Purpose: To identify disease-causing gene mutations in 21 northern Chinese families with congenital cataracts.
Methods: Medical record collection and ophthalmologic examinations were conducted for 21 families with congenital cataracts. A volume of 5 ml of peripheral blood was drawn from each participant for genomic DNA isolation. Thirty-four known candidate genes for congenital cataracts were analyzed in the probands of 21 families with targeted next-generation sequencing (NGS). Bioinformatics analysis of the sequence variants was performed through computational predictive programs. Sanger sequencing was used to perform the cosegregation analysis. Genotyping and haplotype analyses were performed in two patients with a p.V44M mutation in the GJA8 gene.
Results: Twelve disease-causing mutations were detected in 13 of the 21 patients, and the mutation detection rate was 61.9%. The 12 gene mutations included one nonsense, one splice site, seven missense, and three insert and deletion (INDELs) mutations. Four mutations were novel. Of the 13 patients with pathogenic gene mutations, five (38.5%) were affected by mutations in lens crystallin genes, three (23%) were affected by mutations in connexin genes, three (23%) were affected by mutations in transcription factor genes, one (7.7%) was affected by a mutation in a transmembrane transporter gene, and one (7.7%) was affected by a mutation in a chromatin-modifying protein gene. Two families carried the p.V44M mutation in the GJA8 gene. Haplotype analysis revealed a chromosome region of 475 kb containing the mutation in the GJA8 gene was harbored by two families.
Conclusions: Compared with traditional Sanger sequencing, targeted NGS for genetic testing of congenital cataracts markedly increases the mutation detection rate and is cost-effective. The p.V44M mutation in the GJA8 gene was the most common mutation and was due to a founder effect within the Chinese cohort studied. The results of this study expand the gene mutation spectrum of congenital cataracts.