RYR2 and catecholaminergic polymorphic ventricular tachycardia: We have recently used cryo-EM to show that a PKA-phosphorylated CPVT-related RyR2-R2474S mutant channel adopts a pathological “primed” state which can be readily activated by stress signals resulting in a pathological leak of SR Ca2+ that can trigger arrhythmias10.