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Friedreich's ataxia is a genetic disorder that causes progressive damage to the nervous system resulting in symptoms ranging from muscle weakness and speech problems to heart disease. Ataxia (loss of co-ordination) results from the degeneration of nerve tissue in the spinal cord and of nerves that control muscle movement in the arms and legs.
Friedreich's ataxia is caused by a genetic defect which affects male and female children alike and is passed down as a recessive trait. This means that the disease will develop in offspring only when both mother and father transmit the recessive Friedreich's ataxia gene. A child who receives the defective gene from one parent and a normal gene from the other becomes a carrier and never develops the disease. For this reason, there may be carriers of Friedreich's Ataxia in a family that has no known history of the disorder. When both parents are carriers, the chances of a child inheriting Friedreich's ataxia are one in four.
Cases in which a family history of the disease has not been found may represent new genetic changes (mutations) that occur spontaneously (sporadically). All children of someone with FA are carriers, half the grandchildren will be carriers.
Symptoms usually begin between the ages of 5 and 15 but can appear as early as 18 months or as late as 30 years of age. The first symptom is usually difficulty in walking. The ataxia gradually worsens and slowly spreads to the arms and then the trunk. Foot deformities such as clubfoot, flexion (involuntary bending) of the toes, hammer toes, or foot inversion (turning in) may be early signs. Rapid, rhythmic, involuntary movements of the eyeball are common.
Many people with Friedreich's ataxia develop:
scoliosis (a curving of the spine to one side), which, if severe, may impair breathing
heart disease, such as cardiomyopathy
shortness of breath
dysarthria (weakness of the muscles required for speech resulting in abnormal, difficult to understand speech)
auditory neuropathy ('neural deafness' which causes some difficulty in distinguishing certain sounds and/or signals from background noise)
Friedreich's ataxia usually results, within eight to ten years following the onset of symptoms, in an inability to walk. Occasionally, the disease goes into spontaneous remission, which sometimes lasts five to ten years or longer. Remissions, however, are uncommon.
Doctors diagnose Friedreich's ataxia by performing a clinical examination, which includes a medical history and a thorough physical examination. Several tests may be performed, including electromyogram (EMG) and genetic testing.
Although there is no known cure for Friedreich's ataxia, many of the problems associated with the disease can be treated. Orthopaedic intervention, which may include surgery, can alleviate scoliosis, and orthopaedic appliances and physical therapy can help prolong ambulation. Heart problems can also be successfully treated for many years with medication. Insulin therapy is effective in controlling diabetes mellitus.
Research into the biochemistry, neurobiology, and biophysics of central and peripheral nerves, heart and skeletal muscle, and the interactions between muscle and nerve to uncover the pathological process of Friedreich's ataxia is being carried out. In addition, studies of diabetes and heart disease are being conducted in order to determine their relationship with this neurological disorder.
Generally, within 15 to 20 years after the appearance of the first symptoms, the person is confined to a wheelchair, and in later stages of the disease, individuals become completely incapacitated. Most people with Friedreich's ataxia die in early adulthood if there is significant heart disease, the most common cause of death. Some people with less severe symptoms live much longer.
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