Suave, predatory Count Dracula, demonic-looking Nosferatu, and glittery but conflicted Edward Cullen – vampires take many forms, but a thirst for blood and an aversion to sunlight tend to be their defining characteristics.
The word "vampyre" first appeared in the English language sometime in the 18th century, but their origins go back much further. The forerunners to the modern-day vampire can be found in Ancient Greek and Mesotopian folklore, and you can find myths of demonic bloodsucking creatures in cultures all over the world. There's the peuchen in Chile, the Jiangshi in China, the Baobhan Sith in Scotland, and the list goes on.
Most of us will agree that vampires aren't real. Still, as in most cases, there is some fact to the fiction. One of the things that has been linked to vampirism is a blood disorder called erythropoietic protoporphyria (EPP).
EPP is the third most common type of porphyria and the most common to occur during childhood. Sufferers are extremely sensitive to light, to the point of burning and blistering when they're exposed to sunlight.
"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, 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."
A modern-day patient would be advised to stay indoors during daylight hours and they may be prescribed blood transfusions with sufficient heme levels to reduce symptoms. But back in medieval and ancient times, before modern medicine, they might have turned to animal blood and only come out at night to try to relieve symptoms on their own.
Now in a study published in the Proceedings of the National Academy of Sciences, researchers report a newly discovered genetic mutation that is responsible for EPP, suggesting a biological mechanism behind the vampire myth.
"This newly-discovered mutation really highlights the complex genetic network that underpins heme metabolism," says Paw, a 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."
Aside from it being a fascinating explanation for vampirism, the researchers hope this insight can lead to therapies that correct the faulty genes in people with EPP.
"Although vampires aren't real, there is a real need for innovative therapies to improve the lives of people with porphyrias," says Paw.