Safety and Efficacy Study of EPI-743 in Children With Leigh Syndrome

Inclusion Criteria:

   - Clinical and MRI diagnosis of Leigh syndrome

   - Moderate disease severity based on NPMDS score

   - Age under 18 years

   - Documented evidence of disease progression within 12 month of enrollment

   - Availability of MRI that confirms necrotizing encephalopathy

   - Patient or guardian able to consent and comply with protocol requirements

   - Abstention from Coenzyme Q10, Vitamins C & E, lipoic acid and Idebenone

Exclusion Criteria:

   - Allergy to EPI-743, Vitamin E or sesame oil

   - History of bleeding abnormalities or abnormal PT/PTT

   - Diagnosis of concurrent inborn error of metabolism

   - Previous tracheostomy

   - Ventilator dependent or use of noninvasive ventilatory support w/in 1 month of
   enrollment

   - LFTs greater than 2 times ULN

   - Renal insufficiency

   - End stage cardiac failure

   - Fat malabsorption syndrome

   - Use of anticoagulant medications

   - Abstention from Botox for 6 months prior to enrollment and for duration of study