A Long-Term Open-Label Treatment and Extension Study of UX003 rhGUS Enzyme Replacement Therapy in Subjects With MPS 7

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

• Willing and able to provide written, signed 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.

• Willing and able to comply with all study 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 Baseline 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 completion of the primary study, or have had total hysterectomy.

• For UX003 treatment-naïve subjects only, 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.

• For UX003 treatment-naïve subjects only, elevated urinary glycosaminoglycans (uGAG) excretion at a minimum of 2-fold over normal.

• For UX003 treatment-naïve subjects only, aged 5 years and older.