Reduced levels of frataxin in FRDA patients are associated with defects of iron-sulfur cluster (ISC) biosynthesis (Bradley et al., 2000), mitochondrial iron accumulation in heart and dentate nucleus (Foury and Cazzalini, 1997; Waldvogel et al., 1999; Koeppen et al., 2007), and increased susceptibility to oxidative stress (Wong et al., 1999). Here, FXN is linked to Friedreich ataxia.