OMIM ID:
Cataracts, CRYAA Mutations
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
This seems to be a clinically heterogeneous group of lens opacities all due to mutations in the crystallin gene CRYAA. Some patients also have colobomas and may have microcornea and corneal opacities. The lens opacities are usually bilateral but there is considerable asymmetry in their morphology. Opacities may be nuclear, polar, cortical, sutural, embryonal, and anterior subcapsular in location. The cataracts are often present at birth.
Systemic Features
Systemic disease is absent.
Genetics
Inheritance
A variety of mutations in the CRYAA (21q22.3) have been reported in a several ethnic groups. Most pedigrees are consistent with autosomal dominant inheritance but autosomal recessive inheritance has been suggested in other families.
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
Autosomal recessive
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.
In order for autosomal recessive disorders to be expressed, offspring generally must inherit two mutations, one from each carrier parent. Carriers with only one mutation, such as the parents, do not have clinical disease. Note that carrier parents can expect that 1 in 4 children (25%) will inherit both mutations and have the disorder, 2 in 4 children (50%) will be carriers like their parents, while 1 in 4 children (25%) inherit neither mutation.