Classification of porphyrias (hepatic or erythropoietic; acute or cutaneous)

Disease	Classification		Enzyme affected	Inheritance	Major biochemical findings*
Disease	Tissue site	Clinical features	Enzyme affected	Inheritance	Urine	Plasma	Erythrocytes	Feces
ADP	Hepatic^¶	Acute	ALAD	Autosomal recessive	ALA, coproporphyrin III		Zinc protoporphyrin and low ALAD activity
AIP	Hepatic	Acute	PBGD	Autosomal dominant	ALA, PBG, uroporphyrin, coproporphyrin		Low PBGD activity
HCP	Hepatic	Acute and cutaneous	CPOX	Autosomal dominant	ALA, PBG, uroporphyrin, coproporphyrin III			Coproporphyrin III
VP	Hepatic	Acute and cutaneous	PPOX	Autosomal dominant	ALA, PBG, uroporphyrin, coproporphyrin III	Fluorescence peak at approximately 626 nm		Coproporphyrin III and protoporphyrin
PCT	Hepatic	Cutaneous	UROD	Autosomal dominant^Δ	Uroporphyrin and hepta-carboxyl-porphyrin	Uroporphyrin and hepta-carboxyl-porphyrin		Isocoproporphyrin
HEP	Hepatic^¶	Cutaneous	UROD	Autosomal recessive	Uroporphyrin and hepta-carboxyl-porphyrin	Uroporphyrin and hepta-carboxyl-porphyrin	Zinc protoporphyrin and low UROD activity	Isocoproporphyrin
CEP	Erythropoietic	Cutaneous	UROS	Autosomal recessive	Uroporphyrin I and coproporphyrin I	Uroporphyrin I and coproporphyrin I	Uroporphyrin I and coproporphyrin I	Coproporphyrin I
EPP	Erythropoietic	Cutaneous	FECH	Autosomal recessive		Protoporphyrin, fluorescence peak at approximately 634 nm	Metal-free protoporphyrin	Protoporphyrin
XLP	Erythropoietic	Cutaneous	ALAS2	X-linked		Protoporphyrin	Metal-free and zinc protoporphyrin	Protoporphyrin

The table shows the classification based on tissue site (ie, hepatic or erythropoietic) and on clinical features (ie, acute or cutaneous). The affected enzymes, inheritance patterns, and biochemical findings are listed. Refer to UpToDate for details of initial testing for suspected porphyria and diagnostic evaluations for each specific porphyria.

ADP: delta-aminolevulinic acid (ALA) dehydratase porphyria; ALAD: ALA dehydratase; AIP: acute intermittent porphyria; PBGD: porphobilinogen (PBG) deaminase; HCP: hereditary coproporphyria; CPOX: coproporphyrinogen oxidase; VP: variegate porphyria; PPOX: protoporphyrinogen oxidase; PCT: porphyria cutanea tarda; UROD: uroporphyrinogen decarboxylase; HEP: hepatoerythropoietic porphyria; CEP: congenital erythropoietic porphyria; UROS: uroporphyrinogen III synthase; EPP: erythropoietic protoporphyria; FECH: ferrochelatase; XLP: X-linked protoporphyria; ALAS2: ALA synthase 2.
* Increases of importance for diagnosis in most cases.
¶ These hepatic porphyrias also have erythropoietic features, including increases in erythrocyte zinc protoporphyrin.
Δ UROD inhibition in PCT is mostly acquired, but an inherited deficiency of the enzyme predisposes in familial (type 2) disease.

Karl Anderson, MD, FACP.

Graphic 80601 Version 11.0

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Classification of porphyrias (hepatic or erythropoietic; acute or cutaneous)