title: Low incidence of GJB2, GJB6 and mitochondrial DNA mutations in North Indian patients with non-syndromic hearing impairment.
abstract: Mutations at the DFNB1 locus which encode connexin 26 (CX26) and connexin 30 (CX30) proteins, respectively, are main cause for sporadic and familial non-syndromic hearing impairment (NSHI) in many populations. 342-kb deletion [del (GJB6-D13S1830)] of Cx30 gene is second most common connexin mutation. Specific mitochondrial DNA (mtDNA) mutations have been found to be associated with NSHI. In this study, we screened 210 NSHI patients for GJB2 mutations, DeltaGJB6-D13S1830 deletion and three point mutations in mtDNA (A1555G, A3243G, A7445G) using PCR, DHPLC and sequencing in North Indian cohort. 35delG was found to be the most common mutation (10.9%), followed by W24X (3.8%) and W77X (1.9%) mutations. We did not observe GJB6-D13S1830 deletion and three mitochondrial point mutations in our cohort. Most of patients (50/58) carried monoallelic variations. Our results reveal different spectrum of GJB2 mutations specific to North Indian cohort, with 35delG being most prevalent. These results suggest that different types of GJB2 mutations affect autosomal recessive NSHI according to ethnic background.
authors.affiliation: Department of Otolaryngology, Post Graduate Institute of Medical Education and Research, Chandigarh 160012, India.
authors.forename: Seema
authors.initials: S
authors.lastname: Bhalla
authors.forename: Rajni
authors.initials: R
authors.lastname: Sharma
authors.forename: Gaurav
authors.initials: G
authors.lastname: Khandelwal
authors.forename: Naresh K
authors.initials: NK
authors.lastname: Panda
authors.forename: Madhu
authors.initials: M
authors.lastname: Khullar
mesh_terms: D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D006312:Hearing Loss, Bilateral / Q000453:epidemiology / Q000235:genetics*; D006319:Hearing Loss, Sensorineural / Q000453:epidemiology / Q000235:genetics*; D006801:Humans; D015994:Incidence; D007194:India / Q000453:epidemiology; D008297:Male; D009154:Mutation
chemical_list: D000075302:Connexin 30; D017630:Connexins; D004272:DNA, Mitochondrial; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26