CaM-associated arrhythmia syndromes, termed calmodulinopathies, have been linked with dysregulation of Cav1.2, RyR2, Kv7.1, and SK channels (2–7); however, to date, only direct dysregulation of the Ca2+-handling machinery has been linked to arrhythmias in vivo (8). This evidence concerns the gene CALM1 and Arrhythmia.