Phenylketonuria—Past, Present, and Future Directions

Phenylketonuria (PKU) is an autosomal recessive inborn error of metabolism with an incidence that varies throughout the world. PKU is caused by loss of function variants in the phenylalanine hydroxylase gene. This loss of function leads to the accumulation of an amino acid, phenylalanine (Phe), that can reach toxic levels in the blood. PKU is managed with a medical diet and sometimes with medication. If diagnosed early and with strict dietary control, neurocognitive deficits can be prevented. There is an important need to ensure the timely diagnosis of PKU and to develop newer therapies to treat this metabolic disorder.