Article: Hepatoerythropoietic porphyria

What is hepatoerythropoietic porphyria?

Hepatoerythropoietic porphyria is a rare type of porphyria that mainly affects the skin. The disorder results from very low levels of the enzyme responsible for the fifth step in heme production. Heme is a vital molecule for all of the body's organs. It is a component of hemoglobin, the molecule that carries oxygen in the blood.

Hepatoerythropoietic porphyria is a subtype of porphyria.

Most signs and symptoms of this type of porphyria are very similar to those of congenital erythropoietic porphyria, resulting from the skin becoming overly sensitive to sunlight. The signs and symptoms usually begin during infancy or childhood. Areas of skin exposed to the sun develop severe blistering, infections, scarring, changes in pigmentation, and increased hair growth. Other signs of the condition include a low number of red blood cells (anemia) and enlargement of the spleen.

How common is hepatoerythropoietic porphyria?

This type of porphyria is very rare; fewer than 30 patients with the condition have ever been reported worldwide.

What genes are related to hepatoerythropoietic porphyria?

Mutations in the UROD gene cause hepatoerythropoietic porphyria.

The UROD gene makes an enzyme called uroporphyrinogen decarboxylase, which is critical to the chemical process that leads to heme production. Due to mutations in the UROD gene, the activity of this enzyme is very low in people with hepatoerythropoietic porphyria. As a result, heme cannot be produced normally and byproducts of the process (called porphyrins) build up in the body, particularly in the skin.

How do people inherit hepatoerythropoietic porphyria?

People with hepatoerythropoietic porphyria inherit two altered copies of the UROD gene, one from each parent.