Interestingly Asn146 from FXN (human numbering), which is a Van der Waals distance of Trp155 and mutated to Lys in FRDA patients, is also highly conserved, all the eukaryotic frataxins, with the exception of Naegleria and Trichomonas that present Ser, contains an Asn residue at this position, whereas Bacteria show Asn/Ser (polar non charged small side chain). Here, FXN is linked to Friedreich ataxia.