95例前庭水管扩大核心家系SLC26A4基因特异突变图谱

A Distinct Spectrum of SLC26A4 Mutations in 95 Nuclear Families Associated with Enlarged Vestibular Aqueduct

目的探讨中国人群中前庭水管扩大(enlarged vestibular aqueduct,EVA)患者SLC26A4基因突变图谱,为相关基因的筛查及临床应用奠定基础。方法采集95例EVA核心家系,募集84名听力正常者及46名内耳结构正常的听力损失患者作为对照。提取基因组DNA,应用聚合酶链反应(PCR)的方法扩增SLC26A4基因的21个外显子,纯化PCR产物后直接测序,使用DNAStar及BioEdit序列比对软件分析SLC26A4基因的突变位点,利用Clustal软件进行同源氨基酸序列比对分析。结果在95例EVA核心家系中,93例发生了SLC26A4基因突变,约占97.9%(93/95)。其中双等位基因突变占88.4%(84/95),单等位基因和未发现突变的家系分别占9.5%和2.1%。93个家系中共发现38种突变,包括23种国际上尚未报道的突变,15种已报突变(5种仅报道于中国家系)。IVS7-2A>G是所有突变中最常见的突变,其在所有突变体中约占57.63%(102/177),75(75/95)个家系发生了此种突变。结论95例中国EVA核心家系的SLC26A4基因调查中,发现了一个中国特异性的SLC26A4基因突变谱:97.9%的中国EVA患者均可检测到SLC26A4基因的突变,双等位基因突变率约为88.4%;23种新的突变和5种仅报道于中国家系的突变在其他人群未曾检测到;IVS7-2A>G为中国人群前庭水管扩大患者最常见的突变。

Objective To investigate the SLC26A4 mutation spectrum in patients with hearing loss associated with enlarged vestibular aqueduct（EVA） in Chinese, and to provide basic information for the molecular diagnosis of EVA. Methods A total of 95 families with EVA were enrolled in present study. 84 normal hearing individuals and 46 with congenital hearing loss without inner ear malformations were recruited as controls. Genomic DNA was ex- atracted from peripheral blood. All 21 exons of the SLC26A4 gene were amplified by intronic polymerase chain reaction（PCR）, then the PCR products were purified and directly sequenced. The sequences were analysed with DNAS- tar or BioEdit. Results In the present study , pathologic mutations were identified in 93/95 families, making up 97.9 % of all. Bi--alleles mutations were identified in 84（88.4 % ） families. The families with one allele and zero allele mutations were 9.5 % and 2.10% ,respectively. A total of 38 mutations were identified in the present study, in- cluding 23 novel mutations and 15 recurrent mutations. Among the recurrent mutations, 5 mutations had never been reported in other populations except in Chinese. In the present study, IVST--2A〉G was detected in 75/95 families with EVA and represents 57.63% of all mutant alleles. It was the commonest mutation in Chinese. Conclusion The results of present study yielde a distinctive mutation spectrum of SLC26A4 in Chinese. Mutations can be detec- ted in 97.9% of all EVA patients, most of which have bi--alleles mutation. A total of 28 types of mutations found in the present study have never been detected in other populations. IVST--A^G is the commonest mutation in the present study, which account for 57.63% of all mutant alleles. These results summarize the mutation spectrum of SLC26A4 gene in Chinese. It will facilitate molecular diagnosis of EVA in Chinese.