Friedreich’s ataxia (FA) is a genetic disease caused by a mutation in the FXN gene, which leads to problems in multiple body systems. In particular, the nervous system and muscles are affected in FA. While the mental capabilities of people with FA usually remain intact, loss of coordination and muscle strength leads to motor disability as the disease progresses.
Although the rate of progression varies, most people with FA will need a wheelchair within 10 to 20 years after the appearance of symptoms, and most young FA patients (teens or those in their early 20s) require mobility aids such as a cane, walker, or wheelchair. In later stages of the disease, patients often become severely impaired.
FA can affect many organs and, as such, produces a range of symptoms.
The symptom that gives Friedreich’s ataxia its name is ataxia, which refers to a lack of coordination or muscle control during voluntary movements. According to the National Ataxia Foundation, ataxia can look a bit like being intoxicated: common manifestations include lack of coordination, stumbling, falling, and slurred speech, as a result of damage to parts of the brain that coordinate movement.
Gait ataxia, or difficulty walking, usually is the first symptom to become apparent. This worsens gradually and spreads to the arms and the trunk. Other symptoms may include difficulty balancing, paralysis of the leg muscles, difficulty moving the arms, and a loss of reflexes in the knees and ankles.
Because FA affects the muscles used to coordinate speech, the disease often causes a speech disorder called dysarthria. Early on, this presents as slow, slurred speech, often involving slow, jerky, and hesitant speech patterns. As FA progresses, speech may become almost unintelligible.
As the disease progresses, people with FA usually experience profound muscle weakness. Difficulty swallowing, or dysphagia, is common in latter stages, and may necessitate a modified diet. Some people with FA also may experience spasticity (when muscles are abnormally tight), which can lead to painful muscle spasms.
Skeletal deformities are triggered by neuromuscular problems. Many people with FA experience scoliosis (curvature of the spine), which often requires surgical intervention.
Abnormalities of the feet, such as high-arched feet (pes cavus), club feet (talipes equinovarus), deformities of the toes, and foot inversions (feet turning inward), also are common.
People with FA may experience abnormal eye movements and/or optic neuropathy (damage to the nerves that connect the eyes to the brain). It is common for visual acuity to decrease over the course of the disease, which can lead to blindness in a few individuals.
One of the most common symptoms of FA is a loss of tactile (touch) sensation, though this may be confirmed only in laboratory testing. Vibration sense and position sense (the awareness of where one’s own body is in space) often are impaired early on, while perception of light touch, pain and temperature may be affected later.
Hearing abnormalities are common among people with FA, and can progress to deafness in some cases.
People with FA commonly have substantial atrophy (shrinkage) in the nervous system, which can be detected with an MRI scan. It is common for certain brain structures to be smaller than is usual in typically-developing individuals.
Heart abnormalities affect about three-quarters of people with FA, though the severity of these abnormalities varies extensively from person-to-person, and may be validated only after clinical testing.
Hypertrophic cardiomyopathy is a common FA-related heart problem in which the muscles of the heart become enlarged and weakened, which limits the heart’s ability to effectively pump blood throughout the body. Myocardial fibrosis (scarring of the heart muscles) also can occur.
Heart rhythm abnormalities such as tachycardia (fast heart rate) and heart block (slow heart rate accompanied by abnormal electrical signaling in the heart) are common.
While heart problems do not always cause overt symptoms, some common symptoms of heart problems include extreme fatigue, chest pain, shortness of breath (especially with exertion), and abnormally rapid or irregular heartbeat (heart palpitations).
Heart failure — when the heart is unable to adequately pump blood through the body — can occur, especially in the latter stages of FA. Symptoms of heart failure include leg swelling and difficulty breathing while lying flat.
Bladder, bowel, and sexual complaints
People with FA commonly experience urinary urgency (the sudden feeling that one needs to urinate) and urinary frequency (the need to urinate many times throughout the day and/or night, at normal or less-than-normal volumes). Bowel-related symptoms, including constipation or incontinence, also are common.
People with FA often have sexual dysfunction, and this symptom is more common among individuals who also have urinary or bowel symptoms.
Diabetes occurs when sugar levels in the body are very high as a result of abnormalities with the sugar-regulating hormone insulin. Diabetes is common in FA. Various studies have estimated that from 8% to 32% of people with FA have diabetes, and more have abnormalities in sugar metabolism. Symptoms of diabetes include extreme thirst, frequent urination, weight loss, fatigue, and blurry vision.
Variability in FA symptoms
The most common type of mutation that causes FA is an an expansion of a GAA trinucleotide repeat, meaning that the genetic sequence “GAA” gets repeated many more times than is normal in a region of the FXN gene. The number of GAA repeats affects the disease’s severity and age of onset: individuals with an increased number of GAA repeats in the FXN gene usually develop FA earlier, and have more severe symptoms, than those with a lower number of repeats.
Symptoms of Friedreich’s ataxia usually begin from ages 5 to 15. Individuals with a low number of repeats (less than 300) tend to have late-onset disease (after age 25). In rare cases, disease onset can be as late as age 75.
FA can shorten life expectancy, with heart disease being the most common cause of death. However, some people with a less-severe disease may live into their 60s, 70s, or older.
Last updated: April 8, 2021
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