The contribution of GJB2 mutations to slight or mild hearing loss in Australian elementary school children

Background: There is a lack of information on prevalence, cause and consequences of slight/ mild bilateral sensorineural hearing loss ( SNHL) in children. We report the first systematic genetic analysis of the GJB2 gene in a population- derived sample of children with slight/ mild bilateral SNHL. Methods: Hearing tests were conducted in 6240 Australian elementary school children in Grades 1 and 5. 55 children ( 0.88%) were found to have a slight/ mild sensorineural hearing loss. 48 children with slight/ mild sensorineural hearing loss and a matched group of 90 children with normal hearing participated in a genetic study investigating mutations in the GJB2 gene, coding for connexin 26, and the presence of the del( GJB6- D13S1830) and del( GJB6- D13S1854) deletions in the GJB6 gene, coding for connexin 30. Results: Four of 48 children with slight/ mild sensorineural hearing loss were homozygous for the GJB2 V37I change. The four children with homozygous V37I mutations were all of Asian background and analysis of SNPs in or near the GJB2 gene suggests that the V37I mutation arose from a single mutational event in the Asian population. Discussion: Based on the prevalence of carriers of this change we conclude that V37I can be a causative mutation that is often associated with slight/ mild sensorineural hearing loss. No other children in the slight/ mild hearing loss group had a hearing loss related to a GJB2 mutation. One child with normal hearing was homozygous for the R127H change and we conclude that this change does not cause hearing loss. Two children of Asian background were carriers of the V37I mutation. Our data indicate that slight/ mild sensorineural hearing loss due to the GJB2 V37I mutation is common in people of Asian background.