What is Hepatoerythropoietic Porphyria?
HEP is a deficiency of the enzyme uroporphyrinogen decarboxylase; it is the autosomal recessive form of f-PCT. The manifestations of HEP resemble Congenital Erythropoietic Porphyria (CEP), with symptoms of skin blistering that usually begin in infancy.
Skin photosensitivity results in severe blistering and scarring, often with mutilation and loss of facial features and fingers. Increased hair growth (hypertrichosis) on sun-exposed skin, brownish-colored teeth (erythrodontia), and reddish-colored urine are common. There may be bone fragility due to expansion of the bone marrow and vitamin deficiencies, especially vitamin D. Red blood cells have a shortened life-span, and mild or severe hemolytic anemia often results. Synthesis of heme and hemoglobin is actually increased to compensate for the shortened red blood cell survival and is associated with splenomegaly. Bacteria may infect the damaged skin and contribute to mutilation and scarring.
Who gets Hepatoerythropoietic Porphyria?
HEP is a very rare type of autosomal recessive porphyria. Each parent of an affected individual must have a mutation in one of their UROD genes and both must pass their mutation on to their child. This also means that both parents have f-PCT.
What causes Hepatoerythropoietic Porphyria?
HEP is caused by a deficiency of the enzyme uroporphyrinogen decarboxylase, due to the inheritance of mutations in both copies of a person’s URO-decarboxylase genes.
How is Hepatoerythropoietic Porphyria diagnosed?
Diagnosis of HEP can be made by demonstrating significant elevations of specific porphyrins in urine and stool, as well as iidentification of a specific fluorescence emission peak in plasma. DNA testing to identify the specific mutations in an individual’s UROD genes is the most specific and sensitive test to confirm the diagnosis of HEP.
- Also see FAQ: What diagnostic tests are available?
What are treatments for Hepatoerythropoietic Porphyria?
Treatment is the same as for PCT: regularly scheduled phlebotomies (removal of blood) to lower the amount of porphyrins in the liver or a low dose regimen of hydroxychloroquine as well as removal of factors (for example, certain medications) that activated the disease and avoidance and/or protection from sunlight.