Dissecting Genetic Mechanisms of Hypertrophic Cardiomyopathy by ENU Mutagenesis

描述（由申请人提供）：以前的人类遗传学研究已经确定了许多遗传性心血管疾病的病因。肥厚性心肌病（HCM）是最常见的遗传性心血管疾病（患病率1:500），与至少19个基因的突变有关，其中大多数基因编码肌瘤蛋白，少数基因编码z -盘蛋白和钙处理蛋白。然而，只有约50%的患者在先前确定的基因中检测到突变。因此，我们假设，其他迄今未发现的调节肌节、z型椎间盘或细胞钙稳态的基因变异，包括代谢基因，可以直接导致疾病。在小鼠中进行大规模正向遗传学研究是鉴定这些未被发现基因的一种新方法。NHLBI资助了一项小鼠乙基亚硝基脲（ENU）诱变项目，该项目旨在确定导致先天性心脏病的遗传途径。初步研究表明，6%的纯合子胎儿有单独的心脏肥大。因此，我们的总体目标是利用可利用的独特资源，通过这个ENU诱变项目来恢复与HCM相关的新基因。我们的具体目标是：1。恢复ENU诱变小鼠HCM家系。在胎儿中表现为纯合子状态HCM的家系将被询问成人中是否存在杂合子状态的疾病表型，特别是超声心动图异常和HCM的组织病理学特征。杂合状态下明显的表型更有可能与临床相关。2. 鉴定导致HCM突变的新基因。将使用序列捕获阵列对异常杂合成人进行基因分型，以排除先前与HCM相关的基因和功能相关基因的突变。我们将选择大约6个具有潜在新基因突变的家系（包括我们已经确定的HCM家系）。从其中2个谱系中，我们将使用大规模平行全基因组测序来识别新基因的突变。这一探索性建议旨在为未来的多项研究奠定基础：为更广泛的科学界进一步分析感兴趣的谱系库；这一策略一旦得到证实，将扩展到更大的小鼠群体；小鼠和其他模型系统中新突变的进一步机制研究；确定新基因变异在HCM人群中所起的作用。我们认为我们有必要继续进行拟议的项目，这样我们和其他研究人员就不会浪费这个ENU诱变项目产生的HCM小鼠谱系的机会。

DESCRIPTION (provided by applicant): Previous human genetic studies have identified the etiology of many heritable cardiovascular disorders. Hypertrophic cardiomyopathy (HCM), the most common heritable cardiovascular disorder (prevalence 1:500), has been associated with mutations in at least 19 genes, most of which encode sarcomere proteins, along with a few encoding Z-disc and calcium handling proteins. However, mutations are detected in previously identified genes in only ~50% of patients. Therefore, we hypothesize that variants in other heretofore undiscovered genes that regulate the sarcomere, the Z-disc, or cellular calcium homeostasis, including metabolic genes, can directly cause disease. Large scale forward genetics in mice is a novel approach to identifying these undiscovered genes. The NHLBI has funded a mouse ethylnitrosourea (ENU) mutagenesis program that is identifying genetic pathways contributing to congenital heart disease. Preliminary studies show that 6% of fetuses homozygous for a given mutation have isolated cardiac hypertrophy. Therefore, our overall objective is to leverage the unique resource available to us through this ENU mutagenesis program to recover novel genes associated with HCM. Our specific aims are: 1. To recover ENU mutagenized mouse pedigrees with HCM. Pedigrees exhibiting HCM in the homozygous state in fetuses will be interrogated for the presence of the disease phenotype in the heterozygous state in adults, specifically, abnormalities on echocardiograms and histopathology characteristic of HCM. Phenotypes evident in the heterozygous state are more likely to be clinically relevant. 2. To identify novel genes with mutations leading to HCM. Abnormal heterozygous adults will be genotyped to exclude mutations in genes previously associated with HCM and functionally related genes, using sequence capture arrays. We will select ~6 pedigrees with potentially novel genetic mutations (including an HCM pedigree that we have already identified). From 2 of these pedigrees, we will identify mutations in novel genes using massively parallel whole genome sequencing. This exploratory proposal is meant to establish a foundation for multiple future studies: banking of pedigrees of interest for further analysis by the wider scientific community; expansion of this strategy, once proven, to larger cohorts of mice; further mechanistic studies of novel mutations in mice and other model systems; determination of the role of novel genetic variants in our large pre-existing cohorts of human subjects with HCM. We feel that it is imperative for us to pursue the proposed project, so that the opportunity for both us and other investigators to study mouse pedigrees with HCM that are generated by this ENU mutagenesis program is not wasted.