内表型关联的遗传变异与sICAS易感性的关系及其机制研究

Endophenotype is potential quantitative trait associated with the symptoms of the disease, carrying genetic load and linking the gene to disease. Endophenotype has become the focus of genetic studies of complex disease.The findings of several GWASs have suggested that endophenotype associated variants have significant association with the susceptibility to stroke. In this project, we will focus on.endophenotype associated genes of symptomatic intracranial atherosclerotic stenosis (sICAS) and use target region sequencing to investigate the associations between all genetic variants in the potentially functional regions (including exon, 5'UTR, 3'UTR and regulatory regions) of those genes and risk of sICAS. Then, the positive variants will be replicated in another case-control study. In combination with bioinformatics and molecular biology methods, we plan to further evaluate the biological mechanisms of identified variants. These efforts may further clarify the susceptibility to sICAS, provide new insight into the role of endophenotype associated genes and the etiology of sICAS and improve.the prevention and treatment level for sICAS.

内表型是与疾病症状相关、携带有遗传负荷的潜在数量性状，处于基因到疾病通路的中间环节，其相关研究是目前复杂疾病遗传学领域的研究热点。多个GWAS表明，内表型关联的遗传变异与脑卒中的易感性显著相关。因此，本研究拟根据最新研究进展和前期研究结果，针对多个症状性动脉粥样硬化性颅内动脉狭窄(Symptomatic Intracranial Atherosclerotic Stenosis，sICAS）内表型相关基因，采用目标区域捕获测序技术确定其潜在功能区（包括外显子区、5'UTR、3'UTR及调控区）内包含低频位点在内的整体遗传变异图谱，检测遗传变异与sICAS易感性的关联；随后通过大样本的病例-对照研究进行后期验证，并综合应用生物信息学和分子生物学等方法进行生物学机制研究。本课题将进一步阐明sICAS的易感机制，并为揭示内表型相关基因的重要作用以及sICAS发生的生物学机制提供新思路。

本研究从症状性动脉粥样硬化性颅内动脉狭窄(Symptomatic Intracranial Atherosclerotic Stenosis，sICAS）内表型出发，首先研究了与sICAS密切相关的生物标志物，发现甲状腺功能、血常规等可反映sICAS的严重程度及短期预后，血管生成相关因子VEGF、新型脂肪因子Apelin与sICAS密切相关；接着通过大样本的病例对照研究，采用高通量测序技术对101个sICAS内表型相关基因的潜在功能区进行目标区域捕获测序，确定了IL6及RARRES2包含低频罕见变异在内的遗传变异图谱与sICAS易感性的关联，功能学结果显示RERRES2 R162H突变位点可显著增加细胞因子Chemerin的表达。通路分析显示AMPK信号通路相关基因与sICAS发病风险密切相关，其中INSR常见变异rs78312382及低频变异rs41398545与sICAS风险相关，INSR常见变异rs3745551是sICAS合并高血压的独立危险因素，AMPK通路相关基因IL6、LEP、HNF4A、PRKAA1、INSR、LEPR及SIRT1的罕见变异可能与sICAS有关，RNF213基因的常见及低频罕见变异与中国汉族人群的sICAS发病风险无明显相关性；亚组分析结果显示MMP9常见变异rs17576是伴WMH的sICAS的独立危险因素；MiR-139-5p在脑侧枝循环良好的sICAS患者血浆中表达降低，其表达降低对于脑侧枝循环良好具有较高的诊断价值。本研究结果对于指导缺血性脑卒中特别是sICAS的防治、发掘新的药物作用靶点具有重要的临床意义。