Mutation analysis of two families with inherited congenital cataracts

The present study aimed to identify the genetic mutations in two families affected with congenital cataracts. Detailed family histories and clinical data of the family members were recorded. The family members with affected phenotypes were recruited, and candidate gene sequencing was performed to determine the disease-causing mutation. Bioinformatics analysis was performed to predict the function of the mutant gene. Green fluorescent protein-tagged human wild-type CRYAA and GJA8 were sub-cloned, and the mutants were generated by site-directed mutagenesis. A novel mutation, c.416T>C (p.L139P), in CRYAA and a known mutation, c.139G>A (p.D47N), in GJA8 were identified. These mutations co-segregated with all affected individuals in each family and were not observed in the unaffected family members or in unrelated controls. The results of the bioinformatics analysis indicated that the amino acid at position 139 was highly conserved and that the p.L139P mutation was predicted to be damaging, as with p.D47N. Finally, overexpression of the two mutants revealed marked alterations, compared with the wild-type proteins. These results extend the mutation spectrum of CRYAA and provides further evidence that the p.D47N mutation in GJA8 is a hot-spot mutation.