PSAP is a highly conserved preprotein that is proteolytically processed to generate saposins A, B, C, and D that catabolize sphingoglycolipids in the lysosomal compartment Mutations in this gene have been associated with Gaucher disease [28] and Metachromatic leukodystrophy [29]. The gene discussed is PSAP; the disease is metachromatic leukodystrophy.