孤独症基因型-表型关联研究及新致病基因的鉴定

The high heterogeneity of clinical phenotype and genetic etiology of autism spectrum disorders (ASDs) is the major obstacle to elucidating the genetic etiology. However, genotype-phenotype correlations for high-risk pathogenic genes in ASDs are critical for the disorder subtype classification and the future clinical management. Previously, we have established a large ASD cohort called the clinical and genetic resources of autism in China, and a low-cost capture sequencing platform. By using this capture sequencing technology on this sample cohort, we have identified a number of high-risk causative and candidate genes (including TNRC6B), and identified multiple patients with de novo mutations within these genes. Based on those, this project, on the one hand, is going to use capture sequencing and genotype-phenotype association analysis to identify new clinical subtypes and new high-risk pathogenic genes. On the other hand, we are going to establish a TNRC6B conditional knockout mouse model, and study the behavioral and related neurodevelopmental and neurophysiological phenotypes induced by this gene. We will also explore the molecular basis involving in neurodevelopment using the mouse model. This project will is important for detailed disease classification and clinical management of ASD patients, and will illustrate the molecular basis of TNRC6B clinical subtype.

孤独症谱系障碍（ASD）高度的临床表型和遗传病因异质性为该类疾病遗传病因的阐明带来很大障碍。ASD高风险致病基因的基因型-表型关联研究对降低临床和遗传异质性，实现早诊断、早干预及疾病的详细分类和临床管理提供重要科学依据。申请人及其所在团队建立了孤独症临床遗传资源样本库及低成本高效率的捕获测序平台。通过前期捕获测序研究鉴定多个高风险致病基因和候选基因（包括TNRC6B），并发现多个携带这些基因突变的患者。基于此，本项目一方面进行大样本捕获测序和基因型-表型关联研究，鉴定新的临床亚型和新的高风险致病基因；另一方面，针对前期发现的致病基因TNRC6B，利用敲除小鼠模型研究其导致的行为学及相关神经发育和神经生理表型，确定该基因基因型-表型关系并探索其参与神经发育和孤独症发生的分子基础。本项将对实现ASD的详细分类和临床管理提供重要依据，为探索导致TNRC6B临床亚型的分子机制奠定基础。

孤独症谱系障碍是累及遗传与环境因素共同作用的神经发育类疾病，其高度的表型和遗传异质性对临床的精准诊断带来了很大困难。本研究以申请人及其所在团队建立的孤独症临床遗传资源样本库（ACGC）及低成本高效率的捕获平台（MIP）为基础，进行研究并取得以下研究结果：1. 利用MIP技术发现了位于63个基因上的185个新发突变（122个功能缺失突变，63个错义突变），并明确了29个基因在孤独症患者中显著富集新发突变；2. 通过大规模国际合作，我们完成了5个新鉴定基因的基因型-表型关联分析并定义了5个新的孤独症相关的分子亚型：CSDE1、TANC2、GRIA2、NCKAP1及TNRC6B；3. 针对TNRC6B基因进行了小鼠模型和机制研究，发现Tnrc6b神经系统特异性敲除小鼠表现出重复刻板及社交障碍的孤独症样表型，皮层中神经祖细胞数量上升与神经元迁移异常，孤独症患者来源的TNRC6B 功能缺失突变蛋白在细胞中无法正常聚集为颗粒。本项目顺利完成了预期研究，达到预期目标，研究结果发现的新的5个孤独症分子亚型将有助于患者的临床分子诊断，对TNRC6B的神经发育功能及分子机制的研究将为探究该基因变异导致孤独症及相关神经发育障碍的遗传机制提供基础。