Molecular Determinants of Coronary Artery Disease

描述（由申请人提供）：在西方世界，导致死亡和残疾的最重要原因是动脉粥样硬化性冠状动脉疾病（CAD）及其主要并发症——急性心肌梗死（MI）。该项目的长期目标是确定CAD和MI的遗传途径和分子机制。该提案的中心假设是CAD/MI的发病机制涉及干扰CAD/MI复杂分子过程的关键基因的功能突变。为此，最近，在一个常染色体显性CAD/MI的大谱系中，我们发现了一个特定的MEF2A突变（21 bp缺失），这似乎是导致该家族CAD/MI的原因（科学，出版中）。此外，我们已经完成了对CAD/MI易感基因的全基因组扫描，该扫描包括428个患有过早CAD和MI的多重家族的1163名患者（平均发病年龄：44.4 + 9.7岁）。在检测到的8个MI染色体连锁显著易感位点lp34-36中，多点等位基因共享P值<10 -12 （LOD = 11.68）。目前的建议是由这些令人兴奋的结果驱动的。具体目标如下：具体目标1：利用单个大家族和基于模型的连锁分析以及定位克隆来绘制和鉴定新的CAD/MI基因。首先，我们将通过表征MEF2A敲除小鼠和转基因小鼠与CAD/MI相关的表型，继续验证MEF2A突变导致家族性CAD/MI的发现。我们设计了一系列分子生物学和细胞生物学实验来探索MEF2A缺失的分子机制。我们还将确定MEF2A中的snp，并通过关联研究确定某些snp是否增加或降低常见复杂CAD/MI的风险。其次，我们计划继续使用基于模型的连锁分析和位置克隆来定位和鉴定至少一个新的CAD/MI基因。我们招募了三个与ef2a没有关联的大型和扩展的CAD/MI谱系，每个家族在统计上都有足够的能力（模拟LOD评分分别为3.53、7.22和6.62）来进行与CAD和MI显著关联的全基因组扫描。此外，在本研究中，已经确定了16个有4个以上受影响个体的家庭，平均每个家庭有27个活的兄弟姐妹和父母。具体目标2：为了确定染色体区域lp34-36上心肌梗死的易感基因，我们将重点关注染色体lp34-36心肌梗死位点，以进行后续基因发现工作，因为这是迄今为止发现的心肌梗死最重要的连锁（LOD评分为11.68）。我们将进行精细的定位、候选基因鉴定、SNP鉴定和基因分型——家族tdt分析（Sibship不平衡检验）以及基于人群的病例对照研究，以确定候选基因中的特定SNP或SNP单倍型是否与心肌梗死相关。本研究目标的实现可能对CAD和心肌梗死的分子机制的理解产生重大影响。从而促进更好的预防、诊断和治疗。

DESCRIPTION (provided by applicant): The most important cause of death and disability in the Western world is atherosclerotic coronary artery disease (CAD) and its primary complication-acute myocardial infarction (MI). The long-term objective of this project is to define genetic pathways and molecular mechanisms for CAD and MI. The central hypothesis of this proposal is that the pathogenesis of CAD/MI involves functional mutations in key genes that perturb the complex molecular processes involved in CAD/MI. To this end, recently, in a large pedigree with autosomal dominant CAD/MI, we identified a specific MEF2A mutation (21-bp deletion) that appears to be responsible for this family's CAD/MI (Science, in press). Furthermore, we have completed a genomewide scan for susceptibility genes for CAD/MI in a well characterized U.S. cohort consisting of 1,163 affected persons in 428 multiplex families with premature CAD and MI (average age at onset: 44.4 + 9.7 years). Of eight novel significant susceptibility loci detected for MI linkage to the chromosomal region lp34-36 showed multipoint allelesharing P values of <10 -12 (LOD = 11.68). The present proposal is driven by these exciting results. The specific aims are: Specific Aim 1: To map and identify a novel CAD/MI gene using single large families and model-based linkage analysis, and positional cloning. First, we will continue to validate our finding that mutations in MEF2A cause familial CAD/MI by characterizing the MEF2A knockout mice and transgenic mice for phenotype related to CAD/MI. A series of molecular and cell biological experiments are designed to explore the molecular mechanisms of the MEF2A deletion. We will also identify SNPs in MEF2A and determine whether some of the SNPs increase or decrease the risk of common complex CAD/MI by association studies. Secondly, we plan to continue to use model-based linkage analysis and positional cloning to map and identify at least one new CAD/MI gene. We have recruited three large and extended CAD/MI pedigrees that are not linked toMEF2A, and each family has statistically sufficient power (simulated LOD scores of 3.53, 7.22, and 6.62, respectively) to conduct a genomewide scan of significant linkage to CAD and MI. Furthermore, 16 families of more than four affected individuals have been identified with an average of 27 living siblings and parents per family for this study. Specific Aim 2: To identify the susceptibility gene for MI on the chromosomal region lp34-36, We will focus on the chromosome lp34-36 MI locus for our follow-up gene discovery effort because this is the most significant linkage identified for MI to date (LOD score of 11.68). We will perform fine mapping, identification of candidate genes, SNP identification and genotyping_ family-TDT analysis (Sibship Disequilibrium Test) as well as population-based case-control studies to determine whether a specific SNP or SNP haplotype in a candidate gene is associated with MI. The accomplishment of research objectives in this proposal has the potential to have a substantial impact on the understanding of the molecular mechanism of CAD and MI, thereby facilitating better prevention, diagnosis and therapy.