A mutated CRYGD associated with congenital coralliform cataracts in two Chinese pedigrees

To investigate the causal gene mutation and clinical characteristics for two Chinese families with autosomal dominant congenital coralliform cataract.

Two Chinese pedigrees with congenital cataract were investigated. Routine ophthalmic examinations were performed on all patients and non-affected family members. Peripheral blood samples were collected, and the genomic DNAs were extracted. The coding regions of proband's DNAs were analyzed with cataract gene panel. The identified mutation was amplified by polymerase chain reaction, and automated sequencing was performed in other members of two families to verify whether the mutated gene was co-segregated with the disease.

Congenital coralliform cataract was inherited in an autosomal dominant mode in both pedigrees. For each family, more than half of the family members were affected. All patients presented with severe visual impairment after birth as a result of bilateral symmetric coralliform lens opacification. An exact the same defect in the same gene, a heterozygous mutation of c.70C>A (p. P24T) in exon 2 of γD-crystallin gene, was detected in both probands from each family. Sanger sequencing analysis demonstrated that the mutated CRYGD was co-segregated in these two families.

A c.70C>A (p. P24T) variant in CRYGD gene was reconfirmed to be the causal gene in two Chinese pedigrees. It is known that mutated CRYGD caused most of the congenital coralliform cataracts, suggesting that the CRYGD gene is associated with coralliform congenital cataract.