FXN and Friedreich ataxia: Thus, one possibility for the divergent results from FRDAkd mice is that the relatively severe frataxin deficiency or the accelerated rate of decline leads to a greater acute level of neuropathological features in Purkinje cells and climbing fibers than typically noted in FRDA patients or other mouse models (Koeppen et al., 2011; Harding et al., 2020).