Effectiveness of sequencing connexin 26 (GJB2) in cases of familial or sporadic childhood deafness referred for molecular diagnostic testing.
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.
Wu
Bai-Lin
BL
Department of Laboratory Medicine, Children's Hospital, Boston, Massachusetts 02115, USA.
Lindeman
Neal
N
Lip
Va
V
Adams
Albert
A
Amato
R Stephen
RS
Cox
Gerald
G
Irons
Mira
M
Kenna
Margaret
M
Korf
Bruce
B
Raisen
Jay
J
Platt
Orah
O
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
D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26