Finally, somatic instability of the GAA1 allele has been identified in two FRDA patients who have one large GAA2 allele and a small GAA1 allele of either 44 or 66 repeats, while their sibling with one large GAA2 allele and one somatically stable GAA1 allele of 37 repeats was clinically normal (Sharma et al., 2004). This evidence concerns the gene GPAA1 and Friedreich ataxia.