Friedreich's ataxia is an inherited (genetic) disorder that causes certain nerve cells to deteriorate over time. In many cases, this disorder also affects the heart, certain bones and cells in the pancreas that produce insulin. The illness typically begins with difficulty walking. People with Friedreich's ataxia develop clumsy, shaky movements of the legs (called gait ataxia) during childhood or early adolescence. In rare cases, symptoms appear in infants and in middle-aged adults. As the disease gets worse, people may develop bony deformities of the spine and feet, loss of sensation in the limbs, speech problems, abnormal eye movements, heart disease and diabetes.
Scientists believe that many symptoms of Friedreich's ataxia are related to abnormally low levels of frataxin, a protein that helps to protect cells from "free radicals," which are toxic (poisonous) byproducts of the cells' energy production. In a person with Friedreich's ataxia, a segment of the genetic code on chromosome number 9 can have as many as 1,000 repetitions, instead of the normal range of 7 to 22. These repetitions produce an error that leads to a decreased production of frataxin. As free radicals accumulate within cells, and more and more cells are destroyed or altered, the long-term effects of Friedreich's ataxia lead to a thinner spinal cord, enlarged heart muscle, disturbances in speech and eye movement, and loss of the pancreas's ability to regulate blood sugar. Ultimately, almost everyone with Friedreich's ataxia is confined to a wheelchair, and a large percentage of people develop serious heart problems, including heart failure.
Friedreich's ataxia is a recessive disorder, which means that 2 copies of the abnormal ninth chromosome must be inherited (1 from each parent). People who inherit only 1 abnormal copy (approximately 1 of every 90 Americans of European ancestry) don't have the disease, but are "carriers" who can pass the abnormal chromosome to their children.
In the United States, there is a 1 in 50,000 chance that a child will inherit two copies of the abnormal ninth chromosome that produces Friedreich's ataxia. In 85% of cases, symptoms develop before age 25, but rarely before age 5. Although people from all parts of the world suffer from Friedreich's ataxia, studies show that their ancestry is almost always European, North African, Middle Eastern or Indian (Indo-European).
Because Friedreich's ataxia affects many organs, it can produce a variety of symptoms:
- Neuromuscular symptoms involving the limbs include clumsy, shaking movements (ataxia) of the arms and legs, difficulty walking, paralysis of the leg muscles, difficulty moving the arms, and loss of sensation (especially vibration and sense of position) in the limbs.
- Neurological problems include difficulty speaking (usually seen as a slow, hesitating speech pattern), rapid, involuntary, jerky movements of the eyeballs (nystagmus), reduced vision and hearing loss.
- Bony deformities of the spine and feet (usually triggered by neuromuscular problems) include curvature of the spine (scoliosis), high-arched foot, clubfoot, deformities of the toes and foot inversion (foot turns inward).
- Cardiac symptoms may include shortness of breath (especially with exertion), chest pain, abnormally rapid or irregular heartbeat, and symptoms of heart failure (leg swelling, difficulty breathing while lying flat, waking from sleep to urinate).
- Symptoms of diabetes (in 10% of cases) include extreme thirst, frequent urination, weight loss, fatigue and blurry vision.
In most cases, people with a very high number of repetitions tend to develop the illness earlier than others. They also have more severe symptoms. People with a relatively low number of repetitions may not develop symptoms until age 30 or 40 and may not experience severe heart problems.
A doctor will review your symptoms, medical history and any family history of neuromuscular disorders. You will have a thorough physical exam, with special attention paid to your heart, and a neurological examination, with special attention paid to your legs, arms and eyes. Then, depending on the findings, your doctor may order one or more of the following diagnostic tests:
- Nerve conduction studies. Determines whether nerve cell damage has slowed the transmission of nerve impulses.
- Electromyogram. Looks for muscle damage.
- Electrocardiogram. Checks for abnormalities in the heartbeat.
- Echocardiogram. Assesses heart function, measures the thickness of the heart muscle and determines the size of the heart chambers.
- Magnetic resonance imaging. Scans the brain and spinal cord to look for signs of deterioration, especially loss of thickness in the spinal cord.
- Blood tests and urinalysis. Checks for high blood sugar, and tries to rule out other illnesses that may mimic Friedreich's ataxia.
- Holter monitor. A continuous 24-hour electrocardiogram recording of the heart's rhythm to look for potentially dangerous irregular heartbeats.
Genetic testing can confirm the chromosomal abnormality that causes Friedreich's ataxia.
Friedreich's ataxia is an inherited (genetic) problem that is present at birth and persists throughout life.
There is no way to prevent Friedreich's ataxia. Through genetic testing and genetic counseling, people can get information about their risk of passing Friedreich's ataxia on to their children.
There is no way to correct or remove the extra repetitions that cause Friedreich's ataxia. Treatment focuses on relieving symptoms, keeping the condition from getting worse and prolonging life. Treatment may include:
- Physical therapy and occupational therapy
- Bracing or surgery to correct bony deformities. If scoliosis is severe, surgery is usually done at a relatively early age (if possible), because heart disease that typically develops later in the illness makes the operation more dangerous later on.
- Medication for heart disease. Medications such as beta blockers and ACE inhibitors are often used to treat the symptoms of the heart disease related to this condition. Also there is some evidence that these medications might slow down the progressive worsening of heart failure.
- Antioxidant substances, such as vitamin E, coenzyme Q10, and idebenone may potentially delay disease progression.
- Treatment to lower blood sugar. This includes a modified diet, together with oral antidiabetic drugs or insulin.
If a close relative has Friedreich's ataxia, ask your doctor about your risk of carrying the disorder. Depending on your relationship to the affected person, your doctor may recommend that you have genetic testing before you start a family.
The outlook depends on many factors, including when symptoms start (there is a poorer prognosis the earlier the symptoms begin), how bad the symptoms are and the quality of medical care. Typically, people with Friedreich's ataxia are confined to a wheelchair within 15 to 20 years after their symptoms begin. Many eventually become incapacitated. Death in adulthood is common, usually from heart disease. However, with good medical care, some people with less severe cases can live into their sixties or seventies.
National Institute of Neurological Disorders and Stroke
P.O. Box 5801
Bethesda, MD 20824
National Institute of Child Health & Human Development
Building 31, Room 2A32
31 Center Drive
Bethesda, MD 20892-2425
American Academy of Neurology (AAN)
1080 Montreal Ave.
St. Paul, MN 55116
Muscular Dystrophy Association
3300 E. Sunrise Drive
Tucson, AZ 85718