FXN and Friedreich ataxia: Because it is difficult to obtain patient neurons, FRDA fibroblasts have been shown to be useful to study FRDA and to test treatments that reduce oxidative stress, prevent or reverse FXN methylation and improve cell viability.21, 22, 23 In this study, we used FRDA patient and YG8sR mouse model fibroblasts for gene transfer of pHR'SIN-cPPT-SFFV-FXN-WPRE frataxin and the pHR'SIN-cPPT-SFFV-eGFP-WPRE eGFP reporter carrying LVs, which achieved a virus copy number of around 1 and virtually 100% infection of human and mouse FRDA fibroblasts.