Accumulating studies have suggested that canonical signaling cascades, such as WNT/β-catenin, TGF-β/BMP, FGF, Hedgehog, NOTCH, and other factors (SOX9, LHX2, DLX3, GATA3, RUNX1, TP63, MSX2, FOXN1, NFATC1, and TBX1) play important roles in HF development8,18. This evidence concerns the gene SOX9 and hydrops fetalis.