Mutations of GJB2 in three geographic isolates from northern Tunisia: evidence for genetic heterogeneity within isolates

Abstract

Geographically isolated populations have been successfully used to localize genes for recessive inherited diseases, including non-syndromic sensorineural recessive deafness (NSRD). To date, 25 loci for NSRD have been localized on human chromosomes (DFNB loci), and six of the corresponding genes have been identified. Here, we report on the contribution of the DFNB1 locus (GJB2 gene) to NRSD in seven affected families living in three northern Tunisian geographic isolates, and we provide evidence for genetic heterogeneity within isolates. This finding challenges the classical view of a single 'founder' mutation segregating in such isolates.

Fanconi anemia in Tunisia: high prevalence of group A and identification of new FANCA mutations

“…Furthermore, the affected child who is homozygous for the FANCA markers carries the most common haplotype (2-5-2) in the homozygous state, whereas the other FA child carries the same haplotype in a heterozygous state. A similar situation of intrafamilial heterogeneity of mutations has been observed for several other disorders within Arab populations (Carrasquillo et al 1997;Rinat et al 1999;Ben Arab et al 2000).…”

GJB2 (connexin 26) gene mutations in Moroccan patients with autosomal recessive non-syndromic hearing loss and carrier frequency of the common GJB2–35delG mutation

“…This genotype was described by different studies as being associated with a severe to profound hearing loss [7,[36][37][38][39] that we also diagnosed among the affected members of our SF50 family.…”

Autosomal recessive and sporadic deafness in Morocco: High frequency of the 35delG GJB2 mutation and absence of the 342-kb GJB6 variant

“…Since data on the occurrence of GJB2 and GJB6 associated deafness in African populations are scarce (Denoyelle et al, 1997;Brobby et al, 1998;Lench et al, 1998;Ben Arab et al, 2000;Hamelmann et al, 2001;Gasmelseed et al, 2004), and no reports provided yet a systematic study of the prevalence of Cx26 and Cx30 mutations in Moroccan's population, we decided to analyse the prevalence of GJB2 and GJB6 variants among individuals with hearing loss in Morocco by analysing families with inherited sensorineural and sporadic deafness.…”