Genes Gone Awry

Friedreich's ataxia is caused by a genetic defect that prevents adequate production of the protein frataxin. In nerve and muscle cells, frataxin is essential for proper functioning of mitochondria, the energy producers for cells.

The genetic defect involves numerous extra repeats of a GAA-TTC triplet pattern in a person's DNA that prevent expression of the frataxin gene. Where normal cells contain 6 to 34 repeats, Friedreich's ataxia sufferers can have as many as 1,700.