FXN and Friedreich ataxia: In addition, the number of frataxin-positive large principal neurons is moderately but significantly reduced in the DN of mitoDendra-KIKO mice (Fig. 8J-L) compared with control mice at P90 (Fig. 8G-I,M, P<0.05), matching the atrophy of large principal neurons in the DN observed in FRDA patients (Koeppen et al., 2011a, 2015).