FXN and Friedreich ataxia: Actually, several FA mouse models have been generated, which can be classified into four main categories: 1) tissue specific KOs, which present a total loss of frataxin in some tissues; 2) GAA-repeat mice models, which harbor a GAA expansion in the frataxin gene; 3) an inducible mutant, in which frataxin expression is repressed by a shRNA transgene placed under the control of a TET promoter (doxycycline-inducible) [45]; 4) point mutation models, in which mouse frataxin has been genetically modified by CRISPR to present a pathological point mutation.