title: Prevalence of GJB2 mutations and the del(GJB6-D13S1830) in Argentinean non-syndromic deaf patients.
abstract: Genetically caused congenital deafness is a common trait affecting 1 in 2000 children and it is predominantly inherited in an autosomal recessive fashion. Several mutations in the GJB2 gene and a deletion of 342 kb in GJB6 (delGJB6-D13S1830) have been identified worldwide in patients with hearing impairment. The aim of this study was to determine the prevalence of these mutations in Argentina. Non-syndromic 46 probands (17 familial and 29 sporadic cases) were genetically evaluated. Mutations in GJB2 and/or delGJB6-D13S1830 were found in 19 patients, accounting for 41.3% of the sample. Of the 46 patients investigated in this study, 12 (26.1%) were diagnosed to carry sequence variations in both alleles; all but one, were considered causative for hearing impairment in those patients. In 7 out of 46 patients (15.2%) only one mutant allele was detected. Of their 38 chromosomes, 71% resulted with mutations in the GJB2 gene and 11% in GJB6. The most frequent mutation in GJB2 (24%) was c.35delG (11% homozygous and 13% heterozygous and compound heterozygous). In addition, 11 sequence variations different from c.35delG, were identified in the coding region of the GJB2 gene: T8M, V27I, M34T, E47X, R75W, W77R, I82M, L90P, E129K, V153I, M163V. The delGJB6-D13S1830 mutation was found in 4 patients (9%), 3 of them associated with GJB2 mutations, resulting in compound heterozygous for the DFNB1 locus. The present study demonstrates that mutations in the GJB2 gene and the delGJB6-D13S1830 are prevalent in the Argentinean population.
authors.affiliation: Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina. dalamon@dna.uba.ar
authors.forename: Viviana
authors.initials: V
authors.lastname: Dalamón
authors.forename: Agustina
authors.initials: A
authors.lastname: Béhèran
authors.forename: Fernando
authors.initials: F
authors.lastname: Diamante
authors.forename: Norma
authors.initials: N
authors.lastname: Pallares
authors.forename: Vicente
authors.initials: V
authors.lastname: Diamante
authors.forename: Ana Belén
authors.initials: AB
authors.lastname: Elgoyhen
mesh_terms: D000293:Adolescent; D000328:Adult; D000483:Alleles; D001118:Argentina; D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D000075302:Connexin 30; D017630:Connexins / Q000737:chemistry / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005260:Female; D005787:Gene Frequency; D005808:Genes, Recessive; D006319:Hearing Loss, Sensorineural / Q000235:genetics*; D006801:Humans; D007223:Infant; D008297:Male; D008875:Middle Aged; D008958:Models, Molecular; D009154:Mutation; D017384:Sequence Deletion
chemical_list: D000075302:Connexin 30; D017630:Connexins; C000607042:GJB2 protein, human; C491020:GJB6 protein, human; D000072259:Connexin 26; D004247:DNA