What is Friedreich's ataxia?
Friedreich's ataxia (also called FA or FRDA) is a rare inherited disease that causes nervous system damage and movement problems. It usually begins in childhood and leads to impaired muscle coordination (ataxia) that worsens over time. The disorder is named after Nicholaus Friedreich, a German doctor who first described the condition in the 1860s.
In Friedreich’s ataxia the spinal cord and peripheral nerves degenerate, becoming thinner. The cerebellum, part of the brain that coordinates balance and movement, also degenerates to a lesser extent. This damage results in awkward, unsteady movements and impaired sensory functions. The disorder also causes problems in the heart and spine, and some people with the condition develop diabetes. The disorder does not affect thinking and reasoning abilities (cognitive functions).
Friedreich’s ataxia is caused by a defect (mutation) in a gene labeled FXN. The disorder is recessive, meaning it occurs only in someone who inherits two defective copies of the gene, one from each parent. Although rare, Friedreich’s ataxia is the most common form of hereditary ataxia, affecting about 1 in every 50,000 people in the United States. Both male and female children can inherit the disorder.
What are the signs and symptoms?
Symptoms typically begin between the ages of 5 and 15 years, although they sometimes appear in adulthood and on rare occasions as late as age 75. The first symptom to appear is usually gait ataxia, or difficulty walking. The ataxia gradually worsens and slowly spreads to the arms and the trunk. There is often loss of sensation in the extremities, which may spread to other parts of the body. Other features include loss of tendon reflexes, especially in the knees and ankles. Most people with Friedreich's ataxia develop scoliosis (a curving of the spine to one side), which often requires surgical intervention for treatment.
Dysarthria (slowness and slurring of speech) develops and can get progressively worse. Many individuals with later stages of Friedreich’s ataxia develop hearing and vision loss.
Other symptoms that may occur include chest pain, shortness of breath, and heart palpitations. These symptoms are the result of various forms of heart disease that often accompany Friedreich's ataxia, such as hypertrophic cardiomyopathy (enlargement of the heart), myocardial fibrosis (formation of fiber-like material in the muscles of the heart), and cardiac failure. Heart rhythm abnormalities such as tachycardia (fast heart rate) and heart block (impaired conduction of cardiac impulses within the heart) are also common.
About 20 percent of people with Friedreich's ataxia develop carbohydrate intolerance and 10 percent develop diabetes. Most individuals with Friedreich’s ataxia tire very easily and find that they require more rest and take a longer time to recover from common illnesses such as colds and flu.
The rate of progression varies from person to person. Generally, within 10 to 20 years after the appearance of the first symptoms, the person is confined to a wheelchair, and in later stages of the disease individuals may become completely incapacitated.
Friedreich's ataxia can shorten life expectancy, and heart disease is the most common cause of death. However, some people with less severe features of Friedreich's ataxia live into their sixties, seventies, or older.