Study of Recombinant Human N-Acetylgalactosamine 4-Sulfatase in Patients With MPS VI

Inclusion Criteria: * Patient consent * Patient must be five years of age or older * Patient must have documented diagnosis of MPS VI, confirmed at screening by measurable clinical signs and symptoms of MPS VI * Leukocyte ASB enzyme activity level less than 20% of the normal range * Clinical evidence of significant MPS VI disease that provides adequate opportunity to achieve quantitative, short-term therapeutic benefit in three or more of the following parameters: endurance (as measured by a six-minute walk test), forced vital capacity (as measured by spirometry), joint range of motion, urinary glycosaminoglycans, and hepatomegaly. * Ability to perform all protocol tests * Ability to stand independently for six minutes * Sexually active subjects must agree to use an adequate form of contraception Exclusion Criteria: * History of bone marrow transplantation * Pregnant or lactating patient * Use of an investigational drug or device within 30 days prior to study participation. * A medical condition, serious intercurrent illness, or other extenuating circumstances that may significantly decrease study compliance including prescribed follow-up * Known hypersensitivity to rhASB or to components of the study drug * History of cancer (except low grade and fully resolved skin malignancy)