FXN and Friedreich ataxia: In vivo iPSCs derived from FRDA patients (Ku et al., 2010; Hick et al., 2013) and multiple conditional knockout mice (Pook et al., 2001; Puccio et al., 2001; Simon et al., 2004; Al-Mahdawi et al., 2008) were extensively used to investigate the effects of frataxin depletion.