GENE APPROACH TO IMMUNOPHENOTYPIC SUBGROUPS OF CROHN'S DISEASE

多年来，克罗恩病(CD)的一个主要病因危险因素已经很明显地是 遗传易感性。家族聚集性明显增强，全基因组扫描已经确定了一些遗传位点。一个主要的进展是鉴定了NOD2/CARD15为IBD1基因，因为它暗示了先天性免疫系统在CD中的重要性。然而，尽管人们发现了许多易患CD的基因，但我们仍然对决定其严重性的遗传因素知之甚少。PPG的研究人员已经证明，多种CD相关抗体(ASCA、OMPC、12)的存在和数量与更具侵袭性的CD表型(称为CD-HIGR)相关。我们还证明了至少有一种抗体ASCA是家族性的，虽然它与基因组的特定区域有关，但在我们的数据中它与NOD2/CARD15无关。该项目的目标是确定CD相关血清抗体表达的基础基因和CD的表型谱。我们将使用大规模候选基因方法，可能最相关的免疫途径(先天免疫、Th1效应细胞、调节性T和B细胞，以及共刺激途径)由本PPG中的其他项目阐明。为了采用这种方法，我们需要有能力进行大规模的基因分型，并有假说生成和确认两个阶段。现在，技术和患者资源都是可用的。目标1是假设生成步骤，我们将在该步骤中继续 对CD免疫表型亚群可能易感基因的鉴定 在病例/对照设计中进行全面的关联研究。我们将研究大约225-300个基因，每个基因平均有10个标记，这些标记将通过基于单倍型的方法进行分析，该方法捕捉基因中的常见变异。这些基因将与个体定量抗体水平和四分位数和进行测试。这将包括测试2300多个标记器，这将使用Illumina公司的高通量技术来完成。目标2是假设确认步骤，在该步骤中，来自目标1的15个“最好的”基因将在第二个受试者小组中进行测试，这是一个由CD“三人组”(受影响的CD患者和父母双方)组成的独立家族小组，也有1200名受试者。在目标3中，来自目标2的3-5个最好的基因将通过检查同时来自抗体分布的极端并共享相关候选基因的相关单倍型的个体来进行额外变异的测序。由于这个PPG的资源，这个项目提供了一个独特的机会来确定决定CD严重程度的基因，从而提供了对可能导致改进治疗甚至预防的生物途径的洞察。

It has been apparent for some years that a major etiologic risk factor for Crohn's disease (CD) is genetic susceptibility. There is clear increased familial aggregation and a number of genetic loci have been identified by genome-wide scans. A major advance was the identification of NOD2/CARD15 as the IBD1 gene, as it implicated the importance of the innate immune system in CD. However, while a number of genes are being identified that predispose to CD, we still know little of the genetic factors that determine the severity. Investigators in this PPG have demonstrated that the presence and magnitude of multiple CD-associated antibodies (ASCA, OMPC, 12) are associated with a more aggressive CD phenotype (termed CD-HighR). We have also demonstrated that at least one of these antibodies, ASCA, is familial, and while linked to specific regions of the genome, it is not linked/associated with NOD2/CARD15 in our data. The goal of this project is to identify the genes that underlie the expression of CD associated serum antibodies and the phenotypic spectrum of CD. We will use a large scale candidate gene approach, with the likely most relevant immunologic pathways (innate immunity, Th1 effector cells, regulatory T and B cells, and co-stimulatory pathways) being elucidated by other Projects in this PPG. To undertake such an approach we need the capability to do large scale genotyping, and to have both hypothesis generating and confirming stages. Both technology and patient resources are now available. Aim 1 is the hypothesis generating step, in which we will proceed to the identification of putative susceptibility genes for immuno-phenotypic subgroups of CD by performing a comprehensive association study in a case/control design. We will study approximately 225-300 genes, for an average of 10 markers per gene, which will be analyzed by a haplotype based approach that captures the common variation in a gene. The genes will be tested against the individual quantitative antibody levels and quartile sums. This will involve testing over 2300 markers, which will be accomplished using the high throughput technology of Illumina Corporation. Aim 2, is the hypothesis confirmatory step, in which the 15 "best" genes from Aim 1 will be tested in a second panel of subjects, an independent family based panel of CD "trios" (affected CD patients and both parents), that also numbers 1200 subjects. In Aim 3, the 3-5 best genes from Aim 2 will be sequenced for additional variation by examining individuals who are simultaneously from the extremes of the antibody distribution and share associated haplotypes of the associated candidate genes. Because of the resources of this PPG, this project provides a unique opportunity to identify genes that determine the severity of CD, thus providing insight into biological pathways potentially leading to improved therapeutics and even prevention.