Why is phenylketonuria included in newborn screening programs?

Phenylketonuria (PKU) is included in newborn screening programs because it is a treatable inborn error of metabolism that, if left undetected, leads to severe and irreversible intellectual disability and other neurological damage.12

The condition is caused by a deficiency in the enzyme phenylalanine hydroxylase, which prevents the body from properly metabolizing the amino acid phenylalanine. When phenylalanine accumulates in the blood and tissues, it interferes with normal brain development.34

Mandated screening allows for early diagnosis—typically via a simple blood test shortly after birth—which is critical for clinical success. By implementing a strict, low-phenylalanine diet early in life, affected children can prevent the onset of cognitive dysfunction and lead full, healthy, and productive lives. Because early intervention is the only way to avoid permanent damage, screening is considered a vital public health practice.124