A similar screening assay was developed for Friedreich’s ataxia (FRDA), which is a common autosomal recessive degenerative disease resulting from a GGA trinucleotide expansion within an intron (Box 2) of a nuclear gene encoding a protein (frataxin) that controls mitochondrial iron homeostasis (Rotig et al., 1997). This evidence concerns the gene FXN and Friedreich ataxia.