Study of Long-Term Safety and Efficacy on Gene Therapy in Glycogen Storage Disease Type Ia

Inclusion Criteria: 1. Received DTX401 in study 401GSDIA01. 2. Willing and able to provide written informed consent after the nature of the study has been explained, and prior to any research-related procedures being performed. 3. Willing and able to comply with all scheduled study visits, procedures, and requirements. Exclusion Criteria: 1. Planned or current participation in any other interventional clinical study that may confound the safety or efficacy evaluation of DTX401 during this study. 2. Presence or history of any condition that, in the view of the Investigator, poses a risk to subject safety or places the subject at high risk of poor compliance or not completing the study or that would significantly affect the interpretation of study results.