title: GJB2 (Connexin-26) mutations are not frequent among hearing impaired patients in east Greenland.
abstract: OBJECTIVE
  Investigate genetic causes of HI among the Inuit populations in the Arctic with a high prevalence of hearing impairment (HI).
  
  
  METHODS
  A cross-sectional survey with population-based controls.
  
  
  METHODS
  Forty-five patients, with sensorineural or mixed HI and an available blood sample for GJB2 sequencing from DNA, were selected from 166 east Greenlanders by specialist audiology examination, including pure-tone air and bone conduction audiometry from 125 Hz to 8000 Hz. Controls were 108 east- and 109 west-Greenlanders.
  
  
  RESULTS
  Forty-five patients with HI were included, 24 males and 21 females. Median age was 35 years (range: 5-76). The c.35delG allele frequency was 3.3%. One patient, homozygous for the c.35delG GJB2 mutation, had bilateral congenital profound HI. Another with mixed HI was heterozygous for the same mutation. Three were heterozygous for the p.V27I variant and one was heterozygous for the p.V153I variant. The frequency of the c.35delG mutation in the controls varied between 0.5% in west Greenland to 2.3% in east Greenland.
  
  
  CONCLUSIONS
  The c.35delG GJB2 mutation occurs in Greenland with low frequency. We conclude the main causes behind the prevalence of HI in this population are chronic otitis media, noise traumas, and/or unidentified genetic causes.
authors.affiliation: Department of Otolaryngology, Head & Neck Surgery, Rigshospitalet, Copenhagen, Denmark. phom@rh.regionh.dk
authors.forename: Preben
authors.initials: P
authors.lastname: Homøe
authors.forename: Anders
authors.initials: A
authors.lastname: Koch
authors.forename: Nanna Dahl
authors.initials: ND
authors.lastname: Rendtorff
authors.forename: Marianne
authors.initials: M
authors.lastname: Lodahl
authors.forename: Ture
authors.initials: T
authors.lastname: Andersen
authors.forename: Stig
authors.initials: S
authors.lastname: Andersen
authors.forename: Hans
authors.initials: H
authors.lastname: Eiberg
authors.forename: Inge-Merete
authors.initials: IM
authors.lastname: Nielsen
authors.forename: Lisbeth
authors.initials: L
authors.lastname: Tranebjærg
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001301:Audiometry, Pure-Tone; D001844:Bone Conduction / Q000235:genetics; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D003430:Cross-Sectional Studies; D004252:DNA Mutational Analysis; D005260:Female; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D006116:Greenland / Q000453:epidemiology; D006309:Hearing / Q000235:genetics*; D046089:Hearing Loss, Mixed Conductive-Sensorineural / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology; D006319:Hearing Loss, Sensorineural / Q000208:ethnology / Q000235:genetics* / Q000503:physiopathology; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D004930:Inuit / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D019986:Persons with Hearing Disabilities / Q000706:statistics & numerical data; D010641:Phenotype; D015995:Prevalence; D012307:Risk Factors; D055815:Young Adult
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26