This multicenter, multinational, longitudinal study will quantify endurance and respiratory function in subjects diagnosed with MPS IVA and will better characterize the spectrum of symptoms and biochemical abnormalities in MPS IVA disease over time.

Inclusion Criteria:

• Willing and able to provide written, signed informed consent, or in the case of subjects age < 18 years, 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.
• Documented history of reduced GALNS activity relative to the normal range of the laboratory performing the assay, or documented result of molecular genetic testing confirming diagnosis of MPS IVA.
• Willing and able to comply with all study procedures.

Exclusion Criteria:

• Use of any investigational product or investigational medical device within 30 days prior to screening.
• Previous hematopoietic stem cell transplant (HSCT).
• Concurrent disease or condition that would interfere with study participation or pose a safety concern.

Subjects diagnosed with MPS IVA