Phenylketonuria (PKU), or phenylalanine hydroxylase (PAH) deficiency, is a lifelong, inborn error of metabolism that causes an amino acid, known as phenylalanine (Phe) to build up in the blood. High or unstable blood Phe levels can cause a variety of signs and symptoms, including mental, behavioral, neurological, and physical problems.
There is good news because PKU can be treated. With newborn screening, infants are diagnosed early; many symptoms can be prevented with prompt, continuous, and lifelong treatment.
Treatment guidelines recommend beginning treatment as early as possible, starting dietary treatment within the first week of life.1
People with PKU—babies, children, and adults—need to follow a diet that limits the amount of Phe, which is found in large amounts in high-protein foods such as chicken, meat, eggs, dairy, nuts, grains, and legumes. It has been shown that elevated blood Phe levels can cause a variety of signs and symptoms including mental, behavioral, neurological, and physical problems. However, it has also been shown that those who continue lifelong treatment will have lower blood Phe levels, which may result in better physical and mental health outcomes. This is why it is so important to learn how to manage PKU early.
Reference: 1. Vockley J, Andersson HC, Antshel KM, et al; for the American College of Medical Genetics and Genomics Therapeutic Committee. Phenylalanine hydroxylase deficiency: diagnosis and management guideline. Genet Med. 2014;16(2):188-200.