Clinical and Basic Investigations into Phosphomannomutase deficiency (PMM2-CDG)

This is a natural history (observational) protocol designed to collect clinical and biological information in patients with PMM2-CDG (CDG-Ia).

Subjects enrolled in this natural history study will be thoroughly examined for signs and symptoms of PMM2-CDG. Medical history, physical examination, laboratory testing and imaging studies will be performed during a single consultation. Follow-up will occur every 3- 6 months at a minimum, depending on the standard of care at the investigator's institution as well as the clinical status of the individual patient. All medical procedures are routine. No new therapy is offered as part of this study, and no change in the patients routine therapy is dictated by this protocol. The International Co-Operative Ataxia Rating Scale (ICARS) is to be performed every 3 months as an optional assessment. No randomization will be performed.

Inclusion Criteria:

• Informed consent/assent by the patient and/or their legally authorized representative
• Confirmed diagnosis of PMM2-CDG, based on enzymatic or molecular tests
• Willing and able to adhere to study requirements described in the protocol and consent/assent documents

Exclusion Criteria:

• Known or suspected differential diagnosis of any other known CDG (not PMM2-CDG)
• Currently using investigational drug
• Blood loss of ≥ 250 mL or donated blood within 56 days, or donated plasma within 7 days before study screening

Patients with PMM2-CDG, all ages