ACDase deficiency caused by mutations in ASAH1 leads to Farber disease (FD; OMIM#228000), also known as Farber’s lipogranulomatosis, an ultra-rare lysosomal storage disorder (LSD) in which ceramides and related sphingolipids such as sulfatide and GM3 ganglioside accumulate5,6. The gene discussed is ASAH1; the disease is Erdheim-Chester disease.