An Observational Study Comparing Delandistrogene Moxeparvovec With Standard of Care in Participants With Duchenne Muscular Dystrophy

Inclusion Criteria:

• Has a definitive diagnosis of DMD prior to Screening based on documentation ofclinical findings and confirmatory genetic testing.

• Is currently receiving or has been prescribed to start chronic glucocorticoidtherapy at the time of this observational study enrollment.

A participant recruited to Cohorts 1a or 2:

• Is at least 4 years of age at the time of enrollment.

• Is ambulatory per protocol specified criteria.

A participant recruited to Cohort 1b:

• Is non-ambulatory per protocol-specified criteria.

For Delandistrogene Moxeparvovec-treated Participants:

• Will be initiating usual care treatment with delandistrogene moxeparvovec at the time of study enrollment.

For Comparators:

• Is unexposed to DMD gene therapy at the time of study enrollment.

Exclusion Criteria:

• Has any deletion of exon 8 and/or exon 9 in the DMD gene.

• Is currently participating in any DMD interventional study at the time of thisobservational study enrollment.

• Has a medical condition or confounding circumstances (for example, prior traumaticlimitation for mobility or significant behavioral comorbidity) that, in the opinionof the Investigator, might compromise:

• The participant's ability to comply with the protocol-required procedures,

• The participant's wellbeing or safety, and/or

• The clinical interpretability of the data collected from the participant.

Other inclusion/exclusion criteria may apply.