Genetic associations with cardiac chamber-specific traits have recently been studied, including titin (TTN) and BCL2-associated athanogene 3 (BAG3) variants influencing left ventricular volumes and systolic function, while atrial volumes are associated with Ankyrin Repeat Domain 1 (ANKRD1) and myosin light chain 4 (MYL4) variants that also predispose to AF and cardiomyopathies.9 This evidence concerns the gene MYL4 and atrial fibrillation.