Table 1

Categories of porphyria

Type	Acute/cutaneous	Site	Inheritance	Neurological presentation	Enzyme deficiency Gene responsible
Acute intermittent porphyria	Acute	Hepatic	Autosomal dominant	Yes	Porphobilinogen deaminase (HMBS)
Variegate porphyria	Acute and/or cutaneous	Hepatic	Autosomal dominant	Yes	Protoporphyrinogen oxidase (PPOX)
Hereditary coproporphyria	Acute and/or cutaneous	Hepatic	Autosomal dominant	Yes	Coproporphyrinogen oxidase (CPOX)
Aminolevulinic acid dehydratase deficient porphyria	Acute	Hepatic	Autosomal recessive	Yes	5-Aminolevulinic acid dehydratase (ALAD)
Porphyria cutanea tarda*	Cutaneous	Hepatic	Autosomal dominant	No	Uroporphyrinogen decarboxylase (UROD)
Hepatoerythropoietic porphyria	Cutaneous	Hepatic and marrow	Autosomal recessive	No	Uroporphyrinogen decarboxylase (UROD)
Congenital erythropoietic porphyria	Cutaneous	Marrow	Autosomal recessive	No	Uroporphyrinogen III synthase (UROS)
Erythropoietic protoporphyria	Cutaneous	Marrow	Autosomal recessive	No	Ferrochelatase (FECH)
X linked erythropoietic protoporphyria	Cutaneous	Marrow	X linked	No	ALA synthase 2†(ALAS2)

*Porphyria cutanea tarda is frequently acquired, but there is also an autosomal dominant inherited subtype; neither presents with neurological symptoms.
†Gain of function.