title: Distribution and phenotype of GJB2 mutations in 102 Sicilian patients with congenital non syndromic sensorineural hearing loss.
abstract: OBJECTIVE
  To evaluate the frequency of GJB2 mutations and their correlation with phenotype in Sicilian non-syndromic sensorineural hearing loss (NSHL) patients.
  
  
  METHODS
  Sequencing of the coding region, basal promoter, exon 1, and donor splice site of the GJB2 gene; screening for the presence of the two common GJB6 deletions.
  
  
  METHODS
  A cohort of 102 Sicilian NSHL patients.
  
  
  RESULTS
  Fifteen different mutations in GJB2 and seventeen different genotypes were detected. No GJB6 mutations were found. The hearing impairment was profound in the 64.72% of probands (mean PTA0.25-4 kHz of 88.82 ± 26.52 dB HL). A total of 81.37% of patients harboured at least one c.35delG allele; c.167delT and c.-23 + 1G> A were identified in 10.78% and the 9.8% of patients respectively; c.35delG homozygotes presented more severe hearing impairment (75.59% of profound hearing loss) and a higher mean PTA0.25-4 kHz (96.79 ± 21.11 dB HL) with respect to c.35delG/non-c.35delG and c.35delG/Wt patients (P < 0.05).
  
  
  CONCLUSIONS
  This work underlines the role of c.35delG, c.167delT and c.-23 + 1G> A as the most frequent causes of NSHL in Sicily. The c.35delG frequency found is similar to those reported in other populations of the Mediterranean area. The analysis of genetic and audiologic data confirmed a variability in the phenotype associated to a single genotype.
authors.affiliation: * Dipartimento di Biomedicina Sperimentale e Neuroscienze Cliniche, (BioNeC), Sezione di Otorinolaringoiatria, Università degli Studi di Palermo , Palermo , Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Salvago
authors.forename: Enrico
authors.initials: E
authors.lastname: Martines
authors.forename: Eleonora
authors.initials: E
authors.lastname: La Mattina
authors.forename: Marianna
authors.initials: M
authors.lastname: Mucia
authors.forename: Pietro
authors.initials: P
authors.lastname: Sammarco
authors.forename: Federico
authors.initials: F
authors.lastname: Sireci
authors.forename: Francesco
authors.initials: F
authors.lastname: Martines
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D005838:Genotype; D006319:Hearing Loss, Sensorineural / Q000151:congenital / Q000235:genetics*; D006801:Humans; D008875:Middle Aged; D009154:Mutation; D010641:Phenotype; D012189:Retrospective Studies; D012802:Sicily; D055815:Young Adult
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26
keywords: GJB2; Genotype-Phenotype; Sensorineural hearing loss; Sicily