Arylsulfatase A (ARSA) is a lysosomal enzyme that breaks down Cerebroside 3-Sulfate, a major constituent of the myelin sheet, into Cerebroside and Sulfate. The ARSA deficiency results in Metachromatic Leukodystrophy (MLD), a lysosomal storage disease in the central and peripheral nervous systems with severe and progressive neurological symptoms. Recombinant Human ARSA corresponds to the ARSA mature peptide and has sulfatase activity.