Friedreich ataxia or FA is a genetic disease that damages the nervous system that ultimately results in ataxia -- problems with movement and muscle coordination. Friedreich ataxia is named for the German scientist who discovered it. The disease progresses at a different rate for each person. The usual progression leads to wheelchair use ten to 20 years after the first symptoms appear. Complete incapacitation develops in later stages of the illness. Some people with milder forms of FA can live into their sixties or seventies.
Friedreich ataxia is caused by a mutation of the FXN gene, which contains genetic code for a specific protein -- frataxin. FA is a recessive condition and only develops in people born with two mutated FXN genes. Friedreich ataxia is unique because it is the only known genetically inherited condition, with the exception of sex-linked disorders, that needs two copies of the mutated gene to occur.
Cell mitochondria use frataxin to make energy. Cells without enough frataxin can not produce energy efficiently. Toxins may build up and damage cells in a process known as oxidative stress. This effect is most pronounced in the cells of the peripheral nerves, spinal cord, brain, and heart. An additional theory states that a lack of frataxin causes increased iron in mitochondria. The excess mineral reacts with oxygen to form free radicals, which can destroy cells.
People usually start experiencing symptoms between the ages of five and 15. Around 15% of people with FX don't show any symptoms until they are over 25. The first noticeable neurological symptom is almost always gait ataxia, expressed as poor balance and difficulty walking. Slow or slurred speech is another early symptom. Speech eventually becomes hesitant, with frequent starts and stops.
Various symptoms are possible with FA; these differ between individuals with the condition and people rarely experiences all of them. Symptoms include hearing loss, deteriorating vision, lack of reflexes in the legs, involuntary eye movements, and poor concentration. Progressive muscle deterioration often leads to skeletal problems, and 75% of people with FA develop heart problems as well.
Difficulty coordinating muscle movement starts in the lower extremities and spreads. The condition worsens and begins to affect the arms and torso. The accelerating muscle weakness causes increased muscle tone, known as spasticity. Two-thirds of people with FA develop spinal curvature to one side, or scoliosis, and need surgery to correct it.
There is no cure or consistently effective treatment for Friedreich ataxia. Doctors focus on symptom management and alleviating complications. The goal of treatment is to help individuals retain as much function as possible, long-term. Multiple medical specialties are involved in a comprehensive treatment plan. Many people with FA develop diabetes that medication and other routine interventions can manage.
The most common cardiac effect of FA is hypertrophic cardiomyopathy, a thickening of the heart muscle. Symptons include heart palpitations, chest pain, and shortness of breath. Heart disease is usually the cause of death for people with FA, and may be fatal by early adulthood in severe cases. A variety of medications can slow progression, but nothing can stop it entirely.
A thorough physical examination and comprehensive medical history is the first step in diagnosing Friedreich ataxia. The physician looks for poor balance, loss of sensation in the joints, absent reflexes, and other signs of neurological problems. Diagnosis is confirmed with genetic testing. Genetic counseling is also available for people with a family history of FA so they can make educated decisions on having children.
Several tests help with preliminary diagnosis and disease management. An electromyogram or EM measures electrical activity in muscle cells. Nerve conduction studies measure how fast nerves transmit impulses. An electrocardiogram or ECG shows a graphic representation of heartbeats as electrical activity and patterns. An echocardiogram records the motion of the heart muscle. Doctors can view images of the brain and spinal cord using MRI or CT scans.
Research concerning Friedrich ataxia is tied to overall studies on genetic conditions. The same problem limits the treatment of most genetic illnesses. Medical science has identified the genes involved in thousands of conditions, but there is still no treatment for them. CRISPR technology is the focus of a lot of research right now, with the ultimate goal being editing genes to fix mutations and cure illnesses.
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