Long Term Follow-up for RGX-202

Inclusion Criteria: * The parent(s) or legal guardian(s) of the participant has/(have) provided written informed consent and (where applicable) Health Insurance Portability and Accountability Act (HIPAA) authorization after the nature of the study has been explained, prior to any research-related procedures; and, where applicable, the minor participant has provided written or verbal assent according to local requirements. * Must have undergone evaluation in a previous clinical study following a single IV infusion of RGX-202 for the treatment of DMD and either completed or withdrawn early from that study. * Participant and parent(s)/legal guardian(s) are willing and able to comply with scheduled visits, and study procedures. * Sexually active participants must be willing to use a medically accepted method of contraception from the time of the screening visit through 5 years after RGX-202 administration. Exclusion Criteria: * No exclusion criteria apply in this observational follow up study.