FXN and Friedreich ataxia: We used LVs containing the SFFV promoter not only to determine whether LVs could correct FRDA at the molecular level, but also to investigate the effect of high-level FXN expression on cells, which has been previously reported to be cytotoxic in a Drosophila model of FRDA.18 In this Drosophila model, high FXN expression was shown to reduce life span, impair locomotor ability, cause brain damage and even reduced aconitase activity.