Phenylketonuria is a common amino acid metabolic disorder primarily caused by a deficiency of phenylalanine hydroxylase. This deficiency prevents phenylalanine from being converted to tyrosine, leading to the accumulation of phenylalanine and ketone bodies, which are then excreted in large amounts in the urine. This disease is relatively common among genetic amino acid metabolic disorders and is inherited as an autosomal recessive trait. Additionally, due to the lack of phenylalanine hydroxylase, phenylalanine is metabolized through another pathway, resulting in increased production of phenyllactic acid and phenylacetic acid, which are excreted through sweat and urine, giving off a mouse-like urine odor.