The prevalence of the 235delC GJB2 mutation in a Chinese deaf population.
OBJECTIVE
Mutations in the GJB2 gene are the most frequently found mutations in patients with nonsyndromic hearing impairment in populations studied to date. However, the prevalence of mutations varies among different ethnic groups. In most areas of China, genetic testing for nonsyndromic hearing impairment is currently not available because of the lack of information regarding the molecular cause of nonsyndromic hearing impairment. The purpose of this study is to determine the prevalence of a common GJB2 mutation, 235delC, in Chinese deaf children.


METHODS
We collected DNA specimens from 3004 patients with nonsyndromic hearing impairment from 26 regions of China; 368 Han Chinese and 98 Uigur controls, and screened for the 235delC mutation. The coding exon of the GJB2 gene was polymerase chain reaction amplified, followed by restriction enzyme digestion with ApaI and analysis by agarose gel.


RESULTS
Overall, 488 patients (16.3%) were determined to carry at least one 235delC mutant allele, with 233 (7.8%) homozygotes and 255 (8.5%) heterozygotes. Therefore, within the subpopulations examined, the frequency varies from 0% to 14.7% for 235delC homozygotes and from 1.7% to 16.1% for heterozygotes. On the basis of this survey of the patient cohort as stated, Chinese patients with nonsyndromic hearing impairment appear to have a relatively higher 235delC frequency than that of other Asian populations.


CONCLUSIONS
These results demonstrate that an easy and fast genetic testing method for this well-known GJB2 gene mutation can be made available for at least 2 million Chinese patients and family members with nonsyndromic hearing impairment. By screening for the common GJB2 235delC mutation, the molecular cause in as high as 15% of patients with nonsyndromic hearing impairment in certain regions of China can be identified. In addition, patients who are negative for the 235delC mutation would be candidates for further mutational analysis of GJB2 or other deafness-related genes.
Dai
Pu
P
Department of Otorhinolaryngology Head, PLA General Hospital, Beijing, People's Republic of China.
Yu
Fei
F
Han
Bing
B
Yuan
Yongyi
Y
Li
Qi
Q
Wang
Guojian
G
Liu
Xin
X
He
Jia
J
Huang
Deliang
D
Kang
Dongyang
D
Zhang
Xin
X
Yuan
Huijun
H
Schmitt
Eric
E
Han
Dongyi
D
Wong
Lee-Jun
LJ
D000293:Adolescent; D000328:Adult; D044466:Asian People; D002648:Child; D002675:Child, Preschool; D002681:China / Q000453:epidemiology; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D003638:Deafness / Q000453:epidemiology / Q000235:genetics*; D004587:Electrophoresis, Agar Gel; D005260:Female; D016368:Frameshift Mutation / Q000235:genetics*; D005820:Genetic Testing / Q000379:methods; D006801:Humans; D008297:Male; D015995:Prevalence; D015183:Restriction Mapping; D017384:Sequence Deletion / Q000235:genetics*
D017630:Connexins; C000607042:GJB2 protein, human; D000072259:Connexin 26