Excess ceramide has been implicated in liver inflammation and steatosis, potentially by enhancing endoplasmic reticulum stress, lipid uptake, and triglyceride production in the liver.35–39 Both pro- and anti-proliferative functions of ceramide have been reported, explained in part by contextual differences of cell type, subcellular localization, and fatty-acid chain length.40–43 The contribution of Smpd3 and ceramide to liver cell proliferation in the context of WD-induced steatosis remains unclear. Here, SMPD3 is linked to Wilson disease.