GJB2 mutations in non syndromic hearing loss in the republic of macedonia

Abstract

Hearing impairment is a common sensori-neural disorder with the incidence of profound deafness in one per 1,000 births. Non syndromic recessive deafness (NSHL), accounts for approximately 80% of cases of hereditary deafness. It is extremely heterogeneous genetically with over 130 gene loci. Mutations in the GJB2 and GJB6 genes for DFNB1 locus (13q12) are responsible for about half of all cases of autosomal recessive prelingual hearing loss.We determined the prevalence and mutations in the GJB2 gene, and the presence of delD13S1830 in the GJB6 gene in DNA samples from 33 unrelated Macedonian families with recesive NSHL and 200 normal hearing individuals using single-strand conformation polymorphism (SSCP) analysis followed by direct sequencing and specific polymerase chain reaction (PCR).We found mutations in the GJB2 gene in 12 patients, but no delD13S1830 in the GJB6 gene. In 22 mutated chromosomes, 15 (68.2%) had the 35delG mutation, four (6.1%) W24X, two (3.0%) V37I and one (1.5%) R127H.Because of the high mutation rate (36.4%) in the GJB2 gene in NSHL patients, testing should be performed in all cases with prelingual deafness.