FXN and Friedreich ataxia: These existing transgenic and heterozygous knockout FRDA animal models are either mildly symptomatic or restricted in their ability to recapitulate the spatial and temporal aspects of systemic FRDA pathology when they are engineered as tissue-specific conditional knockouts (Miranda et al., 2002; Al-Mahdawi et al., 2004; Al-Mahdawi et al., 2006; Puccio et al., 2001; Simon et al., 2004; Perdomini et al., 2013).