The purpose of the study is to evaluate the safety and efficacy of two dose levels of Naglazyme in infants under the age of one year who have MPS VI by monitoring physical appearance, x-ray of the skeletal system and growth.

The primary objective of the study was to evaluate the efficacy of two dose levels of Naglazyme in preventing the progression of skeletal dysplasia in infants under the age of one year who have MPS VI by monitoring physical appearance, x-ray of the skeletal system and growth.

The secondary objective of the study was to evaluate the efficacy of the two dose levels of Naglazyme in preventing several measures of disease progression in infants under the age of one year who have MPS VI by monitoring urinary GAGs, gross and fine motor function, cardiac function, vision, hearing, and use of health resources.

The safety objective of the study was to evaluate the safety of two dose levels of Naglazyme in infants under the age of one year who have MPS VI.

Inclusion Criteria:

• Signed informed consent by a parent or legal guardian
• Parent or legal guardian willing and able to comply with all study procedures
• Equal to or greater than 36 weeks estimated gestational age by physical exam at birth
• Has a diagnosis of MPS VI based on a documented prenatal diagnosis or fibroblast or leukocyte N-acetylgalactosamine 4-sulfatase (ASB) enzyme activity level of less than 10% of the lower limit of the normal range of the measuring laboratory
• Is less than one year of age
• Has no evidence of skeletal dysplasia based on physical exam

Exclusion Criteria:

• Parent of legal guardian perceived to be unreliable or unavailable for study participation
• Use of any investigational drug within 30 days prior to screening, or requirement for any investigational agent prior to completion of all scheduled study assessments
• Has concurrent disease or condition that would interfere with study participation or safety (i.e., has previously undergone hematopoietic stem cell transplantation such as bone marrow or cord blood transplantation, or major organ transplantation)
• Any condition that, in the view of the principle investigator, renders the subject at high risk from treatment compliance and/or completing the study
• Has known hypersensitivity to Naglazyme
• Has previously received Naglazyme

All patients received weekly infusions of Nagalzyme for a minimum of 52 weeks. The range in time of exposure to Naglazyme for the duration of the study was 52.9 to 153.30 weeks.

Given the small number of patients (4) represented in this study, the outcomes observed in this study may not reflect or predict outcomes observed by physicians in clinical practice.