RYR2 and hydrops fetalis: The data presented here indicate an overall reduction in the density of RyR within IDCM cardiac myocytes and may contribute to the reduced Ca2+ release as previously documented in myocytes from the failing human heart (Beuckelmann et al., 1992) and should be considered alongside the well-documented defects in sarcoplasmic reticulum Ca2+ ATPase SERCA expression in HF (Lipskaia et al., 2010).