China Post-approval Commitment (PAC) Study of Avalglucosidase Alfa in Participants With IOPD

Inclusion Criteria: * Participant must be \<18 years of age, at the time of signing the informed consent. * Participants have documented onset of Pompe disease symptoms before 12 months of age (corrected for gestation if born before 40 weeks); and diagnosis of IOPD is confirmed by GAA enzyme deficiency from any tissue source and GAA gene pathogenic mutations. * Participants must have documented cardiomyopathy at the time of diagnosis. * Contraceptive use should be consistent with local regulations Participant's parent/legally authorized representative (LAR) must be capable of giving signed informed consent. Exclusion Criteria: Participants are excluded from the study if any of the following criteria apply: * Participants with major congenital abnormality that, in the opinion of the Investigator, would preclude participation in the study or potentially decrease survival. * Participants with clinically significant organic disease (with the exception of symptoms relating to Pompe disease). * Participants who have received an ERT other than alglucosidase alfa or avalglucosidase alfa, or any other treatment for Pompe disease, including gene therapy prior to the enrollment. * Participants who have received alglucosidase alfa or avalglucosidase alfa less than 1 week prior to the first dose of avalglucosidase alfa given as IMP Participants who are anticipated to take prohibited therapy (ie, any other treatment for Pompe disease) during this study. * Participants who have taken other investigational drugs (not Pompe disease specific) within 30 days or 5 elimination half-lives in blood of that drug before enrollment, whichever is longer, or are anticipated to take any other concurrent investigational treatments. * Participants not suitable for participation, whatever the reason, as judged by the Investigator, including medical or clinical conditions, or participants potentially at risk of noncompliance to study procedures.