Children and adults who do not receive treatment for PKU may develop a variety of symptoms.
- Children with PKU who are not treated may develop symptoms including behavioral problems, seizures, and severe intellectual and developmental disabilities.1
- Adults with PKU who do not follow a special diet may develop unstable moods2 and take longer to process information.3 Adults with high phenylalanine levels who go back on a PKU diet may be able to improve their mental functioning and slow down any damage to their central nervous systems.4
- Pregnant Women with PKU who do not strictly follow a low-phenylalanine diet may give birth to a child with serious problems, including intellectual and developmental disabilities, a head that is too small (microcephaly), heart defects, and low birth weight.5 Read more about maternal PKU. Women with PKU and uncontrolled phenylalanine levels also have an increased risk of pregnancy loss.6