A Phase 3 Study of UX003 Recombinant Human Betaglucuronidase (rhGUS) Enzyme Replacement Therapy in Patients With Mucopolysaccharidosis Type 7 (MPS 7)

Inclusion Criteria:

- Confirmed diagnosis of MPS 7 based on leukocyte or fibroblast glucuronidase enzyme
assay or genetic testing.

- Elevated urinary glycosaminoglycan (uGAG) excretion at a minimum of 3-fold over the
mean normal for age (at Screening).

- Apparent clinical signs of lysosomal storage disease as judged by the Investigator,
including at least one of the following: enlarged liver and spleen, joint limitations,
airway obstruction or pulmonary problems, limitation of mobility while still
ambulatory.

- Aged 5 - 35 years, inclusive.

- Willing and able to provide written informed consent, or in the case of subjects under
the age of 18 (or 16 years, depending on the region), provide written assent (if
required) and written informed consent by a legally authorized representative after
the nature of the study has been explained, and prior to any research-related
procedures.

- Sexually active subjects must be willing to use acceptable highly effective methods of
contraception while participating in the study and for 30 days following the last
dose.

- Females of childbearing potential must have a negative pregnancy test at Screening and
be willing to have additional pregnancy tests during the study. Females considered not
of childbearing potential include those who have not experienced menarche, or have had
tubal ligation at least one year prior to Screening, or who have had total
hysterectomy.

- Naïve to treatment with UX003.

Exclusion Criteria:

- Undergone a successful bone marrow or stem cell transplant or has any degree of
detectable chimaerism with donor cells.

- Major surgery within 3 months prior to study entry or planned major surgery during the
study that may not allow safe participation in the study.

- Presence or history of any hypersensitivity to rhGUS or its excipients that, in the
judgment of the Investigator, places the subject at increased risk for adverse
effects.

- Pregnant or breastfeeding at Screening or planning to become pregnant (self or
partner) at any time during the study.

- Use of any investigational product (drug or device or combination) within 30 days
prior to Screening, or requirement for any investigational agent prior to completion
of all scheduled study assessments.

- Presence of a condition of such severity and acuity that, in the opinion of the
Investigator, warrants immediate surgical intervention or other treatment or may not
allow safe participation in the study.

- Concurrent disease or condition, or laboratory abnormality 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 introduce
additional safety concerns.