Targeted Exome Sequencing of Congenital Cataracts Related Genes: Broadening the Mutation Spectrum and Genotype-Phenotype Correlations in 27 Chinese Han Families

Abstract

Congenital cataract is the most frequent inherited ocular disorder and the most leading cause of lifelong visual loss. The screening of pathogenic mutations can be very challenging in some cases, for congenital cataracts are clinically and genetically heterogeneous diseases. The aim of this study is to investigate the mutation spectrum and frequency of 54 cartaract-associated genes in 27 Chinese families with congenital cataracts. Variants in 54 cataract-associated genes were screened by targeted next-generation sequencing (NGS) and then validated by Sanger sequencing. We identified pathogenic variants in 62.96% (17/27) of families, and over 52.94% (9/17) of these variants were novel. Among them, three are splicing site mutations, four are nonsense mutations, seven are missense mutations, two are frame shift mutations and one is intronic mutation. This included identification of: complex ocular phenotypes due to two novel PAX6 mutations; progressive cortical cataract and lamellar cataract with lens subluxation due to two novel CRYGS mutations. Mutations were also found in rarely reported genes including CRYBA4, CRYBA2, BFSP1, VIM, HSF4, and EZR. Our study expands the mutation spectrum and frequency of genes responsible for congenital cataracts. Targeted next-generation sequencing in inherited congenital cataract patients provided significant diagnostic information.