The contribution of GJB2 (Connexin 26) 35delG to age-related hearing impairment and noise-induced hearing loss.

HYPOTHESIS: The common GJB2 (Connexin 26) 35delG mutation might contribute to the development of age-related hearing impairment (ARHI) and noise-induced hearing loss (NIHL). BACKGROUND: GJB2, a gene encoding a gap junction protein expressed in the inner ear, has been suggested to be involved in the potassium recycling pathway in the cochlea. GJB2 mutations account for a large number of individuals with nonsyndromic recessive hearing loss, with 35delG being the most frequent mutation in populations of European origin. Other genes involved in potassium homeostasis have been suggested to be associated with ARHI and NIHL, and distortion product otoacoustic emission distortions indicative of hearing loss alterations have been found in 35delG carriers. METHOD: We genotyped 35delG in two distinct sample sets: an ARHI sample set, composed of 2,311 Caucasian samples from nine different centers originating from seven different countries with an age range between 53 and 67 years, and an NIHL sample set consisting of 702 samples from the two extremes of a noise-exposed Polish sample. RESULTS: After statistical analysis, we were unable to detect an association between 35delG and ARHI, nor between 35delG and NIHL. CONCLUSION: Our findings indicate that there is no increased susceptibility in 35delG carriers for the development of ARHI or NIHL.