Status	Description	Organism	Genes	References
	tryptophan hydroxylase 2	Homo sapiens	TPH2	[273]
	Tryptophan 5-hydroxylase 2	Dugesia japonica	tph	[257]
	Tryptophan hydroxylase I	Homo sapiens	TPH1	[273] [274]
	aromatic amino acid hydroxylase	Cupriavidus taiwanensis	phhA	[338]