汉族人群骨性安氏Ⅲ类错颌畸形的遗传机制研究

The polygenetic disease Skeletal Angle Class Ⅲ malocclusion (SCA3M), prevailing in about 10% of the Chinese Han population, seriously affect oral function and facial appearance of the affected individuals. The mechanism underlies the occurrence, development, and progression among different subjects not only puzzled clinicians, but also was an important subject in the field of craniofacial development. Heredity plays an important role in SAC3M, which is still to be unveil. Based on our established multicenter biobank and optimized next-generation sequencing platform, we conducted a two-stage genetic association study to explore the effects of different kinds and frequencies of genetic variations within 350 target genes which controlling bone formation, metabolize and so on, for "common variants of modest effect" (MAF≥5%) and "low-frequency variants of modest effect" (1%≤MAF<5%). We may also discover the rare variants in some individuals. StageⅠsample includes a cohort with 500 severe SAC3M, and 500 matched control subjects for association discovery. Deep resequencing all the exons of targeted genes, about 670k per individual, will be conducted using Solexa sequencing platform to systematic screen the full set of variants. Single-marker association analysis, haplotype association analysis and gene-environment interaction analysis will be performed to estimate the effects of the variations on the SAC3M. In StageⅡ, genotyping of the associated common variations of modest effect and low-frequency variants in another 2000 cases and 2000 controls for association replication, and for association with different severity of malocclusion and quantitative traits using ANB angular as a measurement. Our study will contribute to the capacity to dissect the genetic basis of the SAC3M development, and hence the capacity of molecular diagnosis and individualized treatment.

人群常见的骨性安氏Ⅲ类错颌畸形(SAC3M，患病率约10%)严重影响口腔功能和颜面美观，临床治疗困扰口腔医生，其发生机制也是颌面发育研究的重要课题。遗传在SAC3M发生发展及严重程度差异中起重要作用，但具体不清。本研究拟在已建标本库及优化Solexa平台上系统筛查与骨发育、代谢调节等相关的基因约350个，确定"常见"(MAF≥5%)、"少见"(1%≤MAF<5%)单核苷酸多态对SAC3M的贡献，并筛检潜在的"稀有变异"。研究分为：①发现阶段：对500例重度SAC3M病例及500例对照目标外显子测序(总长度约670K/个体)，发现与SAC3M相关的遗传变异；②验证阶段：对阳性"常见"及"少见"变异在另外2000病例及2000对照中进行基因分型验证，同时探索不同严重程度及ANB（作为数量性状）的遗传变异规律。本研究将为SAC3M分子分型及个体化治疗提供依据，并为颌面发育遗传机制研究提供思路。

骨性安氏III类错颌畸形（SAC3M）是一类常见颅颌面发育畸形，在我国发病率超过10%，严重影响患者口颌功能和颜面美观。通常认为SAC3M是由遗传和环境因素共同作用引起，其中，遗传因素在SAC3M的发生、严重程度及治疗预后中起重要作用，但具体尚不清楚。本课题致力于探索遗传变异对SAC3M的贡献，在共约2500例SAC3M病例及正常对照样本中通过两阶段的关联研究，系统筛查了与骨及软骨发育、代谢和调节等相关的396个基因。首先，在第一阶段对约500例病例及对照通过目标区域深度测序及常见变异进行关联分析，发现了24个与SAC3M 发生相关的常见遗传变异位点；在第二阶段就第一阶段发现的遗传变异并结合最新报道与SAC3M相关的变异对约2000例病例及对照样本中进行了一代测序（mf-RFLP和SNaPshot）扩大样本验证，确定了中国汉族SAC3M人群的遗传变异谱。其次，对罕见变异采用单个基因内所有突变理论频频数的累积效应（Burden test）结合功能打分，发现了与SAC3M 发生相关的3个罕见遗传变异位点。另外，通过分析SAC3M严重程度的特征性代表指标——ANB角度与遗传变异之间的相互关系，建立了SAC3M的遗传学预测模型。此外，通过聚类分析（Cluster Analysis）细化SAC3M患者表型类别，发现SAC3M表型分为4个聚类，为SAC3M疾病的进一步分类和临床诊治提供了新的参考。通过主成分分析（Principle Component Analysis）对SAC3M患者表型降维处理，将代表表型的主成分与各通路常见变异进行关联分析，发现了位于FGF7基因3’UTR的常见变异rs372127537解释了SAC3M的骨面型垂直向不调。通过上述研究，本课题组总结了SAC3M表型的分类特点，发现了一批与SAC3M发生相关的基因遗传变异位点，建立了SAC3M的遗传学预测模型，细化了遗传变异与SAC3M表型的相关联系，拓宽了正畸领域对SAC3M遗传学致病因素的理解，为进一步探索SAC3M表型与遗传变异之间的规律提供了线索和基础。在本基金的资助下，已发表SCI论文4篇，国内核心期刊论文1篇，培养研究生5名，并举办国内学术会议2次。