Blood-sucking vampire or blood disorder? A new study from Boston’s Children’s Hospital has uncovered a genetic mutation that triggers a disease linked to vampire folklore.

Porphyrias is a group of eight known blood disorders which affect the body's ability to produce heme, which is a component of the oxygen-transporting protein, hemoglobin.

It’s the different genetic variations that affect heme production give rise to different clinical presentations of porphyria. One, erythropoietic protoporphyria (EPP), shares symptoms—and even treatments—with legendary vampire lore.

EPP causes people’s skin to become very sensitive to light, and in some cases, prolonged exposure can lead to painful, disfiguring 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 M.D., Ph.D., 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."

Today, treatment of the disease includes blood transfusions containing sufficient heme levels to alleviate symptoms as well as the avoidance of ultraviolet light by staying indoors during the day. But in earlier times, treatment consisted of drinking animal blood and avoiding daylight—linking the condition to the vampire myth.

What’s really happening is the genetic defect is impacting heme production, which leads to a buildup of protoporphyrin components. In EPP, protoporphyrin IX accumulates in the red blood cells, plasma and sometimes the liver.  

When protoporphin IX is exposed to light, it produces chemicals that damage surrounding cells. As a result, people with EPP experience swelling, burning and redness of the skin after exposure to sunlight, including even trace amounts of sunlight that pass through window glass, explained the researchers.

Research on some genetic pathways leading to build-up of protoporphyrin IX have already been described, but many cases of EPP remain unexplained. For their research, the team performed deep gene sequencing on members of a family from Northern France with EPP of a previously unknown genetic signature. They discovered a novel mutation of the gene CLPX, which plays a role 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."

Paw hopes his work leads to therapies that could correct the faulty genes, adding, "Although vampires aren't real, there is a real need for innovative therapies to improve the lives of people with porphyrias."