Clinical Study for Treatment-naïve IOPD Babies to Evaluate Efficacy and Safety of ERT With Avalglucosidase Alfa

Inclusion Criteria: * Participants must have confirmed diagnosis of infantile-onset Pompe disease defined as: the presence of 2 lysosomal acid α-glucosidase (GAA) pathogenic variants and a documented GAA deficiency from blood, skin, or muscle tissue; or the presence of 1 GAA pathogenic variant and a documented GAA deficiency from blood, skin and muscle tissue in 2 separate samples (from either 2 different tissues or from the same tissue but at 2 different sampling dates). * Participants must have established cross-reactive immunological material (CRIM) status available prior to enrollment. * Participants must have cardiomyopathy at the time of diagnosis: ie, left ventricular mass index (LVMI) equivalent to mean age specific LVMI * +1 standard deviation for participants diagnosed by newborn screening or sibling screening; * +2 standard deviation for participants diagnosed by clinical evaluation. * Parents or legally authorized representative(s) must be capable of giving signed informed consent. Exclusion Criteria: * Participants with symptoms of respiratory insufficiency, including any ventilation use (invasive or noninvasive) at the time of enrollment. * Participants with major congenital abnormality. * Participants with clinically significant organic disease (with the exception of symptoms relating to Pompe disease). * Participant received any Pompe disease specific treatment, eg enzyme-replacement gene therapy (ERT). * Participant who has previously been treated in …