Phenylketonuria I

Classical phenylketonuria was described in 1934. The disease is transmitted by an autosomal recessive type. The basis of phenylketonuria is the deficiency of the enzyme, which ensures the conversion of the amino acid phenylalanine into the amino acid tyrosine. As a consequence, a large amount of phenylalanine and various acids that are its derivatives accumulate in the tissues and liquids of the diseased organism. The leading role in the development of phenylketonuria has the toxic effect of phenylalanine on the central nervous system. In addition, with phenylketonuria, the exchange of proteins, fats and hormones is disturbed. Also, a certain value in the formation of disorders of the central nervous system has a dysfunction of the liver, since in this case it does not cope with such a huge amount of toxic products appearing in the body, which are normally neutralized in this organ.

Classical phenylketonuria is the most common disease from the group of protein metabolism disorders. Due to the severe course and the possibility of preventive treatment, this disease is recommended for screening among all newborns. For this purpose, newborns aged 5-7 days take blood and make a special laboratory study. Screening, the so-called given study, is the earliest method of diagnosing the disease in childhood. The detection of the disease before the 8-month-old age ensures the full development of the child. In our country, a massive survey is not implemented in all regions, which explains such a large number of late diagnosed forms of phenylketonuria. Usually the development of the first signs in early childhood can already be observed in 2-6 months. As a rule, the earliest symptoms of the disease are: sluggishness of the child, irritability, anxiety, regurgitation, reduction of muscle tone. Urine in these children acquires a "mouse" odor. In the future, as the child grows, if he has not received treatment, mental retardation develops, in some cases it reaches a deep degree. The appearance of children with phenylketonuria also has its own peculiarities: the skin color, hair and iris are much paler compared to healthy children, which is explained by the low content of melanin pigment in them.

Diagnostics of phenylketonuria is based on a combination of symptoms of the disease, information on the pedigree of the sick child( possible close marriage, a similar disease in close relatives), as well as the results of laboratory studies. Characteristic laboratory signs of phenylketonuria are an increase in the blood content of the amino acid phenylalanine, the appearance in the urine of its derivatives, primarily phenylpyruvic acid, which can be detected using special samples.

Molecular genetic methods for the diagnosis of phenylketonuria are currently being developed. The object of investigation for such diagnostic methods are lymphocytes, chorionic cells and amniotic fluid. Defining a genetic defect with DNA probes is the most reliable diagnostic method, the accuracy of which reaches 100%.

The main way to treat phenylketonuria is to observe a strict diet that excludes the intake of protein and amino acid phenylalanine into the body. The food ration of patients includes vegetables, fruits, juices, as well as special products containing a minimum amount of protein( bread, pasta, cereals, cooked on starch basis).To compensate for the deficiency of protein, children are given protein preparations that are devoid of phenylalanine. Also, patients with phenylketonuria need vitamins( especially group B).In parallel with dieting and taking vitamins, medical therapy is necessary. Drug treatment includes various drugs from the group of nootropics( nootropil, fesam, pyracetam, etc.), anticonvulsants, as well as preparations from the ATP group. Non-pharmacological methods of treatment of phenylketonuria include methods of physiotherapy, such as massage and physiotherapy exercises with repeated courses.

Currently, the question of the duration of treatment and the possible timing of its completion remains unresolved. It is known that the expansion of diet in younger school age inhibits the thinking abilities of children, negatively affects their behavior, attention, memory, ie, adversely affects the function of the brain.