What is Phenylketonuria?

Phenylketonuria (PKU) is the most common inborn error of amino acid metabolism mainly caused by a deficiency of phenylalanine hydroxylase (PAH), an enzyme that convert phenylalanine to tyrosine which body needs to create neurotransmitters. Phenylalanine is found in all proteins and in some artificial sweeteners. Deficiency of PAH can result in the accumulation of excess phenylalanine to a harmful level that causes severe and irreversible intellectual disability if untreated. PKU initially do not have any symptoms. However, without treatment, babies usually develop signs of PKU within a few months.

Signs and Symptoms