The CALM1 N54I mutant (Table 2, and Figure 1), which causes Catecholaminergic Polymorphic Ventricular Tachycardia (CPVT), may interfere with gap junction formation because this residue is in the CaM N-lobe and just precedes the second CaM Ca2+-binding site (EF2, Figure 1; see in the previous). Here, CALM1 is linked to catecholaminergic polymorphic ventricular tachycardia.