During the last decade, various clinical and genetic studies have reported over 30 CaM missense mutations in the three CaM genes, which were found in individuals with severe arrhythmogenic disorders, such as catecholaminergic polymorphic ventricular tachycardia (CPVT), long QT syndrome (LQTS), idiopathic ventricular fibrillation (IVF) and early onset sudden cardiac death [23,24,25,26,27,28]. Here, CALM2 is linked to paroxysmal familial ventricular fibrillation.