This pathway shows disorders related to phenylalanine and tetrahydrobiopterin (BH4) metabolism. Disorders resulting from an enzyme defect are highlighted in pink. Pathological metabolites used as specific markers are highlighted in purple. BH4 is a natural cofactor for PAH, tyrosine-3-hydroxylase, tryptophan-5-hydroxylase and nitric oxide synthase (NOS), where the latter two are key enzymes in the biosynthesis of the neurotransmitters dopamine and serotonin. 

This pathway was inspired by Edition 5, Chapter 20 of the book of Blau (ISBN 9783030677268) (Ed.4 Chapter 1).

[MODIFICATION:idd98f6358]	Invalid interaction type.
[MODIFICATION:bcf5c]	Invalid interaction type.
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[ARROW:id2ca3544d]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:a88b6]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:fc0e8]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:bb27f]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:e3166]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:b672f]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:b341d]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:cde2e]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:bf994]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:bb236]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:d86a4]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:fe54a]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:bb5b3]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:e60d5]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:d59a8]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:e264a]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:e042f]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:d5376]	Invalid interaction type "ARROW" as an output from reaction.
[ARROW:e050a]	Invalid interaction type "ARROW" as an output from reaction.
[Label:cc3d4]	 Label cannot be part of reaction. Tranforming to Unknown
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[Label:c6992]	 Label cannot be part of reaction. Tranforming to Unknown
[Label:ff548]	 Label cannot be part of reaction. Tranforming to Unknown
[Label:ac36d]	 Label cannot be part of reaction. Tranforming to Unknown
[-:-]	Miriam data (PUBMED: 10407772) for f32e5 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 14984687) for f32e5 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 10407772) for f32e5 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 14984687) for a780c already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 10407772) for c1a93 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 10407772) for id32c71291 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 10407772) for id32c71291 already exists. Ignoring...
[UnknownPositiveInfluenceReaction:id32c71291]	Reaction should contain only one reactant and one product.
[UnknownPositiveInfluenceReaction:id9ef7cfc3]	Reaction should contain only one reactant and one product.
[-:-]	Miriam data (PUBMED: 10407772) for id2c686da2 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 14984687) for b111a already exists. Ignoring...
[UnknownPositiveInfluenceReaction:ida371d2ff]	Reaction should contain only one reactant and one product.
[-:-]	Miriam data (PUBMED: 21550412) for ide4d37224 already exists. Ignoring...
[-:-]	Miriam data (PUBMED: 10407772) for ca689 already exists. Ignoring...
[UnknownPositiveInfluenceReaction:id1eb5096c]	Reaction should contain only one reactant and one product.