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

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. 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. 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. 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.