What exactly is PKU?
PKU belongs to a class of diseases that doctors call “inherited metabolic diseases,” or “inborn errors of metabolism.” In these diseases, the body can’t do certain chemical processes required for normal growth and development.2 For people with PKU this means that a certain enzyme is broken.1 Usually, the body uses the enzyme to break down an amino acid called phenylalanine, or Phe. Once Phe is broken down, the body uses it to make another amino acid called tyrosine.1 In people with PKU, the enzyme doesn’t work to break the Phe down into tyrosine. Phe builds up in the body and brain.
