An increase in the occurrence of Ca2+ sparks during diastole has been associated with cardiac dysfunction, especially with the predisposition to arrhythmias [33,34], since the Ca2+ released can induce the activation of adjacent RyR2 producing spontaneous Ca2+ waves capable of provoking automatic ventricular contractions [30,35]. The gene discussed is RYR2; the disease is cardiac arrhythmia.