Friedreich ataxia is the most common cause of inherited ataxia in Caucasian populations. It affects the spinal cord and the heart, is of autosomal recessive inheritance and is due to the partial deficiency of a mitochondrial protein, frataxin, thought to be involved in the biogenesis of iron–sulfur clusters. The major mutation is a trinucleotide repeat expansion in intron 1 of the frataxin gene, which causes reduced synthesis of the corresponding transcript.