title: Update of the spectrum of GJB2 gene mutations in Tunisian families with autosomal recessive nonsyndromic hearing loss.
abstract: Hearing loss is the most frequent sensory disorder. It affects 3 in 1000 newborns. It is genetically heterogeneous with 60 causally-related genes identified to date. Mutations in GJB2 gene account for half of all cases of non-syndromic deafness. The aim of this study was to determine the relative frequency of GJB2 allele variants in Tunisia. In this study, we screened 138 patients with congenital hearing loss belonging to 131 families originating from different parts of Tunisia for mutations in GJB2 gene. GJB2 mutations were found in 39% of families (51/131). The most common mutation was c.35delG accounting for 35% of all cases (46/131). The second most frequent mutation was p.E47X present in 3.8% of families. Four identified mutations in our cohort have not been reported in Tunisia; p.V37I, c.235delC, p.G130A and the splice site mutation IVS1+1G>A (0.76%). These previously described mutations were detected only in families originating from Northern and not from other geographical regions in Tunisia. In conclusion we have confirmed the high frequency of c.35delG in Tunisia which represents 85.4% of all GJB2 mutant alleles. We have also extended the mutational spectrum of GJB2 gene in Tunisia and revealed a more pronounced allelic heterogeneity in the North compared to the rest of the country.
authors.affiliation: Laboratoire de Génomique Biomédicale et Oncogénétique, Institut Pasteur de Tunis, BP 74, 13 Place Pasteur, Tunis 1002, Tunisia.
authors.forename: Zied
authors.initials: Z
authors.lastname: Riahi
authors.forename: Hassen
authors.initials: H
authors.lastname: Hammami
authors.forename: Houyem
authors.initials: H
authors.lastname: Ouragini
authors.forename: Habib
authors.initials: H
authors.lastname: Messai
authors.forename: Rim
authors.initials: R
authors.lastname: Zainine
authors.forename: Yosra
authors.initials: Y
authors.lastname: Bouyacoub
authors.forename: Lilia
authors.initials: L
authors.lastname: Romdhane
authors.forename: Donia
authors.initials: D
authors.lastname: Essaid
authors.forename: Rym
authors.initials: R
authors.lastname: Kefi
authors.forename: Mohsen
authors.initials: M
authors.lastname: Rhimi
authors.forename: Monia
authors.initials: M
authors.lastname: Bedoui
authors.forename: Afef
authors.initials: A
authors.lastname: Dhaouadi
authors.forename: Delphine
authors.initials: D
authors.lastname: Feldmann
authors.forename: Laurence
authors.initials: L
authors.lastname: Jonard
authors.forename: Ghazi
authors.initials: G
authors.lastname: Besbes
authors.forename: Sonia
authors.initials: S
authors.lastname: Abdelhak
mesh_terms: D000293:Adolescent; D000483:Alleles; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D005260:Female; D005787:Gene Frequency; D005808:Genes, Recessive; D034381:Hearing Loss / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation; D014416:Tunisia
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26