Mutations in the human gap junction beta-2 gene (GJB2) that encodes connexin-26 have been shown to cause non-syndromic sensorineural hearing loss (NSSNHL) at the DFNB1 locus on 13q11. Functional and genetic data regarding the disease causing potential of one particular GJB2 sequence variant, 101 T-->C (M34T), have proven contradictory. In this study, we found the prevalence of the M34T allele i...

EDITOR—Existing published data cannot conclusively determine if the M34T allele of connexin-26 (GJB2) is a recessive allele causing hearing loss. The recent article by Houseman et al (J Med Genet 2001;38:20-5) “Genetic analysis of the connexin-26 M34T variant: identification of genotype M34T/ M34T segregating with mild-moderate nonsyndromic sensorineural hearing loss,” does not resolve this que...

Mutations in the gene GJB2, encoding the gap junction protein Connexin26 (Cx26), are the most prevalent cause of inherited hearing loss, and Cx26M34T was one of the first mutations linked to deafness (Kelsell et al., 1997; Nature 387, 80-83). We report the first characterization of the gating properties of M34T, which had previously been reported to be nonfunctional. Although homotypic mutant c...

Mutations in the GJB2 gene, which encodes the gap junction protein connexin26 (Cx26), are the major cause of genetic non-syndromic hearing loss. The role of the allelic variant M34T in causing hereditary deafness remains controversial. By combining genetic, clinical, biochemical, electrophysiological and structural modeling studies, we have re-assessed the pathogenetic role of the M34T mutation...

OBJECTIVE to determinate the role of heterozygosis of M34T mutation of GJB2 gene in non syndromic congenital deafness. METHODS retrospective study between March 2010 and June 2013. Molecular screening for 35delG and M34T mutations of the GJB2 gene was offered to all women undergoing to second trimester genetic amniocentesis. Patients were excluded from the study group if one of the following ...

Autosomal recessive non-syndromic hearing impairment (ARNSHI) is caused by mutations in the gap junction gene GJB2 (Connexin 26; Cx26) in numerous human populations. The aim of this study was to determine the frequency of six GJB2 mutations in 50 Syrian families with congenital deafness and in 180 controls. PCR-RFLP was used to detect the 35delG, 167delT, M34T, W24X, W77R and E47X mutations, an...

Deafness is a partial or total hearing loss that can appear at any ages and with different degrees of severity. About 50% of hearing disorders have a genetic origin, and among them, the nonsyndromic sensorineural deafness represents 70% of the cases. Out of these, the 80% correspond to autosomal recessive inheritance deafness. Autosomal recessive deafness has not been characterized enough at mo...

Connexin26 (Cx26) mutations underlie human pathologies ranging from hearing loss to keratitis ichthyosis deafness (KID) syndrome. Cx26 hemichannels are directly gated by CO2 and contribute to the chemosensory regulation of breathing. The KID syndrome mutation A88V is insensitive to CO2, and has a dominant negative action on the CO2 sensitivity of Cx26WT hemichannels, and reduces respiratory dri...

Three point mutations of the connexin26 (GJB2) gene associated with hereditary deafness were studied using in vitro expression systems. Mutation M34T results in an amino acid substitution in the first transmembrane domain of the connexin protein, W77R is located in the second transmembrane domain and W44C is in the first extracellular loop. Wild-type and mutated connexin vectors were constructe...