Mutation analysis of common GJB2, SCL26A4 and 12S rRNA genes among 380 deafness patients in northern China.

OBJECTIVES

The molecular etiology of nonsyndromic deafness in Chinese population has not been investigated systematically, our study is aim to investigate the molecular etiology of nonsyndromic deafness patients from Northern China (Heilongjiang province), in order to provide genetic test and counseling to families.

METHODS

380 unrelated patients with hearing loss who attended to the Department of Otolaryngology, The Fourth Affiliated Hospital of Harbin Medical University were enrolled to our study. All patients were diagnosed with nonsyndromic deafness by audiologic evaluation, 202 normal-hearing individuals were taken as controls. Mutations in three common deafness-causing genes (GJB2, SLC26A4 and 12S rRNA) were screened by direct sequencing.

RESULTS

Mutations (homozygote or compound heterozygote) in GJB2 accounted for 8.9% (34/380) of the patients, mutations in SLC26A4 accounted for 10.0% (38/380) of the patients screened. Only one case was found to carry 12S rRNA 1555A > G (1/380, 0.26%). Five types of mutations in GJB2 were identified, GJB2 235delC was the most prevalent mutation in our patient group (76/380, 20.0%), followed by 299-300delAT with a frequency of 7.4% (28/380). Two types of mutations in SLC26A4 were detected in our patient group (IVS7-2A > G and 2168A > G). IVS7-2A > G was identified in 27 patients (27/380, 7.1%) and 2168A > G was identified in 14 patients (14/380, 3.7%).

CONCLUSIONS

Our results demonstrate that 19.2% patients with nonsyndromic deafness were caused by mutations in three common deafness genes (GJB2, SLC26A4 and 12S rRNA) in our northern China patient group. GJB2 235delC was the most prevalent mutation, same as in the most Asian populations. These data enrich the database of deafness mutations and provide the standard for clinical diagnose, treatment and genetic counseling in Northern China population.