湖南地区汉族非综合征型耳聋相关基因检测及热点突变分析

目的研究湖南地区汉族非综合征型耳聋（NSHL）患者中GJB2、SLC26A4基因的突变频率和突变热点,了解线粒体DNA（mtDNA）12SrRNA A1555G突变的频率。方法收集湖南地区汉族NSHL患者共139例，抽取外周静脉血并提取DNA；分别采用直接测序、变性高效液相色谱法（denaturing high performance liquid chromatography,DHPLC）和聚合酶联-限制性片段变态（polymerase chain reaction restriction fragment length polymorphism,PCR RFLP）技术对患者进行GJB2、SLC26A4基因和mtDNA 12SrRNA A1555G突变的检测；对SLC26A4基因突变者进行回访并行高分辨颞骨CT检查。结果61例（43.9%）NSHL患者至少携带一种常见耳聋相关基因突变，GJB2、SLC26A4和线粒体DNA 12SrRNA A1555G突变的检出率分别为23%、18.7%和3.6%；共发现6种GJB2和13种SLC26A4基因已报道致病性突变，235delC和IVS7-2A〉G分别是GJB2和SLC26A4基因最常见的突变类型，分别占这两个基因突变等位基因的87.5%和46.5%；与SLC26A4基因突变有关的EVAS的发生率为14.4%，低于该地区GJB2基因相关性耳聋的发生率17.3%。结论湖南地区汉族NSHL中43.9%的患者携带常见耳聋基因突变，反映湖南地区遗传性耳聋高发的现象。GJB2基因突变是该地区NSHL最常见的原因，其次为SLC26A4基因。235delC、IVS7-2A〉G和A1555G突变分别是GJB2、SLC26A4和线粒体DNA基因的热点突变，占所有突变的71.2%。通过筛查，为其中35.3%的患者明确了分子病因。为该地区进一步开展遗传咨询、基因诊断和产前诊断提供了重要的依据,并为临床用药提供指导。

Common deafness genes detection and hot mutation spots analysis in Han people with congenital non syndromic hearing loss in Hunan province

ObjectiveTo investigate the prevalence and hot spots of GJB2 and SLC26A4 genes mutations and to estimate the incidence of the mitochondrial 12S ribosomal RNA A1555G mutation in Han people with non syndromic hearing loss （NSHL） in Hunan province.MethodsThe study included 139 subjects in Hunan area （80 males, 59 females, a mean age of 7.6）.The genomic DNA samples were extracted from peripheral blood. Screenings of GJB2, SLC26A4 gene mutations and mtDNA 12SrRNA A1555G were carried out by direct sequence, DHPLC and PCR RFLP respectively. All individuals found with SLC26A4 mutation were given temporal bone CT scan.ResultsThe study showed 43.9% of the patients carried at least one of the common deafness gene mutations. The detection rates of GJB2, SLC26A4 gene mutations and mtDNA A1555G were 23%, 18.7% and 3.6% respectively. 6 GJB2 and 13 SLC26A4 gene mutations were identified. 87.5% of GJB2 mutant alleles was 235delC and 46.5% of SLC26A4 was IVS7-2A〉G, which implied 235delC and IVS7-2A〉G were the most common mutations in these two genes. The incidence of enlarged vestibular aqueduct syndrome EVAS related to SLC26A4 mutation was 14.4%, which was lower than that of deafness related to GJB2 （17.3%）.Conclusion43.9% of the patients with NSHL carry the common deafness gene mutations, which indicates high incidence of hereditary deafness in Han people of Hunan province. GJB2 gene mutation is the most common cause of NSHL, SLC26A4 is another common gene causing deafness in this area. 235delC, IVS7-2A〉G and A1555G are the hot spots in GJB2, SLC26A4 and mtDNA gene mutations respectively, accounting for 71.2% of all three gene mutations. The molecular etiology in 35.3% of the patients with NSHL has been made clear through this study, which provides important data for further steps in genetic counseling, gene diagnosis and prenatal diagnosis, and also instructions for clinical medication.