Variants in CALM1-encoded calmodulin, a Ca2+ binding protein, and TRDN-encoded Triadin, a cardiac Ca2+ release complex protein, have also been implicated in atypical CPVT and are associated with 1–2% of CPVT cases [27,28]. This evidence concerns the gene CALM1 and catecholaminergic polymorphic ventricular tachycardia.