大前庭水管综合征的基因诊断和SLC26A4基因突变分析

Genetic testing for the enlarged vestibular aqueduct syndrome and mutation analysis of the SLC26A4 gene

目的应用变性高效液相色谱分析和序列分析方法进行大前庭水管综合征患者的SLC26A4(PDS)基因全序列扫描,分析大前庭水管综合征的SLC26A4基因型变化和遗传特征。方法来自35个家庭的38例患者多患中重度感音性耳聋,所有患者颞骨CT均显示前庭水管明显扩大。以高效液相色谱分析结合序列分析进行SLC26A4基因分析。结果共发现32个先证者携带有SLC26A4基因突变,其中纯合突变11例,复合突变9例,单一杂合突变12例,3个先证者未发现突变,在所有受检患者中突变发现率91.4%(32/35)。共发现8种突变类型58个突变,其中IVS7-2A>G突变为中国人最常见的SLC26A4突变,共发现其纯合型10例,杂合突变13例,即有71.9%的患者(23/32)携带此种突变,2168A>G为第二常见突变,共有8名患者携带此杂合突变,另发现1229C>T,IVS15+5G>A,1226G>A,1199-1200insT,946G>T,916-917insG突变形式,后三种突变为国内外尚未报道的新突变。四种复发性突变IVS7-2A>G、2168A>G、1229C>T、IVS15+5G>A在此组病例的30例患者均有出现。三个多发家庭的同胞患者均具有一样的SLC26A4突变。结论大前庭水管综合征是典型的常染色体隐性遗传疾病,SLC26A4基因突变是其明确的致病因素,SLC26A4基因检测是诊断大前庭水管综合征的重要方法之一。

OBJECTIVE DHPLC （Denatured high performance liquid Chromatography） and sequencing analysis were used to screen all exons of SLC26A4 gene in the patients with enlarged vestibular aqueduct （EVA）. The phenotypes and genotypes of this disease were analyzed. METHODS Thirty-eight EVA patients from 35 families suffered from moderate to severe or profound sensori-neuro hearing loss were selected. Diagnosis was confirmed by high-resolution CT scan in each case. DHPLC-plus sequencing were used to analyze the genotype of SLC26A4 in each subject. RESULTS Thirty-two patients （32/35, 91.4%） were found to carry at least one mutation in the SLC26A4 gene. Eleven probands were homozygous for SLC26A4 mutations, 9 carried compound SLC26A4 mutations, while 12 were single heterozygous for SLC26A4 mutation. Eight types of SLC26A4 mutation were revealed. IVS 7-2 A〉G and 2168 A〉G were the most and second most common mutations, respectively.1199-1200insT,946G〉T, and 916-917 ins G were SLC26A4 mutations unreported hitherto, which may be specific to the Chinese population. CONCLUSION The EVA syndrome is a typical autosomal recessive hereditary disease caused by mutations in SLC26A4 gene. Genetic testing of SLC26A4 is the one of the important diagnostic methods for EVA syndrome.