FXN and Friedreich ataxia: Delatycki et al. (1999) stated that the expansion of a GAA trinucleotide repeat sequence (TRS) in the first intron of the FXN gene is responsible for approximately 98% of FRDA cases, and the other 2% occurs due to point mutations in the FXN gene. A study on similar lines also indicated that 97% of cases of Friedreich ataxia are linked to GAA triplet repeat expansion (Lodi et al., 1999).