A novel connexin 50 gene (gap junction protein, alpha 8) mutation associated with congenital nuclear and zonular pulverulent cataract

PURPOSE To characterize the disease-causing mutations in four generations of a Chinese family affected with bilateral congenital nuclear and zonular pulverulent cataract. METHODS Detailed family history and clinical data were recorded. The phenotype was documented using slit-lamp photography. Candidate genes were amplified using PCR and screened for mutations using bidirectional sequencing. RESULTS Affected individuals had nuclear and zonular pulverulent cataract with Y-sutural opacities. Sequencing of the candidate genes revealed a heterozygous c. 139G>C change in the coding sequence of the connexin 50 gene (gap junction protein, alpha 8 [GJA8]), which results in the substitution of a wild-type aspartic acid with a histidine (D47H). This mutation cosegregated with all affected individuals in the family and was not found in unaffected family members or in 100 unrelated controls. CONCLUSIONS Our study has identified a novel connexin 50 gene (GJA8) mutation, resulting in the amino substitution p. D47H in a Chinese family with nuclear and zonular pulverulent congenital cataracts. This mutation is probably the causative lesion for the observed phenotype in this family.