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Diseases » Albinism » Wikipedia
 

Albinism in Wikipedia

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This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Albinism". (Source - Retrieved 2006-09-07 14:09:17 from http://en.wikipedia.org/wiki/Albinism)

Introduction

Albinism (from Latin albus, meaning "white") is a lack of pigmentation in the eyes, skin and hair. Albinism is an inherited condition resulting from the combination of recessive alleles passed from both parents of an individual. This condition is known to affect mammals, fish, birds, reptiles, and amphibians. While the most common term for an individual affected by albinism is "albino", some prefer "person with albinism", because "albino" is sometimes used in a derogatory way. The gene which results in albinism prevents the body from making the usual amounts of the pigment melanin. Albinism used to be categorised as Tyrosinase positive or negative. In cases of Tyrosinase positive albinism, the enzyme tyrosinase is present but is unable to enter pigment cells to produce melanin. In tyrosinase negative cases, this enzyme is not produced. This classification has been rendered obsolete by recent research.

About 1 in 17,000 people have some type of albinism, although up to 1 in 75 are carriers.

There are many alterations of genes which are proven to be associated with albinism. All alterations, however, lead to an alteration of the melanin (pigment/coloring) production in the body. Melanin helps protect the skin from ultraviolet light coming from the sun (see human skin color for more information). Organisms with albinism lack this protective pigment in their skin, and can burn easily from exposure to the sun as a result. Lack of melanin in the eye also results in problems with vision unrelated to photosensitivity, which are discussed further below.

There are two main categories of albinism in humans: oculocutaneous and ocular. In oculocutaneous albinism, pigment is missing from the hair, eyes, and skin. In ocular albinism, only the eyes lack pigment. People with oculocutaneous albinism can have no pigment to almost normal. Some may even tan. People who have ocular albinism have normal skin/hair color and many have normal eye color.

The eyes of an animal with albinism occasionally appear red due to the underlying blood vessels showing through where there is not enough pigment to cover them. In humans this is rarely the case, as a human eye is quite large and thus produces enough pigment to lend opacity to the eye. However, there are cases in which the eyes of an albino person appear red or purple, depending on the amount of pigment present.

People with albinism are generally as healthy as the rest of their species, with growth and development occurring as normal. Many animals with albinism, however, lose their protective camouflage and are unable to conceal themselves from their predators or prey. The survival rate of animals with albinism in the wild is usually quite low. The main problem that people with albinism face is social, as the condition is sometimes a source of teasing during adolescent years.

As albinism is a recessive gene, the chance of offspring with albinism resulting from the pairing of a creature with albinism with a creature without albinism is very low and is discussed below.


Types of albinism

While there is only one type of ocular albinism, there are at least five types of oculocutaneous albinism, one of which has several subtypes. Some are easily distinguished by appearance, but in most cases, genetic testing is the only way to be sure. Apart from HPS (see below) testing has no medical benefits.

  • The type with the usually least amount of pigment is Oculocutaneous albinism type 1 (OCA1) (OMIM 203100). People with this type usually have very white skin, white hair and light blue eyes, however there are cases in which the eyes appear red or purple, depending on the amount of pigment present. OCA1 is caused by an alteration of the tyrosinase gene, and can occur in two variations. The first is OCA1A, and means that the organism cannot develop pigment at all. Vision usually ranges from 20/200 to 20/400. The second is OCA1b, which has several subtypes itself. Many individuals with OCA1b can tan and develop pigment. One subtype of OCA1b is called OCA1b TS (Temperature Sensitive), where the tyrosinase can only function below a certain temperature, which causes the body hair in cooler body regions to develop pigment (i.e. get darker). An equivalent mutation produces the coat pattern in Siamese cats.
  • The most common type of albinism is Oculocutaneous albinism type 2 (OCA2) (OMIM 203200), which is caused by alterations of the P-gene. People with OCA2 generally have more pigment, and better vision than those with OCA1, but cannot tan like some with OCA1b. A little pigment can develop in freckles or moles. People with OCA2 usually have fair skin but not as white as OCA1, and light to golden or reddish blonde hair, and usually blue eyes. Affected people of African descent usually have a different phenotype (appearance): Yellow hair, rather white skin and blue, gray or hazel eyes.
  • Oculocutaneous albinism type 3 (OCA3) or Rufuous (Red) Albinism (OMIM 203290) has only been partially researched and documented. Cases have been reported in Africa and New Guinea, affected individuals have red hair and reddish brown skin and blue or gray eyes.
  • HPS or Hermansky-Pudlak-Syndrome (OMIM 203300) is not a type of OCA itself, but has similar features. HPS has a great range of degrees of pigmentation, from OCA1A-like to almost normal coloring. Vision usually ranges from 20/60 to 20/200. Apart from the hypopigmentation and impaired vision, people with HPS lack dense bodies in their blood platelets which are responsible for releasing clotting factors. For this reason, HPS patients bruise easily and have a hard time stopping bleeding once it begins. HPS has 7 known forms, each caused by a mutation in a different gene. HPS-1 and HPS-4 may also include pulmonary fibrosis, or scarring of lung tissue that prevents the necessary expansion and contraction during breathing. It is believed that this is due to a buildup of fatty ceroid in the lungs. Colitis, or inflammation in the large intestine, is another symptom of most types of HPS, which may cause blood in stool, diarrhea, and nausea.
  • Ocular albinism (OMIM 300500) affects only the eyes. There are two types, One is X-Linked and the other is a Recessive Gene. Nonetheless, skin color can be slightly lighter than those of the rest of the family, or "normal". The eye color can vary greatly, in which case only examination of the retina can reveal OA1.

Visual problems associated with albinism

Eye conditions common in albinism may include (for all will not necessarily be present):

  • Nystagmus, irregular rapid movement of the eyes back and forth.
  • Strabismus, muscle imbalance of the eyes ("crossed eyes" or "lazy eye")
  • Sensitivity to bright light and glare.
  • Far- or Near-sightedness
  • Astigmatism (distortion of a viewed image, usually either horizontally or vertically)
  • Abnormal routing of the optic nerve to the brain

People with albinism suffer from impaired vision, but the degree varies greatly. While a person with albinism may suffer from a standard eye affliction like near-sightedness or far-sightedness, the biggest problem arises from a poorly-developed retina and abnormal nerve connections between the eyes and brain. These abnormalities define albinism, medically. While the effects of this condition are difficult to describe, it can be explained as seeing at a lower resolution. Additionally, most people with albinism suffer from nystagmus (a rapid, involuntary "shaking" of the eyes) which further reduces vision. People with albinism are also likely to have astigmatism or strabismus.

The iris, the colored area in the center of the eye, does not have enough pigment to screen out stray light coming into the eye. Light normally enters the eye only through the pupil, the dark opening in the center of the iris, but in albinism light can pass through the iris as well. Such sensitivity generally leads to a dislike of bright lights, but does not prevent people with albinism enjoying the outdoors, especially when using sunglasses and/or hats. They should avoid prolonged exposure to bright sunlight regardless, as their skin is particularly susceptible to sunburn (see below).

Sun protection and vision aids

Albinism is a condition that cannot be "cured" or "treated" per se, but small things can be done to improve the quality of life for those affected. It is vital that people with albinism use sunscreen when exposed to sunlight to prevent premature skin aging or skin cancer. This poses a problem for those who cannot afford sunscreen, especially in countries with high exposure to sunlight, as in Africa. Special UV-proof clothing and swimsuits are available and are a good alternative to excessive use of sunscreen.

For the most part, treatment of the eye conditions consists of visual rehabilitation. Surgery to correct strabismus may improve the appearance of the eyes. However, since surgery will not correct the misrouting of nerves from the eyes to the brain, surgery will not provide fine binocular vision. In the case of esotropia or "crossed eyes," surgery may help vision by expanding the visual field (the area that the eyes can see while looking at one point). Nystagmus damping surgery can also be performed, to reduce the "shaking" of the eyes back and forth.

Glasses and low-visual aids such as magnifiers, large print materials or closed captioning, as well as bright but angled reading lights can help individuals with albinism, even if their vision cannot be corrected completely. Some people do well using bifocals which have a strong reading lens, prescription reading glasses, or contact lenses. Others use hand-held magnifiers or special small telescopes. Some use bioptics, glasses which have small telescopes mounted on, in, or behind their regular lenses, so that they can look through either the regular lens or the telescope. Newer designs of bioptics use smaller light-weight lenses. Some states allow the use of bioptic telescopes for driving. (See also NOAH bulletin "Low Vision Aids".)

Although still disputed among the experts, many ophthalmologists recommend the use of glasses from early childhood on to allow the eyes the best development possible. Surgery is possible on the ocular muscles to decrease nystagmus, strabismus and common refractive errors, but especially with nystagmus surgery the effectiveness varies greatly and depends on individual circumstances.

Optometrists or ophthalmologists who are experienced in working with low vision patients can recommend various optical aids. Clinics should provide aids on trial loan, and provide instruction in their use. The American Foundation for the Blind (1-800-AFB-LIND) maintains a directory of low vision clinics.

Use of sunglasses and hats with wide brims can make the glare outside bearable. Other things that can help people with albinism are avoiding sudden changes of the lighting situation (switching the light on in complete darkness), using dimmable switches and adding tint to car windows or blinds to normal windows. Lights should be yellowish rather than blue and not point towards the usual position of a person with albinism (like their seat at a table). When possible, people with albinism generally prefer to have the light on their backs rather than face it.

Culture

Under the Spanish casta, albino (or albina, if female) was the term used to categorize an individual who was one-eighth African and seven-eighths Spanish.

Myths and superstitions

Due to albinism's effect on one's outward appearance, cultures around the world have developed many myths and superstitions regarding people with albinism:

  • A common misconception is that albino individuals of a species are sterile; but albinos are fully capable of reproducing.
  • A myth has developed in Zimbabwe that having sex with a woman with albinism will cure a man of HIV. This has led to many women with albinism in the area being raped, [1] by HIV-positive men.
  • In Jamaica, West Indies, people with albinism have been degraded and regarded as cursed. In recent times, the albino dancehall singer Yellowman has helped to end this stereotype.
  • In some cultures, people with albinism are thought to have magical powers or to be able to tell the future.
  • It is also thought by many that people with albinism live short life spans. This is not true, but may be a distorted view of a more reasonable fact that people with albinism have a higher risk of skin cancer if they do not use proper skin protection when in the sun .

Other

Snowdrop, an albino African Penguin, born at Bristol Zoo (England), died in August 2004. Snowdrop would normally have looked like the background penguins

Bristol Zoo was the home to a very rare albino African penguin named Snowdrop. Snowdrop was hatched at the zoo in October 2002 and died in August 2004. For many years, a unique albino gorilla named Floquet de Neu (Snowflake) was the most famous resident of the Parc Zoològic de Barcelona. An albino humpback whale travels up and down the east coast of Australia, and has become famous in the local media. The whale is called Migaloo (the Aboriginal word for "white lad").

Medical science and toxicology can take advantage of the standardized lack of pigment in albino animals in testing for materials' chemical properties. An example of such a test is the test for corrosiveness, which is a skin exposure test performed on albino rabbits.

The 2004 book Weird U.S. chronicled (and further popularized) one of the lesser known "local myths" of the country, Albino Colonies. The book uses firsthand accounts mailed to the authors to paint a picture of various locations in the U.S. (most notably Clifton, New Jersey) where colonies of albino families and neighbors live in seclusion. The accounts tell tales of honking horns to try to bring the albinos out of their houses, being shot at with rock salt by albinos, and even vigilantism by gangs of albinos.

Famous people with albinism

  • Al Beeno, Jamaican dancehall musician
  • Pierre Bourgault, Québécois politician (this is disputed: there are pictures taken circa 1960 that show him with dark hair and dark eyebrows)
  • Brother Ali, American hip hop emcee
  • Connie Chiu, Photo model for Jean-Paul Gaultier
  • Cano Estremera, Puerto Rican salsa musician
  • Edward the Confessor, King of England (1042 - 1066)
  • Tony Evans, American newspaper columnist
  • Brooke Fox, American singer-songwriter
  • Pedro Julio-Hughes, Puerto Rican artist and falconer
  • Stanley Kaoni, Solomon Islander militant leader
  • Salif Keita, Malian popular musician
  • Krondon, underground rapper from south-central Los Angeles, California.
  • Li Yipeng, Lee Hsien Loong's son
  • M. Nahadr, (a.k.a. "M") American performance artist , composer and jazz vocalist
  • Hermeto Pascoal, Brazilian jazz musician
  • Piano Red, American blues musician
  • Nestor Sánchez, Cuban singer
  • Ali Şengöz, Turkish radio DJ
  • William Archibald Spooner, Anglican priest
  • Victor Vernado, famous African American stand up comedian
  • Levan Wee, Lead singer of Ronin, a Singaporean band.
  • Brothers Edgar Winter and Johnny Winter, American blues-rock musicians
  • David Wrench, Welsh-born electronic musician
  • Yellowman, Jamaican dancehall musician

In popular culture

Portrayals of persons with albinism in literature and film are rarely positive. This fact is referred to as the "evil albino stereotype" or albino bias. Positive or at least neutral depictions are listed concisely below; see the "evil albino" article for a list of negative portrayals, for a general discussion of the trend and its exceptions, and for more detail on such characters, both postive and negative.

  • "Silas" is a character from the 2003 book, The Da Vinci Code and the $2006 film$ based on it. Silas is a devout monk of the controversial Catholic organization, Opus Dei, an associate of its head, Bishop Manuel Aringarosa. He is "loaned" to Sir Leigh Teabing in his "Teacher" persona. Silas is also a practitioner of severe corporal mortification to mimic the suffering of Jesus Christ. He wears a cilice that has dug a deep wound in his leg and self-flagellates as part of his prayer ritual. The book treats him as an unwitting pawn; the film, controversially, as a murderous thug.
  • "Powder", the titular character in the movie Powder (a characterization sometimes criticized because his condition is implied to give him supernatural abilities, and of course because the name can be seen as mocking or derogatory; most see the film as a step forward, however, because of its portrayal of the effects of bias against those with albinism).
  • "Whitey" in the movie Me, Myself and Irene (controversial: his nickname and his treatment in the film are offensive to some, but on the other hand are accurately representative of the casual discrimination that persons with albinism are often made to suffer; further, the character does not have any "powers" and is accurately shown as having impaired vision).
  • Elric of Melniboné, the OCA protagonist of an eponymous series of fantasy novels by Michael Moorcock, is both hero and anti-hero. (Moorcock's apparently imperfectly informed description of this character's condition is somewhat exaggerated, and coupled with general frailty that the character must overcome with sorcery and medicines, but overall the characterization is fairly sympathetic.)
  • Pete White in The Venture Bros. animated series on Adult Swim. An albino computer scientist and friend of Dr.Venture from his college years, he runs "Conjectural Technologies" with Master Billy Quizboy, Boy Genius. (Note that the name is stereotypical, but his intelligence is accentuated.)
  • Taarna, heroine of the final segment of the animated film Heavy Metal (not necessarily a true albino, though the distinction would be lost on most viewers).
  • Rei Ayanami and Kaworu Nagisa, characters in the anime Neon Genesis Evangelion.
  • Skywise in the ElfQuest comic books.
  • Bran Davis in The Dark Is Rising occult novel series (a positive portrayal but criticized as inaccurate because the character lacks any vision problems.)
  • Bjørn Beltø in Tom Egeland's Norwegian novel Sirkelens Ende (predating but very similar to The Da Vinci Code, coincidentally it features an albino in a positive light while the latter does the opposite.)
  • "U.V." in the film Disturbing Behavior (a neutral portrayal; he is not a villain, but has a mocking nickname)
  • Snow, is a concept album by progressive rock band; Spock's Beard, which tells the story of an albino psychic who achieves a messianic following.
  • The Albino in The Princess Bride.
  • Though never explicitly described as such in dialogue nor in narration, the art teacher in the "Riley Wuz Here" episode of the adult swim cartoon The Boondocks is quite possibly an Albino of African-American decent. Though described by the character of Riley as being "a white guy", he possesses typically African-American facial features, a large and smooth blonde Afro, and red irises in his eyes (despite the fact that truly red eyes in humans with Albinism is a rarity). While it's interesting to note that no characters really seem to notice the character's apparent (if inaccurate) albinism, some may find cause to complain over the implications that the character is crazy. (On the other hand, the character could simply be a parody of Bob Ross.)

See also

  • Vitiligo (or leukoderma), the patchy loss of skin pigmentation
  • Melanism (or melanosis), the condition of having an unusually high level of skin pigmentation
  • Hermansky-Pudlak syndrome, a condition similar to albinism
  • Leucism, a similar condition in animals, characterized by reduced pigmentation
  • Evil albino, a literary stereotype.
  • Albino bias

References

  1. ^ ipsnews.net
 

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