Mitochondrial damage due to frataxin deficiency, illustration. Frataxin (top right) is an iron chaperone and storage protein found in mitochondria (one at top left), the organelles that produce energy, in the form of adenosine triphosphate (ATP), for a cell. Frataxin deficiency leads to the accumulation of iron (Fe) within the mitochondrion, which leads to the increased production of free radicals. The free radicals interact with lipids (purple and green) in the mitochondrial membrane (across bottom) setting off a chain reaction of oxidative damage. This leads to mitochondrial dysfunction. The genetic neurodegenerative disease Friedreichs ataxia is caused by a deficiency in frataxin.