Natural History Study Protocol in 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 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. No randomization will be performed.

Since no new therapy is offered as part of this study and no change in the patients' routine
therapy is dictated by this protocol, only Serious Adverse Events potentially related to a
procedure specifically requested (if any) by this natural history study will need to be
reported to the Sponsor. However, all non-serious adverse events will be recorded in the
natural history (observational) study CRF database, in order to be considered as a reference
for the planned clinical trial to occur later on under a separate protocol.

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)

- Plan to use investigational drug during study participation

- Blood loss of >250 mL or donated blood within 56 days, or donated plasma within 7
days, of study screening