Phenylketonuria (PKU) is a disease that is directly related to a violation of amino acid metabolism and leads to damage to the central nervous system. Phenylketonuria is predominantly found in girls. Often sick children are born to healthy parents (they are heterozygous carriers of the mutant gene). Related marriages only increase the number of children born with such a diagnosis. Phenylketonuria is most often observed in northern Europe - 1: 10000, in Russia with a frequency of 1: 8-10000 and in Ireland - 1: 4560. Negroes have almost no PKU.
Phenylketonuria - causes
At the heart of phenylketonuria is an enzyme deficiency called phenylalanine-4-hydroxylase, which synthesizes phenylalanine into tyrosine. this implies a large accumulation in the body fluids and tissues of phenylalanine and its derivatives (phenylacetic, phenyllactic, and phenylpyruvic acids, as well as phenylethylamine, phenylacetylglutamine, etc.), which have a toxic effect on the central nervous system and cause disturbances in the metabolism of glyco- and lipoproteins, protein metabolism and hormone metabolism; cause metabolic disorders of serotonin and catecholamines, disorders of amino acid transport, perinatal factors.
Phenylketonuria - Symptoms
The newborn looks completely healthy, the first symptoms of the disease begin to appear when the child reaches 2-6 months. Phenylketonuria is manifested by severe weakness, lack of interest in the environment; anxiety, vomiting, and increased irritability may appear. Already after the child reaches six months of age, you can notice some of his lag in mental development.
The growth of the baby can be normal or reduced. There is also a decrease in the size of the skull, later teething, the baby later begins to sit and walk. Such children are distinguished by their peculiar posture and gait: they walk in swaying, small steps, lowering their shoulders and head, legs spread wide, which are bent at the hip and knee joints.
Also, patients are seated in the “tailor position”, that is, with legs tucked up, which is associated with increased muscle tone. In most cases, phenylketonuria affects fair-haired, blue-eyed children, in whom the skin is completely devoid of pigmentation. Some of these patients have epileptic seizures, a "mouse" smell is characteristic, but they disappear with age. Cyanosis and dermophragism of the extremities, sweating, and increased sensitivity to injuries and sun rays are expressed. More often phenylketonuria in children is manifested by dermatitis, severe eczema, hypotension and a tendency to constipation.
Phenylketonuria - diagnosis
To prevent the irreversible effects of PKU, its diagnosis is carried out immediately after birth. In the maternity hospital on the 4th-5th day of life of a full-term baby and on the 7th - a premature baby takes blood for examination. A drop of capillary blood is impregnated with a special paper form. If the concentration of phenylalanine in the blood is more than 2.2 mg%, then the baby with the parents is sent to the medical-genetic center for examination, further examination and diagnosis.
Phenylketonuria - treatment and prevention
Phenylketonuria is currently treated with the only method - timely organized diet therapy, which is based on the principle of limiting phenylalanine in food. At the same time, products containing an increased amount of protein (cottage cheese, fish, meat, chocolate, cereals, legumes, eggs, baked goods, nuts, etc.) are completely excluded from the diet. In clinical nutrition of patients at PKU, specialized products of foreign and domestic production are used.
For the nutrition of children up to a year, the products are similar in composition to breast milk - Lofenilak, Atenilak and others mixtures. For older children, the use of mixtures of "Maxamum-XP", "Tetrafen", "Phenyl-free" is recommended. For patients with phenylketonuria, the source of fat is butter, ghee, and vegetable oil. Juices, sugars, fruits and vegetables are also included in the diet. Sick children are constantly monitored by a neuropsychiatrist and local pediatrician. The serum phenylalanine content is also regularly monitored according to a special schedule.
