大前庭水管相关SLC26A4基因热点突变区域筛查方案探讨

Screening strategies for SLC26A4 gene hot spot mutation regions in patients with enlarged vestibular aqueduct in China

目的明确中国人群大前庭水管相关SLC26A4基因热点突变区域,制定耳聋人群SLC26A4基因热点突变区域的筛查策略。方法确诊大前庭水管患者263例,所有患者都接受了高分辨率颞骨CT检查,采集受检患者外周血并提取DNA,进行SLC26A4基因编码区20个外显子测序,总结筛查到的各种SLC26A4基因突变类型在不同外显子的分布及各外显子上SLC26A4基因突变数占全部突变的比例。结果 95.4%(251/263)的大前庭水管患者检测到SLC26A4基因突变。至少1个突变在外显子8、19、10、17、15、3上的患者占93.16%(245/263)。68%(179/263)的患者通过外显子8、19、10、17、15、3筛查可以找到两个等位基因突变。除已知的最热点突变IVS7-2A>G外,中国人群中SLC26A4基因热点突变还包括c.2168A>G、c.1226G>A、c.1975G>C、c.1229C>T、c.1174A>T、c.1687_1692insA、IVS15+5G>A、c.2027T>A、c.589G>A、c.281C>T等。结论将SLC26A4基因外显子8、19、10、17、15、3确定为热点突变区域进行首批筛查对提高筛查效率、节省筛查成本具有重要意义。热点突变的明确为研制SLC26A4基因专病诊断芯片提供了依据。

Objective To investigate the hot spot mutation regions of SLC26A4 gene and set up a high-performance screening strategy for molecular diagnosis of enlarged vestibular aqueduct. Methods Two hundred and sixty-three patients diagnosed with enlarged vestibular aqueduct by temporal bone CT scan or head MRI were studied. DNA was extracted from peripheral blood and all 20 exons in the coding region of SLC26A4 gene were sequenced for mutation detection. Distribution of mutations in the exons and the number of various mutations in different exons were analyzed. Results Of the 263 cases, 251 （95.4%） were found carrying SLC26A4 mutations, 245 （93.16%） were found carrying at least one mutation in the exon of 8, 19, 10, 17 and 15, and 68% （179 / 263） were found carrying two SLC26A4 mutations in the exon of 8, 19, 10, 17, 15 and 3. Besides the foregone hot spot mutation IVS7-2AG, c.2168AG, c.1226GA, c.1975GC, c.1229CT, c.1174AT, c.1687_1692insA, IVS15＋5GA, c.2027TA, c.589GA and c.281CT also showed high mutation rates in this group of enlarged vestibular aqueduct patients. Conclusion Exons 8, 19, 10, 17, 15 and 3 of the SLC26A4 gene are the hot spot mutation regions in enlarged vestibular aqueduct patients in China. Identification of the SLC26A4 gene hot spot mutation regions and set-up of a screening strategy using this information are meaningful for improving testing efficiency and reducing testing cost. Identification of these hot spot mutations also provides basis for development of SLC26A4 gene chips.