The study will evaluate the safety and efficacy of gene transfer therapy in boys with DMD. It is a randomized, double-blind, placebo-controlled study. The participants who are randomized to the placebo arm will have an opportunity for treatment with gene transfer therapy at the beginning of the second year.

This is an open-label single-dose gene transfer therapy study evaluating the safety of SRP-9001 (delandistrogene moxeparvovec) intravenous (IV) administration in boys with DMD. This study will consist of 2 Cohorts. Cohort A will include participants ages 3 months to 3 years, and Cohort B will include participants ages 4 to 7 years old. All participants in the study will receive IV SRP-9001.

The purpose of this study is to evaluate the safety and efficacy of exogenous gene transfer in DMD patients by measuring biological and clinical endpoints in three parts: two 48-week randomized, double-blinded, placebo-controlled periods (Part 1 and Part 2), and an open-label follow-up period (Part 3). Patients who are randomized to placebo in Part 1 will have the opportunity for treatment with SRP-9001 (delandistrogene moxeparvovec) in Part 2.

This study will follow patients who are screened and confirmed with a genetic diagnosis of Limb-girdle muscular dystrophy type 2E (LGMD2E/R4), Limb-girdle muscular dystrophy type 2D (LGMD2D/R3), or Limb-girdle muscular dystrophy type 2C (LGMD2C/R5). These enrolled patients will be followed to evaluate mobility and pulmonary function for up to 3 years after enrollment. Additional patient data will be collected from the time the individual began experiencing LGMD symptoms to the present.

This study will be comprised of 2 parts: Part 1 (dose escalation) will be conducted to evaluate the safety and tolerability of 2 doses (100 milligrams/kilogram [mg/kg] and 200 mg/kg) of eteplirsen in approximately 10 participants with DMD; Part 2 (dose finding and dose comparison) will be conducted for the selection of a high dose (100 mg/kg versus 200 mg/kg) and its comparison with the 30 mg/kg dose of eteplirsen, in approximately 144 participants with genetically confirmed deletion mutations amenable to treatment by skipping exon 51.

The main objective of this study is to evaluate the safety and tolerability of long-term treatment with casimersen or golodirsen in patients with Duchenne muscular dystrophy (DMD).

The proposed clinical trial is the first-in-human, single-center, open-label, gene delivery study of SRP-9003 (bidridistrogene xeboparvovec) in participants with LGMD2E.

The main objective of this study is to evaluate the efficacy of SRP-4045 (casimersen) and SRP-4053 (golodirsen) compared to placebo in participants with DMD with out-of-frame deletion mutations amenable to skipping exon 45 and exon 53, respectively.

This study will be comprised of 2 parts: 1) Part A (Multiple Ascending Dose [MAD]) will be conducted to evaluate the safety and tolerability of SRP-5051 (vesleteplirsen) at MAD levels to determine doses to be administered in Part B, and 2) Part B will be conducted to further evaluate the SRP-5051 doses selected in Part A. Participants enrolling in Part B will be those who completed Part A or Study 5051-102 and meet applicable eligibility criteria for Part B, as well as additional participants who meet applicable eligibility criteria for enrollment at the beginning of Part B.