RYR2 and hydrops fetalis: Recent advances in resolving the structure of RyR2 in HF at a high resolution [45,238,239,240,241] using single-particle cryogenic-electron microscopy (cryo-EM) would be the perfect tool for solving the complete structure of RyR at an atomic resolution in order to clarify the architecture of multiple functional states, ligand-binding sites, and gating mechanisms, including RyR2 abnormalities, during HF.