Although this metabolite, commonly known as psychosine, contributes to the neuropathology of Krabbe disease (6,7,61), as demonstrated by interbreeding twi mice with a strain genetically engineered with Asah1 deficiency, or by administration of carmofur (an inhibitor of psychosine biosynthesis), these measures did not completely correct the neurological phenotype, nor did they fully restore survival in mutant animals (8). This evidence concerns the gene ASAH1 and Krabbe disease.