Gene-Gene Interactions Between A LMNA Variant and Common Polymorphisms Drive Early-Onset Atrial Fibrillation
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Atrial fibrillation (AF) is a common arrhythmia with a complex genetic basis, yet the molecular mechanisms linking rare and common variants remain unclear. Using induced pluripotent stem cell-derived atrial cardiomyocytes, we uncover a novel mechanism by which a rare pathogenic LMNA variant encoding Lamin A/C disrupts chromatin accessibility and gene regulation at AF-associated loci. Specifically, reduced accessibility at an SCN5A enhancer harboring an AF associated variant leads to reduced sodium current, conduction abnormalities, and re-entrant AF. These electrophysiological defects are rescued by CRISPR-mediated activation of the SCN5A promoter and enhancer, providing the first molecular evidence of epistatic gene-gene interactions driving arrhythmia risk and mechanistically linking atrial myopathy and AF. At the population level, we demonstrate that carriers of LMNA protein-altering variants with a high polygenic risk score are at two-fold increased risk of early-onset AF, highlighting the need to integrate rare and common variants for more accurate AF risk assessment.
