This approach was chosen for two reasons: (i) Farber disease is progressive and early treatment will likely be more efficacious since it can prevent rather than reverse pre-existing disease, and (ii) ACDase is a soluble lysosomal enzyme that can be secreted from the genetically modified cells and taken up by non-transduced cells through a receptor-mediated mechanism. The gene discussed is ASAH1; the disease is Farber lipogranulomatosis.