GENES AS IMMUNOPHENOTYPIC SUBGROUPS OF CROHN'S DISEASE

几年来，克罗恩病（CD）的主要病因风险因素是 遗传易感性有明显增加的家族聚集性和一些遗传位点已确定的全基因组扫描。一个主要的进展是NOD 2/CARD 15作为IBD 1基因的鉴定，因为它暗示了先天免疫系统在CD中的重要性。然而，虽然一些基因被确定为易患CD，我们仍然知道一点的遗传因素，决定了严重性。本PPG的研究者已经证明，多种CD相关抗体（ASCA、OMPC、12）的存在和强度与更具侵袭性的CD表型（称为CD-HighR）相关。我们还证明，这些抗体中至少有一种ASCA是家族性的，虽然与基因组的特定区域相关，但在我们的数据中，它与NOD 2/CARD 15不相关。本项目的目标是鉴定CD相关血清抗体表达的基因和CD的表型谱。我们将使用大规模候选基因方法，其中可能最相关的免疫途径（先天免疫、Th 1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，我们需要进行大规模基因分型的能力，并具有假设生成和确认阶段。技术和患者资源现在都可用。目标1是假设生成步骤，我们将继续进行 涉及通过以下方法鉴定CD免疫表型亚组的推定易感基因： 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，平均每个基因10个标记，将通过基于单倍型的方法进行分析，该方法捕获基因中的常见变异。将根据个体定量抗体水平和四分位数总和检测基因。这将涉及测试超过2300个标记，这将使用Illumina公司的高通量技术来完成。目标2是假设验证步骤，其中将在第二组受试者中测试来自目标1的15个“最佳”基因，第二组受试者是一个独立的基于家族的CD“三人组”（受影响的CD患者和父母双方），也有1200名受试者。在目标3中，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，对来自目标2的3-5个最佳基因进行测序以获得额外的变异。由于PPG的资源，该项目提供了一个独特的机会来识别决定CD严重程度的基因，从而深入了解可能导致改善治疗甚至预防的生物学途径。

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.