ACER3 and hydrops fetalis: In the salvage pathway, we found that ceramidase, alkaline ceramidase 1 (ACER1, −1.70 ± 0.28; p = 0.047), which catalyzes the hydrolysis of ceramide to sphingosine, was downregulated in HF tissue, while alkaline ceramidase 3 (ACER3: 1.19 ± 0.26, p = 0.029) was upregulated in these tissues.