Identification of a missense mutation in MIP gene via mutation analysis of a Guangxi Zhuang ethnic pedigree with congenital nuclear cataracts.

At present, congenital cataract is the world's leading cause of blindness among children. The aim of the present study was to determine and analyze the genetic disorder associated with a congenital nuclear cataract in a three-generation family of Guangxi Zhuang ethnicity. A total of 3 affected individuals and 5 unaffected family members underwent appropriate comprehensive medical examinations, mainly of the eyes. The white blood cells of the family members were collected and genomic DNA was extracted from 100 healthy individuals, as the control group. The sequences of candidate genes were determined by polymerase chain reaction amplification followed by direct sequencing. The functional consequences of the mutation were analysed with biology software. A missense mutation (c.97C>T) was found in exon 1 of major intrinsic protein of lens fiber (MIP) gene. Therefore, the arginine of the highly conserved codon 33 was changed to cysteine. This mutation was identified in the affected family members, but not identified in unaffected family members or the 100 normal controls. The mutation in the MIP gene is the genetic cause of the congenital cataract in the ethnic Guangxi Zhuang family.