Barth Syndrome
Subjects will be randomized (1:1) to subcutaneous (SC) injections of either elamipretide or placebo for up to 72 weeks of treatment by a central randomization. Trial personnel, Sponsor, CRO and trial subjects will be masked to treatment throughout the study.
1. Willing and able to provide signed informed consent form (ICF) prior to participation in any trial-related procedures. If applicable, informed consent in writing from parent(s) or legally acceptable representative(s) and, informed assent from subject (if age appropriate according to local requirements) should be provided. 2. Agrees to adhere to the trial requirements for the length of the trial. 3. Must have genetically confirmed Barth syndrome (pathogenic variant in the TAZ gene). 4. Male aged ≥5 years at time of the Screening Visit. 5. Left Ventricular Ejection fraction of ≥50% by 3D Echocardiogram at the Screening Visit. 6. Able to administer IMP or have an appropriate designee who can administer the IMP (i.e., a capable family member or a caregiver). 7. Subjects with female partners of childbearing potential must be willing to use a highly effective method of contraception (e.g., abstinence, dual method of contraception) from the date they sign the ICF until 28 days after the last dose of IMP.
1. Unable to perform the 6MWT, 3TUG, or 5XSST functional tests or undergo echocardiography. 2. Any disease or medical condition that in the opinion of the Investigator would prevent the subject from successfully participating in the trial and reliably completing the assessments or might confound trial results. 3. Participation in other investigational drug or device clinical trials within 30 days or 5 half-lives (whichever is longer) of Screening; or is currently enrolled in a non-interventional