Variability in noise susceptibility in a Swedish population: the role of 35delG mutation in the connexin 26 (GJB2) gene

Abstract

Although it seems that genetic factors can influence individual susceptibility to noise, still very little is known about the genes or the mechanisms involved. The connexin 26 (Cx26) (GJB2) gene is of particular interest to study in relation to noise, since the gene encodes the gap junction protein Cx26. Noise has a metabolic and mechanical effect on the inner ear and may, therefore, interfere with gap junction channels. In order to investigate whether abnormally high susceptibility to noise induced hearing loss (NIHL) in humans is associated with the common 35delG mutation in the Cx26 gene, 1200 noise‐exposed workers were investigated in Sweden. Using a selection procedure based on audiometric analysis, noise exposure data and questionnaires, noise‐exposed workers were divided into two categories: noise susceptible and noise resistant. There was a correspondence in noise susceptibility between this noise‐exposed population and the international reference ISO Standard 1999. Blood samples were drawn from 245 highly selected male subjects (103 noise susceptible, 112 noise resistant and 30 randomized cases), and genomic DNA was analysed with respect to the Cx26 35delG mutation. The incidence of 35delG carriers among this cohort was determined by multiplex, allele‐specific PCR. Two of the 245 subjects (0.8% ‐ [95% confidence interval 0.1–2.9]) were found to be heterozygous carriers of the 35delG mutation, while the remaining 243 subjects were all non‐carriers. Both the heterozygous carriers were found in the noise susceptible group. Statistical evaluation of the results demonstrated no significant difference in carrier incidence between the noise susceptible and noise resistant individuals in our Swedish noise‐exposed population. In conclusion, there was no support for a major role of Cx26 35delG mutation in explaining the variability in noise susceptibility in this Swedish population.

• noise‐induced hearing loss
• susceptibility
• connexin 26