Fig. 1From: The complete European guidelines on phenylketonuria: diagnosis and treatmentPhenylalanine hydroxylating system. BH4: tetrahydrobiopterin; DHPR: dihydropteridine reductase; GTP: guanosine triphosphate; GTPCH: GTP cyclohydrolase I; Phe: Phenylalanine; PAH: phenylalanine hydroxylase; PCD: phenylalanine carbinolamie-4a-dehydratase; PTPS: 6-pyruvoyl-tetrahydropterin synthase; SR: sepiapterin reductaseBack to article page