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"Ataxia," which refers to coordination problems such as clumsy or awkward movements and unsteadiness, occurs in many different diseases and conditions. The ataxia of Friedreich's ataxia results from the degeneration of nerve tissue in the spinal cord and of nerves that control muscle movement in the arms and legs. The spinal cord becomes thinner and nerve cells lose some of their myelin sheath (the insular covering on all nerve cells that helps conduct nerve impulses).
Additional recommended knowledge
Friedreich's ataxia is the most prevalent inherited ataxia, affecting about 1 in 50,000 people in the United States. Males and females are affected equally.
A 1984 Canadian study was able to trace 40 cases of classical Friedreich's disease from 14 French-Canadian kindreds previously thought to be unrelated to one common ancestral couple arriving in New France in 1634: Jean Guyon and Mathurine Robin. 
Friedreich's ataxia is an autosomal recessive congenital ataxia and is caused by a mutation in gene FXN (formerly known as X25) that codes for frataxin, located on chromosome 9. This protein is essential for proper functioning of mitochondria (it has been shown to be connected with the removal of iron from the cytoplasm surrounding the mitochondria, and in the absence of frataxin, the iron builds up and causes free radical damage). Nerve and muscle cells appear to be particularly sensitive to the deleterious effects of this type of mitochondrial dysfunction.
The classic form of Friedreich's ataxia has been mapped to 9q13-q21. In most cases, the mutant gene contains expanded GAA triplet repeats in the first intron; in a few pedigrees, point mutations have been detected. Because the defect is located on an intron (which is removed from the mRNA transcript between transcription and translation), this mutation does not result in the production of abnormal frataxin proteins. Instead, the mutation causes gene silencing (i.e., the mutation decreases the transcription of the gene)through induction of a heterochromatin structure in a manner similar to position-effect variegation.
Relationship to muscular dystrophy
Friedreich's ataxia and muscular dystrophy, though often compared, are different diseases. Muscular dystrophy is the result of muscle tissue degeneration, whereas Friedreich's ataxia is the result of nerve degeneration caused by a trinucleotide repeat expansion mutation. Research on both disorders is supported by funding from the Muscular Dystrophy Association.
Symptoms typically begin sometime between the ages of 5 to 15 years, but in Late Onset FA may occur in the 20's or 30's. Symptoms include any combination, but not necessarily all of the following:
It presents before 25 years of age with progressive staggering or stumbling gait and frequent falling. Lower extremities are more severely involved.
These symptoms are slow and progressive. Long-term observation shows that many patients reach a plateau in symptoms in the patient's early adulthood. Because of many of these symptoms, a person suffering from Friedrich's Ataxia may require some surgical interventions (mainly for the spine and heart). Often a metal rod is inserted in the spine to help prevent or slow the progression of scoliosis. As progression occurs, assistive devices such as a cane or walker or a wheelchair are required for mobility (independence).
20% cases are found in association with diabetes mellitus type 1 or 2 or pancreatic β cell dysfunction.
The primary site of pathology is spinal cord and peripheral nerves. Sclerosis and degeneration of spinocerebellar tracts, lateral corticospinal tracts, and posterior columns. In peripheral nerves there is a loss of large myelinated fibres.
The symptoms can be treated but there is no treatment for Friedrich's Ataxia at this time. There are several clinical trials taking place, including one for idebenone, in the United States. Assistive Technology, such as a standing frame, can help reduce the secondary complications of prolonged use of a wheelchair. In many cases, patients experience significant heart conditions as well. These conditions, fortunately, are much more treatable, and are often countered with ACE inhibitors such as Lisinopril and other heart medications such as Digoxin.
Patient Recruitment for Friedreich's Ataxia Upcoming Clinical Research Trials: to sign up
FARA Electronic News Bulletin for latest research and news relevant to Friedreich's ataxia: To sign up
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Friedreich's_ataxia". A list of authors is available in Wikipedia.|