Which of the following metabolic disorders is characterized by an impaired ability to convert phenylalanine to tyrosine due to a deficiency of the enzyme phenylalanine hydroxylase?

Phenylketonuria (PKU) is a metabolic disorder caused by a deficiency of the enzyme phenylalanine hydroxylase, which is necessary for the conversion of phenylalanine to tyrosine. This leads to the accumulation of phenylalanine in the body, causing intellectual disability and other symptoms if left untreated.