phenylketonuria (pku) a human disease characterized by mental retardation results from the
Phenylketonuria Phenylketonuria is a genetic disorder inherited from a person's parents.[1] It is due to mutations in the PAH gene, which results in low levels of the enzyme phenylalanine hydroxylase.[1] This results in the buildup of dietary phenylalanine to potentially toxic levels.[1] It is autosomal recessive, meaning that both copies of the gene must be mutated for the condition to develop.[1] There are two main types, classic PKU and variant PKU, depending on if any enzyme function remains.[1] Those with one copy of a mutated gene typically do not have symptoms.[1] Many countries have newborn screening programs for the disease.[3]