RYR2 and catecholaminergic polymorphic ventricular tachycardia 1: In assessing four different hypotheses to explain the mechanisms of the RyR2 mutation and CPVT1, we have seen that the modulation of the RyR2 open probability is greatly influenced by the RyR2 mutation affecting its response towards the cytosolic Ca2+ sensitivity and luminal Ca2+ dependency.