[GJB2 235delC single allelic mutation modulates the phenotype associated with the mitochondrial A1555G mutation].
OBJECTIVE
To investigate a non-syndromic deafness family in which potential interaction between the GJB2 gene and a mitochondrial gene appeared to be the cause of hearing impairment.


METHODS
Audiological examination was performed by pure-tone audiometry (PTA). Blood samples from 8 members of the pedigree were obtained. DNA was extracted from the leukocytes. The coding region of the GJB2 gene and mitochondrial DNA target fragments were amplified by polymerase chain reaction (PCR). The PCR products were analyzed by sequencing.


RESULTS
Direct sequencing showed that the proband had both a heterozygous mutation of 235delC in the GJB2 gene and a mitochondrial 1555 A to G mutation. The proband had profound hearing loss. The maternal relatives had sensorineural hearing loss in the higher frequencies or no hearing loss.


CONCLUSIONS
The GJB2 mutations may be an aggravating factor in the phenotypic expression of the non-syndromic hearing loss associated with the A1555G mitochondrial mutation.
Li
Qi
Q
Department of Otolaryngology and Head and Neck Surgery, Nanjing Children's Hospital, Nanjing Medical University, Nanjing, Jiangsu, P.R. China.
Fang
Ru-ping
RP
Zhou
Hong-gen
HG
Dai
Pu
P
Tian
Li
L
Lin
Di
D
Huang
Qun
Q
Song
Jian-min
JM
D000293:Adolescent; D000328:Adult; D000483:Alleles; D001483:Base Sequence; D002648:Child; D000072259:Connexin 26; D017630:Connexins / Q000235:genetics*; D004252:DNA Mutational Analysis; D004272:DNA, Mitochondrial / Q000235:genetics*; D005260:Female; D005838:Genotype; D034381:Hearing Loss / Q000235:genetics; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D009154:Mutation; D010375:Pedigree; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide
D017630:Connexins; D004272:DNA, Mitochondrial; C000607042:GJB2 protein, human; D000072259:Connexin 26