Molecular Analysis of the GJB2 Gene in Iraqi Patients with Sensorineural Non-Syndromic Hearing Loss

Saied A Jaradat, Bothaynah Jubran, Firas Alzoubi, Paul Hoff Backe, Hani Musa Bader, Hazem Haddad

Abstract


Objective: Increasingly, with advanced screening methods, the incidence of congenital deafness at birth is recognized as one of the most common defects worldwide. In over 50% of sensorineural hearing loss, a mutation in the Gap junction beta 2 (GJB2) gene, encoding connexin 26 (Cx26) protein is identified. In this study, we aimed to sequence exon 2 of the GJB2 gene in sixty-three unrelated Jordanian and Iraqi patients with recessive inheritance deafness.

Methods: DNA from 63 patients and 50 healthy controls was analyzed for mutations in the GJB2 gene by polymerase chain reaction and DNA sequencing.

Results: Six recurrent mutations were identified in 9 out 53 Iraqi patients (16.9%), included in the study. The c.35delG mutation was found in a homozygous genotype in four unrelated patients. Structural analyses of the Arg98Trp missense mutation which is heterozygous in one patient suggested that a mutation at this residue might potentially impair the permeability of Cx26 gap junctions.

Conclusions: To our knowledge, the present study is the first to screen for mutations in the GJB2 gene in non-syndromic sensorineural deafness patients of Iraqi origin. Three of the identified mutations (Arg98Trp; glu119lys and His100Argfs*14) in this report are described for the first time in Arabic nationality patients. The overall mutation detection rate in the GJB2 coding region in this study is slightly lower than that of other Mediterranean populations, which suggest other mutated allele may be within other regions of the GJB2 gene, which were not sequenced in this study or in other hearing loss loci.

Keywords


GJB2; Cx26; c.35delG; Sensorineural deafness; Jordan; Iraq.

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