Clinical Characteristics
Ocular Features
Most cataracts arise as part of the aging process. However, early onset lens opacities may be familial, often transmitted in an autosomal dominant pattern. These have a highly variable appearance and may be unilateral or bilateral. There can be considerable interocular asymmetry in morphology, density, location, and rate of progression. This is also true of intrafamilial characteristics. Age of onset is variable.
Systemic Features
There are no associated systemic abnormalities.
Genetics
Inheritance
At least 25 loci scattered among multiple chromosome have been identified to cause simple autosomal dominant cataracts (See 604219). It is not yet possible to make phenotypic – genotypic correlations due to the large variation in clinical characteristics.
Pedigree
Autosomal dominant
Autosomal dominant disorders require only one mutation for the disease to be expressed. Since an affected parent has two chromosomes, only one of which has the mutant gene, parents can expect that half (50%) of their children will receive that one and inherit the disease. It is common for individuals that inherit the mutation, however, to not have evidence of the disease (nonpenetrance).
Autosomal dominant inheritance leads to a vertical pattern of transmission