Heart disease in Friedreich’s ataxia

Figure 1 Postulated functions of frataxin. (1) Frataxin is a general iron chaperone that provides Fe²⁺ to ferrochelatase (FCH) for heme biosynthesis, mitochondrial iron-sulfur (Fe-S) cluster biogenesis, and maintenance of the mitochondrial aconitase (Ac) Fe-S cluster; (2) Frataxin may directly interact with respiratory chain complexes (I-V); (3) Frataxin prevents oxidative stress, protects mitochondrial proteins and mitochondrial DNA (mtDNA) from free Fe²⁺, and prevents the Fenton reaction by converting Fe²⁺ to Fe³⁺, thereby blocking hydroxyl radical formation. ADP: Adenosine diphosphate; ATP: Adenosine triphosphate; cyt c: Cytochrome c; e⁻: Electron; SOD: Superoxide dismutase; FXN: Frataxin.