Positional Cloning and Candidate Gene Approach to Familial Atrial Fibrillation

家族性房颤的定位克隆和候选基因方法

• 批准号: 9282942
• 负责人: Dawood Darbar
• 金额: $ 2.97万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-04-01 至 2018-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9282942
• 关键词: 16q22; 1q21; 4q25; Action Potentials; Adult; Affect; Architecture; Arrhythmia; Atrial Fibrillation; Award; Biological Assay; Candidate Disease Gene; Cardiac; Cell Line; Cessation of life; Chromosomes; Code; Collaborations; Complex Genetic Trait; DNA Resequencing; Dementia; Development; Developmental Gene; Disease; Electrophysiology (science); Generations; Genes; Genetic; Genetic Predisposition to Disease; Genotype; Goals; Health; Heart Diseases; Heart failure; Hereditary Disease; Heritability; Human; In Vitro; Inherited; Intervention; Ion Channel; Link; Mediating; Meta-Analysis; Morbidity - disease rate; Mutation; Pathogenicity; Pathway interactions; Patients; Phenotype; Play; Population; Predisposition; Protocols documentation; Research Personnel; Risk; Risk Factors; Role; Signaling Protein; Single Nucleotide Polymorphism; Sodium; Sodium Channel; Spinal Ganglia; Stroke; Susceptibility Gene; Systemic disease; Testing; Variant; Work; Zebrafish; base; case control; cohort; common treatment; exome sequencing; ganglion cell; genetic association; genetic linkage analysis; genetic pedigree; genetic variant; genome wide association study; in vivo; insight; mortality; new therapeutic target; novel; positional cloning; proband; rare variant; risk variant; targeted treatment; voltage; voltage clamp

DESCRIPTION (provided by applicant): Atrial fibrillation (AF), the most common sustained cardiac arrhythmia in adults, is associated with significant morbidity and increased mortality. While risk factors for AF are multifactorial, ~30% of patients have AF that is unassociated with underlying heart or systemic disease ('lone' AF). Over the last decade, we and others have shown that lone AF has a substantial genetic basis. The human cardiac sodium channel is responsible for the rapid upstroke of the cardiac action potential (AP) and blockers of Nav1.5, the canonical sodium channel encoded by SCN5A, are antiarrhythmic. We and others have shown that mutations in SCN5A cause a range of cardiac channelopathies including AF characterized by enhanced late sodium current (INa-L), prolonged AP duration and early afterdepolarizations. Genome wide association studies (GWAS) have implicated a second sodium channel Nav1.8, encoded by SCN10A, in AF susceptibility. We have identified multiple rare SCN10A variants in patients with lone AF. This raises the hypothesis, to be tested here, that rare variation in SCN10A is associated with AF. In Specific Aim 1, we will conduct a case-control genetic association study to determine whether a priori rare potentially pathogenic SCN10A variants are enriched in lone AF probands than in controls. In addition, we will ascertain extended pedigrees for each rare SCN10A variant carrier to determine familial aggregation with AF and determine genotype-phenotype correlations. Rare SCN10A variants that are highly conserved, predicted to be deleterious and aggregate with AF will be functionally characterized by expressing them in a dorsal root ganglia cell-line to determine the peak and INa-L. In vitro functional characterization of rare SCN10A variants will enable their AF-association and may provide novel insights into underlying genetic mechanisms of the arrhythmia. Furthermore, these studies also have the potential of uncovering Nav1.8 as a novel therapeutic target for antiarrhythmic intervention. In the previous cycle of this award, we used positional cloning and candidate gene approaches to identify genes encoding cardiac ion channels and signaling proteins which impart a large risk for the arrhythmia. In contrast, GWAS have identified common AF susceptibility loci with modest effects. While these approaches have provided important insights into the genetic architecture of AF, collectively they explain only a small fraction of the heritability of AF. This raises the hypothesis that rare variants with modest or large effects may be identified by whole exome sequencing (WES). In Specific Aim 2, we will screen a large cohort of patients with AF for rare variants in genes implicated by WES and GWAS as candidates for mediating AF susceptibility. We have identified four high priority novel candidate genes that cosegregated with AF using WES. Furthermore, in collaboration with other AF investigators, we have uncovered six additional AF susceptibility loci and five novel candidate genes when a meta-analysis of AF GWAS was performed. We will functionally characterize each gene variant using in vitro electrophysiology and in vivo zebrafish expression in order to determine their pathogenicity.

描述(申请人提供)：房颤(房颤)，成人最常见的持续性心律失常，与显著的发病率和增加的死亡率有关。虽然房颤的危险因素是多因素的，但约30%的患者房颤与潜在的心脏或全身疾病(‘孤立性’房颤)无关。在过去的十年里，我们和其他人已经证明孤立性房颤有很大的遗传基础。人的心脏钠通道负责心脏动作电位(AP)的快速上升，而由SCN5A编码的典型钠通道NaV1.5的阻断剂具有抗心律失常作用。我们和其他人已经证明，SCN5A基因突变会导致一系列心脏通道病，包括以晚期钠电流增强(INA-L)、AP持续时间延长和早期后除极为特征的房颤。全基因组关联研究表明，由SCN10A编码的第二个钠通道Nav1.8与房颤易感性有关。我们在孤立性房颤患者中发现了多种罕见的SCN10A变异。这提出了一个假设，这里要检验的是，SCN10A的罕见变异与房颤有关。在具体目标1中，我们将进行一项病例对照遗传关联研究，以确定先天罕见的潜在致病SCN10A变异是否在孤立性房颤先证者中比在对照组中丰富。此外，我们将确定每个罕见SCN10A变异携带者的扩展家系，以确定房颤的家族聚集性，并确定基因-表型相关性。罕见的高度保守的、被预测为有害的和与房颤聚集的SCN10A变体将通过在背根节细胞系中表达它们来确定峰值和Ina-L来确定其功能特征。罕见的SCN10A变异的体外功能特征将使它们能够与房颤相关联，并可能为研究心律失常的潜在遗传机制提供新的见解。此外，这些研究还有可能发现Nav1.8作为抗心律失常干预的新治疗靶点。在这个奖项的前一个周期，我们使用位置克隆和候选基因方法来识别编码心脏离子通道和信号蛋白的基因，这些基因给心律失常带来了很大的风险。相反，GWAS已经确定了常见的房颤易感基因座，但影响不大。虽然这些方法对房颤的遗传结构提供了重要的见解，但总的来说，它们只解释了房颤遗传性的一小部分。这提出了一种假设，即罕见的变异与适度 或者，大的效应可以通过整个外显子组测序(WES)来识别。在特定的目标2中，我们将筛选一大批房颤患者，寻找WES和GWAs所涉及的基因中的罕见变异，作为介导房颤易感性的候选。我们已经利用WES鉴定了四个与房颤共分离的高优先级新候选基因。此外，在与其他房颤研究者的合作下，我们发现了6个额外的房颤易感基因和5个新的候选基因。我们将使用体外电生理学和体内斑马鱼表达来确定每个基因变体的功能特征，以确定它们的致病性。