What is the role of heredity in Friedreich's hereditary ataxia and is it possible to treat it?

Friedreich's ataxia is a rare disease characterized by malfunctions in the nervous system. It is inherited through recessive autosomes. Affected cords of the spinal cord, mainly - lateral and posterior. Then the disorder progresses and causes mass destruction of the cells of the spinocerebellar tract. In the absence of proper treatment leads to degeneration and death of the cranial nerves, the cerebellum, as well as to disruptions in the operation of the cerebral hemispheres.

Cytological and biochemical basis of the development of the disease

The main reason is a failure in the metabolism of iron in the body. It is concentrated in the mitochondria and disrupts the processes of cellular respiration. As a result, the number of free radicals increases sharply inside the cell, which enter into chemical reactions and destroy the cell. Disturbances in glandular metabolism are caused by abnormalities in the synthesis of protein - frataxin. Either it is produced in insufficient quantities, or with a distorted structure. Frataxin regulates the transfer of iron in the mitochondria and, if necessary, reduces the content of cytosolic iron.

As a result of disturbances in metabolic processes, the genes responsible for the production of permease and ferroxidase are activated. These enzymes have frataxin-like functions and are almost not observed in healthy people. Their increased production is one of the symptoms of Friedreich's ataxia. It leads to an even greater excess of iron in the cells.

Heredity

The transmission of the disease is inherited by the Friedreich disease gene, there is no precise information about its location, however, scientists suggest that it is localized in the ninth chromosome. The gene is capable of mutating in various ways, these are explained by several varieties of the course of the disease. Almost half of all known ataxias are Friedreich's ataxia. Clinical symptoms appear at the age of 20 years, much less often in 25-30 years. And women and men get sick with the same frequency. Not once this disease was not recorded only in representatives of the Negroid race. Therefore, scientists believe that the origins of the disease should be sought specifically for the specific chromosomes of the European race.

The cells of the central nervous system suffer the most, the elements of the peripheral nervous system are much less susceptible to destruction. So far, it has not been possible to explain why only spinal cord pathways are affected. In the cardiovascular system, the tissue of the myocardium is affected, in the pancreas - islets of Langerhans. Often there are visual disturbances due to destruction of retinal tissue and a violation of the synthesis of bone cells - osteocytes.

The disease is constantly progressing over time. In the absence of proper therapy, the lethal outcome occurs within 20 years of the onset of the first symptoms. First the following symptoms appear:

• uncertain gait
• coordination disorder
• dysarthria

After a while the patient is unable to control her movements and can not move without help. In case of adequate treatment and in the absence of other chronic diseases, patients can live up to 80 years.

Symptoms of the disease

Early manifestations include the inhibition of knee and Achilles reflexes. These symptoms appear long before the others and are usually observed at the age of 13-16.Often they are accompanied by rheumatic heart disease.

Not always the specialist assumes the presence of a rare disease, so the primary symptomatology is often taken for a separate disease and treated appropriately. And only in a few years there are specific signs of skeletal deformation: scoliosis, deformity of the joints of the limbs. The clinical symptom is "Friedreich's foot," an atypically concave foot. Also there is excessive mobility of the fingers in the joints - the patient can flex his fingers without effort.

Friedreich's hereditary ataxia is diagnosed in advanced form with the following symptoms:

• muscle hypotension, a critical decrease in the tonus of skeletal muscles
• Babinsky
• azflexia
• absence of vibration sensitivity

All these signs are characteristic for any type of nervous ataxia. At the final stages of the development of cerebellar ataxia, complete muscle atrophy and there is a constant weakness.

In 85% of patients, in addition to the main symptomatology there are accompanying disorders: hormonal disorders, endocrine system disorders, cataracts, retinal regression, heart muscle lesions. Often develop a variety of cardiomyopathies, characterized by increased heart rate, tinnitus, causeless dyspnea, pain in the thoracic region. From the side of the endocrine system, the ovaries, the pancreas, are most affected.

Diagnosis of the disease

Previously widely used computed tomography, but recent studies prove its low efficiency. To successfully diagnose Friedreich's ataxia, a comprehensive examination and specific tests are needed. In the first place, a magnetic resonance examination is carried out, which makes it possible to detect changes in the nervous tissue of the spinal cord even at an early stage. To determine the severity of the lesion of the nervous system use electrophysiological diagnostics.

Glucose tolerance tests are performed to confirm the diagnosis, as well as X-ray examination of the spinal column. The whole complex of diagnostic measures is aimed at successfully distinguishing diseases from other nervous disorders with similar symptoms. Similar signs have multiple sclerosis, as well as some diseases associated with metabolic disorders.

DNA testing is also conducted and a consultation with a medical geneticist is scheduled. Often a full biochemical blood test is used for diagnosis. Timely diagnosis and proper treatment of Friedreich's ataxia prevent serious complications. With constant supervision of a specialist, the quality of life of patients does not decrease.

Treatment of the disease

First of all, drugs are prescribed that normalize the exchange of iron in the mitochondria. Then - antioxidants and drugs that bind free radicals. Without fail, patients take vitamins A and E, as well as specific chemicals that slow down the process of destruction of the nervous tissue.

Otherwise, the treatment is selected depending on the symptomatology. Concomitant therapy is aimed at relieving pain and other unpleasant manifestations.

The appointment of physiotherapy and physiotherapy exercises is very effective. The muscles of the patients need constant maintenance of the tone, physiological therapy helps to relieve the pain and maintains the working capacity of the muscle tissue.

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