Friedreich’s ataxia, although rare, is the most prevalent inherited ataxia, affecting about 1 in every 50,000 people. Males and females are affected equally.

Friedreich’s ataxia is an autosomal recessive disease, which means the patient must inherit two affected genes, one from each parent, for the disease to develop. A person who has only one abnormal copy of a gene for a recessive genetic disease such as Friedreich’s ataxia is called a carrier. A carrier will not develop the disease but could pass the affected gene on to his or her children. If both parents are carriers of the Friedreich’s ataxia gene, their children will have a 1 in 4 chance of having the disease and a 1 in 2 chance of inheriting one abnormal gene that they, in turn, could pass on to their children. About one in 90 Europeans carries one affected gene.

Symptoms usually begin between the ages of 5 and 15 but can, on rare occasions, appear as early as 18 months or as late as 30 years of age. The first symptom to appear is usually difficulty in walking, or gait ataxia. 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 inward) may be early signs. Over time, muscles begin to weaken and waste away, especially in the feet, lower legs, and hands, and deformities develop.

Other symptoms include loss of tendon reflexes, especially in the knees and ankles. There is often a gradual loss of sensation in the extremities, which may spread to other parts of the body. Dysarthria (slowness and slurring of speech) develops, and the person is easily fatigued. Rapid, rhythmic, involuntary movements of the eyeball (nystagmus) is common. Most people with Friedreich’s ataxia develop scoliosis (a curving of the spine to one side), which, if severe, may impair breathing.

Other symptoms that may occur include chest pain, shortness of breath, and heart palpitations. These symptoms are the result of various forms of heart disease that often accompany Friedreich’s ataxia, such as cardiomyopathy (enlargement of the heart), myocarditis (inflammation of the walls of the heart), myocardial fibrosis (formation of fiber-like material in the muscles of the heart), and cardiac failure. Heart rhythm abnormalities such as tachycardia (fast heart rate) and heart block (impaired conduction of cardiac impulses within the heart) are also common.

About 20 percent of people with Friedreich’s ataxia develop carbohydrate intolerance and 10 percent develop diabetes mellitus. Some people lose hearing or eyesight.

The rate of progression varies from person to person. 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. Life expectancy is greatly affected, and most people with Friedreich’s ataxia die in early adulthood if there is significant heart disease, the most common cause of death. However, some people with less severe symptoms of Friedreich’s ataxia live much longer.

Doctors diagnose Friedreich’s ataxia by performing a careful clinical examination, which includes a medical history and a thorough physical examination. Tests that may be performed include:

• electromyogram (EMG), which measures the electrical activity of muscle cells,
• nerve conduction studies, which measure the speed with which nerves transmit impulses,
• electrocardiogram (EKG), which gives a graphic presentation of the electrical activity or beat pattern of the heart,
• echocardiogram, which records the position and motion of the heart muscle,
• magnetic resonance imaging (MRI) or computed tomography (CT) scan, which provides a picture of the brain and spinal cord,
• spinal tap to evaluate the cerebrospinal fluid,
• blood and urine tests to check for elevated glucose levels, and
• genetic testing to identify the affected gene.

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 patients maintain optimal functioning as long as possible. Diabetes, if present, can be treated with diet and medications such as insulin, and some of the heart problems can be treated with medication as well.

Orthopedic problems such as foot deformities and scoliosis can be treated with braces or surgery. Physical therapy may prolong use of the arms and legs. Scientists hope that recent advances in understanding the genetics of Friedreich’s ataxia may lead to breakthroughs in treatment.