: Seckel syndrome is a rare inherited disorder mainly involving retarded growth, mental retardation, small head and a facial appearance resembling a bird. It is often referred to as bird-headed dwarfism. There are three subtypes of the disorder. Type 2 tends to have less severe motor and mental retardation and the head is not small. Type 2 also involves at least one café au lait spot. Additional variable symptoms may also occur.
  • Seckel syndrome 3: Seckel syndrome is a rare inherited disorder mainly involving retarded growth, mental retardation, small head and a facial appearance resembling a bird. It is often referred to as bird-headed dwarfism. There are three subtypes of the disorder with type 1 being the most severe.
  • Seckel syndrome 4: A rare, recessively inherited disorder involving retarded growth, small head, mental retardation and a characteristic bird-head facial appearance.
  • Seckel-like syndrome, type Buebel: A rare syndrome characterized by dwarfism and other abnormalities characteristic of Seckel syndrome as well as hand and foot anomalies.
  • Seckle syndrome: A rare genetic disorder characterized by short stature, microcephaly and a prominent nose.
  • Seemanova-Lesny syndrome: A rare disorder characterized by spasticity, seizures, absent abdominal reflexes, small head and mental retardation.
  • Seizures - intellectual deficit due to hydroxylysinuria: A rare syndrome characterized by mental retardation, seizures and high levels of hydroxylysine in the urine.
  • Seizures mental retardation hair dysplasia: A rare syndrome characterized mainly by seizures, mental retardation and hair abnormalities.
  • Sengers-Hamel-Otten syndrome: A very rare syndrome characterized mainly by obesity, buildup of fluid inside the skull (hydrocephalus) and impaired sex hormone production.
  • Senior-Loken Syndrome: A rare inherited disorder characterized by kidney dysfunction and progressive eye disease.
  • Septo-Optic Dysplasia: A rare birth defect characterized by impaired vision and pituitary deficiency.
  • Septooptic dysplasia - digital anomalies: A very rare syndrome characterized mainly by finger and toe abnormalities as well as abnormal development of the optic nerve and pituitary gland. Antenatal exposure to sedatives may be a factor in the cause of the disorder.
  • Severe achondroplasia with developmental delay and acanthosis nigricans: A very rare inherited disorder characterized by abnormal bone development and brain and skin abnormalities.
  • Shaken Baby Syndrome: A condition caused by violent shaking of a baby.
  • Short limb dwarf mental retardation myopia: A rare syndrome characterized mainly by short stature, mental retardation and myopia.
  • Short stature - abnormal skin pigmentation - mental retardation: A very rare syndrome characterized mainly by short stature, mental retardation and skin pigmentation abnormalities.
  • Short stature mental retardation eye anomalies: A very rare syndrome characterized mainly by short stature, mental retardation and eye defects.
  • Shoulder girdle defect - mental retardation, familial: A very rare syndrome characterized mainly by mental retardation and a shoulder abnormality.
  • Shprintzen omphalocele syndrome: A rare syndrome characterized mainly by abnormal development of the pharynx and larynx which can result in a narrowed airway. Protrusion of intestines through the belly button also occurs. The voice is high pitched and spinal curvature and learning problems are other common symptoms.
  • Shprintzen-Golberg craniosynostosis: A very rare syndrome characterized by premature fusion of skull bones and a Marfanoid appearance, skeletal anomalies and learning problems.
  • Shwachman syndrome: A rare disorder where a pancreatic defect impairs digestive enzyme production and malfunction of the bone marrow produces blood abnormalities, particularly blood cells involved with fighting infection. These defects produce a range of symptoms as a result of malabsorption and poor ability to fight infections. Characterized by a lack of digestive enzymes and low immunity due to low leukocyte level.
  • Shwachman-Diamond Syndrome:
  • Sialidosis type II: A very rare inherited metabolic disorder where a defect in the enzyme alpha-neuraminidase prevents glycoproteins being metabolized - a severe form of Sialidosis type I.
  • Sialidosis type II, congenital: A very rare inherited metabolic disorder where a defect in the enzyme alpha-neuraminidase prevents glycoproteins being metabolized. The congenital form usually results in death in the newborn period.
  • Sialidosis type II, infantile: A very rare inherited metabolic disorder where a defect in the enzyme alpha-neuraminidase prevents glycoproteins being metabolized. The infantile form is characterized by structural or functional kidney problems.
  • Sialidosis type II, juvenile: A very rare inherited metabolic disorder where a defect in the enzyme alpha-neuraminidase prevents glycoproteins being metabolized.
  • Sialuria, Finnish type: A rare inherited biochemical disorder characterized by the accumulation of sialic acid in the tissues and excretion of sialic acid in the urine. This condition is an adult form of sialuria.
  • Siderius type X-linked mental retardation syndrome: A rare inherited form of mental retardation involving a defect on chromosome Xp11.2. The symptoms are evident in males but females may be carriers.
  • Simpson-Golabi-Behmel syndrome: A rare genetic disorder characterized by accelerated growth and other defects.
  • Simpson-Golabi-Behmel syndrome, type 1 (SGBS1): A rare genetic disorder characterized by accelerated growth, a peculiar face and other defects.
  • Simpson-Golabi-Behmel syndrome, type 2: A rare genetic disorder characterized by hydrops fetalis and various other severe abnormalities. The condition usually results in death within two months of birth.
  • Singh-Chhaparwal-Dhanda syndrome: A very rare syndrome characterized mainly by short stature, mental retardation, eye defects and a missing kneecap.
  • Single upper central incisor: A very rare syndrome characterized by various defects in the middle of the face.
  • Skeletal dysplasia - coarse facies - mental retardation: A very rare syndrome characterized by a coarse face, mental retardation and skeletal abnormalities.
  • Small syndrome: A rare genetic disease characterized by deafness, muscle weakness and wasting, mental retardation and eye disorders.
  • Smith-Fineman-Myers syndrome 1: A rare inherited disorder characterized mainly by mental retardation and low facial muscle tone. The genetic defect occurs on chromosome Xq13.
  • Smith-Fineman-Myers syndrome 2: A rare inherited disorder characterized mainly by mental retardation and low facial muscle tone. The genetic defect occurs on chromosome Xq23.
  • Smith-Lemli-Opitz Syndrome: A rare genetic condition involving a severe defect in the process of cholesterol synthesis resulting in low cholesterol levels in cells but high levels of the chemicals that are made into cholesterol.
  • Smith-Magenis Syndrome:
  • Smith-Martin-Dodd syndrome: A very rare syndrome characterized mainly by small eyes, a hernia and a heart defect (tetralogy of Fallot).
  • Snyder-Robinson syndrome: A rare syndrome characterized by mental retardation, reduced muscle tone, abnormal walk, weak bones and an asymmetrical face.
  • Sohval-Soffer syndrome: A very rare syndrome characterized mainly by mental retardation, hypogonadism and skeletal abnormalities.
  • Soto's Syndrome: A rare hereditary disorder characterized by excessive growth during the first few years of life as well as various other mental and physical anomalies.
  • Sparse hair - ptosis - mental retardation: A very rare syndrome characterized mainly by sparse hair, droopy eyelids and mental retardation.
  • Spastic diplegia, infantile type: A rare genetic disorder characterized by the early onset of lower leg spasticity and weakness and mental retardation.
  • Spastic paraplegia 15, autosomal recessive: A rare syndrome characterized mainly by progressive stiffness and increased reflexes in the leg muscles as well as vision problems.
  • Spastic paraplegia 16, X-linked: A rare condition characterized by spasticity and weakness of the arms and legs, mental retardation, impaired vision and poor bowel and bladder control. In most cases, sufferers never gain the ability to walk.
  • Spastic paraplegia 2, X-linked: A very rare genetic disorder characterized by lower leg spasticity and weakness. It has an early onset, progresses slowly and eventually the brain becomes involved as well which produces sensory, speech and eye problems.
  • Spastic paraplegia 4, autosomal dominant: A rare syndrome characterized mainly by progressive stiffness and increased reflexes in the leg muscles. The severity of the condition is very variable as is the age of onset.
  • Spastic paraplegia glaucoma precocious puberty: A rare syndrome characterized by premature puberty, mental retardation, glaucoma and progressive spastic paraplegia.
  • Spastic paraplegia type 5A, recessive: A rare disorder characterized mainly by progressive stiffness and weakness of lower leg muscles. Bladder and speech problems are also usually present.
  • Spastic paraplegia type 5B, recessive: An extremely rare form of lower leg spasticity and weakness.
  • Spastic paraplegia with precocious puberty: A rare genetic disorder characterized mainly by early onset of progressive weakness of the lower legs as well as premature onset of signs of puberty.
  • Spastic paresis - glaucoma - mental retardation: A very rare syndrome characterized by progressive stiffness and weakness of the legs, glaucoma and mental retardation.
  • Spastic quadriplegia - retinitis pigmentosa - mental retardation: A very rare syndrome characterized mainly by progressive stiffness and weakness of the legs and arms, eye problems and mental retardation. The spastic paraplegia is not progressive.
  • Spastic tetraplegic - cerebral palsy: A rare disorder characterized by the association of spasticity (muscle tightness of the arms and legs as well as cerebral palsy.
  • Spasticity - mental retardation: A rare disorder characterized by the association of spasticity and mental retardation.
  • Spasticity - mental retardation - epilepsy, X-linked: A rare syndrome characterized by epilepsy, spasticity and mental retardation. The disorder is inherited in a X-linked manner and thus only males present with symptoms though female carriers may have some mild symptoms such as hyperreflexia.
  • Sphingolipidosis: A group of diseases involving the abnormal metabolism and storage of a substance called sphingolipid. Symptoms will vary depending on the disease. Examples of diseases from this group include gangliosidosis, Gaucher's disease and Niemann-Pick disease.
  • Spinocerebellar ataxia - amyotrophy - deafness: A very rare syndrome characterized by muscle weakness and wasting, ataxia and deafness.
  • Spinocerebellar ataxia - dysmorphism: A rare inherited syndrome characterized by ataxia and unusual facial appearance.
  • Spinocerebellar ataxia 21: A rare genetic disorder (chromosome 7p21.3-p15.1 defect) characterized by extrapyramidal features and cognitive impairment. The condition progresses slowly over decades. Gait ataxia and dysarthria (speech disorder) also occur and are symptoms common to all the spinocerebellar ataxia types.
  • Spinocerebellar ataxia 27: A rare genetic disorder (chromosome FGF14; 13q34 defect) characterized by tremors, dyskinesia and psychiatric episodes. Gait ataxia and dysarthria (speech disorder) also occur and are symptoms common to all the spinocerebellar ataxia types.
  • Spinocerebellar ataxia, autosomal recessive 5: A rare neurological disorder caused by a genetic defect (chromosome 15q24-q26, recessive) and resulting in ataxia, mental problems and a skin disorder. Symptoms start during infancy and more than half of the patients never gain the ability to walk.
  • Spinocerebellar ataxia-dysmorphism syndrome: A rare genetic disorder characterized by characteristic facial anomalies, ataxia, delayed psychomotor development and various skeletal deformities.
  • Spinocerebellar degenerescence, book type: A very rare syndrome characterized by movement problems and mental retardation that originates from a brain defect.
  • Spondyloepimetaphyseal dysplasia, genevieve type: A recessively inherited disorder characterized mainly by abnormal bone development (epiphyses, metaphyses and vertebrae) as well as mental retardation. The abnormalities become progressively worse with age.
  • Spondylometaphyseal dysplasia, X-linked: A rare disorder characterized by spine and long bone abnormalities and facial anomalies. The disorder is inherited in a X-linked manner which means that males exhibit the full extent of the symptoms whereas female carriers often have only mild symptoms.
  • Stevenson-Carey syndrome: A rare syndrome involving various congenital abnormalities and mental retardation.
  • Stickler Syndrome: A rare genetic disorder characterized by joint problems, distinctive facial characteristics and eye and ear abnormalities.
  • Stickler Syndrome, type I: A rare genetic disorder characterized by joint problems, distinctive facial characteristics and eye and ear abnormalities. Type 1 is caused by a genetic defect on chromosome 12q13.11-q13.2
  • Stickler Syndrome, type II: A rare genetic disorder characterized by joint problems, distinctive facial characteristics and eye and ear abnormalities. Type 2 is caused by a genetic defect on chromosome 1p21
  • Stickler Syndrome, type III: A rare genetic disorder characterized by joint problems, distinctive facial characteristics and ear abnormalities. Type 3 is caused by a genetic defect on chromosome 6q21.3. Type 3 doesn't involve any of the eye problems that occur in type 1 and 2.
  • Stiff baby syndrome: A rare inherited neurological disorder characterized by increased muscle tone during infancy and an exaggerated startle response later in life.
  • Stimmler syndrome: A rare disorder characterized by dwarfism, diabetes, small head and high levels of alanine in the urine.
  • Stoll-Geraudel-Chauvin syndrome: A very rare syndrome characterized mainly by short stature, mental retardation and wide set eyes.
  • Stratton-Parker syndrome: A very rare syndrome characterized by short stature, heart positioned on the wrong side of the chest (dextrocardia) and a bone development anomaly.
  • Striatonigral degeneration infantile: A genetic neurological disorder caused by progressive damage to a part of the brain called the striatum.
  • Sturge-Weber Syndrome: A rare genetic disorder characterized by excessive blood vessel growth, calcium accumulation inside the brain and seizures.
  • Subcortical laminar heterotopia: A rare inherited disorder where a part of the brain tissue is misplaced during development. More specifically, the abnormal tissue is found in the subcortical part of the brain.
  • Succinic Semialdehyde Dehydrogenase Deficiency: A condition which is characterized by a deficiency of succinic semialdehyde dehydrogenase
  • Symmetrical thalamic calcifications: A very rare disorder involving the calcification of a part of the brain called the thalamus which results in various abnormalities.
  • Syndactyly - cataract - mental retardation: A very rare syndrome characterized mainly by webbed fingers and toes, cataract and mental retardation.
  • TAU syndrome: A very rare syndrome characterized mainly by reduced blood platelet level and absent ulna bone (forearm bone).
  • TORCH Syndrome: Infection of a fetus by any of a group of infectious agents which have been transmitted from the mother through the placenta. The infections include toxoplasmosis, rubella, cytomegalovirus, herpes virus, hepatitis and syphilis. The severity and nature of symptoms is determined by the type of infection.
  • Tay Sachs Disease: A condition which is causes GM2 gangliosidosis
  • Tay-Sachs disease - juvenile onset: A rare inherited biochemical disorder involving the deficiency of an enzyme called Hexosaminidase A. There are two forms of the disease - juvenile and adult onset.
  • Telencephalic leukoencephalopathy: Neurological disease of the brain where the protective sheaths covering the nerves in the brains are destroyed or fail to develop properly.
  • Temtamy preaxial brachydactyly syndrome: A rare syndrome characterized by mental retardation, deafness, retarded growth, finger abnormalities and various other anomalies.
  • Temtamy syndrome: A rare disorder characterized by a brain abnormality, unusual facial appearance and eye coloboma.
  • Tetra-amelia with ectodermal dysplasia and lacrimal duct abnormalities: A rare disorder involving tear duct abnormalities, missing arms and legs, retarded development and an unusual facial appearance.
  • Tetrahydrobiopterin deficiencies: A rare genetic disorder where insufficient levels of tetrahydropterin leads to a build up of phenylalanine in the blood which can cause toxic side effects such as nerve damage or even brain damage. The condition does not usually cause any significant symptoms.
  • Tetrasomy X: A rare chromosomal disorder which causes mental retardation, small head and various other anomalies.
  • Thiele syndrome: A very rare syndrome characterized mainly by mental retardation, unusual facial appearance and a small head.
  • Thiolase deficiency: A rare syndrome involving a deficiency of an enzyme called thiolase which results in mental retardation and muscle problems.
  • Thompson-Baraitser syndrome: A very rare syndrome characterized mainly by liver fibrosis, kidney cysts and mental retardation.
  • Thoracic dysplasia - hydrocephalus syndrome: A very rare syndrome characterized by abnormal chest development and excess fluid inside the skull.
  • Thrombocytopenia - cerebellar hypoplasia - short stature: A very rare syndrome characterized mainly by short stature, low blood platelets and abnormal brain development.
  • Thumb deformity, alopecia, pigmentation anomaly: A very rare syndrome characterized mainly by a deformed thumb, lack of hair and abnormal pigmentation.
  • Thyrotropin deficiency, isolated: An inherited deficiency of thyroid hormone (thyrotropin) which causes mental retardation, growth and other problems.
  • Timothy syndrome: A rare syndrome characterized by webbed fingers and a heart defect. Most affected individuals die during early childhood or infancy.
  • Toriello syndrome: A rare syndrome characterized by brachial arch defects and other abnormalities such as short stature, mental retardation and small head.
  • Tourette Syndrome: A neurological disorder involving vocal and movement tics where where uncontrollable movements or verbal utterances are made.
  • Tranebjaerg-Svejgaard syndrome: A rare syndrome characterized mainly by mental retardation, seizures and a skin disorder.
  • Transplacental infections: An infection that passes from the mother to the fetus via the placenta. A large variety of infections can occur like this and the type and severity of symptoms can vary greatly depending on the type of infection and the stage of fetal development at which infection occurs. Examples of transplacental infections include cytomegalovirus, herpes virus, hepatitis, syphilis, toxoplasmosis and rubella.
  • Tricho-hepato-enteric syndrome: A very rare syndrome characterized mainly by hair and liver abnormalities as well as severe diarrhea that usually starts in early infancy and can lead to death.
  • Tricho-retino-dento-digital syndrome: A very rare syndrome characterized by hair, eye, tooth and finger abnormalities.
  • Trichodental syndrome: A very rare syndrome characterized by short fine hair and dental abnormalities.
  • Trichoscyphodysplasia: A rare inherited skeletal disorder involving abnormal bone development which results in short stature, short hands and feet and alopecia is also present.
  • Trichothiodystrophy - sun sensitivity: A rare condition characterized by short brittle hair
  • Trigonocephaly - bifid nose - acral anomalies: A rare syndrome characterized mainly by a prominent triangular shaped forehead, short head, bulbous nose, small jaw, large mouth, poor muscle tone and foot abnormalities.
  • Trigonocephaly - ptosis - coloboma: A rare syndrome characterized by droopy eyelids, brain malformation, a triangular shaped prominent forehead and an eye abnormality.
  • Trigonocephaly - ptosis - mental retardation: A very rare syndrome characterized mainly by droopy eyelids, mental retardation and a triangular shaped forehead.
  • Triose phosphate-isomerase deficiency: A very rare inherited condition involving a deficiency of triose phosphate-isomerase.
  • Triosephosphate isomerase 1: A rare inherited blood disorder involving a deficiency of red cell triosephosphate isomerase which is involved in the glycolysis (glucose metabolism) process to produce energy. The disorder is characterized by anemia, recurring infection and often progressive neurological degeneration. The severity of the disorder is variable with some patients having central nervous system involvement while others don't.
  • Trisomy 12 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 12 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect.
  • Trisomy 13 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 13 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect. There appears to be a direct correlation between the number of cells in the body containing the chromosomal defect and severity of symptoms and survival.
  • Trisomy 18 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 18 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect.
  • Trisomy 21 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 1 in some of the body's cells. The presence of trisomy 20 in all cells causes Down's syndrome and thus the presence in fewer body cells results in conditions that are similar to Down's but tend to be milder.
  • Trisomy 22: A disorder that is characterised by the occurrence of three copies of chromosome 22
  • Trisomy 22 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 22 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect.
  • Trisomy 3 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 3 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect.
  • Trisomy 6: A rare chromosomal disorder involving the duplication of chromosome 6 which results in variable symptoms including mental retardation, retarded growth, facial anomalies and various other abnormalities. Full Trisomy 6 is results in spontaneous abortion whereas various degrees of Trisomy 6q can result in syndromes of variable severity depending on the size of the duplication.
  • Trisomy 8 mosaicism: A very rare chromosomal disorder where there is an extra copy of chromosome 8 in some of the body's cells. Some cases with this chromosomal abnormality have no clinical symptoms. The presence of abnormalities in some cases is dependent on which body cells contain the chromosomal defect.
  • Tsao-Ellingson syndrome: A very rare syndrome characterized mainly by spasms during infancy and broad thumbs.
  • Tsukuhara syndrome: A very rare syndrome characterized mainly by a curved spine, premature fusion of skull bones and a small head.
  • Tuberous sclerosis: A rare genetic disorder characterized by harmartomatous skin nodules, seizures, phakomata and bone lesions.
  • Tuberous sclerosis, type 1: A rare genetic disorder with a variety of abnormalities such as seizures, mental retardation, skin lesions and nodules in various body tissues and organs.
  • Tuberous sclerosis, type 2: A rare genetic condition characterized by mental and physical retardation, seizures and numerous benign tumors that can occur on the skin or in organs. The severity of symptoms can vary greatly depending on where the tumors occur.
  • Turner-mongolism polysyndrome: A rare syndrome characterized by webbed neck, elbow abnormalities and infantilism.
  • UDP-Galactose-4-epimerase deficiency: A condition which is characterised by a mutation in the UDP-galactose-4-epimerase gene.
  • Ulnar hypoplasia with mental retardation: A condition which is characterised by short upper limbs, club feet, and absence of fingernails
  • Uniparental disomy: A condition which is characterised by the uniparental disomy of chromosomes
  • Uniparental disomy 13: A condition which is characterised by the uniparental disomy of chromosome 12
  • Uniparental disomy of 11: A condition which is characterised by the uniparental disomy of chromosome 11
  • Uniparental disomy of 2: A condition which is characterised by the uniparental disomy of chromosome 2
  • Uniparental disomy of 6: A condition which is characterised by the uniparental disomy of chromosome 6
  • Uniparental disomy, paternal, chromosome 14: A condition which is characterised by the uniparental disomy of chromosome 14
  • Unusual facies, arachnodactyly, hypogenitalism and failure to thrive: A very rare syndrome characterized by an unusual facial appearance, small genitals, failure to thrive and long, thin fingers.
  • Unusual facies, hepatic fibrosis, renal cysts and mental retardation: A rare syndrome characterized mainly by liver fibrosis, unusual facial appearance, kidney cysts and mental retardation.
  • Unusual facies, hypotonia, mental retardation and radioulnar synostosis: A very rare syndrome characterized by unusual facial appearance, reduced muscle tone, mental retardation and fused forearm bones.
  • Unusual facies, mental retardation, short stature, hemolytic anemia and delayed puberty: A rare syndrome characterized mainly by an unusual facial appearance, mental retardation, short stature, hemolytic anemia and delayed puberty.
  • Unusual facies, short webbed neck, mental retardation, short stature: A rare syndrome characterized by an unusual facial appearance, short webbed neck, mental retardation and short stature
  • Upper limb defect eye and ear abnormalities: A rare disorder characterized by underdeveloped thumb and ear, deafness and an eye defect.
  • Upton Young syndrome: A syndrome which is characterised by the association of multiple symptoms including mental retardation and multiple nevi
  • Urban Roger Meyer syndrome: A syndrome which is characterised by genital anomalies, mental retardation, and obesity
  • Urban rogers meyer syndrome: A rare syndrome characterized by mental retardation, short stature, hand contractures, genital anomalies and other abnormalities.
  • Urocanase deficiency: A condition characterised by the deficiency of the urocanase enzyme
  • VACTERL hydrocephaly: A rare syndrome characterized by the VACTERL abnormalities (vertebral anomalies, anal atresia, congenital cardiac disease, tracheoesophageal fistula, renal anomalies, radial dysplasia, limb defects) as well as a buildup of fluid inside the skull (hydrocephalus).
  • VACTERL with hydrocephalus, X-linked: A rare X-linked syndrome characterized by the VACTERL abnormalities (vertebral anomalies, anal atresia, congenital cardiac disease, tracheoesophageal fistula, renal anomalies, radial dysplasia, limb defects) as well as a buildup of fluid inside the skull (hydrocephalus).
  • Vagneur Triolle Ripert syndrome: A condition that is characterised by lymphoedema of the lower extremities and recurrent respiratory system problems
  • Valinemia: A very rare metabolic disorder where a deficiency of the enzyme valine transaminase results in increased blood and urine levels of the amino acid called valine.
  • Van Bogaert-Hozay syndrome: A rare disorder characterized by destruction of ends of finger bones, mental retardation, skin wasting and eye and facial abnormalities.
  • Van Buchem disease type 2: A disease which is characterised by early onset osteoporosis
  • Van Maldergem Wetzburger Verloes syndrome: A syndrome characterised by abnormalities of the cerebrum, face, and articular joints.
  • Van den Bosch syndrome: A syndrome which is characterised by mental deficiency, choroideremia, acrokeratosis, verruciformis, anhidrosis, skeletal deformity
  • Varadi Papp syndrome: A syndrome characterised by deformities of the oral-facial-digital areas
  • Vasquez Hurst Sotos syndrome: A rare genetic disorder characterized by underdeveloped genitals, obesity, mental retardation and skeletal abnormalities.
  • Velocardiofacial syndrome: An inherited syndrome of cardiac defects and craniofacial anomalies
  • Venencie Powell Winkelmann syndrome: A congenital condition that is characterised by the occurrence of a number of clinical signs and symptoms
  • Verloes Gillerot Fryns syndrome: A syndrome characterised by multiple congenital abnormalities and mental retardation.
  • Viljone Kallis Voges syndrome: A syndrome characterised by microcephaly, short statures, brachydactyly, lowe set ears, prominent nose and mental retardation
  • Vitamin D toxicity: Excessive consumption of vitamin D can cause symptoms of toxicity.
  • Vitamin K antagonists embryofoetopathy: Abnormalities and deformities that occur in infants due to exposure to oral anticoagulants during the fetal stage.
  • Vitiligo mental retardation facial dysmorphism uremia: A condition that is characterised by a number of symptoms including mental retardation, facial dysmorphism and uremia
  • W syndrome: A rare genetic disorder involving distinctive facial features, mental retardation, speech problems and limb deformities.
  • WAGR Syndrome: A syndrome that is due to the deletion of chromosome 11.
  • Waaler Aarskog syndrome: A rare syndrome characterized mainly by hydrocephaly and upwardly displaced shoulder blade (Sprengel anomaly).
  • Waardenburg syndrome, type 3: A rare syndrome involving deafness, pigmentation and musculoskeletal abnormalities
  • Walker Dyson syndrome: A syndrome that is characterised by mental retardation, aniridia and vision problems.
  • Walker-Warburg Syndrome: A rare inherited disorder characterized by brain malformations and retinal and muscle abnormalities.
  • Warburg Sjo Fledelius syndrome: A syndrome that is characterised by visual and neurological problems as well as microgenitalia
  • Warburton Anyane Yeboa syndrome: A syndrome that is characterised by the occurrence of aneuploidy that can be manifested as monosomies or trisomies
  • Warfarin syndrome: Various physical and other abnormalities that can result from the use of the drug Warfarin during the first trimester of pregnancy.
  • Watson syndrome: A rare syndrome characterized by short stature, reduced intelligence, café au lait spots and narrowing of pulmonary valves.
  • Weaver Johnson syndrome: A syndrome that is characterised by craniosynostosis and cleft lip
  • Weaver Syndrome: A syndrome that is considered a variant of the Marshall-Smith syndrome
  • Weaver Williams syndrome: Any condition that affects the testicles
  • Weaver like syndrome: A rare genetic syndrome characterized by a large mouth, unusual facial features, skeletal anomalies and other abnormalities. The disorder is similar to another genetic disorder called Weaver syndrome but tends to involve endocrinologic abnormalities as well.
  • Webster Deming syndrome: A craniofrontonasal dysplasia that is x-linked in inheritance
  • Weismann-Netter-Stuhl Syndrome: A very rare inherited disorder characterized by bone development abnormalities.
  • Weleber Hecht Bigley syndrome: A syndrome that is characterised by cataract hyperostosis and dislocating patella
  • Wellesley Carmen French syndrome: A syndrome characterised visual difficulties and growth retardation
  • Whelan syndrome: A rare genetic disorder characterized by oral frenula, oral clefts, underdeveloped nose flapss, finger abnormalities and hydronephrosis.
  • White matter hypoplasia corpus callosum agenesia mental retardation: A rare disorder characterized by abnormal brain development and mental retardation.
  • White matter hypoplasia, corpus callosum agenesia, and mental retardation: A syndrome which is characterised by white matter hypoplasia, corpus callosum agenesia, and mental retardation
  • Whooping Cough: An infectious condition caused by the bacteria Bordetella pertussis
  • Wieacker syndrome: A rare disorder involving muscle weakness and wasting, foot deformities, mental retardation and face muscle anomalies.
  • Wieacker-Wolff Syndrome:
  • Wiedemann Oldigs Oppermann syndrome: A rare syndrome characterized mainly by excessive hair growth, mental retardation and skeletal abnormalities.
  • Wiedemann-Tolksdorf syndrome: A syndrome involving mental retardation, speech problems, rapid growth, unusual face and finger and toe anomalies.
  • Wildervanck syndrome: A rare birth disorder involving hearing loss, fusion of vertebrae and eye movement abnormalities/
  • Wildervanck syndrome 2: A syndrome characterized by mental retardation from birth, short stature, eye problems and various other abnormalities.
  • Wilkes Stevenson syndrome: A syndrome that is characterised by multiple congenital abnormalities
  • Williams Syndrome: A syndrome characterised by mental retardation, facial abnormalities and emotional instability
  • Wilson-Turner X-linked mental retardation: A condition that is characterised by mental retardation with gynecomastia and obesity
  • Winship Viljoen Leary syndrome: A syndrome that is characterised by microcephaly with mental retardation and cardiomyopathy
  • Wittwer sydnrome: A syndrome that is characterised by the occurrence of growth retardation, blindness, hearing loss, dysmorphic features, epilepsy, mental retardation and the absence of speech
  • Wolcott-Rallison syndrome: A very rare genetic condition characterized primarily by the onset of diabetes mellitus during infancy and epiphyseal dysplasia (abnormal joint development).
  • Wolf-Hirschhorn Syndrome: A syndrome which is caused by a partial deletion of the short arm of chromosome 4.
  • Wolf-Hirschorn syndrome: A syndrome characterised by the partial deletion of the short arm of chromosome 4
  • Woodhouse Sakati syndrome: A condition which consists of numerous symptoms such as diabetes, hypogonadism, deafness and mental retardation
  • Worster Drought syndrome: A mild form of tetraplegic cerebral palsy
  • Wrinkly skin syndrome: A very rare genetic disorder characterized by wrinkly skin that occurs primarily on the palms and soles but can occur on other parts of the body. The condition is also associated with various other abnormalities.
  • Wyatt disease: A cytomegalus virus infection that occurs before birth.
  • Wyburn Mason's syndrome: A rare genetic condition mainly involving enlarged brain blood vessels and skin and eye abnormalities.
  • X chromosome, duplication Xq13 1 q21 1: A condition characterised by the duplication of the long arm of chromosome X.
  • X chromosome, trisomy 26-28: A condition characterised by the duplication of the long arm of chromosome X.
  • X chromosome, trisomy Xp3: A condition characterised by the duplication of the long arm of chromosome X.
  • X chromosome, trisomy Xpter Xq13: A condition characterised by the duplication of the long arm of chromosome X.
  • X chromosome, trisomy Xq: A condition characterised by the duplication of the long arm of chromosome X.
  • X chromosome, trisomy Xq25: A condition characterised by the duplication of the long arm of chromosome X.
  • X-linked mental retardation craniofacial abnormal microcepahly club: An x-linked condition that is characterised by mental retardation and dysmorphic facies
  • X-linked mental retardation craniofacial abnormal microcephaly club: A rare inherited disorder characterized by mental retardation, small head, club foot and facial and skull abnormalities. The condition is inherited in a X-linked manner and thus only males present with the full severity of the symptoms. Female carriers may be mildly symptomatic or have no symptoms at all.
  • Xylosylprotein 4-beta-galactosyltransferase (XGPT) deficiency: A variant of the connective tissue disorder called Ehlers-Danlos. It is caused by a deficiency of galactosyltransferase I.
  • Young Hughes syndrome: A sex linked condition that is characterised by mental retardation and hypogonadism
  • Young Simpson syndrome: A condition that is characterised by mainly mental retardation and physical signs of hypothyroidism
  • Yunis Varon syndrome: A multisystem genetic disease that affects the skeletal system in particular
  • Zazam Sheriff Phillips syndrome: A medical condition that is characterised by deformities of the eyes and face
  • Zellweger Syndrome: A leukodystrophy that is caused by a absence of peroxisomes
  • Zlotogora syndrome: A condition that is characterised by facial dysmorphism and psychiatric problems
  • Zori Stalker Williams syndrome: A condition that is characterised by deformities of the head, chest and nails
  • Zunich neuroectodermal syndrome: A very rare genetic syndrome characterized by a range of symptoms such as colobomas of the eye, heart defects, ichthyosiform dermatosis, mental retardation and ear defects.

 

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