FGF21 and hydrops fetalis: Interestingly, enrichment analysis highlights GDF15 (HF Beta = −0.41, p = 0.0002) (Figure 4D), and its interaction with other mitokines, including FGF21, which was less abundant in HF compared to NF and LF (HF Beta = −0.534, p = 0.025) (Figure 4E).