FXN and Friedreich ataxia: This is further potentiated by secondary deficiency of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC1α) that impairs mitochondrial biogenesis.7,8 However, despite notable progress in understanding frataxin function and FRDA pathogenesis, the reasons why most cells do not seem to be functionally impaired by the low frataxin levels found in FRDA patients, while other cell types are vulnerable, are not yet understood.