phenylalanine hydroxylase

Full Definition

The hepatic enzyme responsible for converting the amino acid phenylalanine to tyrosine, requiring tetrahydrobiopterin as a cofactor. Deficiency or absence of this enzyme leads to phenylketonuria (PKU), one of the most common conditions detected through newborn screening. When this enzyme is deficient, phenylalanine accumulates in the blood and can cause severe intellectual disability if untreated. Understanding this enzyme's function is essential for interpreting newborn screening results and implementing appropriate dietary interventions.

Usage

Usage note: Often abbreviated as PAH in technical contexts; ensure consistency within documents.

In Context

• "Genetic analysis revealed a mutation in the phenylalanine hydroxylase gene confirming the PKU diagnosis." — Diagnostic report
• "Phenylalanine hydroxylase activity determines the severity of PKU phenotype." — Medical genetics textbook