(Department of OtolaryngologyHead and Neck Surgery, Key Laboratory of ENT major disease research in Hunan Province, Xiangya Hospital, Central South University, Changsha 410008, China) Abstract:ObjectiveTo investigate the prevalence and hot spots of GJB2 and SLC26A4 genes mutations and to estimate the incidence of the mitochondrial 12S ribosomal RNA A1555G mutation in Han people with nonsyndromic hearing loss (NSHL) in Hunan province.MethodsThe study included 139 subjects in Hunan area (80 males, 59 females, a mean age of 7.6).The genomic DNA samples were extracted from peripheral blood. Screenings of GJB2, SLC26A4 gene mutations and mtDNA 12SrRNA A1555G were carried out by direct sequence, DHPLC and PCRRFLP respectively. All individuals found with SLC26A4 mutation were given temporal bone CT scan.ResultsThe study showed 43.9% of the patients carried at least one of the common deafness gene mutations. The detection rates of GJB2, SLC26A4 gene mutations and mtDNA A1555G were 23%, 18.7% and 3.6% respectively. 6 GJB2 and 13 SLC26A4 gene mutations were identified. 87.5% of GJB2 mutant alleles was 235delC and 46.5% of SLC26A4 was IVS7-2A>G, which implied 235delC and IVS7-2A>G were the most common mutations in these two genes. The incidence of enlarged vestibular aqueduct syndrome EVAS related to SLC26A4 mutation was 14.4%, which was lower than that of deafness related to GJB2 (17.3%).Conclusion43.9% of the patients with NSHL carry the common deafness gene mutations, which indicates high incidence of hereditary deafness in Han people of Hunan province. GJB2 gene mutation is the most common cause of NSHL, SLC26A4 is another common gene causing deafness in this area. 235delC, IVS7-2A>G and A1555G are the hot spots in GJB2, SLC26A4 and mtDNA gene mutations respectively, accounting for 71.2% of all three gene mutations. The molecular etiology in 35.3% of the patients with NSHL has been made clear through this study, which provides important data for further steps in genetic counseling, gene diagnosis and prenatal diagnosis, and also instructions for clinical medication.