Mitochondrial diseases, and in particular 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 ATP molecules in the process of cellular respiration. In addition, fatty acids are oxidized in it , a cycle of tricarboxylic acids and many other processes take place. Studies conducted at the end of the 20th century have revealed the key importance of mitochondria also in processes such as drug sensitivity, cell aging , apoptosis (programmed cell death). Accordingly, a violation of their functions leads to insufficient energy exchange, and as a result, damage and cell death. These disorders are especially pronounced in the cells of the nervous system and skeletal muscles.
Mitochondriology
Genetic studies have made it possible to determine that mitochondria have their own genome, 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 field that studies diseases associated with impaired mitochondrial functions, mitochondrial cytopathies. They can be either sporadic or congenital, inherited through the mother.
Symptomatology
Mitochondrial syndrome can manifest itself in various human systems, but the most pronounced manifestations receive neurological symptoms. This is due to the fact that nervous tissue is most susceptible to hypoxia. Hypotension, inability to adequately tolerate physical activity, various myopathies, ophthalmoparesis (paralysis of the oculomotor muscles), ptosis are characteristic signs that make it possible to suspect mitochondrial syndrome in case of skeletal muscle damage. From the nervous system, there may be stroke-like manifestations, convulsions, pyramidal disorders, mental disorders. As a rule, the mitochondrial syndrome in a child is always manifested by a developmental delay or loss of already acquired skills, psychomotor disturbances. The endocrine system does not exclude the development of diabetes, dysfunctions of the thyroid and pancreas, growth retardation, puberty. 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.
Diagnostics
Mitochondrial diseases are most often detected during 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 a background of pronounced muscle weakness in the patient, mitochondrial pathologies can be suspected.
- Lactic acidosis very often accompanies mitochondrial diseases. Of course, only his presence is not enough to make a diagnosis, but measuring the level of lactic acid in the blood after exercise can be very informative.
- Skeletal muscle biopsy and histochemical examination of the obtained biopsy is the most informative.
- Good results show the simultaneous use of light and electron microscopy of skeletal muscles.
Mitochondrial Encephalopathy (Leu Syndrome)
One of the most common childhood diseases associated with genetic changes in mitochondria is Leah syndrome, first described in 1951. The first signs appear at the age of one to three years, but earlier manifestations are possible - in the first month of life or, conversely, after seven years. The first manifestations are delayed development, weight loss, loss of appetite, repeated vomiting. Over time, neurological symptoms join - impaired muscle tone (hypotension, dystonia, hypertonicity), cramps, 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, disorders of swallowing and respiratory function appear.
One of the children suffering from such a pathology was Pugachev Yefim, whose mitochondrial syndrome was diagnosed in 2014. His mother, Elena, asks for help from all concerned people.
Mitochondrial syndrome in a child
The 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 serious condition of patients associated with the multisystem of lesions, and the lack of a single criterion for evaluating 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.