Abstract: Methods of modifying a frataxin gene are disclosed, comprising removing some or all of endogenous GAA trinucleotide repeats within the frataxin gene, e.g., within an intron (e.g., intron 1) of the frataxin gene. The removal may be effected using a CRISPR/CAS nuclease system. Such modification may be used to increase frataxin expression in the cell, and also to treat a subject suffering from Friedreich ataxia. Reagents, kits and uses of the method are also disclosed, for example to modify a frataxin gene and to treat a subject suffering from Friedreich ataxia.