Signs and symptoms
... Newborns with PKU don''t show any outward indication of this underlying genetic defect. Without treatment, though, these babies typically develop signs and symptoms of PKU within a few months. Signs a...

Causes
... PKU is caused by a mutation in a single gene. In normal circumstances, this gene contains the instructions for making phenylalanine hydroxylase (PAH) — an enzyme necessary for processing the ami...

Risk factors
... The risk of inheriting PKU really comes down to genetics. Children with two parents who carry at least one copy of the mutated gene for PKU are the only ones at risk of developing this condition. The ...

When to seek medical advice
... If routine newborn screening tests indicate that your baby may have PKU, you''ll need to see a doctor immediately, to prevent problems before they start. You may also be referred to a doctor who speci...

Screening and diagnosis
... Almost all cases of PKU are found through newborn screening. All 50 states in the United States require that newborns be tested for PKU. Canada and many other countries also routinely screen infants f...