Phenylketonuria (PKU) is a genetic disorder characterized by the body's inability to properly process phenylalanine due to a significant lack of the enzyme phenylalanine hydroxylase. Newborns are typically tested for PKU using a blood sample collected via a heel prick, often on a Guthrie card. Management of the condition involves adhering to a diet low in phenylalanine to maintain normal blood levels and prevent potential brain damage. If not treated, PKU can lead to severe and permanent intellectual disabilities, microcephaly, and behavioral issues. It is crucial to maintain the dietary restrictions, particularly during pregnancy, to avoid any cognitive impairments. PKU is an inherited condition, passed down in an autosomal recessive pattern, similar to other forms of phenylalanine hydroxylase deficiency.