Positional Cloning and Candidate Gene Approach to Familial Atrial Fibrilation

家族性房颤的定位克隆和候选基因方法

• 批准号: 9130220
• 负责人: Dawood Darbar
• 金额: $ 28.65万
• 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/9130220
• 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 Atrium; 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（由申请人提供）：房颤（AF）是成人中最常见的持续性心律失常，与显著的发病率和死亡率增加相关。虽然AF的风险因素是多因素的，但约30%的患者患有与基础心脏病或全身性疾病无关的AF（“孤立性”AF）。在过去的十年里，我们和其他人已经证明，孤独性房颤有很大的遗传基础。人心脏钠通道负责心脏动作电位（AP）的快速上升，并且由SCN 5A编码的典型钠通道Nav1.5的阻断剂具有抗心律失常作用。我们和其他人已经表明，SCN 5A突变导致一系列心脏通道病，包括AF，其特征是增强的晚期钠电流（INa-L），延长AP持续时间和早期后除极。全基因组关联研究（GWAS）表明，由SCN 10A编码的第二个钠通道Nav1.8与AF易感性有关。我们在孤立性房颤患者中发现了多种罕见的SCN 10A变异。这提出了一个假设，即SCN 10A的罕见变异与房颤相关。在具体目标1中，我们将进行一项病例对照遗传关联研究，以确定是否先验罕见的潜在致病性SCN 10A变异在孤立性房颤先证者中比对照组中更丰富。此外，我们将确定每个罕见SCN 10A变异携带者的扩展家系，以确定AF的家族聚集性并确定基因型-表型相关性。高度保守的、预测为有害的并且与AF聚集的罕见SCN 10A变体将通过在背根神经节细胞系中表达它们以确定峰和INa-L来进行功能表征。罕见的SCN 10A变体的体外功能表征将使其AF相关，并可能提供心律失常的潜在遗传机制的新见解。此外，这些研究也有可能揭示Nav1.8作为抗肿瘤干预的新治疗靶点。在该奖项的前一个周期中，我们使用定位克隆和候选基因方法来鉴定编码心脏离子通道和信号蛋白的基因，这些基因对心律失常有很大的风险。相比之下，GWAS已经确定了具有适度影响的常见AF易感位点。虽然这些方法为AF的遗传结构提供了重要的见解，但它们只能解释AF遗传性的一小部分。 或大的效应可以通过全外显子组测序（WES）鉴定。在特定目标2中，我们将筛选一个大型AF患者队列，以确定WES和GWAS涉及的基因中的罕见变异作为介导AF易感性的候选基因。我们已经确定了四个高优先级的新的候选基因，共分离与AF使用WES。此外，与其他AF研究者合作，我们在对AF GWAS进行荟萃分析时发现了6个额外的AF易感基因位点和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对每个基因变体进行功能表征，以确定其致病性。