Hereditary diseases of amino acid metabolism

Hereditary diseases of amino acid exchange occupy a special place in the huge variety of genetically determined diseases of childhood. Manifestations of this disease do not occur immediately, but after a certain time after birth. Most disorders of amino acid metabolism lead to severe irreversible disturbances in the psychomotor and physical development of children. The leading role in the diagnosis of hereditary defects in the exchange of amino acids belongs to biochemical methods. However, biochemical diagnostic methods that require large-scale studies using complex equipment and rare reagents are available mainly only to specialized centers for hereditary pathology and can not be widely used in conventional medical institutions. There is an opinion that those symptoms that arise in hereditary amino acid metabolism disorders are so similar that it is impossible to distinguish them without special methods of investigation. Nevertheless, to some extent this is feasible. On the basis of a detailed study of the manifestations of various hereditary disorders of amino acid metabolism, several groups of people are identified that are threatened by the development of such diseases for subsequent targeted laboratory testing. Each of the isolated groups corresponds to certain hereditary metabolic diseases of amino acids.

Children with the following abnormalities are subject to special laboratory examination:

1) combination of mental retardation with visual impairment;

2) the combination of mental retardation with convulsive syndrome;

3) change in odor or color of urine;

4) combination of damage to the liver and central nervous system;

5) a combination of mental retardation with skin lesions.

In this case, great importance is attached to the presence in this family of related marriages, patients with a similar disease, deaths in childhood for unexplained reasons. The first signs of the disease can be seen in the first half of life. The course of pregnancy and childbirth is also of great importance for the correct diagnosis of the disease, since the exchange of proteins can be disrupted not only as a result of a genetic defect, but also under the influence of other causes, for example, birth trauma.

Among the hereditary disorders of amino acid metabolism, there are a number of diseases that occur quite heavily. With such diseases, symptoms can be determined already in the first days or weeks of a child's life. A common feature of these disorders is the predominance of symptoms of central nervous system damage in the picture. A child who seems healthy at birth, on the 3rd-5th day of life refuses to eat, becomes sluggish, drowsy or, on the contrary, extremely excitable and restless, oppression of reflexes, changes in muscle tone( decrease or, conversely, increase), convulsions. In an extremely difficult case, lethargy and coma may occur. Also, the appearance of vomiting, a decrease in appetite, an increase in liver size, a violation of breathing, the development of hemorrhagic syndrome. In case of suspicion of a violation of protein metabolism, a purposeful laboratory examination is necessary. Thus, newborns who have convulsions in combination with breathing disorders and severe central nervous system depression( refusal to eat, lethargy, poor movement, progressive drowsiness, suppression of unconditioned reflexes, decreased muscle tone and reflexes, lethargy, coma) should bewere examined for non-ketotic hyperglycinemia and hereditary urea synthesis defects.