CALM variant carriers in this registry present with cardiac arrhythmia phenotypes including LQTS (49%), CPVT (28%), overlap LQTS/CPVT (4%), and a few cases of IVF, sudden unexplained death (SUD), or atypical phenotypes (Crotti et al., 2019). This evidence concerns the gene CALM2 and catecholaminergic polymorphic ventricular tachycardia.