GJB

Mutations in the GJB2 gene are a major cause of non‐syndromic recessive hearing loss in many countries. In a significant fraction of patients, only monoallelic GJB2 mutations known to be either recessive or of unclear pathogenicity are identified. This paper reports a novel GJB2 mutation, −3438C→T, found in the basal promoter of the gene, in trans with V84M, in a patient with profound hearing impairment. This novel mutation can abolish the basal promoter activity of GJB2. These results highlight the importance of extending the mutational screening to regions outside the coding region of GJB2.

This article reviews the most prevalent sensory illness of mammals especially humans – Genetic Deafness or hearing loss (HL). For genetic hearing loss more than 100 candidate genes have been discovered. The most common candidate gene of these all that is found all around the world is GJB2 gene. Different types of mutations are found in GJB2 gene. Some of these mutations are non-sense while some are sense mutations. This study is focus on mutation in GJB2 gene and its prevalence in different region of the world.

This paper presents a mutation as well as a genotype-phenotype analysis of the GJB2 and GJB6 genes in 476 samples from non-syndromic unrelated Argentinean deaf patients (104 familial and 372 sporadic cases). Most of them were of prelingual onset (82 %) and 27 % were cochlear implanted. Variation of sequences was detected in 171 of the 474 patients (36 %). Overall, 43 different sequence variations were identified in GJB2 and GJB6. Four of them are reported for the first time in GJB2: c.233dupG, p.Ala78Ser, p.Val190Asp and p.Cys211Tyr. Mutations in GJB6 were detected in 3 % of patients [nine del(GJB6-D13S1830) and three del(GJB6-D13S1854)]. Of the 43 different variations identified in GJB2, 6 were polymorphisms and of the others, 10 (27 %) were truncating and 27 (73 %) were nontruncating. Patients with two truncating mutations had significantly worse hearing impairment than all other groups. Moderate phenotypes were observed in a group of patients carrying biallelic mutations (23 %). This work shows the high prevalence of GJB2 mutations in the Argentinean population and presents an analysis of moderate phenotypes in our cohort.