The purpose of the study is evaluate the efficacy, safety, and pharmacokinetics of weekly intravenous infusions of 1 mg/kg recombinant human N-acetylgalactosamine 4-sulfatase (rhASB) in patients diagnosed with Mucopolysaccharidosis VI (MPS VI)

Inclusion Criteria:

• Patient consent
• Patient must be five years of age or older
• Patient must have documented biochemical or genetic proof of MPS VI
• Patient must walk at least 1 meter, but less than 250 meters, in the first 6 minutes of the baseline 12-minute walk test
• If female of childbearing potential, patient must have a negative pregnancy test

Exclusion Criteria:

• Patient is under consideration for or has undergone a successful bone marrow transplant (BMT).
• Pregnant or lactating patient
• Patient has received an investigational drug within 30 days prior to study enrollment
• Patient has been previously treated with rhASB
• Patient has a medical condition, serious intercurrent illness, or other extenuating circumstance that may significantly confound study results or decrease study compliance
• Patient has a known hypersensitivity to rhASB or to components of the study drug
• History of cancer (except low grade and fully resolved skin malignancy)