Evaluation of the Safety and Efficacy of Infantile-onset Pompe Disease Gene Therapy Drug

Inclusion Criteria: * Age \< 6 months * Patient has diagnosis of infantile onset Pompe disease * The patient's legal guardian(s) must be able to understand the purpose and risks of the study and voluntarily provide signed and dated informed consent prior to any study-related procedures being performed. Exclusion Criteria: * Left ventricle ejection fraction (LVEF) \< 40%; * Patient who has AAV9 neutralizing antibody titer ≥ 1:100； * Patient who has received enzyme replacement therapy (ERT) more than twice; * Patient who has respiratory dysfunction before enrollment, including the blood oxygen (O2) saturation level \< 90%, or the partial pressure of carbon dioxide (PCO2) in venous blood \> 55 mmHg, or PCO2 in arterial blood \> 40 mmHg; * Patient who has laboratory abnormalities of: creatinine \> Upper Limit of Normal (ULN), hemoglobin \< 90 g/L; * Patient with congenital organ absence; * Patient with a history of glucocorticoid allergy; * Patient who is positive for human immunodeficiency (HIV) antibody, hepatitis B surface antigen, hepatitis C antibody, or treponema pallidum antibody; * Patient who has participated in a previous gene therapy research trial; * Patient who has any concurrent clinically significant major disease or any other condition that, in the opinion of the investigator, makes the subject unsuitable for participation in the study.