A relevant finding described herein is that the expression of a recombinant Nqo15 in FRDA patient’s cells led to an increase of the oxygen consumption rate (Fig. 6B, C), that, based on the structural similarity between frataxin and Nqo15, could indirectly suggest a functional interaction of human frataxin with the mitochondrial respiratory complex I. Of note, we found a significant decrease of the NDUFS1 subunit, the homologue of T. thermophilus Nqo3 which faces Nqo15 (Fig. 6A), in all FRDA patients’ cells used in this work (Fig. 5 and Supplementary Fig. 5). This evidence concerns the gene NDUFS1 and Friedreich ataxia.