title: GJB2 gene mutations in cochlear implant recipients: prevalence and impact on outcome.
abstract: OBJECTIVE
  To determine the prevalence of GJB2 gene mutations in patients undergoing cochlear implantation (CI) and their impact on rehabilitative outcome following implantation.
  
  
  METHODS
  Prospective determination of GJB2 mutation by sequence analysis by denaturing high-performance liquid chromatography and its correlation with outcome following CI.
  
  
  METHODS
  Two tertiary academic medical centers.
  
  
  METHODS
  Subjects who have met the audiologic criteria and have undergone CI.
  
  
  RESULTS
  Of 77 cochlear implant recipients screened, 13 (18%) harbored a detectable sequence alteration in the GJB2 gene. Only 3 of these 13 patients had hearing loss clearly attributable to a biallelic GJB2 mutation. There were 2 patients with homozygous mutations, including a 35delG and a 167delT mutation, and a third with a compound heterozygous mutation. Of the remaining 10 patients, 8 had 1 deafness allele, while 2 had a normal polymorphism that was not believed to be implicated in the hearing loss. Six patients had the common 35delG mutation: 5 patients had heterozygous mutations, which are probably not related to the underlying hearing loss (a second deafness allele cannot be ruled out in these cases because of the screening methodology used), while 1 patient had a homozygous mutation, which was clearly implicated in the patient's deafness. Rehabilitative outcome among those with detectable sequence alterations, as well as the 3 patients with biallelic mutations, varied but were similar on average when compared with outcomes seen in our entire CI population.
  
  
  CONCLUSIONS
  A large percentage of implant candidates harbor mutations or sequence alterations in the GJB2 gene, although only a small number of these changes are biallelic and a clear cause of the hearing loss. These results demonstrate that patients with GJB2-related deafness clearly benefit from CI.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, Johns Hopkins University, JHOC, Baltimore, MD 21287, USA. llustig@jhmi.edu
authors.forename: Lawrence R
authors.initials: LR
authors.lastname: Lustig
authors.forename: Doris
authors.initials: D
authors.lastname: Lin
authors.forename: Holly
authors.initials: H
authors.lastname: Venick
authors.forename: Jan
authors.initials: J
authors.lastname: Larky
authors.forename: Jennifer
authors.initials: J
authors.lastname: Yeagle
authors.forename: Jill
authors.initials: J
authors.lastname: Chinnici
authors.forename: Colleen
authors.initials: C
authors.lastname: Polite
authors.forename: Anand N
authors.initials: AN
authors.lastname: Mhatre
authors.forename: John K
authors.initials: JK
authors.lastname: Niparko
authors.forename: Anil K
authors.initials: AK
authors.lastname: Lalwani
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D001301:Audiometry, Pure-Tone; D002648:Child; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D019929:Cochlear Implantation / Q000534:rehabilitation; D003054:Cochlear Implants; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D012048:Correction of Hearing Impairment; D034381:Hearing Loss / Q000235:genetics* / Q000628:therapy; D006801:Humans; D007223:Infant; D008875:Middle Aged; D011446:Prospective Studies; D017422:Sequence Analysis, DNA; D016896:Treatment Outcome
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26