Friedreich's ataxia is a genetically inherited disorder, which “causes progressive damage to the nervous system resulting in symptoms ranging from muscle weakness and speech problems to heart disease,” according to the ]]>National Institute of Neurological Disorders and Stroke (NINDS)]]>. The ]]>National Institutes of Health (NIH)]]> adds that one in 22,000 to 29,000 develop Friedreich's ataxia.
For a patient to develop Friedreich's ataxia, she must receive the abnormal genes from both parents; this is referred to as an autosomal recessive genetic disorder. It is possible for both parents to be carriers (each having only one abnormal gene copy) and pass the disorder on. The gene responsible for Friedreich's ataxia is Frataxin, or FXN, which is found on chromosome nine. The abnormality with FXN results in an overproduction of the trinucleotide repeat, or GAA. The NIH states that a Friedreich's ataxia patient has 1,000 copies of GAA in her body, compared to eight or thirty in a non-Friedreich's ataxia patient; higher GAA quantities cause an earlier onset and faster progression of the disorder.
The NINDS notes that the onset of Friedreich's ataxia is usually during childhood, between the ages five and fifteen; however, the earliest onset is 18 months, and the latest onset is 30 years. The first symptoms affect mobility, such as walking, and then progress to the arms and trunk. Another issue that can arise from Friedreich's ataxia is scoliosis, which is a condition that causes curvature of the spine; the NINDS warns that this can cause breathing problems in some patients. Distortion to the foot is another problem: clubfoot, hammer toes, flexion of toes (involuntary bending), and foot inversion (turning in) can occur. In addition to the mobility problems, the patient may also experience a loss of coordination and lack of reflexes in the legs. The NIH adds that ten percent of patients suffer from hearing loss. Other symptoms of Friedreich's ataxia are abnormal speech and vision problems.