全外显子组测序鉴定非综合征型先天小耳畸形家系致病突变

Microtia is a congenital deformity where the external ear is underdeveloped. In China, the prevalence rate of microtia is 5.18 per 10000 births. Greater than 90% of individuals with microtia experience conductive hearing loss on the affected side, which harms the patient's sound in both mind and health. Previous studies on nonsyndromic microtia were mainly focused on plastic surgery and environment causes. Thus far, no confident genetic risk factors were reported. We collected a nonsyndromic bilateral microtia pedigree, containing 5 generations with 56 individuals, in a transmission mode of autosomal dominance. After excluding 7 known risk genes, we conclude that other gene mutations may lead to the disease for the pedigree. Whole exome sequencing is a new powerful technology and has been successfully used in mapping causal genes for several rare and common diseases. The advantages of whole exome sequencing include requirement of small sample size, direct hit on causing mutations, and good reproducibility on the finding. Here, we will use this new technology to capture all exon mutations for 5 carefully selected individuals from this pedigree, analyze these mutations with bioinformatics methods, and confirm the reliability of candidate mutations with 300 microtia patients and 200 healthy people. Our results will not only improve the etiology knowledge of microtia, but also be helpful for genetic consultation and future gene therapy.

先天小耳畸形是一种常见的外中耳发育异常疾患，在我国的发病率为5.18/万，为第二大颅面部先天畸形疾病。约90%的患者存在患侧听力障碍，严重影响患者的身心健康。国内外针对非综合征型小耳畸形的遗传病因学研究较少，至今未找到确信的致病基因。我们收集了一个非综合征型双侧小耳畸形罕见家系,包含5代56名成员。我们前期研究证实该家系符合单基因显性遗传模式，在排除7个可能风险基因后，推测新的致病基因是导致该家系发病的遗传因素。全外显子组测序这一新技术是目前最有效的定位新致病基因的研究手段，其优势在于所需样本量小，直接命中致病突变，重复性好。我们将采用全外显子组测序技术结合生物信息学方法获取该大家系的致病突变，并在散发患者中检测该致病突变的贡献度，为认知小耳畸形的分子病因，遗传咨询以及基因治疗提供遗传学支持。

先天性小耳畸形是我国第二大颌面部畸形，其严重影响患者身心健康。迄今为止，国内外仍未找到该病的致病突变位点。我们前期收集到一个非综合征型小耳畸形大家系，包含5代56名成员。我们采用基因芯片的方法对该家系的致病基因定位后找到了一个高度连锁的染色体区域 4p15.3 2–4p16.2。对家系代表样本进行外显子组测序后，并未在该区域内的基因上找到功能相关的变异位点。因此推测导致该家系发病的突变位点可能位于基因调控区，我们对该候选区域内功能相关的5个基因进行了全基因测序研究后发现NKX3-2基因的3‘非翻译区找到了一个共分离位点，对该位点的功能研究即将开展。本研究首次在我国小耳畸形患者中筛查到候选致病突变，为揭示该病的遗传发病机制提供了重要支持，为该病的遗传咨询和预防提供基础。