Mitochondrial diseases, and in particular the mitochondrial syndrome, which can be manifested by lesions of the central nervous system, heart and skeletal muscle pathologies, are today one of the most important sections of neuropediatrics.
Mitochondria - what is it?
As many remember from the school biology course, mitochondria is one of the cellular organelles, whose main function is the formation of an ATP molecule during cellular respiration. In addition, fatty acids are oxidized in it, the cycle of tricarboxylic acids and many other processes take place. Studies conducted at the end of the 20th century revealed the key role of mitochondria in such processes as drug sensitivity, cell aging, and apoptosis (programmed cell death). Accordingly, a violation of their functions leads to a lack of energy exchange, and as a result, damage and death of the cell. These disorders are especially pronounced in the cells of the nervous system and skeletal muscles.
Mitochondriology
Genetic studies have determined that mitochondria haveits own genome, which is different from the genome of the cell nucleus, and disturbances in its functioning are most often associated with mutations occurring there. All this made it possible to single out a scientific direction that studies diseases associated with impaired mitochondrial functions - mitochondrial cytopathies. They can be either sporadic or congenital, inherited through the mother.
Symptomatics
Mitochondrial syndrome can manifest itself in various human systems, but the most pronounced manifestations are neurological symptoms. This is due to the fact that the nervous tissue is most strongly affected by hypoxia. Characteristic signs that allow suspecting mitochondrial syndrome in case of damage to skeletal muscles are hypotension, inability to adequately tolerate physical activity, various myopathies, ophthalmoparesis (paralysis of the oculomotor muscles), ptosis. On the part of the nervous system, there may be stroke-like manifestations, convulsions, pyramidal disorders, mental disorders. As a rule, mitochondrial syndrome in a child is always manifested by a developmental delay or loss of already acquired skills, psychomotor disorders. On the part of the endocrine system, the development of diabetes, dysfunctions of the thyroid and pancreas, growth retardation, and puberty are not excluded. Heart lesions can develop both against the background of pathologies of other organs, and in isolation. Mitochondrial syndrome in this case is represented by cardiomyopathy.
Diagnosis
Mitochondrial diseases more oftenmost are found in the neonatal period or in the first years of a child's life. According to foreign studies, this pathology is diagnosed in one newborn out of 5 thousand. For diagnosis, a comprehensive clinical, genetic, instrumental, biochemical and molecular examination is carried out. To date, there are a number of methods to determine this pathology.
- Electromyography - with normal results against the background of pronounced muscle weakness in the patient, it is possible to suspect mitochondrial pathologies.
- Lactic acidosis very often accompanies mitochondrial diseases. Of course, its presence alone is not enough to make a diagnosis, but measuring the level of lactic acid in the blood after exercise can be very informative.
- Biopsy of skeletal muscle and histochemical examination of the resulting biopsy is the most informative.
- Good results show the simultaneous use of light and electron microscopy of skeletal muscles.
Mitochondrial encephalopathy (Ley syndrome)
One of the most common childhood diseases associated with genetic changes in mitochondria is Leigh's syndrome, first described in 1951. The first signs appear at the age of one to three years, but earlier manifestations are also possible - in the first month of life or, on the contrary, after seven years. The first manifestations are developmental delay, weight loss, loss of appetite, repeatedvomiting. Over time, neurological symptoms join - a violation of muscle tone (hypotension, dystonia, hypertonicity), convulsions, impaired coordination.
The disease affects the organs of vision: atrophy of the optic nerves, retinal degeneration, oculomotor disorders develop. In most children, the disease gradually progresses, signs of pyramidal disorders increase, swallowing and respiratory function disorders appear.
One of the children suffering from this pathology was Yefim Pugachev, who was diagnosed with mitochondrial syndrome in 2014. His mother, Elena, asks for help from all caring people.
Mitochondrial syndrome in a child
Forecast, unfortunately, today is most often disappointing. This is due both to the late diagnosis of the disease, the lack of detailed information about the pathogenesis, the severe condition of patients associated with the multisystemic lesions, and the lack of a single criterion for assessing the effectiveness of therapy.
Thus, the treatment of such diseases is still under development. As a rule, it comes down to symptomatic and supportive therapy.
