基于整合组学分析发现并验证DISC1基因多态性与sALS的易感性

发布时间：2018-04-29 04:32

本文选题：散发性肌萎缩侧索硬化症 + 神经系统发育通路　；参考：《南昌大学》2017年硕士论文

【摘要】：目的:肌萎缩侧索硬化症(amyotrophic lateral sclerosis,ALS)是一种罕见的和毁灭性的神经退行性疾病,主要累及运动神经元导致进行性麻痹,并最终致死。ALS约5%~10%的患者有家族史,称为家族性肌萎缩侧索硬化症(FALS),剩余90%~95%属于散发性肌萎缩侧索硬化症(sALS)。散发性肌萎缩侧索硬化症是一种受遗传和环境共同影响的衰老性复杂疾病。目前,全基因组关联研究(Genome-wide association study,GWAS)已经揭示了很多易感基因和大量的风险SNP位点与sALS有关,但是其致病的分子机制仍需进一步探索。更重要的是,现有的GWAS筛查之间的重复性低;且几乎所有的筛查仅针对严格符合全基因组显著性水平(P10-5)的少数位点开展研究,大量微小效应的遗传变异被忽略。据此本研究通过整合多个GWAS筛查与sALS相关的微小效应位点;利用通路分析探讨可能致ALS的分子机制;进一步通过两阶段的关联分析策略发现并验证中国人群特异的功能基因。方法:基于两个不同族群来源的sALS相关的全基因组关联研究(GWAS)(美国和爱尔兰研究)构建sALS相关整合数据集。通过基因集富集分析(Gene set enrichment analysis,GSEA),评价族群间GWAS的重复性。利用通路分析揭示两研究间共支持的功能通路,以及在这些通路中sALS相关的易感基因。为了进一步验证sALS与功能相关靶基因之间的关联,我们采用了两阶段病例对照研究(500例sALS患者,500例健康对照)。发现并分步骤验证候选基因的sALS易感位点。结果:通过对两个sALS相关的全基因组关联研究(GWAS)(美国和爱尔兰研究)的整合分析,本研究在3,227个亚显著候选基因集中发现了371个共支持易感基因;而GSEA分析,不仅表明两研究在整体水平(P10-4)存在显著重复性,也提示两个GWAS筛查所确定的ALS易感基因具有相似的功能背景。通路分析发现这两个独立研究间存在34个共支持的GO(Gene Ontology)生物过程(biological processes)通路(P10-2),其中10个通路与NSD功能有关。而基于79个已报道的ALS易感或致病基因的通路分析,也印证了NSD在ALS发病进程中的重要作用(P=0.0013)。在这些通路中,与神经系统发育功能(nervous system development,NSD-function)有关的神经系统发育通路(nervous system developmental pathway,GO:0007399)进一步被已报道的sALS的易感及致病基因所支持。在基于中国人群的全基因组病例对照研究中,17个NSD功能相关的共支持易感基因中,有4个(DISC1,CNTN4,NRXN3和ERBB4)呈现出与sALS有显著关联(P0.01)。而在第二阶段中国汉族人群病例对照研究的进一步印证中,参与神经系统发育通路的DISC1基因的多态性位点rs3737597与sALS密切相关。结论:神经系统发育通路是sALS的一种潜在发病机制,其中DISC1基因的rs3737597基因型多态性可能发挥了一些作用;用结合了低显著性阈值和通路分析的整合策略来阐明复杂疾病的发病机制是可行的。
[Abstract]:Objective: amyotrophic lateral sclerosis (amyotrophic lateral sclerosis) is a rare and destructive neurodegenerative disease, involving motor neurons leading to progressive paralysis, and resulting in death. About 50.0% of the patients have a family history. It is called familial amyotrophic lateral sclerosis, the remaining 90% belongs to sporadic amyotrophic lateral sclerosis. Sporadic amyotrophic lateral sclerosis is a complex aging disease affected by heredity and environment. At present, Genome-wide association study has revealed that many susceptible genes and a large number of risk SNP loci are associated with sALS, but the molecular mechanism of its pathogenicity needs to be further explored. More importantly, there is low reproducibility among the existing GWAS screening, and almost all of the screening studies are carried out on a few sites that are strictly consistent with the whole genome significance level (P10-5), and a large number of genetic variations with small effects are ignored. In this study, we integrated multiple GWAS screening microeffector sites associated with sALS, explored the molecular mechanisms that might cause ALS by pathway analysis, and further identified and validated specific functional genes in Chinese population by two-stage association analysis strategy. Methods: sALS related integrated data sets were constructed based on sALS associated genome-wide association study of two different ethnic groups (American and Irish studies). Gene set enrichment analysis was used to evaluate the reproducibility of GWAS among different populations. Pathway analysis was used to reveal the co-supporting functional pathways and the susceptibility genes associated with sALS in these pathways. To further verify the association between sALS and function-related target genes, a two-stage case-control study was conducted in 500 patients with sALS and 500 healthy controls. SALS susceptibility sites of candidate genes were identified and verified step by step. Results: based on the integrative analysis of two genome-wide association studies related to sALS, GWASA (American and Irish study), 371 co-supporting susceptible genes were found in 321 subsignificant candidate genes, while GSEA analysis, Not only does the two studies have significant reproducibility at the whole level of P10-4] but also the ALS susceptibility genes identified by the two GWAS screening have similar functional background. Pathway analysis revealed that there were 34 GO(Gene Ontology biological processes (P10-2) pathways between the two independent studies, 10 of which were related to the function of NSD. Based on the pathway analysis of 79 reported genes of ALS susceptibility or pathogenicity, it is confirmed that NSD plays an important role in the pathogenesis of ALS. Among these pathways, the neurodevelopmental pathway associated with nervous system development (NSD-function) is further supported by the reported susceptibility and pathogenicity of sALS. In a genome-wide case-control study based on Chinese population, four of the 17 co-supporting susceptibility genes associated with NSD function showed significant association with sALS. In the second stage of the case control study in Chinese Han population, the polymorphic rs3737597 of the DISC1 gene involved in the neurodevelopmental pathway was closely related to sALS. Conclusion: the neurodevelopmental pathway is a potential pathogenesis of sALS, in which the rs3737597 genotype polymorphism of DISC1 gene may play a role in the pathogenesis of sALS. It is feasible to elucidate the pathogenesis of complex diseases by integrating low significant threshold and pathway analysis.
【学位授予单位】：南昌大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：R744.8

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