Untreated PKU can lead to: Irreversible brain damage and marked intellectual disability beginning within the first few months of life. Neurological problems such as seizures and tremors. Behavioral, emotional and social problems in older children and adults.

How does phenylalanine affect the brain?

The high plasma phenylalanine concentrations increase phenylalanine entry into brain and restrict the entry of other large neutral amino acids. In the literature, emphasis has been on high brain phenylalanine as the pathological substrate that causes mental retardation.

Does phenylketonuria cause mental retardation?

After all, PKU is a rare, genetic disorder of amino acid metabolism identified at birth by pediatricians and treated by geneticists. But, PKU is also a disorder that, if left untreated, leads to severe behavioral difficulties and ultimately mental retardation.