Friedreich ataxia
Friedreich's ataxia; Spinocerebellar degeneration
Friedreich ataxia is a rare disease passed down through families (inherited). It affects the muscles and heart.
The central nervous system comprises the brain and spinal cord. The peripheral nervous system includes all peripheral nerves.
Causes
Friedreich ataxia is caused by a defect in a gene called frataxin (FXN). Changes in this gene cause the body to make too much of a part of DNA called trinucleotide repeat (GAA). Normally, the body contains about 8 to 30 copies of GAA. People with Friedreich ataxia have as many as 1,000 copies. The more copies of GAA a person has, the earlier in life the disease starts and the faster it gets worse.
Friedreich ataxia is an autosomal recessive genetic disorder. This means you must get a copy of the defective gene from both your mother and father.
Symptoms
Symptoms are caused by the wearing away of structures in areas of the brain and spinal cord that control coordination, muscle movement, and other functions. Symptoms most often begin before puberty. Symptoms may include:
- Abnormal speech
- Changes in vision, particularly color vision
- Decrease in ability to feel vibrations in lower limbs
- Foot problems, such as hammer toe and high arches
- Hearing loss, this occurs in about 10% of people
- Jerky eye movements
- Loss of coordination and balance, which leads to frequent falls
- Muscle weakness
- No reflexes in the legs
- Unsteady gait and uncoordinated movements (ataxia), which gets worse with time
Muscle problems lead to changes in the spine. This may result in scoliosis or kyphoscoliosis.
Heart disease most often develops and may lead to heart failure. Heart failure or dysrhythmias that do not respond to treatment may result in death. Diabetes may develop in later stages of the disease.
Exams and Tests
The following tests may be done:
- ECG
- Electrophysiological studies
- EMG (electromyography)
- Genetic testing
- Nerve conduction tests
- Muscle biopsy
- X-ray, CT scan, or MRI of the head
- X-ray of the chest
- X-ray of the spine
Blood sugar (glucose) tests may show diabetes or glucose intolerance. An eye exam may show damage to the optic nerve, which most often occurs without symptoms.
Treatment
Treatment for Friedreich ataxia includes:
- Counseling
- Speech therapy
- Physical therapy
- Walking aids or wheelchairs
Orthopedic devices (braces) may be needed for scoliosis and foot problems. Treating heart disease and diabetes help people live longer and improve their quality of life.
Outlook (Prognosis)
Friedreich ataxia slowly gets worse and causes problems doing everyday activities. Most people need to use a wheelchair within 15 years of the disease's start. The disease may lead to early death.
Possible Complications
Complications may include:
- Diabetes
- Heart failure or heart disease
- Loss of ability to move around
When to Contact a Medical Professional
Contact your health care provider if symptoms of Friedreich ataxia occur, especially if there is a family history of the disorder.
Prevention
People with a family history of Friedreich ataxia who intend to have children may want to consider genetic screening to determine their risk.
References
Mink JW. Movement disorders. In: Kliegman RM, St. Geme JW, Blum NJ, Shah SS, Tasker RC, Wilson KM, eds. Nelson Textbook of Pediatrics. 21st ed. Philadelphia, PA: Elsevier; 2020:chap 615.
Warner WC, Sawyer JR. Neuromuscular disorders. In: Azar FM, Beaty JH, eds. Campbell's Operative Orthopaedics. 14th ed. Philadelphia, PA: Elsevier; 2021:chap 35.
Version Info
Last reviewed on: 10/31/2022
Reviewed by: Neil K. Kaneshiro, MD, MHA, Clinical Professor of Pediatrics, University of Washington School of Medicine, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
