E70.0: Classical phenylketonuria

Your body is unable to properly process the amino acid phenylalanine.

Amino acids perform many different functions in the body. The body needs amino acids to, for example, produce proteins. Some amino acids have to be consumed via food. Other amino acids can be produced in the body. Phenylalanine is normally taken with food. It is increasingly found in meat, dairy products and pulses, for example. If phenylalanine cannot be processed properly, the phenylalanine consumed accumulates in the body.

If too much phenylalanine accumulates in the blood, it can damage the brain. In the case of babies and children, the brain is then unable to develop properly. The person’s mental capacities may then be restricted. To take in and use new knowledge, we need mental abilities. These include the abilities to speak, to concentrate, and to memorize things. Under certain circumstances the mental abilities may not develop properly. You may then have difficulties in dealing with other people. Movements may also be changed.

If children repeatedly have excess phenylalanine in their blood, their development is generally delayed. They may be smaller than usual and have a smaller head circumference. Seizures can also occur. Certain mental disorders can occur more frequently than normal, too. For example, it can be difficult to concentrate for a long period of time. An increased need to move is also possible.

As a result of the disorder you can have paler skin and hair and a paler eye color than family members who do not have this condition. Typically, there is also an unpleasant body odor.

Early, sustained treatment of the disorder can prevent the symptoms to some extent. Symptoms may nonetheless be present. These include mental disorders, for example.

The disease is hereditary. It occurs when certain segments of genetic information are changed. The genetic information holds a complete blueprint of the body's structure. The disorder can occur if both parents carry the changed genetic information. The parents can pass the changed genetic information on to their children without falling ill themselves.