Porphyria classification

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Classification

The 8 porphyrias are:

1. Acute intermittent Porphyria (AIP)
2. ALA dehydratase deficiency
3. Porphyria cutanea tarda (PCT)
4. Congenital Erythropoetic Porphyria (CEP)
5. Hepatoerythropoetic Porphyria (HEP)
6. Erythopoetic Protoporphyria (EPP)
7. Hereditary coproporphyria (HCP)
8. Variegate Porphyria (VP)

These disorders can also be divided based on the type of precursors that accumulate and the subsequent manifestations that occur. ALA dehydratase deficiency (Plumboporphyria) and AIP are characterized by the accumulation of -aminolevulinic acid (ALA) and Porphobilinogen (PBG). Their manifestations are primarily neuropathic. PCT, CEP, HEP and EEP are characterized by accumulation of porphyrin and have cutaneous manifestations only. HCP and VP have accumulation of porphyrin precursors and porphyrins. They have both neuropathic and cutaneous manifestations.

Enzyme	Location of enzyme	Associated porphyria	Type of porphyria
δ-aminolevulinate (ALA) synthase	Mitochondrion	X-linked sideroblastic anemia (XLSA)	Erythropoietic
δ-aminolevulinate (ALA) dehydratase	Cytosol	Doss porphyria/ALA dehydratase deficiency	Hepatic
hydroxymethylbilane (HMB) synthase (or PBG deaminase)	Cytosol	acute intermittent porphyria (AIP)	Hepatic
uroporphyrinogen (URO) synthase	Cytosol	Congenital erythropoietic porphyria (CEP)	Erythropoeitic
uroporphyrinogen (URO) decarboxylase	Cytosol	Porphyria cutanea tarda (PCT)	Hepatic
coproporphyrinogen (COPRO) oxidase	Mitochondrion	Hereditary coproporphyria (HCP)	Hepatic
protoporphyrinogen (PROTO) oxidase	Mitochondrion	Variegate porphyria (VP)	Mixed
Ferrochelatase	Mitochondrion	Erythropoietic protoporphyria (EPP)	Erythropoietic