Formation of glucosylsphingosine (GlcSph) and Lyso-globotriaosylsphingosine (lyso-GB3) depends on acid ceramidase activity as can be concluded from studies using acid ceramidase deficient Farber Disease fibroblasts, studies with the acid ceramidase inhibitor carmofur (an organohalogen compound that also can trigger the generation of 5-FU, a pyrimidine analogue) and studies using isotope labeled GSL species [23,24]. Here, ASAH1 is linked to Farber lipogranulomatosis.