Phenylketonuria
Phenylketonuria is a hereditary disease associated with a violation of the metabolism of an amino acid such as phenylalanine.
ETIOLOGY
The cause of the development of this disease is a genetic mutation, as a result of which the production of the enzyme phenylalanine-4-hydroxylase, which is necessary for the conversion of the amino acid phenylalanine into tyrosine, is disrupted. As a result of the impossibility of carrying out this reaction, phenylalanine and its metabolic products accumulate in the body. These substances, in turn, are toxic to the nervous system. They disrupt the processes of protein and fat metabolism, hormone production, amino acid transport, which has a particularly negative effect on the development and functioning of the brain.
It is noted that phenylketonuria is more common in girls and in children where parents are in a closely related marriage. The type of inheritance of the disease is autosomal recessive.
CLINICAL PICTURE
Symptoms of phenylketonuria do not appear immediately after birth, but as phenylalanine and its metabolic products accumulate in the body. Most often, the first manifestations of the disease develop at the age of 2 months, in the absence of treatment by 6 months, the picture becomes more distinct.
The first alarm signals are lethargy and apathy in the baby, although the child, on the contrary, can be anxious, easily excitable, vomiting episodes are possible. In addition, convulsive seizures of the epileptiform type may join over time, muscle hypertonicity, hyperkinesis, limb tremor, ataxia may be observed. Also, a specific sign is a kind of “mouse” smell coming from a child.
By the age of 6 months, a lag in mental development becomes obvious, up to the development of oligophrenia and idiocy.
In physical development, the lag is not so obvious, but it also exists. It is expressed by a decrease in the size of the skull, later teething, violation of crawling and walking. Their gait is also peculiar: children walk with small steps, swaying, and stand with their legs spread wide apart, bent at the hip and knee joints.
diagnostics
Since the development of the disease can be prevented, timely diagnosis is fundamentally important. Therefore, all children in the maternity hospital are screened for capillary blood. Full-term babies are usually tested on day 4-5, and premature babies on the seventh. The marker is the concentration of phenylalanine in the blood. If the indicators change, children are referred to a medical and genetic consultation, as well as under the supervision of a pediatrician and a gastroenterologist.
treatment
The main treatment consists in following a special diet after diagnosis. If the disease is not detected immediately, then it is only possible to prevent the aggravation of symptoms, but it will not be possible to fully restore the child’s health.
Initially, a diet is carried out with the exception of phenylalanine, which is contained in protein products (meat, eggs, offal, dairy products, fish). In addition, legumes, nuts, mushrooms, chocolate, cereals, bakery products are excluded. Protein hydrolysates and amino acid mixtures are used instead. The child can eat fruits, vegetable dishes. The sources of fats are vegetable and butter. Carbohydrates can also be included in the diet. Protein food is gradually added in limited quantities.
To adjust the diet and assess the condition, regular monitoring of the level of phenylalanine in the blood is necessary. At first, studies are conducted weekly, and as the condition stabilizes, once a month. At the age of one year, it is enough to conduct tests 1 time every 2-3 months.
A particularly strict diet should be observed during the period of active brain development – usually up to 12-14 years. After the recommendations of doctors vary: there is an opinion that patients with phenylketonuria should follow a strict diet for life, other experts believe that after puberty, patients can switch to regular food. In addition, research is underway in a number of countries to develop a drug, the use of which will help to significantly ease the diet.
forecast
With timely treatment, the prognosis is favorable. In our country, support is provided to families where there are patients with phenylketonuria. In particular, children are provided with special medical nutrition up to the age of 18, are observed in medical institutions and when registering a disability, are provided with social benefits.
