Genetic determinants of total cholesterol levels in American Indians

描述（由申请人提供）：冠心病（CHD），引起心脏病发作和心绞痛，是美国唯一的主要死亡原因。CHD发展的最强风险因素包括脂质和脂蛋白的循环水平，这两者都受到遗传因素的强烈调节。对血脂水平有显著影响的变异体已被确定为一些单基因家族性疾病，但这些仅占CHD的一小部分。相反，常见脂质异常的遗传决定因素仍然未知。该项目的总体计划是识别和表征有助于调节空腹血清总胆固醇浓度的遗传变异。这项研究的重点是一个位点，它最初已被定位的基础上连锁数据的19号染色体在至少15项研究，然后缩小到1-LOD支持间隔<15.7 cM的皮马印第安人。该提案的具体目标是首先通过对2，884名皮马印第安人的研究样本中的一组密集SNP标记进行基因分型，对19 p上空腹血清TC浓度的QTL进行优化和优先定位。然后对来自NIDDM遗传学（GENNID）研究的701名非裔美国人（我们先前观察到其与TC浓度相关）和来自圣安东尼奥家族胆囊疾病研究（SAFGS）的740名墨西哥裔美国人（他们更有可能与皮马印第安人共享更大的遗传相似性）的所有QTL相关SNP等位基因和单倍型进行基因分型。这一目标的完成将验证目标1中获得的结果。下一步将利用创新的条形码方法进行下一代测序，以充分表征与TC浓度相关的区域，并确定可能对胆固醇代谢产生功能性影响的特定变体。最后，我们提出了一个探索性的功能特性与强大的QTL相关的等位基因，这将提供一个基础的发展，一个全面的调查的分子机制，这些特定的变异影响调节胆固醇代谢的重点是一个独立的赠款申请。结合起来，这些目标将确定对空腹总胆固醇浓度具有关键影响的新变体。确定影响胆固醇浓度的遗传机制将促进我们对脂质代谢的理解，从而增强对动脉粥样硬化过程的病理生理学的认识。

DESCRIPTION (provided by applicant): Coronary heart disease (CHD), which causes heart attacks and angina, is the single leading cause of death in the United States. The strongest risk factors for CHD development include circulating levels of lipids and lipoproteins, both of which are strongly regulated by genetic factors. Variants with significant effects on lipid levels have been identified for a number of monogenic familial disorders, but these account for only a small proportion of CHD. In contrast, genetic determinants for common lipid abnormalities remain unknown. The overall plan for this project is to identify and characterize genetic variants that contribute to the regulation of fasting serum concentrations of total cholesterol. The focus of this study is a locus which has been initially mapped on the basis of linkage data to chromosome 19 in at least 15 studies, then subsequently narrowed to a 1-LOD support interval <15.7 cM in Pima Indians. The specific goals of this proposal are to first refine and prioritize localization of the QTL(s) for fasting serum TC concentration on 19p by genotyping a dense set of SNP markers in a study sample of 2,884 Pima Indians. All QTL-associated SNP alleles and haplotypes will then be genotyped in 701 African American individuals from the Genetics of NIDDM (GENNID) study, in whom we have previously observed linkage for TC concentration, and 740 Mexican American individuals from the San Antonio Family Gallbladder Disease Study (SAFGS), who are more likely to share greater genetic similarity with Pima Indians. Completion of this aim will provide validation of findings obtained in Aim 1. The next step will utilize an innovative bar-code approach to next-generation sequencing to fully characterize regions showing association with TC concentration, and identify specific variants that are likely to exert functional effects on cholesterol metabolism. Finally, we propose an exploratory characterization of functional effects associated with strong QTL-related alleles, which will provide a basis for the development of a full-scale investigation of the molecular mechanisms by which these specific variants affect regulation of cholesterol metabolism as the focus of an independent grant application. Combined, these aims will identify novel variants with critical effects on fasting total cholesterol concentration. Identification of the genetic mechanisms influencing cholesterol concentrations will advance our understanding of lipid metabolism, leading to an enhanced knowledge of the pathophysiology of the atherosclerotic process.