Phenylalanine hydroxylase

Phenylalanine hydroxylase (PAH) is an enzyme that is critical in the metabolic process of the amino acid phenylalanine. It is encoded by the PAH gene and is primarily found in the liver.

Function

Phenylalanine hydroxylase catalyzes the hydroxylation of the aromatic side-chain of phenylalanine to generate tyrosine. This reaction requires molecular oxygen and tetrahydrobiopterin as cofactors.

Clinical significance

Deficiency of PAH activity results in phenylketonuria (PKU), one of the most common inherited diseases of amino acid metabolism. PKU is characterized by elevated levels of phenylalanine in the blood and central nervous system, and can lead to mental retardation if untreated.

Genetics

The PAH gene is located on the long arm of chromosome 12 (12q23.2). Mutations in this gene result in phenylketonuria and less commonly, hyperphenylalaninemia.

See also

• Phenylketonuria
• Hyperphenylalaninemia
• Tetrahydrobiopterin

References

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External links

• GeneCards: PAH
• Genetics Home Reference: PAH

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