What Is Friedreich's Ataxia?
Friedreich's ataxia is a rare, inherited disorder that damages the spinal cord, peripheral nerves (part of the nervous system outside the brain and spinal cord), and cerebellum part of the brain. This disease has been mainly observed to develop in children and teenagers. It slowly gets worse over time. As the disease progresses, it causes awkward, unsteady movements and nerve injury leading to loss of feeling. Apart from nervous system symptoms, people with this disorder may also have other health problems, such as diabetes and heart disease.
This rare condition is named after a German doctor, Nicholaus Friedreich, who discovered it during the 1860s. Ataxia is a term for lack of muscle control. It causes gait (pattern of movement) problems.
Friedreich’s ataxia affects around one in 50,000 people throughout the world. It is the most common disorder in a group of related disorders known as hereditary ataxias.
What Causes Friedreich's Ataxia?
Friedreich's ataxia is an inherited or hereditary disease. It is caused by a defect in a gene called FXN. This gene can be passed down in a family. However, it is a recessive genetic disorder. This means that a copy of the defective gene must be passed down from both parents to get affected by this disease. The FXN gene carries instructions for a protein called frataxin, and mutations in this gene result in reduced energy production in cells of the nervous system and the heart.
People having Friedreich’s ataxia running in their families are at greater risk of developing this disease. However, suppose the defective gene is passed down only from one parent. In that case, the person only becomes a carrier of the disease, meaning they just carry the gene but do not usually experience any symptoms of the disease.
What Are the Symptoms of Friedreich's Ataxia?
The severity and sequence of symptoms in Friedreich's ataxia vary significantly from one person to another. The first symptom usually noticed is ataxia (loss of balance and coordination). However, other symptoms, including heart problems, may appear later.
1. Ataxia, Weakness, and Spasticity:
Ataxia usually affects the legs and torso, leading to frequent tripping and irregular walking patterns. As the disease progresses, it causes a decline in balance and coordination and weak muscles in the legs that are easily fatigued, making walking even more difficult.
Several years later, Friedreich's ataxia may cause difficulty with speech, leading to words coming out in a slow and jerky pattern. This problem is called dysarthria which is caused by weakness of the tongue and other facial muscles or difficulty in controlling these muscles. This is not related to the impairment of intellect or language skills.
Some people might develop difficulty in swallowing, which leads to the entry of food into the airway and causes choking or infections in the respiratory tract.
Spasticity (muscle tightness) is another complaint of people with Friedreich’s ataxia and may be especially prominent in late-onset cases.
2. Sensory Impairment:
Loss of tactile (touch) sensation is often a fundamental symptom of Friedreich’s ataxia that is mainly detected through laboratory testing. The sense of vibration and position (awareness of the position of the body in space) get affected earlier in the disease, and perception of light touch, temperature, and pain may be affected later. Many people with Friedreich’s ataxia might also have diminished or absent reflexes in their legs, such as the knee-jerk reflex. A small fraction of people might also have a loss of hearing or visual impairment.
3. Skeletal Abnormalities:
Specific skeletal abnormalities are commonly seen in Friedreich’s ataxia. These include:
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Inversion (inward turning) of the feet.
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Pes cavus, shortened foot with a high arch.
These conditions can lead to painful blisters and calluses in those people who continue
to walk.
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The curvature of the spine, or scoliosis. It can be painful, and because it alters the shape of the chest cavity, it also interferes with breathing.
4. Cardiac Difficulties:
Heart failure accounts for the leading cause of death in Friedreich’s ataxia. Heart abnormalities occur in about 75 percent of people with Friedreich’s ataxia, but the severity of the disease varies widely.
Some abnormalities are so mild that they can only be noticed through specialized laboratory testing, while others may have life-threatening complications.
These include:
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Hypertrophic Cardiomyopathy- Enlargement of the heart muscle that shrinks the blood-filled chambers of the heart and decreases its ability to pump, leading to heart failure. This is the most commonly seen heart abnormality in Friedreich’s ataxia.
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Arrhythmia- Too fast or too slow (abnormal) heartbeat. It can be life-threatening.
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Extreme fatigue.
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Pain in the chest.
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Shortness of breath.
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Lightheadedness.
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Heart palpitations (feeling of the heart beating too fast).
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Pooling of blood in the ankles.
It is suggested that people with Friedreich’s ataxia should have regular checkups with a cardiologist.
5. Diabetes:
About ten percent of people affected with Friedreich's ataxia have diabetes, and about 20 percent have pre-diabetes, another form of diabetes called glucose intolerance. Both occur due to decreased production of insulin by the pancreas, which helps in the storage and utilization of sugar (glucose).
How Is Friedreich's Ataxia Diagnosed?
Friedreich's ataxia (FA) is typically seen in childhood, between 10 and 15 years of age, but also has been diagnosed from 2 to 50 years of age. Later onset usually has a less severe course.
The diagnosis of Friedreich’s ataxia typically begins with a physical exam followed by the assessment of the personal and family history.
Other tests may include-
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Test to check for reflexes, balance, coordination, and nerve sensitivity (electromyography).
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Blood tests help identify treatable conditions causing ataxia.
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MRI (magnetic resonance imaging) or CT (computed tomography) scan.
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Nerve conduction studies (nerve conduction velocity test) use electrical impulses to check nerve activity.
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Heart tests to evaluate heart function.
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Genetic tests to find the defective gene that causes the disorder.
How Is Friedreich's Ataxia Treated?
Currently, there is no cure for Friedreich’s ataxia, and the treatment aims to target specific symptoms rather than the disease itself.
These include-
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Braces that support and strengthen the arms, legs, feet, and spine.
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Physical therapy helps stretch tight muscles and enhance flexibility.
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Speech therapy helps re-train the tongue and the facial muscles to improve speech and swallowing.
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Surgery to treat the deformities of the feet and scoliosis (curvature of the spine).
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Certain drugs such as ACE inhibitors, diuretics, beta-blockers for heart symptoms, and insulin therapy for diabetes.
Conclusion:
Friedreich's ataxia is a genetic neuromuscular disease that affects the nerves and muscles and causes heart problems and diabetes. There is no permanent cure for this condition, but the symptoms can be managed effectively by specific treatment options involving therapy, medications, and surgery.
