Table 2 Human porphyrias: major clinical... | American Society of Hematology

Table 2

Human porphyrias: major clinical and laboratory features

Porphyria	Deficient enzyme	Inheritance	Principal symptoms, NV or CP	Enzyme activity, % of normal	Increased porphyrin precursors and/or porphyrins*
Porphyria	Deficient enzyme	Inheritance	Principal symptoms, NV or CP	Enzyme activity, % of normal	Erythrocytes	Urine	Stool
Acute hepatic porphyrias
ADP	ALA-dehydratase	AR	NV	∼ 5	Zn-protoporphyrin	ALA, coproporphyrin III	—
AIP	HMB- synthase	AD	NV	∼ 50	—	ALA, PBG, uroporphyrin	—
HCP	COPRO-oxidase	AD	NV and CP	∼ 50	—	ALA, PBG, coproporphyrin III	Coproporphyrin III
VP	PROTO-oxidase	AD	NV and CP	∼ 50	—	ALA, PBG, coproporphyrin III	Coproporphyrin III, Protoporphyrin
Hepatic cutaneous porphyrias
PCT	URO-decarboxylase	Sporadic or AD	CP	< 20	—	Uroporphyrin, 7-carboxylate porphyrin	Isocoproporphyrin
Erythropoietic cutaneous porphyrias
CEP	URO-synthase	AR	CP	1-5	Uroporphyrin I, coproporphyrin I	Uroporphyrin I, coproporphyrin I	Coproporphyrin I
EPP	Ferrochelatase	AR†	CP	∼ 20-30	Primarily free protoporphyrin	—	Protoporphyrin
XLP	ALA-synthase 2	XL	CP	> 100‡	Free and zinc protoporphyrin	—	Protoporphyrim

Porphyria	Deficient enzyme	Inheritance	Principal symptoms, NV or CP	Enzyme activity, % of normal	Increased porphyrin precursors and/or porphyrins*
Porphyria	Deficient enzyme	Inheritance	Principal symptoms, NV or CP	Enzyme activity, % of normal	Erythrocytes	Urine	Stool
Acute hepatic porphyrias
ADP	ALA-dehydratase	AR	NV	∼ 5	Zn-protoporphyrin	ALA, coproporphyrin III	—
AIP	HMB- synthase	AD	NV	∼ 50	—	ALA, PBG, uroporphyrin	—
HCP	COPRO-oxidase	AD	NV and CP	∼ 50	—	ALA, PBG, coproporphyrin III	Coproporphyrin III
VP	PROTO-oxidase	AD	NV and CP	∼ 50	—	ALA, PBG, coproporphyrin III	Coproporphyrin III, Protoporphyrin
Hepatic cutaneous porphyrias
PCT	URO-decarboxylase	Sporadic or AD	CP	< 20	—	Uroporphyrin, 7-carboxylate porphyrin	Isocoproporphyrin
Erythropoietic cutaneous porphyrias
CEP	URO-synthase	AR	CP	1-5	Uroporphyrin I, coproporphyrin I	Uroporphyrin I, coproporphyrin I	Coproporphyrin I
EPP	Ferrochelatase	AR†	CP	∼ 20-30	Primarily free protoporphyrin	—	Protoporphyrin
XLP	ALA-synthase 2	XL	CP	> 100‡	Free and zinc protoporphyrin	—	Protoporphyrim

AR indicates autosomal recessive; AD, autosomal dominant; XL, X-linked; NV, neurovisceral; CP, cutaneous photosensitivity; and —, not applicable.

Increases that may be important for diagnosis.

A polymorphism in intron 3 of the wild-type allele affects the level of enzyme activity and clinical expression.

Increased activity resulting from “gain-of-function” mutations in ALAS2 exon 11.