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.
Sjogren-Larsson syndrome: A rare inherited neurological and skin disorder characterized by mental retardation, spastic paraplegia and thickened scaly skin (ichthyosis). The condition involves a deficiency of fatty alcohol oxidoreductase which causes an accumulation of long-chain fatty alcohols.
Spastic paraplegia 19, autosomal dominant: A rare genetic disorder characterized mainly by progressive spasticity and weakness of the lower legs. The condition is generally slow progressing with wheelchair confinement occurring only rarely.