Friedreich's ataxia is a rare disease passed down through families (inherited) that affects the muscles and heart.

Friedreich's ataxia is caused by a defect in a gene called Frataxin (FXN), which is located on chromosome 9. Changes in this gene cause the body to produce too much of part of DNA called trinucleotide repeat (GAA). Normally, the body contains about 8 to 30 copies of GAA. Those with Individuals with Friedreich's ataxia have as many as 1,000 copies. The more copies of GAA a patient has, the earlier in life the disease starts and the faster it gets worse.

Friedreich's ataxia is an autosomal recessive genetic disorder. This means you must get a copy of the defective gene from both your mother and father.

About 1 in every 22,000-29,000 develop this disease. Family history of the condition raises your risk.

Symptoms are caused by the wearing away of structures in areas of the brain and spinal cord that control coordination, muscle movement, and some sensory functions. Symptoms generally begin in childhood before puberty, and may include:

• Unsteady gait and uncoordinated movements (ataxia) -- gets worse with time
• No reflexes in the legs
• Abnormal speech
• Loss of coordination and balance, which leads to frequent falls
• Decrease in ability to feel vibrations in lower limbs
• Muscle weakness
• Changes in vision, particularly color vision
• Hearing loss -- occurs in about 10% of patients
• Jerky eye movements
• Foot problems, such as hammer toe and high arches

Muscle problems lead to changes in the spine, which may result in scoliosis or kyphoscoliosis.

Heart disease usually develops and may lead to heart failure. Death may result from heart failure or dysrhythmias that do not respond to treatment. Diabetes may develop in later stages of the disease.

The following tests may be performed:

• ECG
• Genetic testing for the frataxin gene
• X-ray of the chest
• X-ray of the spine
• Electrophysiological studies
• EMG (electromyography)
• Nerve conduction tests
• Muscle biopsy
• X-ray, CT scan, or MRI of the head

Tests of the heart may show a condition called hypertrophic cardiomyopathy in about 66% of persons with this condition.

Blood sugar (glucose) tests may reveal diabetes or glucose intolerance. An eye exam may show damage to the optic nerve, which usually occurs without symptoms.