ATP1A1 and hydrops fetalis: Seventy-nine proteins were found commonly DE between the donor and HF groups in the LV vs RV analyses, however, 4 were expressed in opposite directions such as ATPase Na+/K+ transporting Subunit alpha 1 (ATP1A1, FC = 0.323, FDR = 6.79 × 10−3), which was up-regulated in HF LV (Fig. 4b, c, Supplementary Data 8).