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