TNFAIP3 (A20) and Susceptibility to Systemic Lupus Erythematosus

描述(申请人提供)：系统性红斑狼疮(SLE)是一种炎症性自身免疫性疾病，其特征是产生自身抗体和形成免疫复合体。经过二十多年的人类和小鼠模型研究，SLE的遗传易感性已经得到了很好的描述，然而，除了极少数例外，确切的遗传变异仍然难以捉摸。随着基于人类基因组全序列的高密度单核苷酸多态(SNP)图谱的出现，以及在数千名受试者中使用高密度阵列对这些多态进行基因分型的能力，SLE的遗传格局正以前所未有的分辨率被揭示。我们实验室最近发表的工作已经确定并确认了一个令人信服的新的与TNFAIP3(A20)的关联，TNFAIP3(A20)是一种关键的NF-kB信号负调控因子。这项修订建议中提供的新的初步数据表明，TNFAIP3相关性在多个独立的欧洲来源的SLE样本收集中令人信服地复制，最佳标记rs5029939的荟萃分析P值为1.51x10-15(OR=2.09)。通过推测，我们确定了11个新的相关变异，并定义了TNFAIP3 SLE风险单倍型对跨越TNFAIP3编码区的109kb DNA片段的限制。使用协调的生物信息学方法，我们评估了风险单倍型上每个SNP的功能潜力，并确定不太可能是任何当前分型或推测的SNP负责遗传关联。最后，初步的功能数据表明，TNFAIP3基因座上的SLE风险等位基因导致了TNFAIP3表达的缺陷和对核因子-kB激活的调节。该项目的主要目标是在人类系统性红斑狼疮中分离与TNFAIP3区域相关的精确变异。我们将通过检验这种关联延伸到非欧洲血统的系统性红斑狼疮队列的假设来做到这一点。我们将利用人群单倍型结构的差异，使用跨种族作图方法缩小SLE风险区间。同时，我们将对该区域进行深度重新测序，首先使用常规测序将重点放在启动子、外显子和UTR区域。然而，我们将迅速利用序列捕获和大规模并行测序技术，在完全可操作时对整个风险单倍型进行重新测序。最后，我们将检验“表达表型”假说和“F127C”假说作为SLE相关风险单倍型的可能功能效应。完成后，我们预计已经确定了与欧洲裔美国人、非裔美国人、亚洲人和西班牙裔人口中系统性红斑狼疮相关的确切变异(S)。我们希望对相关的变异如何改变A20的结构和功能有一个初步的机械性理解，以一种倾向于自身免疫的方式。这些结果将大大增加我们对SLE的遗传和病理生理学基础的了解，并有助于改善SLE患者和相关的自身免疫性疾病，因为TNFAIP3的变异预示着风险。 公共卫生相关性：系统性红斑狼疮是一种严重的、使人衰弱的自身免疫性疾病，在世界范围内是一个重大的医疗负担。我们的研究将描述SLE和TNFAIP3之间的遗传联系，TNFAIP3是控制炎症和免疫系统功能的关键基因。这项工作有可能导致系统性红斑狼疮的新疗法，以及诊断和监测疾病的新测试。

DESCRIPTION (provided by applicant): Systemic lupus erythematosus (SLE) is an inflammatory autoimmune disease characterized by autoantibody production and immune complex formation. Genetic predisposition to SLE has been well characterized with over two decades of work in human and murine models, however the precise genetic variants responsible have, with few exceptions, remained elusive. With the advent of high-density single nucleotide polymorphism (SNP) maps based on the complete sequence of the human genome and the ability to genotype these polymorphisms using high density arrays in thousand of subjects, the genetic landscape of SLE is being revealed with unprecedented resolution. Recently published work from our laboratory has identified and confirmed a convincing novel association with TNFAIP3 (A20), a critical negative regulator of NF-kB signaling. New preliminary data presented in this amended proposal demonstrates that the TNFAIP3 association is convincingly replicated in multiple independent European-derived SLE sample collections with a meta-analysis P-value of 1.51x10-15 (OR=2.09) for the best marker, rs5029939. Through imputation, we identify 11 new associated variants and define the limits of the TNFAIP3 SLE risk haplotype to a 109 kb DNA segment that spans the TNFAIP3 coding region. Using a coordinated bioinformatics approach, we evaluated the functional potential for each SNP on the risk haplotype and determined that it is unlikely that any of the currently typed or imputed SNPs are responsible for the genetic association. Finally, preliminary functional data suggest that the SLE risk alleles in the TNFAIP3 locus result in a defect in TNFAIP3 expression and regulation of NF-kB activation. The primary objectives of this project are focused on isolating the precise variant responsible for the association in the region of TNFAIP3 in human SLE. We will do this by testing the hypothesis that the association extends to SLE cohorts of non-European ancestry. We will exploit differences in population haplotype structure to narrow the SLE risk interval using a trans-racial mapping approach. In parallel, we will deeply resequence the region, focusing first on promoter, exons and UTR regions using conventional sequencing. We will, however, rapidly employ sequence capture and massively parallel sequencing technology to resequence the entire risk haplotype when fully operational. Finally, we will test the "expression phenotype" hypothesis and the "F127C" hypothesis as likely functional effects of the SLE associated risk haplotype. When complete, we expect to have identified the precise variant(s) responsible for association with SLE in European American, African American, Asian and Hispanic populations. We expect to have an initial mechanistic understanding for how the associated variants alter A20 structure and function in a manner that predisposes to autoimmunity. These results should add significantly to our understanding of the genetic and pathophysiologic basis of SLE and lead to improvements for patients with SLE and related autoimmune disorders for which variants in TNFAIP3 portend risk. PUBLIC HEALTH RELEVANCE: Systemic lupus erythematosus is a severe, debilitating autoimmune disease that represents a significant healthcare burden worldwide. Our study will characterize a genetic association between SLE and TNFAIP3, a gene critical for controlling inflammation and immune system function. This work has the potential to lead to new treatments for SLE and to new tests for diagnosing and monitoring the disease.