A Long-term Observational Study Evaluating Eteplirsen, Golodirsen, or Casimersen in Routine Clinical Practice

Key Inclusion Criteria: * Is willing to provide informed assent or consent (if applicable) and has a parent(s) or legal guardian(s) or is a participant ≥18 years of age who is (are) willing to provide informed consent for the participant to participate in the study and comply with study data collection procedures. * Has an established clinical diagnosis of DMD, as documented prior to screening by a genetic report. * Receiving, or initiating treatment with, eteplirsen, golodirsen, or casimersen at the time of observational study enrollment. Note: Participants with a prescription for eteplirsen, golodirsen, or casimersen at enrollment must initiate the exon-skipping therapy within 6 months of the date of enrollment or will no longer be eligible for this study. Note: Enrollment of eteplirsen participants has been completed, no additional participants will be enrolled. Key Exclusion Criteria: * Is currently participating in any DMD interventional study at the time of this study enrollment. * Has declined to provide consent for collection of their genetic data. * Has a medical condition or confounding circumstances that, in the opinion of the Investigator, might compromise: 1. The participant's ability to comply with the protocol-required procedures 2. The participant's wellbeing or safety, and/or 3. The clinical interpretability of the data collected from the participant. Other inclusion/exclusion criteria may apply.