Abstract:

Objective   To investigate the molecular etiology of sporadic hearing impairment by analyzing 235delC  the mutation of the GJB2 in congenital deaf patients in Erdos and Hohhot，Inner Mongolia. Methods   The medical histories of 131 patients with sporadic hearing impairment were collected by a questionnaire survey. The audiological examination was conducted with pure-tone audiometry and acoustic admittance measurement. GJB2 235delC mutation was identified by both  PCR and restriction enzyme ApaI digestion，then the positive samples were tested with direct sequencing. 50 cases of normal Chinese people and 100 cases of normal Canadian people were used for cross reference. Results   131 patients with sporadic hearing impairment were all diagnosed with sensorineural hearing impairment. 4 cases had homozygous deletion C at position 235 (Han 3 cases，Mongoloid 1 case)and 3 cases (Han 2 cases，Mongoloid 1 case) had heterozygous mutation  in 131 patients.  One carrier with the GJB2 235delC mutation was found in 50 cases of normal Chinese people，no 235delC mutation in 100 cases of normal Canadian people. Conclusions   GJB2 235delC mutation is one of the molecular etiologies in sporadic patients with sensorineural hearing loss. GJB2 235delC allelic frequency between Mongoloid and Han ethnic deaf group in Inner Mongolia does not have great diversity. Screening the mutationsof GJB2 235delC gene can identify pathogenesis in sporadic patients with sensorineural hearing loss, and plays an important part in early diagnosis, genetic counseling, prevention and treatment of deafness in sporadic hearing impairment caused by genetic mutation.

Key words: GJB2； Deafness； Gene； Mutation