title: Mutation analysis of GJB2 and GJB6 genes in Southeastern Brazilians with hereditary nonsyndromic deafness.
abstract: In developed countries deafness has a genetic cause in over 60% of the cases. Contrastingly, in Brazil, it is estimated that only 16% of all deafnesses are caused by genetic factors. Among hereditary hearing deficiencies, approximately half is caused by mutations in the Gap Junction Protein Beta-2 (GJB2) gene, which encodes the protein Connexin 26 (Cx26). There are four mutations in this gene that present high prevalence in specific ethnical groups, namely, 35delG, 167delT, 235delC, and W24X. The 35delG mutation is the most frequent one, occurring in homozygosity or in compound heterozygosity with mutations in the GJB2 and GJB6 genes. This study aims to determine the prevalence of GJB2-35delG, GJB2-167delT, GJB2-235delC, GJB2-W24X, del (GJB6-D13S1830), and del (GJB6-D13S1854) mutations in patients with nonsyndromic deafness in the Espirito Santo State, Brazil. A total of 77 individuals were evaluated, from which 88.3% presented normal genotypes for all analyzed mutations, 1.3% were compound heterozygotes for 35delG-GJB2/D13S1830-GJB6, 1.3% were compound heterozygotes for 35delG/D13S1854-GJB6, 3.9% were homozygotes for the 35delG mutation and 5.2% were heterozygotes for 35delG/GJB2. The frequency of mutant alleles 35delG/GJB2, del (D13S1830/GJB6), and del (D13S1854/GJB6) was 7.8, 0.65, and 0.65%, respectively. Mutations 167delT, 235delC, and W24X were not detected. Determining the prevalence of specific mutations related to inherited deafness in a population can contribute to the development of more efficient and affordable molecular diagnostic protocols, and help in the genetic counseling of patients and their families.
authors.affiliation: Laboratório de Genética e Biologia Molecular, Faculdades Integradas São Pedro-FAESA, Rodovia Serafim Derenzi, 3115, São Pedro, 29048-450, Vitória, ES, Brazil.
authors.forename: Melissa de Freitas
authors.initials: Mde F
authors.lastname: Cordeiro-Silva
authors.forename: Andressa
authors.initials: A
authors.lastname: Barbosa
authors.forename: Marília
authors.initials: M
authors.lastname: Santiago
authors.forename: Mariana
authors.initials: M
authors.lastname: Provetti
authors.forename: Raquel Spinassé
authors.initials: RS
authors.lastname: Dettogni
authors.forename: Thais Tristão
authors.initials: TT
authors.lastname: Tovar
authors.forename: Eliete
authors.initials: E
authors.lastname: Rabbi-Bortolini
authors.forename: Iúri Drumond
authors.initials: ID
authors.lastname: Louro
mesh_terms: D000293:Adolescent; D000328:Adult; D001938:Brazil; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000235:genetics*; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000208:ethnology* / Q000235:genetics*; D006579:Heterozygote; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D009154:Mutation
chemical_list: D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26