Mechanistic Characterization of GWAS Loci in SLE

 描述（由申请人提供）：系统性红斑狼疮（SLE或狼疮）是一种具有显著遗传性的衰弱性自身免疫性疾病。其特点是广泛的临床表现，包括致病性自身抗体的产生和多系统器官损害。与欧洲裔美国人（EA）相比，亚洲人的SLE患病率至少高3倍，临床表现更严重，包括危及生命的肾损伤。种族间的遗传变异可以解释疾病严重程度和临床表现的潜在差异。开发新的和更有效的预防和治疗方法需要更好地了解疾病机制。虽然最近的全基因组关联研究（GWAS）已经确定了40多个基因/位点，但区分病理性和良性DNA变化是一个重大挑战。缺乏对GWAS信号的因果效应的理解阻碍了SLE诊断和治疗的发展。GWAS结果表明，SLE在亚洲人的遗传结构可能不同于更广泛研究的欧洲来源的人群。因此，有必要确定影响亚洲人群SLE发展的主要致病变异。我们的研究团队拥有超越GWAS所需的经验、专业知识、资源和基础设施，以加速发现这些信号及其功能效应背后的因果变异。我们已经成功地从IFIH 1、ITGAM和NCF 2基因座鉴定出SLE易感变异体，并通过实验确定了影响SLE风险的机制。基于我们来自> 11，000名韩国人和中国人的初步数据，我们建议研究亚洲人中的6个高度显著（10-99<P<10-11）候选基因/位点。其中四个位点是新的，在早期的GWAS中没有报道。我们的长期目标是检测这些基因的功能变异，将它们与SLE症状联系起来，并确定其生物学机制。目的1是通过进行深度测序，然后进行基于插补的关联分析，确定亚洲人群中6个候选基因内的功能变异。我们还将确定这些变异体与SLE临床亚表型和自身抗体谱之间的关系。重要的SNP，特别是罕见的变异，将通过后续基因分型进行验证。目的2是预测和验证SLE易感变体的机制效应。我们将采用生物信息学分析和分子建模来优先考虑相关的变体，并通过调整我们已建立的功能测定管道来选择推定的SNP进行适当的实验验证。我们还将确定涉及我们的目标易感SNP的网络，以及影响可能影响SLE发病机制的途径的基因。最后，我们将通过实验验证变体的功能效应，以确定疾病机制。这些结果将为这些变异导致狼疮的机制提供新的见解，并加速识别和验证新靶点以及开发治疗方法和未来的狼疮治疗干预措施。

 DESCRIPTION (provided by applicant): Systemic lupus erythematosus (SLE or lupus) is a debilitating autoimmune disease with substantial heritability. It is characterized by a broad spectrum of clinical manifestations including pathogenic autoantibody production and multi-system organ damage. Compared to European-Americans (EA), Asians have at least 3-fold higher prevalence of SLE and more severe clinical manifestations, including life-threatening kidney damage. Genetic variation between ethnicities could account for underlying differences in disease severity and clinical manifestations. Development of new and more effective approaches for prevention and treatment requires improved understanding of disease mechanisms. While recent genome-wide association studies (GWAS) have identified over 40 genes/loci, differentiating between pathological and benign DNA changes is a major challenge. Lack of understanding causal effects underlying GWAS signals has hindered development of SLE diagnostics and treatments. GWAS results indicate that the genetic architecture of SLE in Asians may differ from more extensively studied European-derived populations. Thus, it is necessary to identify primary causal variants that influence SLE development in Asian populations. Our research team has the experience, expertise, resources and infrastructure necessary to move beyond GWAS to accelerate the discovery of causal variants underlying these signals and their functional effects. We have successfully identified SLE predisposing variants from IFIH1, ITGAM, and NCF2 loci, and experimentally defined mechanisms influencing SLE risk. Based on our preliminary data from >11,000 Koreans and Chinese, we propose to study 6 highly significant (10-99<P<10-11) candidate gene/loci in Asians. Four of these loci are novel, not reported in earlier GWAS. Our long-term goals are to detect functional variants from these genes, associate them with SLE symptoms, and define their biological mechanisms. Aim 1 is to pinpoint functional variants within 6 candidate genes in Asian populations by performing deep sequencing followed by imputation-based association analysis. We will also define the relationship between these variants and SLE clinical sub-phenotypes and autoantibody profiles. Significant SNPs, especially rare variants, will be validated with follow-up genotyping. Aim 2 is to predict and validate mechanistic effects of SLE-predisposing variants. We will employ bioinformatic analysis and molecular modeling to prioritize associated variants and select putative SNPs for appropriate experimental validation by adapting our established pipeline for functional assays. We will also identify networks involving our target predisposing SNPs, and genes affecting pathways that could influence SLE pathogenesis. Finally, we will experimentally validate functional effects of variants to define disease mechanisms. These results will provide new insights into mechanisms by which these variants contribute to lupus, and accelerate identification and validation of novel targets as well as development of treatments and future therapeutic interventions for lupus.