In May 2005, galsulfase (Naglazyme; BioMarin), a recombinant form of human N-acetylgalactosamine 4-sulfatase, was approved by the US FDA for the treatment of patients with mucopolysaccharidosis type VI, a rare lysosomal storage disorder caused by a deficiency of N–acetylgalactosamine 4-sulfatase. It is the first approved product for the treatment of mucopolysaccharidosis type VI, and has been granted orphan drug status.