Porphyrias, a group of eight known blood disorder, affect the body’s molecular machinery for making heme. Heme is a part of the oxygen-transporting protein, hemoglobin. When heme drags with iron, it gives blood its hallmark red color.
The different genetic distinctions that affect heme production give rise to different clinical presentations of porphyria. This includes one form that may be responsible for vampire folklore.
Is this blood disorder a clinical cause for nocturnal blood drinking?
Erythropoietic protoporphyria (EPP) is the most known kind of porphyria to occur in childhood. EPP causes people’s skin to become very sensitive to light. Extended exposure to sunshine can cause painful, damaging blisters.
“People with EPP are chronically anemic, which makes them feel very tired and look very pale with increased photosensitivity because they can’t come out in the daylight,” says Barry Paw MD, PhD, of the Dana-Farber/Boston Children’s Cancer and Blood Disorders Center. “Even on a cloudy day, there’s enough ultraviolet light to cause blistering and disfigurement of the exposed body parts, ears and nose.”
Staying indoors during the day and receiving blood transfusions comprising sufficient heme levels help lessen some of the disorder’s symptoms. In ancient times, drinking animal blood and developing only at night may have achieved a similar effect. This is why it adds to further fuel to the legend of vampires.
Now, Paw and his team of international investigators report in a paper the Proceedings of the National Academy of Sciences. They reported newly discovered genetic mutation that activates EPP. It brightens a novel biological mechanism potentially accountable for stories of vampires” and identifies a potential therapeutic target for treating EPP.
The nature of EPP’s “supernatural” blood disorder symptoms
To produce heme, the body goes through a process called porphyrin synthesis, which happens in the liver and bone marrow. Any genetic flaws that impact this process can disturb the body’s ability to produce heme. The lessened heme production leads to a buildup of protoporphyrin components. In the case of EPP, type of protoporphyrin called protoporphrin IX gathers in the red blood cells, plasma and sometimes the liver.
When protoporphin IX is visible to light, it produces chemicals that harm surrounding cells. As a result, people with EPP experience swelling, burning and redness of the skin after contact to sunlight. Even trace amounts of sunlight that pass through window glass.
Some genetic pathways leading to build-up of protoporphyrin IX have already been defined, but many cases of EPP remain unsolved. The researchers performed deep gene sequencing on members of a family from Northern France with EPP of a genetic signature. Paw’s team learned a novel mutation of the gene CLPX, which plays a part in mitochondrial protein folding.
“This newly-discovered mutation really highlights the complex genetic network that underpins heme metabolism,” says Paw, who was co-senior author on the study. “Loss-of-function mutations in any number of genes that are part of this network can result in devastating, disfiguring disorders.”
Myth vs. reality of the blood disorder
Paw suggests that recognizing the several gene mutations that contribute to porphyria could pave the way for future therapies. Those gene mutations could correct the damaged genes responsible for these related blood disorder.
“Although vampires aren’t real, there is a real need for advanced therapies to improve the lives of people with porphyrias,” says Paw.
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