What are porphyrias?

Porphyrias are rare disorders that mainly affect the skin or nervous system. These disorders are usually inherited, meaning they are caused by gene mutations NIH external link passed from parents to children.

If you have porphyria, cells fail to change chemicals in your body—called porphyrins and porphyrin precursors—into heme, the substance that gives blood its red color. When these chemicals build up in your body, they cause illness. Depending on the type of porphyria you have, porphyrins or porphyrin precursors may build up in the liver or the bone marrow. Bone marrow is the spongy tissue inside most of your bones.

What are the types of porphyria?

Experts often divide porphyrias into two groups—acute porphyrias and cutaneous porphyrias—based on whether they primarily affect the nervous system or the skin.

Acute porphyrias

Four types of acute porphyrias affect the nervous system. Two of those types can also affect the skin. Symptoms for acute porphyrias develop over hours or days and last for days or weeks.

Table 1. Types of acute porphyria

Type of Acute Porphyria	Parts of the Body Affected	Where Porphyrins or Porphyrin Precursors Build Up
acute intermittent porphyria	nervous system	liver
variegate porphyria	nervous system and skin	liver
hereditary coproporphyria	nervous system and skin	liver
delta-aminolevulinic acid (ALA) dehydratase deficiency porphyria	nervous system	liver

Cutaneous porphyrias

Four types of cutaneous porphyrias affect only the skin and cause chronic, or long lasting, symptoms. People with cutaneous porphyria may develop skin symptoms—such as blistering or pain—after their skin is exposed to sunlight.

Table 2. Types of cuteaneous porphyria

Type of Cutaneous Porphyria	Parts of the Body Affected	Where Porphyrins Build Up
porphyria cutanea tarda	skin	liver
protoporphyrias: erythropoietic protoporphyria and x-linked protoporphyria	skin	bone marrow
congenital erythropoietic porphyria	skin	bone marrow
hepatoerythropoietic porphyria	skin	liver