【作者】 杨小龙；

【导师】 郭玉芬；

【作者基本信息】 兰州大学 ， 耳鼻咽喉科学， 2013， 硕士

【摘要】 耳聋影响患者的日常交流与信息获取,是一种严重影响人类身心健康和生活质量的疾病。研究发现引起耳聋的病因包括遗传因素和环境因素,其中60%的耳聋是由遗传缺陷引起的,与耳聋相关的基因多达140个,但绝大部分耳聋患者是由少数几个单基因的缺损导致。全国范围的聋病分子流行病学调查数据显示GJB2、SLC26A4、线粒体基因mtDNA (A1555G和C1494T突变)是导致中国大部分遗传性耳聋发生的3个最为常见的耳聋基因,但不同地区和不同民族间检出率有明显差异。中国西北地区藏族、土族、蒙古族的常见聋病基因研究报道甚少,因此我们对来自甘肃、青海的189例藏族、土族、蒙古族非综合征型耳聋患者进行常见聋病基因突变特征研究,以初步了解该地区遗传性耳聋病因学特点,为聋病基因诊断、遗传咨询提供科学依据。本研究收集中国西北地区121例藏族、49例土族、19例蒙古族非综合征型耳聋患者的临床资料和静脉血样,提取基因组DNA,PCR扩增后对GJB2基因编码区、SLC26A4基因第8、18外显子进行直接测序,1mtDNA行特异性PCR后对阳性样品行测序验证。结果三个民族在藏族和土族中检测到GJB2致病突变,蒙古族中未检测到致病突变,这可能是由于样本量太小,抽样误差所致。藏族的GJB2等位基因突变率为5.8%(14/242),其中c.235delC为最常见的突变方式,另外还检测到其他4种突变：c.94C>T、c.257C>G、c.299-300delAT、c.504insAACG;土族的GJB2等位基因突变率为11.2%(11/98),突变方式有两种：c.235de1C、 c.176-191del16。c.235de1C是这两个民族GJB2的热点突变,这也进一步证实c.235de1C是中国人中最为常见的突变形式。明确了3.3%(4/121)的藏族患者和10.2%(5／49)的土族患者为GJB2基因突变所致。统计分析显示藏族和土族GJB2等位基因突变率之间无差异,但c.235de1C携带率藏族低于土族。这三个少数民族SLC26A4基因突变携带率分别为：4.54%、6.12%、15.79%。其中,c.919-2A>G是SLC26A4基因的热点突变,这也与国内其他的关于SLC26A4基因的研究结果一致。明确了5%的藏族患者、6.12%的土族患者和15.79%的蒙古族患者是由SLC26A4基因突变导致。统计学分析显示蒙古族的SLC26A4等位基因频率和c.919-2A>G携带率最高,土族次之,藏族最低。mtDNA12S rRNA基因突变携带率在这三个少数民族中分别为5.79%、10.2%和5.26%,统计分析显示三个民族mtDNA12S rRNA突变率之间的差异无统计学意义。结论：西北地区藏族、土族、蒙古族中GJB2基因、SLC26A4基因、线粒体DNA突变高发,常见耳聋基因筛查有助于推动本地区这三个少数民族基因诊断和遗传咨询的进步。更多还原

【Abstract】 Deafness affects patients’daily communication and access to information, and influences human physical and mental health and the quality of life. Studies have found that the causes of deafness including genetic factors and environmental factors. About60%deafness people are caused by genetic defects. Genes related to deafness were about140, but the majority patients with deafness was caused by a handful of single gene defects. Nationwide deaf disease molecular epidemiology survey data shows that GJB2, SLC26A4and mtDNA (A1555G and C1494T) mutations were three most common deafness genes in hereditary deafness. But the detection rates of different regions and different ethnic groups were obvious different. At present studies in China’s northwest ethnic minorities, especially Tibetan, Tu nationality and Mongolian are rare. The aim of this study is to research common deafness gene mutation characteristics in189cases of Tibetan, Tu nationality and Mongolian NSHI patients from Gansu and Qinghai province. We can preliminary understand the hereditary deafness etiology characteristics in this region, and provide a scientific basis for disease gene diagnosis and genetic counselingIn this study, we collected189Tibetan, Tu nationality and Mongolian NSHI patient’s data and peripheral blood. We extract DNA from peripheral blood. PCR and direct sequencing were used to analyze the coding region of GJB2, mtDNA and exons8and18of SLC26A4gene. The disease causative mutations were detected in Tibetan and Tu nationality patients whereas the GJB2mutations were not detected in Mongolian cases in present work due to the selection effect of low sample coverage. The mutant allele rate of GJB2gene is5.8%(14/242) in Tibetan, of which c.235delC is the most prevalent mutation. Four other kinds of pathogenic mutations were detected in Tibetan patients:c.94C<T, c.257C<G, c.299-300delAT and c.504insAACG. The mutant allele rate of GJB2gene is11.22%(11/98) in Tu nationality patients. Two kinds of mutations were detected:c.235delC and c.176-191de116. c.235de1C is the hot spot of GJB2mutations in Tibetan and Tu nationality, which indicates that235delC is the most common forms of GJB2mutation in Chinese people. We have identified that3.3%(4/121) Tibetan patients and10.2%(5/49) Tu nationality patients were caused by GJB2gene mutations. There was no significant difference between Tibetan and Tu nationality in mutant allele rate of GJB2gene. The c.235delC carry rate of Tu nationality was higher than Tibetan.Mutant allele frequency of SLC26A4in Tibetan, Tu nationality and Mongolian were4.54%,6.12%and15.79%respectively, c.919-2A>G was the most common mutation of the SLC24A4gene, which is consistent with other domestic research results concerning the SLC26A4gene.5%Tibetan,6.12%Tu nationality and15.79%Mongolian patients were caused by SLC26A4gene mutations. Statistical analysis showed that mutant allele frequency of SLC26A4and c.919-2A>G carry rate were highest in Mongolian, next in Tu nationality, minimum in Tibetan. The mutation frequency of mtDNA12SrRNA in Tibetan, Tu nationality and Mongolian deaf populations was5.79%,10.2%and5.26%. There was no significant difference between Tibetan, Tu nationality and Mongolian in mutation frequency of mtDNA12SrRNA.In conclusion, the mutation of GJB2gene, SLC26A4gene and mtDNA gene among Tibetan, Tu nationality and Mongolian in northwest of China are high. Common deafness gene screening helps us with the progress of the gene diagnosis and genetic counseling in the three minority nationalities in our region.更多还原