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.