RYR2 and hydrops fetalis: According to studies on human cardiac tissue, RyR2 phosphorylation and mutations have been linked to deadly ventricular arrhythmias, atrial fibrillation, malfunction of the SA and AV nodes, atrial stalemate, dilated cardiomyopathy, HF, and sudden cardiac death (Foti et al., 2020; Tester et al., 2020).