Exploratory Muscle Biopsy Assessment Study in Patients With Late-Onset Pompe Disease Treated With Alglucosidase Alfa

Inclusion Criteria:

- The patient has confirmed acid α-glucosidase [GAA] enzyme deficiency from any tissue
source and/or confirmed GAA gene mutations and without known cardiac hypertrophy.

- The patient is able to ambulate a distance without stopping and without an assistive
device. Use of assistive device for community ambulation is appropriate.

- The patient has a certain forced vital capacity (FVC) in upright position.

- The patient, if female and of childbearing potential, must have a negative pregnancy
test (urine beta-human chorionic gonadotropin [β-hCG]) at baseline.

Exclusion Criteria:

- The patient has had previous treatment with enzyme replacement therapy (ERT).

- The patient is wheelchair dependent.

- The patient requires invasive-ventilation (non-invasive ventilation is allowed).

- The patient is participating in another clinical study using investigational
treatment.

- The patient cannot submit to magnetic resonance imaging (MRI) examination because of
a formal contraindication such as a pacemaker, implanted ferromagnetic metals, etc.

- The patient, in the opinion of the Investigator, is unable to adhere to the
requirements of the study.