Which condition is a result of a deficiency in the enzyme phenylalanine hydroxylase?

Phenylketonuria (PKU) is caused by a deficiency in the enzyme phenylalanine hydroxylase, which plays a crucial role in the metabolic pathway that converts phenylalanine into tyrosine. When this enzyme is deficient or absent, phenylalanine accumulates in the body to toxic levels, leading to neurological damage and cognitive impairment if not managed with a dietary restriction of phenylalanine.

In PKU, the lack of proper conversion results in the increased levels of phenylalanine, which can cause significant developmental issues, including intellectual disability, seizures, and behavioral problems. Newborn screening for PKU is critical, as early detection and management can significantly improve outcomes.

In contrast, the other conditions listed involve different metabolic pathways and are not the result of phenylalanine hydroxylase deficiency. Maple Syrup Urine Disease is associated with a deficiency in branched-chain alpha-keto acid dehydrogenase, homocystinuria results from issues with cystathionine beta-synthase or other enzymes involved in homocysteine metabolism, and alkaptonuria is due to a deficiency in homogentisate oxidase. Each of these conditions has its own unique biochemical basis and clinical