Evaluation of the GJB2 and GJB6 Polymorphisms with Autosomal Recessive Nonsyndromic Hearing Loss in Iranian Population

Hearing loss (HL), with more than 100 gene loci, is the most common sensorineural defects in humans. The mutations in two GJB2 and GJB6 (Gap Junction Protein Beta 2, 6) genes are responsible for nearly 50% of autosomal recessive nonsyndromic hearing loss. The aim of the present study was to evaluate polymorphisms of 111C>T (rs7329857) and 337G>T (rs7333214) in GJB2 (encoding connexin 26) and GJB6 (encoding connexin 32) genes, respectively.   In this study, 32 blood samples were obtained from Iranian patients with HL defect and 32 normal blood samples were prepared. After genomic deoxyribonucleic acid extraction, genotyping in rs7333214 and rs7329857 polymorphisms was conducted using tetra-amplification refractory mutation system-polymerase chain reaction and the obtained data were analyzed.   In this study, the prevalence rates of CC, CT, and TT genotypes in GJB2 gene were reported as 84.4%, 68.7%, and 0% in the affected subjects and 0%, 15.6%, and 31.3% in the control samples, respectively, which were statistically significant (P=0.004). In relation to GJB6 gene, the prevalence rates of GG, GT, and TT genotypes were 65.2%, 78.1%, and 25% in the control subjects and 21.9%, 9.4%, and 0% in the affected samples, respectively, which were not statistically significant (P>0.05).   The results of this study revealed that 111C>T polymorphism in GJB2 gene was involved in the incidence of HL in the studied population and could be suggested as a prognostic factor in genetic counseling before marriage and pregnancy.