Observational Study for Subjects With Pompe Disease Undergoing Immune Modulation Therapies

The purpose of this research study is to determine the effect(s) of medications that alter
the immune system on anti-rhGAA immune response in Pompe patients receiving rhGAA enzyme
replacement therapy (ERT). The investigators would also like to determine whether treating
Pompe Disease with medications that affect the immune system has any effects on the overall
health or disease progression of Pompe.

Subjects will be patients between the ages of 0 months and 65 years who have been diagnosed
with Pompe Disease, confirmed by mutational analysis and/or GAA enzyme activity assay.

Subjects will be eligible regardless of whether they have begun enzyme replacement therapy
prior to enrollment. All Subjects will receive enzyme replacement therapy as standard of care
during the course of the Study, although they may not have begun ERT treatment at the time of
enrollment. In addition to ERT, subjects may receive an immunomodulatory regimen as part of
their standard of care; this may include rituximab, sirolimus, methotrexate, IVIg or other
immunomodulatory agents such as pharmacological chaperone N-butyldeoxynojirimycin (NB-DNJ),
alone or in combination, at the discretion of their caregiver(s).

Inclusion Criteria:

- patients between the ages of 0 months and 65 years

- diagnosed with early-onset Pompe Disease, confirmed by mutational analysis and/or GAA
enzyme assay

- eligible regardless of whether they have begun enzyme replacement therapy prior to
enrollment

- all subjects will receive ERT as standard of care during the course of the study,
although they may not have begun ERT treatment at the time of enrollment

- subjects may receive an immunomodulatory regimen as part of their standard of care;
this may include rituximab, sirolimus, methotrexate, Gamunex, Hizentra, Zavesca or
other immunomodulatory agents, alone or in combination, at the discretion of their
caregiver(s)

Exclusion Criteria:

- subject is unable to meet the study requirements

- subjects medical condition contraindicates participation or Study Investigators feel
that participation is otherwise not in the subject's best interest

- subject does not receive ERT treatment