title: Effectiveness of sequencing connexin 26 (GJB2) in cases of familial or sporadic childhood deafness referred for molecular diagnostic testing.
abstract: OBJECTIVE
  Hearing loss is a common congenital disorder that is frequently associated with mutations in the GJB2 gene encoding the connexin 26 protein (Cx26). We sought to evaluate the effectiveness of direct DNA sequencing for detection of Cx26 mutations as a clinical diagnostic test.
  
  
  METHODS
  We designed a clinical assay using a three-step polymerase chain reaction (PCR)-based DNA sequencing strategy to detect all possible mutations in the open reading frame and flanking sequences of Cx26. The results of the first 324 cases of childhood deafness referred for diagnostic testing were analyzed.
  
  
  RESULTS
  A total of 127 of the 324 (39.2%) cases had at least one mutant Cx26 allele (36.1% of sporadic cases, 70% of familial cases). Of these 127 case, 57 (44.8%) were homozygotes or compound heterozygotes. Thirty-four different mutations were identified, including 10 novel mutations, 6 of which (T8M, K15T, R32L, M93I, N206S, and 511-512insAACG) may be pathogenic. We also provide new evidence on the pathogenicity or nonpathogenicity of 12 previously reported mutations, and clarify the confusing nomenclature of the 313-326del14 mutation.
  
  
  CONCLUSIONS
  A simple and rigorous method for efficient PCR-based sequence analysis of Cx26 is a sensitive clinical assay for evaluating deaf children. Its widespread use is likely to identify additional pathogenic mutations and lead to a better understanding of the clinical significance of previously identified mutations.
authors.affiliation: Department of Laboratory Medicine, Children's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: Bai-Lin
authors.initials: BL
authors.lastname: Wu
authors.forename: Neal
authors.initials: N
authors.lastname: Lindeman
authors.forename: Va
authors.initials: V
authors.lastname: Lip
authors.forename: Albert
authors.initials: A
authors.lastname: Adams
authors.forename: R Stephen
authors.initials: RS
authors.lastname: Amato
authors.forename: Gerald
authors.initials: G
authors.lastname: Cox
authors.forename: Mira
authors.initials: M
authors.lastname: Irons
authors.forename: Margaret
authors.initials: M
authors.lastname: Kenna
authors.forename: Bruce
authors.initials: B
authors.lastname: Korf
authors.forename: Jay
authors.initials: J
authors.lastname: Raisen
authors.forename: Orah
authors.initials: O
authors.lastname: Platt
mesh_terms: D000483:Alleles; D002648:Child; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004252:DNA Mutational Analysis; D003638:Deafness / Q000175:diagnosis* / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D017422:Sequence Analysis, DNA; D009626:Terminology as Topic
chemical_list: D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26