Relative frequency of GJB2 gene mutations in autosomal recessive non-syndromic hearing loss (ARNSHL) patients in Lorestan population

Background: Congenital hearing loss due to different genetic and environmental causes affects 1 in 1000 newborns. Mutations in the GJB2 (Gap Junction Beta-2) gene encoding the gap junction protein connexin 26 have been established as the main cause of autosomal recessive non-syndromic hearing loss. Materials and methods: The aim of this study was to study the frequency of GJB2 Mutations in Lorestan non-syndromic deaf population by using ARMS/PCR, DHPLC and Direct sequencing. Results: 106 chromosomes from 53 patients were studied. Eighteen chromosome (17%) carried GJB2 mutations including: 35delG, 314del14, 512insAACG, -3170G>A, W24X, V95M, 510insCGAA. The last mutation is a novel GJB2 mutation and 35delG mutation was diagnosed in 10 chromosomes (9/4%), (4 patients were homozygote and 2 patients were heterozygote). Also polymorphism V153I were found in 3 families. ‏‏‏This frequency is significantly higher compared to the whole population of Iran. Conclusion: Unexpectedly, in this research just 17 percent of cases are covered. In this study 510 insCGAA mutation was seen. This is a new mutation which is not reported in other studied populations in the world. Hence, this research shows that – at least in our studied population- the effect of other genes that could cause non-syndromic hearing loss is possible and should be studied