A Prospective Study to Observe & Describe Clinical Outcomes of Alglucosidase Alfa Treatment in Patients ≤6 Months of Age With Infantile-onset Pompe Disease (IOPD)

Primary Objective: To describe the effect of routine practice with alglucosidase alfa in patients with IOPD ≤6 months of age, on invasive ventilation-free survival after 52 weeks of treatment. Secondary Objectives: * To describe the effect of routine practice with alglucosidase alfa on invasive ventilation-free survival and survival at 12 and 18 months of age, as well as on change in left ventricular mass (LVM) Z score, Alberta Infant Motor Scale (AIMS) score, body weight, body length, and head circumference Z scores, and urinary glucose tetrasaccharide (Hex4), at Week 52 of treatment. * To describe the safety, tolerability, and immunogenicity of alglucosidase alfa in the routine practice of IOPD treatment.