CALM1 and catecholaminergic polymorphic ventricular tachycardia: CaM mutations associated with the CPVT phenotype are generally characterized by a relatively small impairment of C-lobe Ca2+ binding (e.g., CALM1-p.N98S, CALM1-p.N54I, and CALM3-p.A103V) (84, 85), which (as shown for CALM3-p.A103V) (85) corresponds to a minor effect on ICaL CDI.