Japanese Leigh syndrome case treated with EPI-743

Abstract Background Leigh syndrome is a mitochondrial disease caused by respiratory chain deficiency, and there are no proven effective therapies. EPI-743 is a potent cellular oxidative stress protectant and results of clinical trials for mitochondrial diseases are accumulating. Case At 5 months, a girl presented with the scarce eye movement and diminished muscle tone. She was diagnosed with Leigh encephalopathy from blood and cerebrospinal fluid lactate elevation and MRI findings. Sequence analysis for mitochondrial DNA revealed a T10158C mutation in the mitochondrial encoded ND3 gene in complex I. Results At 8 months, succinate was prescribed expected to restore the electron transport chain system. After that her condition got worse and succinate was discontinued. Subsequent administration of EPI-743 improved her eye movement, fine motor movements of the extremities, and bowel movement. She is now 5 years old. Although brain atrophy has progressed, she has still respiratory free time. Conclusion Our patient showed visible improvement with EPI-743 treatment and the only patient surviving after 4 years. There is a possibility that EPI-743 is modifying the natural course of the syndrome.