The demise of RyR2 in both HF and CPVT have been considered jointly in this review, not least because RyR2 dysfunction, resulting in the diastolic leak and arrhythmia (DADs) in both conditions provide important clues to the underlying regulation and channel gating of RyR2 and its relationship to its microdomain environment. The gene discussed is RYR2; the disease is hydrops fetalis.