Information for US patients

What causes PKU?

Inheriting PKU

PKU is caused by a certain type of inherited metabolic disorder, whereby a person with the condition inherits one copy of the PKU genetic defect from each of their parents. Sometimes one or both parents have PKU themselves, but sometimes the parents are just carriers of the condition and do not have symptoms themselves. When two carriers of PKU have a child there is a one in four (25%) chance that the baby will have PKU.1

Lady in a florist


Happy family


Diagnosing PKU

In the United States, PKU is primarily diagnosed shortly after birth, via the Newborn Screening Program, where a blood sample is taken from the heel of the baby’s foot and sent for analysis.1

Early testing is important as it provides the opportunity to start treating a baby with PKU as early as possible. It is important to ensure that you, or your child, follows the medication, formula and diet instructions prescribed by your doctor, as when a treatment plan is followed children with PKU can expect to develop like any other child.1

Find out more about PKU treatment


1. National PKU Alliance. What is PKU –About PKU. Available at: (Accessed: June 9th 2022.)