What enzyme deficiency leads to the condition known as phenylketonuria (PKU)?

Phenylketonuria (PKU) is primarily caused by a deficiency in the enzyme phenylalanine hydroxylase. This enzyme is crucial for the conversion of phenylalanine, an amino acid found in many protein-rich foods, into tyrosine. In individuals with PKU, the lack of sufficient phenylalanine hydroxylase results in the accumulation of phenylalanine, which can lead to severe intellectual disability and other neurological issues if not managed through dietary restrictions.

The understanding of this specific enzyme's function is vital in the context of managing the condition. Dietary interventions aimed at reducing phenylalanine intake can prevent the harmful effects of its accumulation. Monitoring phenylalanine levels is also an essential part of care for those diagnosed with PKU.

The other enzymes listed do not play a direct role in the metabolism of phenylalanine or in the development of PKU. Identification of phenylalanine hydroxylase as the defective enzyme is critical for accurate diagnosis and effective management of this genetic disorder.