[Mutation screening of the COCH gene in familial and sporadic patients with late onset nonsyndromic sensorineural hearing loss among Chinese population].
OBJECTIVE
To investigate the mutational of the coagulation factor C homology (COCH) gene related to autosomal dominant sensorineural nonsyndromic hearing loss (DFNA) with late onset in Chinese population.


METHODS
Peripheral blood samples were collected from he members of 26 DFNA families, members of 19 small DFNA families with un recognized inheritance pattern, and 22 sporadic patients with sensorineural nonsyndromic late onset hearing loss, the hearing loss of all of which occurred during the age range 10 - 40, and 100 normal controls. From different parts of China, these subjects underwent questionnaire survey too. Genomic DNA was isolated, COCH mutation was screened by PCR and sequencing, and restriction endonuclease analysis was used to detect the mutation sites of the COCH gene. The conservation in evolution of the target amino acid sequences was analyzed using CluatalX1.82 software.


RESULTS
DNA sequencing of coding regions and exon/intron boundaries of COCH 2 - 12 exons identified a heterozygous G-to-A substitution at position 1625 in exon 12 in a large DFNA family, leading to a C542Y substitution, and a heterozygous T-to-C substitution at position 1535 in exon 12 in a small family, leading to a M512T substitutions. Both the residues of Cys542 and M512 were conserved across human, mouse, chicken, and zebrafish. These mutations were not detected in the 100 control subjects.


CONCLUSIONS
The C542Y and the M512T mutations cause hearing loss in Chinese DFNA families.
Sun
Qing
Q
Institute of Otorhinolaryngology, General Hospital of Chinese People's Liberation Army, Beijing 100853, China.
Yang
Shu-Zhi
SZ
Kang
Dong-Yang
DY
Zhang
Xin
X
Cao
Ju-Yang
JY
Liu
Xin
X
Dai
Pu
P
Yuan
Hui-Jun
HJ
Han
Dong-Yi
DY
D000595:Amino Acid Sequence; D044466:Asian People / Q000235:genetics*; D002681:China; D004252:DNA Mutational Analysis; D016326:Extracellular Matrix Proteins; D005192:Family Health; D034381:Hearing Loss / Q000208:ethnology / Q000235:genetics*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D011506:Proteins / Q000235:genetics*; D017386:Sequence Homology, Amino Acid
C110668:COCH protein, human; D016326:Extracellular Matrix Proteins; D011506:Proteins