FXN and Friedreich ataxia: Furthermore, unlike the lethal prenatally models in which frataxin is completely depleted and the neuron-specific knockouts showing a too severe early onset phenotype (Cossée et al., 2000; Simon et al., 2004), KIKO mice display frataxin levels close to patients’ values (20–30% of control levels) (Sahdeo et al., 2014; Lazaropoulos et al., 2015), and neurological signs (i.e., cerebellar gait ataxia, decreased peripheral sensitivity, and motor strength impairment) resembling those occurring in late-onset FRDA patients (McMackin et al., 2017).