Phenylketonuria(PKU)is a rare condition caused by the body's inability to properly breakdown an amino acid called phenylalanine(PHE), due to a missing enzyme, phenylalanine hydroxylase(PAH). When the enzyme is missing and/or not functioning properly, it increases the level of PHE in the body. High levels of PHE can cause severe brain damage or nerve damage unless the children are on a strict low PHE diet. A low PHE diet restricts the intake of protein rich foods and can pose a significant burden to both the patient and the family.