S100A9 and hydrops fetalis: Zhang et al. identified six hub genes (BCL3, HCK, PPIF, S100A9, SERPINA1, and TBC1D9B) as potential biomarkers of HF by using the weighted gene co-expression network analysis (WGCNA) method through three HF datasets, namely, GSE59867, GSE1869, and GSE42955 (38).