Highly Prevalent GJB2 Gene Mutations among Congenital Nonsyndromic Hearing Impairment in a South Indian Population

Abstract

Hearing impairment (HI) is due to genetic (autosomal recessive) having a frequency of one in 1000 children. Hearing impairment has a widespread gene involvement of various chromosomes. Mutations in the GJB2 gene on chromosome 13 were frequent findings for congenital non-syndromic hearing impairment. To make it more complicated, it has been observed that these mutations show population variations. Objective: To determine the prevalence of the most common mutations in the GJB2 gene among the Indian population. Methods: In this study, 38 subjects (22 cases and 16 controls) enrolled, and the degree of hearing loss was assessed. To identify the involvement of GJB2 gene mutations p.W24X and c.235delC among the populations, PCR Technique and RFLP were adopted. Results: The mutations under investigation were at a higher prevalence rate, i.e., 45.45% for c.235delC and a lower prevalence rate of 18.18% for p.W24X, and both the mutations had heterozygous natures. Conclusion: This paper is the first of this kind that tries to identify a prevalent mutation in the GJB2 gene in the population of Karnataka state. The results are supported to some extent by previous Indian studies involving other than the current population. It is also noteworthy that the mutations identified are heterozygous and, therefore, are not pathogenic. This implies either the existence of potential mutations in the gene’s unexplored region or the possible co-implication of another connexin gene, i.e., the digenic origin of the hearing loss, which could be related to the putative formation of heteromeric connexons or heterotypic channels.