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A novel trafficking-defective HCN4 mutation is associated with early-onset atrial fibrillation.

ABSTRACT: Atrial fibrillation (AF) is the most common arrhythmia, and a recent genome-wide association study identified the hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) as a novel AF susceptibility locus. HCN4 encodes for the cardiac pacemaker channel, and HCN4 mutations are associated with familial sinus bradycardia and AF.The purpose of this study was to determine whether novel variants in the coding region of HCN4 contribute to the susceptibility for AF.We sequenced the coding region of HCN4 for novel variants from 527 cases with early-onset AF from the Massachusetts General Hospital AF Study and 443 referents from the Framingham Heart Study. We used site-directed mutagenesis, cellular electrophysiology, immunocytochemistry, and confocal microscopy to functionally characterize novel variants.We found the frequency of novel coding HCN4 variants was 2-fold greater for individuals with AF (7 variants) compared to the referents (3 variants). We determined that of the 7 novel HCN4 variants in our AF cases, 1 (p.Pro257Ser, located in the amino-terminus adjacent to the first transmembrane spanning domain) did not traffic to cell membrane, whereas the remaining 6 were not functionally different from wild type. In addition, the 3 novel variants in our referents did not alter function compared to wild-type. Coexpression studies showed that the p.Pro257Ser mutant channel failed to colocalize with the wild-type HCN4 channel on the cell membrane.Our findings are consistent with HCN4 haploinsufficiency as the likely mechanism for early-onset AF in the p.Pro257Ser carrier.

SUBMITTER: Macri V

PROVIDER: S-EPMC4130372 | biostudies-literature | 2014 Jun

REPOSITORIES: biostudies-literature

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A novel trafficking-defective HCN4 mutation is associated with early-onset atrial fibrillation.

Macri Vincenzo V Mahida Saagar N SN Zhang Michael L ML Sinner Moritz F MF Dolmatova Elena V EV Tucker Nathan R NR McLellan Micheal M Shea Marisa A MA Milan David J DJ Lunetta Kathryn L KL Benjamin Emelia J EJ Ellinor Patrick T PT

Heart rhythm 20140304 6

<h4>Background</h4>Atrial fibrillation (AF) is the most common arrhythmia, and a recent genome-wide association study identified the hyperpolarization-activated cyclic nucleotide-gated channel 4 (HCN4) as a novel AF susceptibility locus. HCN4 encodes for the cardiac pacemaker channel, and HCN4 mutations are associated with familial sinus bradycardia and AF.<h4>Objective</h4>The purpose of this study was to determine whether novel variants in the coding region of HCN4 contribute to the susceptibi ...[more]

PMID: 24607718

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Project description:Importance:Atrial fibrillation (AF) is the most common arrhythmia affecting 1% of the population. Young individuals with AF have a strong genetic association with the disease, but the mechanisms remain incompletely understood. Objective:To perform large-scale whole-genome sequencing to identify genetic variants related to AF. Design, Setting, and Participants:The National Heart, Lung, and Blood Institute's Trans-Omics for Precision Medicine Program includes longitudinal and cohort studies that underwent high-depth whole-genome sequencing between 2014 and 2017 in 18?526 individuals from the United States, Mexico, Puerto Rico, Costa Rica, Barbados, and Samoa. This case-control study included 2781 patients with early-onset AF from 9 studies and identified 4959 controls of European ancestry from the remaining participants. Results were replicated in the UK Biobank (346?546 participants) and the MyCode Study (42?782 participants). Exposures:Loss-of-function (LOF) variants in genes at AF loci and common genetic variation across the whole genome. Main Outcomes and Measures:Early-onset AF (defined as AF onset in persons <66 years of age). Due to multiple testing, the significance threshold for the rare variant analysis was P?=?4.55?×?10-3. Results:Among 2781 participants with early-onset AF (the case group), 72.1% were men, and the mean (SD) age of AF onset was 48.7 (10.2) years. Participants underwent whole-genome sequencing at a mean depth of 37.8 fold and mean genome coverage of 99.1%. At least 1 LOF variant in TTN, the gene encoding the sarcomeric protein titin, was present in 2.1% of case participants compared with 1.1% in control participants (odds ratio [OR], 1.76 [95% CI, 1.04-2.97]). The proportion of individuals with early-onset AF who carried a LOF variant in TTN increased with an earlier age of AF onset (P value for trend, 4.92?×?10-4), and 6.5% of individuals with AF onset prior to age 30 carried a TTN LOF variant (OR, 5.94 [95% CI, 2.64-13.35]; P?=?1.65?×?10-5). The association between TTN LOF variants and AF was replicated in an independent study of 1582 patients with early-onset AF (cases) and 41?200 control participants (OR, 2.16 [95% CI, 1.19-3.92]; P?=?.01). Conclusions and Relevance:In a case-control study, there was a statistically significant association between an LOF variant in the TTN gene and early-onset AF, with the variant present in a small percentage of participants with early-onset AF (the case group). Further research is necessary to understand whether this is a causal relationship.

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A novel trafficking-defective HCN4 mutation is associated with early-onset atrial fibrillation.

Publications

A novel trafficking-defective HCN4 mutation is associated with early-onset atrial fibrillation.

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