OMIM ID:
Cataracts, Coppock-Like
Alternate Names
Defective Genes
Clinical Characteristics
Ocular Features
Coppock-like cataracts consist of bilateral progressive opacities of the embryonic lens nucleus. They are characterized by a pulverulent opacification with a gray disc appearance associated with variable zonular opacities. Visual symptoms often begin during adolescence and some patients require cataract surgery by the 5th decade of life.
Systemic Features
There is no systemic disease associated with this type of cataract.
Genetics
Inheritance
CCL cataracts are embryonic in origin, developing during the time when gamma-crystallin genes are active. The gamma E-crystallin gene is a pseudogene and the mutation in its promoter reactivates its activity 10-fold. It is postulated that overexpression of the gamma-crystallin fragment is responsible for the nuclear opacification.
Mutations in at least 3 genes have been associated with this type of cataract. In some families the mutations are in the CRYGC gene (2q33-q35), and in others mutations in CRYBB2 (22q11.2-q12.2) seem to be responsible. It is of interest that one form of congenital cerulean cataract, CCA3 (608983), found in a single family, results in mutations in CRYGD also located at 22q11.2-q12.2. A five-generation Chinese family has been reported in which mutations in GJA3 (13q12.11) was associated with this type of lens opacity.
Other forms of autosomal dominantly inherited, congenital, progressive lens opacities include congenital cerulean (115660, 601547, 608983, 610202), Volkmann type (115665), lamellar (116800), and congenital posterior polar (116600) cataracts. Due to clinical heterogeneity, it is not always possible to classify specific families based on the appearance and natural history of the lens opacities alone.
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