RYR2 and paroxysmal familial ventricular fibrillation: Naturally occurring mutations in the cardiac ryanodine receptor (RyR2) have been linked various cardiac arrhythmias, such as catecholaminergic polymorphic ventricular tachycardia (CPVT), idiopathic ventricular fibrillation, and atrial fibrillation, and structural heart diseases, such as dilated, hypertrophic, and non-compaction cardiomyopathies [2–5].