A novel mutation in MIP associated with congenital nuclear cataract in a Chinese family

PURPOSE To identify the underlying genetic defect in a Chinese family affected with autosomal dominant congenital nuclear cataract. METHODS A four-generation Chinese family with inherited nuclear cataract phenotype was recruited. Detailed family history and clinical data were recorded. All reported nuclear cataract-related candidate genes were screened for causative mutations by direct DNA sequencing. Effects of amino acid changes on the structure and function of protein were predicted by bioinformatics analysis. RESULTS All affected individuals in this family showed nuclear cataracts. Sequencing of the candidate genes revealed a heterozygous c.559C>T change in the coding region of the major intrinsic protein (MIP), which caused a substitution of highly conserved arginine by cysteine at codon 187 (p.R187C). This mutation co-segregated with all affected individuals and was not observed in unaffected family members or 110 ethnically matched controls. Bioinformatics analysis showed that the mutation was predicted to affect the function and secondary structure of MIP protein. CONCLUSIONS This study identified a novel disease-causing mutation p.R187C in MIP in a Chinese cataract family, expanding the mutation spectrum of MIP causing congenital cataract.