In summary, we identified 19 genes (LAMA5, ITGB4, ITGA3, THBS1, NOG, ACVR1B, INHBA, TGFβ2, BMP2, BMP5, WNT10A, SOX2, WNT16, WNT14, WNT5A, PTCH1, PTCH2, SHH, and FZD1) that play a key role in Stage A of HF development. This evidence concerns the gene SOX2 and hydrops fetalis.