FXN and Friedreich ataxia: LV expressing human FXN (hFXN) under CMV (human immediate-early cytomegalovirus) promoter and HSV-1 carrying full genomic DNA of FXN, with its endogenous promoter, enhancer elements and introns, have shown therapeutic benefits in human fibroblasts derived from FRDA patients, resulting in the partial or complete restoration of the normal cellular phenotype in response to oxidative stress (Fleming et al., 2005; Gomez-Sebastian et al., 2007).