Friedreich’s ataxia (FA) is a rare, inherited, progressive disease that primarily affects the nerves and muscles. Named after the German scientist who first described it, FA causes loss of control of body movements (ataxia). It typically begins in childhood or adolescence and worsens with age.
The first sign of FA is usually difficulty walking due to the loss of coordination of leg muscles. A person with FA will usually need a wheelchair within 10 years of symptom onset. Patients may be completely incapacitated by middle age and may have a shortened lifespan.
What causes FA?
FA is caused by mutations in the gene FXN. This gene carries instructions for making a protein called frataxin, which is important for the proper functioning of mitochondria, organelles that produce the necessary energy for cellular processes.
Because of the mutated gene, cells cannot make enough functional frataxin protein, which leads to a disruption in energy production within cells. This causes damage to multiple bodily systems, particularly the nervous system and muscles.
A person will only develop FA if they have disease-causing mutations in both of their copies of the FXN gene — one inherited from each biological parent. In most cases, neither parent shows signs of FA, so they are often not aware that the disease runs in the family.
How is FA diagnosed?
The only conclusive diagnostic test for FA is genetic testing to identify disease-causing mutations in a person’s copies of the FXN gene.
Other tests that may aid in its diagnosis include nerve conduction studies, tests of heart function, urinary and blood tests, and MRI scans. Their results can help identify particular problems that are characteristic of FA, and may rule out other conditions that may cause similar symptoms.
What are the symptoms of FA?
The symptom that gives FA its name is ataxia, which refers to a lack of coordination or muscle control during voluntary movements. Common manifestations of ataxia also include stumbling, falling, and slurred speech.
Usually, motor symptoms of FA begin in the lower body, then spread to the upper body. Difficulty walking (gait ataxia) is typically one of the first symptoms noticed. As the disease progresses, weak muscles in the mouth and throat can make speech and eating difficult.
Neuromuscular problems in FA can lead to skeletal deformities such as scoliosis, when the spine curves to one side. Skeletal abnormalities affecting the feet also are common.
Nerve damage caused by FA can lead to sensory issues, such as abnormal eye movements, impaired vision or hearing, and loss of sense of touch.
FA also can cause symptoms affecting the urinary system and bowels, such as constipation and urinary urgency, which is the sudden feeling that one needs to urinate. Sexual impairment frequently accompanies these symptoms.
Problems related to heart health, such as hypertrophic cardiomyopathy — when the heart’s muscles become enlarged and weakened — and abnormal heart rhythms are common among people with FA. Many FA patients will eventually develop heart disease.
Diabetes also is common among people with FA, affecting as many as one-fifth of patients.
How is FA treated?
No cure currently exists for FA, so treatment primarily aims at managing symptoms. Walking aids, wheelchairs, and physical or occupational therapy can help with mobility and muscle strength. Medications can control some symptoms of heart disease. Insulin or glucose-lowering drugs may control diabetes, and surgery can correct spine curvature or foot deformities.
Speech therapy and emotional counseling also may be helpful.
The search for better treatments is ongoing, with many research trials underway, some attempting to uncover details about what causes FA, and others looking at new treatments.
What is the prognosis of FA?
The prognosis of FA is associated with the age at which symptoms first manifest. For most FA patients, symptoms start in early adolescence (between ages 10 and 15), though more rarely, some individuals have an age of onset that is substantially earlier or later. Age of onset is closely impacted by the specific mutations in an individual’s FXN genes.
In general, a younger age at onset is tied to more severe symptoms and a shorter lifespan. Most people with FA live into their 40s or 50s. The presence of other health conditions, such as heart disease or diabetes, can greatly impact prognosis and lifespan.
Last updated: April 12, 2021
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