OBJECTIVETo explore the characteristics of mutations 4 common deafness-related genes among 216 patients from Shanghai area with non-syndromic hearing impairment (NSHI).

METHODSThirteen mutation sites in the four genes, namely GJB2 (c.35delG, c.176del16, c.235delC, c.299delAT, and c.155delTCTG), SLC26A4 (c.IVS7-2A>G, c.2168A>G, and c.1229C>T), mtDNA 12SrRNA (m.1494C>T, m.1555A>G, m.7445A>G, and m.12201T>C) and GJB3 (c.538C>T) were detected among the 216 patients and 41 individuals with normal hearing. The frequency and types of mutations were compared between the two groups.

RESULTSAmong the 216 NSHI patients, the total detection rate was 16.20% (35/216). GJB2 mutations were found in 17(7.87%) of the 216 patients, which included 5 cases with homozygous c.235delC mutation, 5 with homozygous c.235delC mutation, 1 with homozygous c.299delAT mutation, and 1 with homozygous c.299delAT mutation. c.235delC and 299delAT mutations were found in 5 cases. SLC26A4 mutation was found in 12(5.56%) of the 216 patients, which included 2 cases with homozygous c.IVS7-2A>G mutation, 9 with homozygous c.IVS7-2A>G mutation, and 1 with homozygous c.2168A>G mutation. Homogeneous mtDNA 12SrRNA m.1555A>G mutation was found in 6(2.78%) of the 216 patients. No GJB3 gene mutation was detected. No mutation of the 4 genes were detected in the 41 individuals with normal hearing. In 2 cases of the 12 patients with SLC26A4 gene mutation, CT scan of the temporal bone has confirmed expansion of vestibular aqueduct.

CONCLUSIONAbove results indicated that GJB2 and SLC26A4 were the major genes involved with hearing loss in Shanghai area.