ATP2A2 and Wilson disease: As the PCR manoeuvre evaluates the release and recapture of Ca2+ by the sarcoplasmic reticulum (SR), this behaviour observed in the WD group can be attributed to impairment in Ca2+ reuptake by SR Ca2+-ATPase (ATP2A2), Ca2+ release by ryanodine receptor (RYR2) or affinity of Ca2 binding in troponin C. The Ca2+ stimulation manoeuvre showed no difference in the systolic functional parameters between the groups (Fig. 1C); this fact suggests that the most probable hypothesis is that the RYR2 function and Ca2+ binding in troponin C are not damaged in the WD group.