TNFAIP3 (A20) and Susceptibility to Systemic Lupus Erythematosus

描述（由申请人提供）：系统性红斑狼疮（SLE）是一种以自身抗体产生和免疫复合物形成为特征的炎症性自身免疫性疾病。在人类和小鼠模型中，经过20多年的研究，SLE的遗传易感性已经得到了很好的表征，然而，除了少数例外，确切的遗传变异仍然难以捉摸。随着基于人类基因组完整序列的高密度单核苷酸多态性（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性进行基因分型的能力，SLE的遗传景观正以前所未有的分辨率被揭示。我们实验室最近发表的研究发现并证实了与TNFAIP3 （A20）的令人信服的新关联，TNFAIP3 （A20）是NF-kB信号的关键负调控因子。该修订提案中提出的新的初步数据表明，TNFAIP3关联在多个独立的欧洲来源的SLE样本收集中得到了令人信服的复制，最佳标记rs5029939的meta分析p值为1.51x10-15 （OR=2.09）。通过代入，我们确定了11个新的相关变异，并将TNFAIP3 SLE风险单倍型的限制定义为跨越TNFAIP3编码区的109 kb DNA片段。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，并确定任何当前分型或输入的SNP都不太可能负责遗传关联。最后，初步的功能数据表明，TNFAIP3位点的SLE风险等位基因导致TNFAIP3表达和NF-kB激活调节的缺陷。该项目的主要目标是在人类SLE中分离导致TNFAIP3区域关联的精确变异。我们将通过检验这种关联延伸到非欧洲血统的SLE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，使用跨种族制图方法来缩小SLE的风险区间。同时，我们将对该区域进行深度重测序，首先关注启动子，外显子和UTR区域，使用常规测序。然而，我们将迅速采用序列捕获和大规模平行测序技术，在完全操作时对整个风险单倍型进行重测序。最后，我们将检验“表达表型”假说和“F127C”假说是否可能是SLE相关风险单倍型的功能影响。完成后，我们期望能够确定与欧洲裔美国人、非洲裔美国人、亚洲人和西班牙裔人群SLE相关的精确变异。我们期望对相关变异如何改变A20结构和功能的机制有一个初步的了解，从而容易产生自身免疫。这些结果将显著增加我们对SLE的遗传和病理生理基础的理解，并导致SLE和相关自身免疫性疾病患者的改善，这些疾病的TNFAIP3变异预示着风险。

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.