Loss of FXN has been reported to cause various ETC and respiratory defects in different animal models, including yeast, fly, mouse, as well as FRDA patients (Al-Mahdawi et al., 2006; Anderson et al., 2005; Carletti et al., 2014; Koutnikova et al., 1997; Puccio et al., 2001; Rotig et al., 1997; Wilson and Roof, 1997). Here, FXN is linked to Friedreich ataxia.