Phenylketonuria - what is it? Symptoms, diagnosis and treatment. How is phenylketonuria inherited

A huge amount of hereditary diseases that the child receives from the father or from the mother is being diagnosed Ecological conditions, unhealthy diet, unhealthy lifestyle - all this leads to the fact that cells mutate, genetic information undergoes significant changes. It is from this that a huge number of hereditary diseases arise. One of them is phenylketonuria. Not many people know what this disease is, so we will try to figure it out.

Essence of the concept

Phenylketonuria is a hereditary disease, it is associated with serious disorders in protein metabolism. This, in turn, leads to damage to the nervous system.

The inoperability of just one enzyme, phenylalanine, and as a result, such serious health problems as phenylketonuria.What is this condition when a large amount of toxic substances accumulate in the body? All toxic compounds are stored in biological fluids, so it is usually not difficult for doctors to diagnose the disease.

phenylketonuria what is it

If you do not take action in time, you can observe serious damage to the nervous system, and this already leads to disruptions in the functioning of the whole organism.

Thus, without appropriate treatment, the patient’s normal life is out of the question.

Causes of disease

All proteins are composed of amino acids, of which only 20, but among them are those that are synthesized in the human body. Some should only come from outside. Phenylalanine is also an essential amino acid. In a healthy person, he, getting inside, turns into tyrosine. It is a completely different amino acid, and only a few percent of the substance is sent to the kidneys and there is converted to phenylketone, a fairly toxic substance.

If a person does not have the enzyme phenylalanine-4-hydroxylase, or the one that turns phenylalanine into another substance,then in this case phenylketonuria develops. Every doctor will tell you that this is quite a serious symptom, so urgent measures should be taken.

And a gene mutation in chromosome 12 can lead to the absence of the desired enzyme. 12

Varieties of phenylketonuria

If we consider the forms of the disease, they may be:

  1. Classic. In this case, we observe that phenylketonuria is a recessive symptom. Such a form occurs in one child per ten thousand healthy children. If you do not take action, it is unlikely that a sick person will live to thirty years.
  2. Variable form. It is not inherited, but causes its mutation in the genes. Its course is more severe, and early mortality is predicted with a probability of almost 100%.

phenylketonuria disease

In addition to forms, doctors also distinguish types of phenylketonuria:

  1. The first type is characterized by the fact that there is a lack of the enzyme phenylalanine-4-hydroxylase, which is responsible for the conversion of phenylalanine. In 98% of cases he is diagnosed.
  2. Second. It is distinguished by a low content of the enzyme dihydropteridin reductase. Such patients have convulsions, as well as mental retardation.Despite its rare occurrence, mortality from this type can occur at 2–3 years of age.
  3. The third type is characterized by the fact that tetrahydrobiopterin deficiency occurs. As a result, there is a decrease in brain volumes, which leads to mental retardation.

Symptoms of the disease

Immediately after the birth of a child, it is difficult to diagnose the disease by its appearance or behavior. The main symptoms will begin to appear a little later. However, even in the maternity hospital, doctors are quite capable of making a diagnosis of phenylketonuria. Symptoms of this disease are as follows:

  • frequent vomiting for no apparent reason;
  • tearfulness;
  • lethargy;
  • rash may appear all over the body;
  • urine has a "mouse" smell;
  • the child is lagging behind in physical and mental development from his peers.

It is enough to take a blood test and urine to make the correct diagnosis.

Signs of Phenylketonuria

Gradually, in the absence of proper treatment, the patient will be able to observe such signs:

  1. Convulsive syndrome. It begins to manifest itself in early childhood and persists in adults.
  2. Lack of pigment in the skin and hair.Therefore, such patients are usually blond and have white skin.
  3. Inflammatory processes that unknowingly can be mistaken for an allergic reaction.

signs of phenylketonuria

The first signs of mental retardation can be seen in a child already at the age of six months. He ceases to memorize new information, and it seems that he is completely incapable of learning. Parents should be wary when the baby forgets what it has long learned, for example, how to hold a spoon, sit, play with a rattle. The alarm must be beaten even if the child stops recognizing parents and loved ones, as well as excessive tearfulness does not pass with age.

Here are the signs that phenylketonuria has, the symptoms of the disease should be considered only in combination, because separately they may well occur in healthy children.

Disease detection

You can make a correct diagnosis in two ways:

  1. Conduct a blood and urine test for a newborn while still in the maternity hospital. this is usually done in all cases.
  2. Determine the presence of phenylketones in the biological fluids of an adult with relevant signs.

The children in the hospital take blood on the 4-5th day and determine the content of phenylalanine. If it is found, then the child with the mother is sent for a consultation to the genetics.

phenylketonuria symptoms

Before discharge, be sure to ask if your child has been tested for phenylketonuria. Despite the small incidence of this disease, the best solution would still be to insure.


Since phenylketonuria is inherited as a recessive trait, for a child to manifest it, it is necessary that both parents have a defective gene. That is why kinship marriages are prohibited in many countries.

If we consider the case of the birth of children in an ordinary family, then the carriers of such a mutation can have them:

  1. 25% chance of a baby being born sick.
  2. In 50% of cases, the baby is healthy, but is the carrier of the defective gene.
  3. The fourth part of the offspring will be absolutely normal.

phenylketonuria is inherited

This scheme does not give a complete picture of the birth rate of sick children. It only reflects the probability, so each married couple may have its own percentage of defective genes, and, unfortunately, it is impossible to predict the outcome. There are now consultations in which geneticists help couples predict the birth of a sick child in them, while telling how phenylketonuria is inherited.


As soon as the child is diagnosed, measures must be taken immediately. First of all, you need to exclude from the diet protein foods. It is necessary to observe such strict restriction up to 10-12 years, and it is better and all life.

Since babies are breastfed and usually do not use anything other than breast milk, doctors recommend that mother reduce her baby’s intake. It is possible to do this only under one condition: give the baby expressed milk to accurately see its quantity.

Feed will have mixtures that do not contain phenylalanine. When it comes to the introduction of complementary foods, it is necessary to choose mashed potatoes and porridge without adding milk. You can give juices, vegetable puree.

The doctor must prescribe and drug treatment. Usually these are drugs that contain phosphorus, because this element is not for nothing considered to be an “element of life and thought,” since it plays an important role in the work of our brain. Also prescribed drugs containing iron, calcium, they help to improve blood circulation and brain activity.

Treatment should not be reduced to the complete elimination of phenylalanine, as in this case it can be observed a lack of it, which leads to loss of strength, loss of appetite.In addition, diarrhea begins and skin rash appears.

To find out how effective the treatment is, periodically take a blood and urine test for phenylalanine.

Children's disease

It is in childhood that the organism develops at a pace that will not be at other times in life. Therefore, at this time it is important to take all measures for the normal development of the nervous system. Children with phenylketonuria need not only medication and special nutrition, but also a special attitude.

First of all, it is a constant attention so that the slightest deviations in development will not hide from the mother’s keen eyes. You can apply the following treatments:

  • physiotherapy, which will help the child develop normally physically;
  • massage;
  • psychological help;
  • correctional pedagogy.

children with phenylketonuria

Parents should understand that the life and health of their child will be more dependent on themselves. What kind of environment they can create around a sick baby, how accurately the recommendations of doctors on nutrition will be observed, whether close people will react to deviations in mental and physical development - all these moments are very important.

Traditional medicine to get rid of the disease

Folk recipes are used in the treatment of many diseases. No exception and phenylketonuria. That this disease will require a review of the whole way of life is a fact. The child must grow up and have an idea of ​​his illness. Parents are obliged to explain to him in an accessible form when he will be able to realize the information received, how serious is his position. Diet and treatment must be followed throughout life. Only in this case, you can guarantee a full existence.

Folk healers with phenylketonuria recommend eating more plant proteins. In such food, phenylalanine is much less than in animal products. Do not enter into the diet to enter fruits and vegetables. They contain many vitamins and microelements, which are indispensable for the normal functioning of the nervous system. That is, traditional medicine is of the opinion that it is desirable for such a patient to follow a vegetarian diet.

Food with phenylketonuria

Phenylalanine is found in almost all foods that have protein. It is necessary to try to eliminate them from your diet, and first of all it concerns milk and meat.

If phenyketonuria is diagnosed, nutrition should be reviewed first.All products can be divided into several groups:

  1. Always allowed to use: potatoes, sugar, tea, vegetable oils.
  2. You can use in small quantities: rice, honey, butter, bakery products, vegetables and fruits.

It is completely necessary to exclude from your menu: eggs, fish and meat, milk, pasta, legumes, nuts, corn, dairy products, chocolate.

phenylketonuria food

Given the fact that phenylalanine is converted into tyrosine in a healthy body, patients with phenylketonuria should include foods that contain it in sufficient quantity in the diet. To such food can be attributed to mushrooms and vegetable components.

Future forecast for phenylketonuria

Obviously, the disease requires immediate action, otherwise the person’s life will be short.

Phenylketonuria disease requires careful attention to the patient. If you follow a strict diet and follow all the recommendations of doctors, then the child will be able to grow and develop normally. The prognosis will also depend on which diseases accompany the genetic ailment and whether there are other pathologies.

Gradually, with age, the body can to some extent adapt to the increased content of phenylalanine, so you can sometimes allow easing in the diet. The main thing is not to get carried away by these weaknesses and stop in time and switch to proper nutrition.

If a woman suffers from this ailment, then she will have to deal more strictly with the observance of all the recommendations, because she is the future mother. Only in this case, she has the opportunity to give birth to a healthy child.

This is especially true given that the methods of prevention of this disease are practically non-existent.

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