Spectrum of Gjb2 Gene Mutations in Nonsyndromic Autosomal Recessive Deaf Patients in Yazd

Hearing loss is the most common sensory neural defect in humans, affecting 1 in 1000 neonates, with over half of these cases predicted to be hereditary in nature. Most hereditary hearing loss is inherited in a recessive fashion, accounting for approximately 80 % of non-syndromic hearing loss (NSHL). Mutations in GJB2 gene are major cause of inherited deafness in the European and American populations. To date, more than 90 mutations have been reported in this gene. Although most of these mutations are rare but 35delG mutation is the most common deafness causing allelic variant of GJB2 in most parts of the world.

In this project, 120 probands from 120 families with ARNSHL in Yazd Province were studied. Mutations Screening of GJB2 was performed by Amplification Refractory Mutation System (ARMS)-PCR for detection of 35delG and then all samples excluding 35delG homozygote were analyzed by DHPLC and Direct Sequencing.

GJB2-related deafness was present in 7.5% of this population. We identified 4 mutations (35delG, 312del14, 314del14 and 167delT) and 4 polymorphisms (V153I, V27I, E114G and R127H) in this study.

Prevalence of GJB2 mutations in this population was lower than American and European populations, and also other provinces of Iran. Interestingly, 312del14 rather than 35delG was the most common mutation found in the population under study. 56.25 % of GJB2 mutant alleles carried 312del14 mutation. To date, this frequency has not been reported in any of the world populations.