An Intermediate Size Expanded Access Protocol of Elamipretide

Key Inclusion Criteria: 1. ≥1 year and ≤ 80 years of age or ≥12 years for Barth Syndrome in SPIES-007 2. Patients with genetically confirmed rare primary mitochondrial diseases including Barth Syndrome 1. observed cardiomyopathy, renal impairment, neuropathic, or ophthalmic manifestation 2. where such disease is serious or life-threatening and no comparable or satisfactory alternative therapy options available. 3. Patients without genetic confirmation of a rare disease with known mitochondrial dysfunction but do exhibit serious or life-threatening clinical manifestations of mitochondrial dysfunction. 4. Is self-able or has caregiver willing and able to administer SC injection. 5. Would potentially benefit from treatment with elamipretide and cannot be treated satisfactorily with any approved medicinal product in the opinion of the treating physician. Key Exclusion Criteria: 1. Known hypersensitivity to elamipretide or any excipients. 2. Women who are pregnant, are planning on becoming pregnant, or are breast-feeding. 3. Patients receiving any other investigational agent within 30 days of dosing. 4. Any active, serious psychiatric, medical, or other conditions/situations which, in the treating physician's opinion, could compromise the patient's safety.