Question: What is (are) Friedreich ataxia ?
Answer: Friedreich ataxia is an inherited condition that affects the nervous system and causes movement problems. People with this condition develop impaired muscle coordination (ataxia) that worsens over time. Other features include the gradual loss of strength and sensation in the arms and legs, muscle stiffness (spasticity), and impaired speech. Many individuals have a form of heart disease called hypertrophic cardiomyopathy. Some develop diabetes, impaired vision, hearing loss, or an abnormal curvature of the spine (scoliosis). Most people with Friedreich ataxia begin to experience the signs and symptoms around puberty. This condition is caused by mutations in the FXN gene and is inherited in an autosomal recessive pattern.
Source: GARD

Question: What are the symptoms of Friedreich ataxia ?
Answer: What are the signs and symptoms of Friedreich ataxia? Symptoms usually begin between the ages of 5 and 15 but can, on occasion, appear in adulthood or even as late as age 75. 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. 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 eye (nystagmus) are 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 ataxia, such as cardiomyopathy (enlargement 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 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 10 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 may be affected, and many people with Friedreich ataxia die in adulthood from the associated heart disease, the most common cause of death. However, some people with less severe symptoms of Friedreich ataxia live much longer, sometimes into their sixties or seventies. The Human Phenotype Ontology provides the following list of signs and symptoms for Friedreich ataxia. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) Reduced visual acuity 5% Visual impairment 5% Abnormal echocardiogram - Abnormal EKG - Abnormality of visual evoked potentials - Areflexia of lower limbs - Autosomal recessive inheritance - Babinski sign - Congestive heart failure - Decreased amplitude of sensory action potentials - Decreased pyruvate carboxylase activity - Decreased sensory nerve conduction velocity - Diabetes mellitus - Dysarthria - Gait ataxia - Hypertrophic cardiomyopathy - Impaired proprioception - Juvenile onset - Limb ataxia - Mitochondrial malic enzyme reduced - Nystagmus - Optic atrophy - Pes cavus - Scoliosis - Sensory neuropathy - Visual field defect - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: What causes Friedreich ataxia ?
Answer: What causes Friedreich ataxia? Friedreich ataxia is caused by mutations in the FXN gene. This gene provides instructions for making a protein called frataxin. One region of the FXN gene contains a segment of DNA known as a GAA trinucleotide repeat. This segment is made up of a series of three DNA building blocks (one guanine and two adenines) that appear multiple times in a row. Normally, this segment is repeated 5 to 33 times within the FXN gene. In people with Friedreich ataxia, the GAA segment is repeated 66 to more than 1,000 times. The length of the GAA trinucleotide repeat appears to be related to the age at which the symptoms of Friedreich ataxia appear. The abnormally long GAA trinucleotide repeat disrupts the production of frataxin, which severely reduces the amount of this protein in cells. Certain nerve and muscle cells cannot function properly with a shortage of frataxin, leading to the characteristic signs and symptoms of Friedreich ataxia.
Source: GARD