Study of UX003 Recombinant Human Beta-Glucuronidase (rhGUS) Enzyme Replacement Treatment in Mucopolysaccharidosis Type 7, Sly Syndrome (MPS 7) Patients Less Than 5 Years of Age

Inclusion Criteria

• Confirmed diagnosis of MPS 7 based on leukocyte or fibroblast glucuronidase enzyme assay, or genetic testing.
• Under 5 years of age at the time of informed consent.
• Written informed consent of Legally Authorized Representative after the nature of the study has been explained, and prior to any research-related procedures.

Exclusion Criteria

• Undergone a successful bone marrow or stem cell transplant or has evidence of any degree of detectable chimaerism with donor cells.
• Any known hypersensitivity to rhGUS or its excipients that, in the judgment of the Investigator, places the subject at increased risk for adverse effects.
• Use of any investigational product (drug or device or combination) other than UX003 within 30 days prior to Screening, or requirement for any investigational agent prior to completion of all scheduled study assessments at any time during the study.
• Has a condition of such severity and acuity, in the opinion of the Investigator, which may not allow safe study participation. For patients with hydrops fetalis, the ongoing interventions to manage fluid balance can be continued; if the addition of enzyme replacement therapy (ERT) is considered a fluid-overload risk, the individual should be excluded.
• Has a concurrent disease or condition that, in the view of the Investigator, places the subject at high risk of poor treatment compliance or of not completing the study, or would interfere with study participation or affect safety. Since hydropic patients have a high rate of mortality, the risk of death prior to 1 year of age should not be considered sufficient to exclude the patient from the study for compliance.