FXN and Leber hereditary optic neuropathy: Many of those compounds are already adopted in clinical trials, such as DMF that is used for the treatment of relapsing multiple sclerosis (Tecfidera, Biogen-Idec) [18,19,20], EPI-743 evaluated in mitochondrial diseases [25,27,28], idebenone, in treating Leber hereditary optic neuropathy (LHON) [29,30] and in FRDA [31,32], and NAC showing protective effects in frataxin-deficient cell types and in ethylmalonic encephalopathy [33,34].