遗传性低中频感音神经性耳聋致病基因的鉴定及功能研究

Human nonsyndromic hereditary hearing loss is monogenic inherited disease, mainly affect high frequencies, low-middle-frequency sensorineural hearing loss is relatively rare. In our previous study, we identified a novel heterozygous missense mutation c.2011G>A in exon17 of MYO7A and a novel heterozygous missense mutation c.2086 C>T in exon8 of WFS1 in two Chinese families with autosomal-dominant nonsyndromic low-frequency hearing loss respectively. We also conducted the mutation screening of low-middle-frequency sensorineural hearing loss related genes in five small families and forty-five sporadic cases with low or middle frequency hearing loss. A novel mutation of WFS1 was identified in a sporadic case with low-frequency hearing loss. The preliminary data suggested that several novel genes or novel mutations in known genes underlying low-middle-frequency sensorineural hearing loss yet to be discovered. In this study, using the next generation sequencing technology, we are going to identify the causative genes for ten cases with low-middle-frequency sensorineural hearing loss. Gene function and mechanism study will help to decipher the pathogenesis of low-middle-frequency sensorineural hearing loss. All the work will lay the foundation for preventing the recurrence risk of low-middle-frequency sensorineural hearing loss.

遗传性非综合征型耳聋属单基因遗传病，主要影响高频，低频和中频耳聋相对少见。课题申请人在前期研究工作中为两个以低频听力损失为特点的常染色体显性非综合征型耳聋大家系分别鉴定出MYO7A基因和WFS1基因新的突变位点,收集了5个遗传性低中频听力损失小家系和45例散发病例，并筛查了已知低中频听力损失相关基因，发现一例低频听力损失散发病例携带WFS1基因新的突变。根据前期研究结果提示遗传性低中频感音神经性耳聋一定还存在新的致聋基因或已知基因新的突变位点。本研究拟在已收集的低中频感音神经性耳聋小家系及散发病例中选取10例，应用高通量外显子组测序技术进行致病基因的鉴定，对新发现的致病基因进行初步的功能研究，探讨遗传性低中频感音神经性耳聋可能的发生机制，为遗传性低中频感音神经性耳聋的预防奠定基础。

遗传性非综合征型耳聋属单基因遗传病，主要影响高频，低频和中频耳聋相对少见。迄今为止，仅有3个基因与中频感音神经性耳聋相关，包括TECTA, EYA4 和 COL11A2。本课题组收集到一个6代相传的以中频感音神经性耳聋为特点的遗传性耳聋大家系，编号为HG-Z087。 通过遗传学及表型分析，将HG-Z087家系确定为典型的常染色体显性遗传非综合征型耳聋大家系,为学语后、迟发性、渐进性，早期表现为中频听力下降的表型特征。研究通过对家系中一个典型病例进行外显子组测序，经过数据分析，变异筛选和家系验证，鉴定出EYA4基因C1643G杂合突变为该家系致病原因，该突变位点是EYA4目前尚未报道的的一个新的突变位点，该突变使EYA4蛋白第548位苏氨酸替换为精氨酸。.本课题组收集到两个氨基糖甙类药物性耳聋大家系，编号分别为HB-Z038和HB-L064。对两个非综合征型感音神经耳聋大家系的成员进行病史调查、全身体检、纯音听阈、声导抗检查；收集、整理临床听力学资料；进行家系遗传学特征的分析并绘制系谱图。收集两个大家系成员的外周静脉血样本，从白细胞中提取基因组DNA，聚合酶链反应扩增，应用直接测序法检测中国人常见的药物性耳聋相关基因——线粒体DNA12S rRNA A1555G 突变。根据调查两个家系均来自湖北省，两个家系的母系受检者共18人存在线粒体DNA 12S rRNA 1555 位点A→G 的突变。本研究提示线粒体DNA A1555G 点突变是导致两个大家系致聋的主要因素之一，具有母系遗传耳聋特点。