Phenylketonuria (PKU)

What is phenylketonuria (PKU)? Phenylketonuria (PKU) is a rare genetic disorder in which the body cannot break down an amino acid called phenylalanine (say "fehn-uhl-AL-uh-neen"), which is a part of protein. This substance is found in breast milk, many types of baby formula, and most foods, especially those with a lot...