Phenylketonuria dietary management and an emerging development / Penelope D. Manta-Vogli, Kleopatra H. Schulpis

Phenylalanine hydroxylase (PAH) deficiency, commonly referred as phenylketonuria, is an inherited metabolic disease characterized by a decreased activity of the mentioned enzyme that breaks down the amino acid (AA) phenylalanine (Phe) to tyrosine (Tyr). The disorder is characterized by high Phe blood levels resulting in intellectual disability, seizures, eczema, and more. If Phe levels are reduced, brain function and other symptoms are improved. Although individuals with PAH deficiency are currently seen as a spectrum of this enzyme's residual activity (2014 American College of Medical Genetics guidelines), some practitioners find practical utility in referring to older categories: "classic/severe," "moderate," "mild," and "mild hyperphenylalaninemia," the latter not needing Phe restriction.

Nutrition.