[Genetic analysis and prenatal diagnosis for non-syndromic hearing impairment]

To detect genetic mutations underlying non-syndromic hearing impairment (NSHI) and establish a method for prenatal diagnosis.

Sixty six NSHI patients were included in this study. DNA was extracted from peripheral blood. Genetic mutations were detected by gene chip analysis and direct sequencing of GJB2 gene. For 7 pregnant women at high risk, prenatal genetic diagnosis was provided.

Fourteen cases (21.21%) were found to have GJB2 mutations by both methods (homozygous 235delC mutation in 3 cases, homozygous 176del16 mutation in 2 cases, 235delC and 299delAT compound heterozygous mutation in 2 cases, 299delAT and 176del16 compound heterozygous mutation in 1 case, c.339T > G and 313del12bp compound heterozygous mutation 1 case, and 235delC heterozygous mutation in 5 cases). 13 (19.70%) had SLC26A4 mutations (IVS7-2 A >G homozygous mutation in 2 cases, IVS7-2 A > G homozygous mutation in 2 cases, IVS7-2 A > G and 2168A > G compound heterozygous mutation in 3 cases, 2168A>G heterozygous mutation in 3 cases, and IVS7-2 heterozygous mutation in 3 cases); and 3 had mtDNA12S rRNA mutation (1555A > G mutation in 2 cases, 1494C > T mutation in 1 case). Prenatal diagnosis suggested that 3 fetuses have carried a heterozygous mutation. Two fetuses were detected as normal and confirmed to have normal hearing after birth. Two fetuses were found to have carried compound mutations of GJB2.

Gene chip combined with GJB2 gene analysis is an accurate and effective method for the diagnosis of NSHI. The results can facilitate accurate prenatal diagnosis.