The following genes are part of the chemical pathway for making heme:
*ALAD: aminolevulinic acid, δ-, dehydratase (deficiency causes ala-dehydratase deficiency porphyria)
*ALAS1: aminolevulinate, δ-, synthase 1
*ALAS2: aminolevulinate, δ-, synthase 2 (deficiency causes sideroblastic/hypochromic anemia)
*CPOX: coproporphyrinogen oxidase (deficiency causes hereditary coproporphyria)
*FECH: ferrochelatase (deficiency causes erythropoietic protoporphyria)
*HMBS: hydroxymethylbilane synthase (deficiency causes acute intermittent porphyria)
*PPOX: protoporphyrinogen oxidase (deficiency causes variegate porphyria)
*UROD: uroporphyrinogen decarboxylase (deficiency causes porphyria cutanea tarda)
*UROS: uroporphyrinogen III synthase (deficiency causes congenital erythropoietic porphyria)