Dysfunction of systolic Ca transport caused by dysfunction of the type 2 ryanodine receptor (RyR2) in the sarcoplasmic reticulum is associated with a variety of heart diseases, including catecholaminergic polymorphic ventricular tachycardia, atrial fibrillation, and HF (Connell et al., 2020). Here, RYR2 is linked to hydrops fetalis.