title: Causes of hearing impairment in the Norwegian paediatric cochlear implant program.
abstract: Severe to profound hearing impairment (HI) is estimated to affect around 1/2000 young children. Advances in genetics have made it possible to identify several genes related to HI. This information can cast light upon prognostic factors regarding the outcome in cochlear implantation, and provide information both for scientific and genetic counselling purposes. From 1992 to 2005, 273 children from 254 families (probands) were offered cochlear implants in Norway. An evaluation of the causes of HI, especially regarding the genes GJB2, GJB6, SLC26A4, KCNQ1, KCNE1, and the mutation A1555G in mitochondrial DNA was performed in 85% of the families. The number of probands with unknown cause of HI was thus reduced from 120 to 68 (43% reduction). Ninety-eight (46%) of the probands had an identified genetic etiology of their HI. A relatively high prevalence of Jervell and Lange-Nielsen syndrome was found. The main causes of severe and profound HI were similar to those found in other European countries. GJB2 mutations are a common cause of prelingual HI in Norwegian cochlear implanted children.
authors.affiliation: Department of Otolaryngology, Faculty Division Rikshospitalet, University of Oslo, Norway. geir@siem.no
authors.forename: Geir
authors.initials: G
authors.lastname: Siem
authors.forename: Toril
authors.initials: T
authors.lastname: Fagerheim
authors.forename: Christoffer
authors.initials: C
authors.lastname: Jonsrud
authors.forename: Claude
authors.initials: C
authors.lastname: Laurent
authors.forename: Erik
authors.initials: E
authors.lastname: Teig
authors.forename: Sten
authors.initials: S
authors.lastname: Harris
authors.forename: Trond P
authors.initials: TP
authors.lastname: Leren
authors.forename: Andreas
authors.initials: A
authors.lastname: Früh
authors.forename: Ketil
authors.initials: K
authors.lastname: Heimdal
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003054:Cochlear Implants; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial; D005260:Female; D034381:Hearing Loss / Q000209:etiology* / Q000235:genetics / Q000628:therapy*; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation; D009664:Norway; D015995:Prevalence; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D017630:Connexins; D004272:DNA, Mitochondrial; C000607042:GJB2 protein, human; D000072259:Connexin 26