The mean concentrations (± SD) of total frataxin in healthy controls and homozygous FRDA cases in blood samples taken at year-1 were significantly different (p < 0.001) at 34.2 ± 4.2 ng/mL and 6.8 ± 4.0 ng/mL, respectively (Figure 4C). This evidence concerns the gene FXN and Friedreich ataxia.