Dissection of two rheumatoid arthritis risk loci from genome-wide studies

描述（由申请人提供）：虽然类风湿性关节炎有明确的遗传基础，但我们对遗传的理解仍然不完整。类风湿性关节炎是一种破坏性关节炎，折磨着多达1%的成年人。从20世纪70年代中期到2007年，只有两个RA易感基因位点被明确证实;在过去的一年里，我们已经确定并验证了另外两个基因位点。然而，三个关键问题是：（1）我们不知道每个基因座的确切因果突变，（2）我们还没有所有RA突变的完整目录，（3）我们不了解这些等位基因如何干扰人类免疫细胞导致疾病。本提案的目标是解决这三个关键问题。重要的是，这些关键问题影响了利用遗传学在临床发作前预测RA风险和开发新疗法的长期目标。为了实现我们的目标，我们提出了三个具体目标：具体目标1：确定两个新发现的RA易感基因位点的常见致病突变。我们最近在染色体9 q33（包括TRAF 1基因）和6 q23（包括TNFAIP 3）上发现了两个新的RA易感基因座。我们将使用最先进的测序技术（Solexa）来识别这些基因座内的所有已知遗传变异，并在5,000多个RA病例对照样本中确定每个基因座上最准确的推定因果突变集。具体目标二：在TRAF 1和TNFAIP 3基因中寻找罕见的蛋白质编码突变，这些突变也会导致RA风险（独立于常见突变）。我们将再次使用最先进的测序技术（Solexa）。在这里，我们将通过对500例RA病例和500例RA对照的TRAF 1和TNFAIP 3编码区进行重新测序，寻找在RA病例中比对照中更常见的罕见DNA变异。具体目标3：使用假设驱动的实验测试常见和罕见RA易感性突变的功能。我们将生成关于常见和罕见变体的预测功能的假设（目的1和2），并在相关免疫组织类型中测试这些假设（例如，单核细胞和B细胞）。这将提供深入了解这些等位基因如何导致RA。完成这些目标将为我们完全了解所有RA基因突变的最终目标提供实质性进展-这是遗传学转化为临床护理之前的必要步骤。此外，这种方法将适用于其他RA易感基因，因为他们被确定。 公共卫生相关性：了解类风湿性关节炎的遗传基础的长期目标是改善这种常见和衰弱疾病患者的护理。从理论上讲，识别特定的DNA片段（“等位基因”）应该有助于在症状发作之前或在骨破坏发生之前的疾病过程中早期诊断可治疗的疾病。此外，遗传学应该提供对疾病途径重要步骤的洞察，允许开发针对高危个体中这些途径的新疗法。

DESCRIPTION (provided by applicant): While there is a clear inherited basis to rheumatoid arthritis, a destructive arthritis that afflicts up to 1% of the adult population, our genetic understanding remains incomplete. From the mid-1970's until 2007, only two RA susceptibility loci had been confirmed unequivocally; over the last year, we have identified and validated two additional gene loci. However, three key issues are: (1) we do not know the exact causal mutation at each locus, (2) we do not yet have a complete catalogue of all RA mutations, and (3) we do not understand how these alleles perturb human immune cells to cause disease. The goal of this proposal is to address these three key issues. Importantly, these key issues impact the long-term goal of using genetics to predict risk of RA prior to clinical onset and to develop new therapeutics. To accomplish our goals, we proposed three Specific Aims: Specific Aim 1: Identify the common causal mutations two newly identified RA susceptibility gene loci. We have recently identified two new RA susceptibility loci on chromosomes 9q33 (includes TRAF1 the gene) and 6q23 (includes TNFAIP3). We will use state-of-the-art sequencing technology (Solexa) to identify all known genetic variants within these loci, and define the most accurate set of putative causal mutations at each locus in more than 5,000 RA case-control samples. Specific Aim 2: Search for rare protein coding mutations in the TRAF1 and TNFAIP3 genes that also contribute to RA risk (independent of common mutations). We will again use state-of- the-art sequencing technology (Solexa). Here, we will search for rare DNA variants that are more commonly observed in RA cases than in controls by re-sequencing the coding regions of TRAF1 and TNFAIP3 in 500 RA cases and 500 RA controls. Specific Aim 3: Test the function of common and rare RA susceptibility mutations using hypothesis-driven experiments. We will generate hypotheses about the predicted function of common and rare variants (Aims 1 and 2), and test these hypotheses in a relevant immune tissue type (e.g., mononuclear and B-cells). This will provide insight into how these alleles cause RA. Completing these Aims will provide substantial progress towards our ultimate goal of a complete understanding of all RA genetic mutations - a necessary step before genetics can be translated to clinical care. Moreover, this approach will be applicable to other RA susceptibility genes as they are identified. PUBLIC HEALTH RELEVANCE: A long-term goal of understanding the genetic basis of rheumatoid arthritis is to improve care of patients with this common and debilitating disease. In theory, identifying specific pieces of DNA ("alleles") should aid in diagnosing a treatable condition either prior to onset of symptoms, or early in the course of disease before bone destruction occurs. In addition, genetics should provide insight into important steps of the disease pathway, allowing for the development of new therapies that target these pathways in at-risk individuals.