Friedreich’s Ataxia is a genetic disorder that affects the body’s ability to produce energy. It usually begins between ages 2 and 5 and gradually worsens over time. The disease causes loss of balance, muscle weakness, slurred speech, and difficulty walking. There is no cure for Friedreich’ s Ataxia, but there are treatments that help manage symptoms.
Friedreich’s ataxia is a rare inherited condition that causes progressive damage to the nervous system and movement problems.
Friedreich’s ataxia is named after German physician Nikolaus Friedreich, who described it in the 1860s.
It frequently begins in childhood and results in impaired muscle coordination (ataxia) that worsens over time.
Friedreich’s ataxia is characterized by the degeneration of nerve fibers in the spinal cord and peripheral nerves, which results in the thinning of these nerves.
Peripheral nerves carry information from the brain to the body and from the body to the brain. For example, a message indicating that the feet are cold or a signal to the muscles to start a movement.
The cerebellum, part of the brain that coordinates balance and movement, also degenerates to a lesser extent.
This damage results in uncomfortable and unsteady movements and impaired sensory functions.
The disorder also causes heart and spinal problems in a third of those affected, and some people with the condition will also develop diabetes.
The disorder does not alter thinking and reasoning abilities (cognitive functions).
Cause of Friedreich’s Ataxia
Friedrich ataxia is caused by a defect in a gene called FXN, which causes the production of a protein called frataxin.
People who inherit two defective copies of the gene, one from each parent, will develop the disease.
A person must therefore inherit two copies of the defective FXN gene to develop the disease.
A person who inherits only one mutated copy of the gene is called a carrier. He will not develop the disease, but could transmit the mutation to his children.
Almost all people with FA (98%) have two copies of this mutant form of FXN, but it is not found in all cases of the disease. About two percent of those affected have other defects in the FXN gene responsible for the disease.
Although rare, Friedreich’s ataxia is the most common form of inherited ataxia, affecting approximately 1 in 50,000 people. Both male and female children are able to inherit the condition.
The rate of progression varies from person to person. Generally, within 10 to 20 years of the onset of the first symptoms, the person is confined to a wheelchair.
Individuals can become completely dependent in severe stages of the disease.
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 the disease survive past the age of 60.
The signs and symptoms
Symptoms usually begin between ages 5 and 15, although they sometimes appear in adulthood.
About 15 percent of cases of Friedreich’s ataxia appear after the age of 25.
The first neurological symptom to appear is usually difficulty walking and poor balance (walking ataxia). This may be described as feeling dizzy or even drunk.
Another early sign of the disease is slowness and slurred speech (dysarthria).
Over time, speech becomes hesitant and jerky (often referred to as « speech sweeping »).
Difficulty coordinating movements (ataxia) can affect all muscles. It gradually worsens and spreads to the arms and trunk (torso)
As muscle weakness progresses, most affected individuals develop increased muscle tone (spasticity).
Up to two-thirds of people with Friedreich’s ataxia also develop scoliosis (a curvature of the spine to one side) which often requires surgery.
Most affected people also develop difficulty swallowing, due to difficulty coordinating the muscles of the tongue and throat.
In addition to movement disorders, there is often a loss of sensation in the arms and legs, which can spread to other parts of the body.
Other signs include loss of normal reflexes, especially in the knees and ankles, and muscle weakness.
Many people with advanced stages of Friedreich’s Ataxia also develop hearing and vision loss.
Other symptoms that may occur include heart palpitations and shortness of breath. These symptoms are the result of various forms of heart disease that often accompany Friedreich’s ataxia, such as enlargement of the heart (hypertrophic cardiomyopathy), formation of fibrous material in the muscles of the heart (myocardial fibrosis), and heart failure. cardiac.
Heart rhythm abnormalities such as rapid heart rate (tachycardia) and impaired conduction of cardiac nerve impulses in the heart are also common.
About 50% of people with the disease develop carbohydrate intolerance and 30% develop diabetes.
Most people with the disease tire very easily and find that they need more rest. They take longer to recover from common illnesses such as colds and flu.
Diagnosis of Friedreich’s Ataxia
A diagnosis of Friedreich’s ataxia requires a careful clinical examination, which includes a medical history and a thorough physical examination, particularly looking for balance difficulties, loss of joint sensation (proprioception), absence of reflexes and signs of neurological problems.
Genetic testing now provides a conclusive diagnosis.
Other tests that can aid in the diagnosis or management of the disorder include:
- electromyogram (EMG), which measures the electrical activity of muscle cells,
- nerve conduction studies, which measure the rate at which nerves transmit impulses
- electrocardiogram (ECG), which assesses the heart’s electrical activity or heart rhythm,
- echocardiogram, which records the position and movement of the heart muscle,
- blood tests to check glucose levels and,
- magnetic resonance imaging (MRI) or computed tomography (CT) which provide images of the brain and spinal cord that are helpful in ruling out other neurological diseases.
How is the protein frataxin affected?
The cell with the FXN gene provides instructions to produce a protein called frataxin.
If the FXN gene is faulty, the amount of frataxin produced by the cell is reduced dramatically, causing disease.
Frataxin is found in the cell’s energy-producing organelles called mitochondria. Research suggests that without a normal level of frataxin, certain cells in the body (particularly cells in the peripheral nerves, spinal cord, brain, and heart muscle) produce energy less efficiently and have been hypothesized to an excessive accumulation of free radicals leading to what is known as ‘oxidative stress’, destroying cells.
Can Friedreich’s Ataxia be cured or treated?
As with many degenerative diseases of the nervous system, there is currently no effective cure or treatment for Friedreich’s Ataxia.
However, many of the symptoms and accompanying complications can be treated to help individuals maintain optimal functioning for as long as possible.
A multidisciplinary team approach is essential to the treatment of the individual with Friedreich’s Ataxia.
Doctors can prescribe treatments for diabetes, if any; some heart problems can also be treated with medication.
Orthopedic problems such as foot deformities and scoliosis can be corrected with braces or surgery.
Physiotherapy can prolong the use of arms and legs. Swallowing and speech problems should be monitored closely.
Hearing impairment can be helped with hearing aids.