The primary objective of this study is to evaluate the effect of 2.0 mg/kg/week BMN 110 in a patient population that has limited ambulation, in a period of up to 144 weeks.

Effect is defined by the following key domains:

• Upper extremity function and dexterity
• Mobility

Inclusion Criteria:

• Is willing and able to provide written, signed informed consent (or their legally authorized representative) after the nature of the study has been explained and prior to performance of any research-related procedure. Patients who do not meet country and local age requirements for informed consent must be willing and able to provide written assent after the nature of the study has been explained and prior to performance of any research-related procedure.
• Has documented clinical diagnosis of MPS IVA based on clinical signs and symptoms of MPS IVA and documented reduced fibroblast or leukocyte GALNS enzyme activity or genetic testing confirming diagnosis of MPS IVA.
• Is ≥ 5 years of age.
• If sexually active, is willing to use an acceptable method of contraception while participating in the study.
• Females of childbearing potential must have a negative pregnancy test at the Screening Visit and be willing to have additional pregnancy tests during the study.
• Is willing and able to perform all study procedures as physically possible.

Exclusion Criteria:

• Is able to walk farther than a specified distance as assessed by the 6MWT.
• Has previous hematopoietic stem cell transplant (HSCT).
• Has received previous treatment with BMN 110.
• Has a known hypersensitivity to any of the components of BMN 110.
• Has had major surgery within 3 months prior to study entry or is planning to have a major surgery during the first 24 weeks of the study.
• Has used any other investigational product or investigational medical device within 30 days prior to the Screening Visit or requires any investigational agent prior to completion of all scheduled study assessments.
• Is pregnant or breastfeeding at the Screening Visit or planning to become pregnant (self or partner) at any time during the study.
• Has a concurrent disease or condition, including but not limited to symptomatic cervical spine instability or severe cardiac disease or complete paralysis due to a spinal cord injury (defined as an inability to move arms and legs), that would interfere with study participation or safety as determined by the Investigator.
• Has any condition that, in the view of the Investigator, places the patient at high risk of poor treatment compliance or of not completing the study.