Identifying genes regulating platelet reactivity

描述(申请人提供)：冠状动脉、脑动脉和外周动脉的血小板血栓是全球发病率和死亡率的最常见原因。这些疾病的有害临床结果有公认的遗传成分，但只有少数血小板基因变异与这些疾病有关。这项应用的目标是识别导致血小板反应性的基因和遗传变异。我们的初步数据表明，血小板的反应性既是可遗传的，也是可复制的。我们发现，人类对次最大肾上腺素刺激的血小板聚集反应表现为双峰分布，具有显著不同且不重叠的反应。我们选择了一些不相关的欧洲、美国和非洲裔美国受试者，他们的血小板表现出极端的血小板反应性。全基因组关联研究是识别这一复杂生理系统的限速蛋白(基因)的有效方法。在目标1中，我们将使用Illumina Human Hap550珠芯片在我们患有高反应性和低反应性血小板的受试者的整个基因组中对&gt；550,000个标签SNPs进行基因分型。在进行质量控制后，将对基因型和单倍型数据进行分析。假发现率将被用来选择一组假阳性率低于0.5的SNPs。为了增强我们的候选列表，以包括新的基因和在基因组扫描平台中没有很好代表的基因，在目标2中，我们将使用来自具有极端血小板反应的欧洲裔美国人和非裔美国人的血小板的mRNA进行微阵列表达分析。在目标3中，目标1中识别的基因座和目标2中的基因将被定位，以获得具有致病遗传变异的较强LD的SNPs。在目标4中，我们将使用目标3中确定的目标数量的SNP(~300-350)来对约翰霍普金斯大学GeneSTAR队列中的所有受试者进行重复研究。这些研究的成功完成，将通过发现与血小板功能有关的新基因，对血小板生理和关键信号通路产生新的见解。在这些基因中发现的变异有望成为血栓形成、出血以及潜在的抗血小板药物影响的因素。我们使用数量性状极值的新方法可能会被证明对其他研究具有经济价值。

DESCRIPTION (provided by applicant): Platelet thrombi in coronary, cerebral and peripheral arteries are the most common cause of global morbidity and mortality. There is a well-established genetic component to the deleterious clinical outcomes of these disorders, but only a small number of platelet gene variations have been associated with these disorders. The goals of this application are to identify the genes and genetic variations responsible for platelet reactivity. Our preliminary data demonstrates that platelet reactivity is both heritable and reproducible. We find that the human platelet aggregation response to submaximal epinephrine stimulation is represented by a bimodal distribution with dramatically different and non-overlapping responses. We have selected groups of unrelated European American and African American subjects whose platelets demonstrate the extremes of platelet responsiveness. Genome wide association studies are powerful approaches for identifying rate- limiting proteins (genes) for this complex physiologic system. In Aim 1 we will genotype >550,000 tagSNPs throughout the genome of our subjects with hyper- and hyporeactive platelets using the Illumina HumanHap550 BeadChip. After performing quality control, analyses will be carried out on genotype and haplotype data. The False Discovery Rate will be used to select a group of SNPs with a false positive rate less than 0.5. To enhance our list of candidates to include novel genes and genes not well-represented in the genome scan platform, in Aim 2 we will perform microarray expression analyses with mRNA from platelets from a subset of European-Americans and African-Americans with extremes of platelet reactivity. In Aim 3 the loci identified in Aim 1 and the genes from Aim 2 will be mapped to obtain SNPs in stronger LD with the causative genetic variant. In Aim 4 we will use the targeted number of SNPs identified in Aim 3 (~300-350) to perform a replication study on all subjects in the Johns Hopkins University GeneSTAR cohort. The successful completion of these studies will result in new insights into platelet physiology and crucial signaling pathways via the discovery of novel genes responsible for platelet function. The variants identified in these genes are expected to be factors modifying thrombosis, hemorrhage and potentially the effects of anti-platelet agents. Our novel approach of using the extremes of a quantitative trait may prove economically valuable for other studies.