What causes Hepatoerythropoietic Porphyria?
HEP is extremely rare, it is caused by low levels of the same enzyme that causes PCT, UROD. In Familial PCT, there is only one changed copy of the UROD gene, the other copy is normal. In HEP both copies of the UROD gene have changes.
The low levels of UROD enzyme causes porphyrins to accumulate because there isn’t enough enzyme activity to process them. These porphyrins accumulate in the skin, bone marrow, teeth, and bones. Exposure to sunlight and some forms of artificial light activates the accumulated porphyrins in the skin and results in severe blistering.
What are symptoms of Hepatoerythropoietic Porphyria?
Symptoms include:
- Blistering on light-exposed parts of the body, most commonly the hands, arms and face
- Fluid-filled blisters can rupture and become infected, leading to scarring, bone loss and deformities
- Increased hair growth on sun-exposed skin
- Brownish-colored teeth (erythrodontia)
- Reddish-colored urine
What is Hepatoerythropoietic Porphyria diagnosed?
HEP is diagnosed using biochemical testing, starting with testing plasma and urine for elevated porphyrins. Additional testing is required to rule out other reasons that porphyrins may be high (ex. lead exposure) and other types of porphyria.
How do you treat Hepatoerythropoietic Porphyria?
The standard treatments for PCT (regularly scheduled phlebotomies or low doses of hydroxychloroquine), are generally less effective in HEP but can still be tried.
How do you manage Hepatoerythropoietic Porphyria?
People with HEP should see a porphyria specialist at least once a year for regular follow-up. People who have severe anemia may need to see a specialist more regularly.
Light Avoidance
Avoiding exposure to sunlight is the most important way to manage symptoms for people with HEP. People with HEP need to wear protective clothing, and have windows tinted in their cars and homes. Most sunscreens are not effective because they do not block light in the blue-violet range, which is the type of light that triggers reactions in porphyria.
Blister/Wound Care
There is a risk of developing infections in blisters, particularly if they rupture. Prescription antibiotic ointments may be required to manage infections. Care from a dermatologist is recommended.
How do you monitor and what are long-term complications of Hepatoerythropoietic Porphyria?
Photomutilation can result in the loss of facial features (nose, ear and lids) and digits. Hypertrichosis on sun exposed skin, reddish-brown colored teeth (erythrodontia), and reddish-colored urine are common features.
How is Hepatoerythropoietic Porphyria inherited?
HEP is an autosomal recessive condition. Autosomal means that the defect is not on the chromosomes that determine sex, and recessive means that patients who have HEP have inherited two changed copies of the UROD gene, one from each of their parents. When someone with HEP has children, all their children will have familial PCT since they will inherit one copy of the changed UROD gene. The children will not necessarily develop symptoms of PCT but should have genetic counseling.