A Study to Understand the Long-term Safety and Effects of an Experimental Gene Therapy for Duchenne Muscular Dystrophy.

Long-term Follow-up Safety and Efficacy Study in Participants With Duchenne Muscular Dystrophy Who Have Received Fordadistrogene Movaparvovec in a Preceding Clinical Study

The purpose of this study is to understand the safety and effects of an experimental gene therapy called fordadistrogene movaparvovec. We are seeking participants from previous Pfizer interventional studies. We will follow participants' experience in this study for 10 years after the end of their previous study. Participants will have 1 annual onsite visit and a few annual remote visits. The exact number of remote visits will be decided by their study doctor.

Inclusion Criteria:

• Participants who received fordadistrogene movaparvovec in a previous Pfizer interventional study.

Exclusion Criteria:

• Investigator site staff directly involved in the study and their family members