Prevalence of the 35delG mutation in the GJB2 gene in two samples of non-syndromic deaf subjects from Chile

Carolina Ríos,Mónica Acuña,Corina Farfán,Mariela Torrente,Margarita Arancibia,Lucía Cifuentes

doi:10.4067/s0716-97602013000300003

Carolina Ríos, Mónica Acuña

Open Access

https://doi.org/10.4067/s0716-97602013000300003

Copy DOI

Abstract

Hearing loss is the most common inherited sensorial deficiency in humans; about 1 in 1000 children suffer from severe or profound hearing loss at birth. Mutations in the GJB2 gene are the most common cause of prelingual, non-syndromic autosomal recessive deafness in many populations; the c.35delG mutation is the most common in Caucasian populations. The frequency of the c.35delG mutation was estimated in two samples of deaf patients from Santiago, Chile. Unrelated non-syndromic sensorioneural deaf patients were examined: Group 1 consisted of 47 unrelated individuals with neurosensory deafness referred to the Chilean Cochlear Implant Program; Group 2 included 66 school children with prelingual deafness attending special education institutions for deaf people. Individuals with profound to moderate isolated neurosensory hearing loss with unknown etiology were included. The presence of the c.35delG mutation was evaluated by the allele-specific polymerase chain reaction method (PCR), and in some cases it was confirmed by direct DNA sequencing of the coding region of the GJB2 gene. Deaf relatives were present in 20.3% of the cases. We found 19.5% (22/113) patients with the c.35delG mutation, 6 of them homozygous; these rates are similar to frequencies found in other Latin American countries.

Highlights

Hearing loss is the most common inherited sensory deficiency in humans; approximately 1 in 1000 children suffer from severe or profound bilateral permanent hearing loss at birth or during early childhood (Morton, 1991)
The presence of the c.35delG mutation was evaluated by the allele-specific polymerase chain reaction method (PCR), and in some cases it was confirmed by direct DNA sequencing of the coding region of the GJB2 gene
A total of 113 patients (90 sporadic and 23 familial cases) with idiopathic non-syndromic sensorineural hearing loss were genotyped for the c.35delG mutation at the GJB2 gene

Summary

Introduction

Hearing loss is the most common inherited sensory deficiency in humans; approximately 1 in 1000 children suffer from severe or profound bilateral permanent hearing loss at birth or during early childhood (Morton, 1991). Analyses of the GJB2 gene in patients with autosomal recessive inherited deafness, especially due to the c.35delG mutation, have shown that 10% to 50% of them presented only one mutant allele (Kenneson et al, 2002). Studies of these heterozygous patients for GJB2 mutations have found other mutations in the GJB6 gene, which encodes connexin-30 ( located at the DFNB1 locus, 35 kb from the GJB2 gene); in these cases there is a digenic origin of deafness (Del Castillo et al, 2005, Cordeiro-Silva et al, 2011)

Objectives

Methods

Results

Conclusion