Mapping And Mutation Analysis For Hereditary Congenital Cataract Due To The Mutation Of The Gap-junction Protein Gene

Background and Objective:Congenital cataract is an important cause for children blindness, approximately one third of cases in infant blindness. The incidence rate of cataract is about0.01-0.06%in infants, and roughly half of congenital cataracts are hereditary. The completion of the Human Genome Project promoted the cloning of genes hereditary diseases. Thirty-nine loci have been mapped in the hereditary congenital cataracts, and twenty six genes have been cloned in these loci.Achievements in there search of hereditary congenital cataracts Provide the foundation in understanding of occurrence and development of cataract. However, the relationship between genotype and Phenotype is still not clear. Thus, we need further study in hereditary congenital cataracts to find more new genes and mutations. The research on function of the mutated genes will promote understanding the pathologic mechanism and enhance prevention and cure of diseases.Materials and methodsThis study is focused on the family with the autosomal dominant congenital cataract, The diagnostic criteria are multiple patients in the family in at least two generations. A family with hereditary congenital cataract was recruited from Jiangxi province, China. Patients were given a physical examination and their blood samples were collected for DNA extraction. Genotyping was performed by microsatellite markers, and a logarithm of odds (LOD) score was calculated. Mutation detection was performed by direct sequencing. ResultsLinkage to the gap-junction protein Connexin50(GJA8) locus was identified in this family. DNA sequencing of the gene revealed a c.145C>G mutation in exonl, which resulted in a conservative substitution of Glutamine to Glutamic acid at position49(p.Q49E). This mutation was identified in all of the affected individuals but was not found in the100control chromosomes. ConclusionsOur results identify that the c.145C>G mutation in GJA8-1is responsible for the autosomal dominant congenital nuclear cataract disease in this Chinese family which have not been reported before.