Phenylketonuria, or PKU, is a metabolic genetic disease that leads to the surplus of phenylalanine amino acid in the body. This anomaly appears due to the defective PAH gene encoding the enzyme which converts phenylalanine to tyrosine, which is, in turn, the precursor of an important neurotransmitter dopamine. The conversion failure causes an accumulation of phenylalanine, which affects the normal operation of the main brain messengers, among which is the serotonin, a molecule essential in the development of the central nervous system.
As it comes to infants, phenylketonuria can be easily diagnosed through neonatal screening on the fourth day of their life. In case of families-at-risk and when the possible mutations can be predicted, it is possible to make a prenatal diagnosis by genetic analysis. The positive test result means that there is a high concentration of phenylalanine in the baby's blood. Before the onset of neonatal screening and respective treatment, a high concentration of phenylalanine in the child’s blood was prejudicial to the proper development of the brain causing the mental retardation.


Phenylketonuria is a genetic disease, which means that the child inherits it from his mother and father – even in cases where PKU was absent in the previous generations.
It is possible that the parents of a child with PKU have one defective gene for to the phenylalanine-hydroxylase enzyme and one functional gene, but the disease still has not developed.
In children with phenylketonuria both genes that control the production of the phenylalanine-hydroxylase enzyme are defective.
Approximately 1 out of 50 people has a defective PKU gene, meaning that he is a still immune carrier. Three is a little chance that two carriers will encounter each other – only about 1 out of 2500, and for this reason PKU is defined as a rare disease: in Italy the annual number of children born with PKU is 60.


Special low-protein diet or protein-free diet that is low in phenylalanine render the treatment of phenylketonuria possible. By following this dietary therapy alongside the consumption of natural food in small amounts the intake of phenylalanine provided is sufficient to ensure a normal develpment. Because uncontrolled hyperphenylalaninemia can damage brain in the childhood, such a dietary restriction should be established from the first month of life and maintained throughout lifetime.


AMMeC (acronym in Italian) – Congenital Metabolic Diseases Prevention Association:
Online forum for phenylketonuria:


The DMF “Antifen”, “Phenylade” and “Xphe” products for people with phenylketonuria are the ideal solution for the growth by an adequate intake of essential amino acids except phenylalanine.