MYL4 and atrial fibrillation: Cardiac structural genes have been associated with arrhythmias like early-onset AF and arrhythmogenic cardiomyopathy, including genes encoding the sarcomere proteins myosin light chain 4 (MYL4) [10,105], titin (TTN) [124], cytoskeletal heart-enriched actin-associated protein CHAP (SYNPO2L) [156], and desmosomal proteins [7,157].