Screening of 35delG, W24X, W77X and Q124X Variants in connexin 26 gene associated with Non-Syndromic Hearing Impairment

Abstract

Introduction: Hearing deficiency is the most common sensory incompetence that affects millions of people all over the world. Profound Deafness is a common disorder that occurs in 1:1000 neonates and the cause is hereditary. Gap Junction Beta2 (GJB2) gene which codes for connexion 26 protein is implicated in hearing. Mutation or defect in this gene leads to the most common form of the congenital disorder called Deaf Mutism (DM). The present study aims to screen the common variants associated with hearing impairment. Objective: To Screen common variants 35delG, W24X, W77X, and Q124X in connexin 26 gene of the North Karnataka population. Methods: 613 deaf-mute children from districts of North Karnataka were screened and 184 Non Syndromic Sensorineural Hearing-impaired children were included in the study. Genomic DNA was isolated using peripheral blood. Our gene of interest was amplified by Polymerase Chain Reaction (PCR) using target-specific primers. The PCR product was subjected to sequencing to analyze the mutations. Result: In our population prevalence of W24X, W77X variants were 25% & 5.4% respectively and 35 del G and Q124X mutations were absent. Along with this common variant, I33T (5.4%) and R127H (14.6%) were also observed. Conclusion: above findings suggests that Gap junction Beta 2 gene plays a crucial role in hearing impairment. Mutation analysis of the entire GJB2 gene in our population may help to define the etiology of deafness as well as the development of population-specific prenatal and perinatal genetic markers.