Frequency of a very rare 35delG mutation in two ethnic groups of Iranian populations

The 35delG mutation in the Connexin 26 gene (Cx26), at the DNFB1 locus is the most common mutation in the patients with autosomal recessive non-syndromic hearing loss (ARNSHL). We have studied a total of 224 deaf cases from 189 families in two populations of Iran (Sistan va Bluchestan and Hormozgan provinces) by prescreening nested PCR, polyacrylamide gel electrophoresis and consequent direct sequencing method for all cases. The aim of the present work was to find prevalence of GJB2 mutations in the populations studied. Four different GJB2 mutations including 35delG, W24X, R127H and (V27I + E114 G) were identified in 11 of 189 families (5.8). Two polymorphisms (V27I and V153I) also were detected in 14 families. A polymorphism S86T was determined in all cases. Homozygote 35delG mutation was found only in 1 of 189 families (0.5).The rate of Cx26 mutations found in this study was lower than other Iranian populations. So the cause of deafness in the populations studied remains to be detected in other loci or genes. © 2014, Iranian Journal of Public Health. All rights reserved

Frequencies of mutations in the connexin 26 gene (GJB2) in two populations of Iran (Tehran and Tabriz)

While hearing loss has been considered to be a very heterogeneous disorder, mutations in Gap junction beta 2 (GJB2) gene encoding Connexin 26 (Cx26) protein are the major cause of autosomal recessive and sporadic non-syndromic deafness in many populations. In this study, we have investigated the prevalence of the GJB2 gene mutations using nested PCR pre screening strategy and direct sequencing method. Two hundred and seventy two hearing impaired subjects were studied from 210 families obtained from two large cities of Iran (Tehran and Tabriz). Twenty four different genetic variants were identified. Cx26 mutations were found in 53 of the 210 families (25.2) including T8M, 35delG, W24X, R32H, V371, E47X, 167delT, delE120, Y136X, R143W, R184P, 235delC and V27I+E114G. Homozygosity and compound heterozygosity for the Cx26 mutations were found in 39 of 210 (18.5) families. Homozygosity for the 35delG mutation was the most common that causes hearing loss in 28 (13.3) patients. Six novel variants H16R, E101E, K102Q, G200R, 327delG and G130A were detected in this study. As a conclusion, the present survey revealed that the rate of mutation in Cx26 gene in our area is lower than in Europe; nevertheless, this rate is regarded as a considerable cause of deafness in the cited provinces in Iran