KCNN4 and hydrops fetalis: A number of genes related to ion transport were modulated in HF macrophages (e.g., Kcnk6 (coding for the K+ channel efflux TWIK2), Kcnq1, Kcnn4, Cask (calcium/calmoduline dependent serine protein kinase), Eif2ak3 (PERK), Sik1 and Mpp5 (MAGUK)) (Figure 4).