New York, Sep 7: A blood disorder that makes people chronically anemic and forces them to stay indoors during the day might have triggered the blood-sucking vampire imagery in folklore, suggests new research. Porphyrias, a group of eight known blood disorders, affect the body's molecular machinery for making heme, which is a component of the oxygen-transporting protein, hemoglobin. When heme binds with iron, it gives blood its hallmark red colour. The different genetic variations that affect heme production give rise to different clinical presentations of porphyria -- including one form that may be responsible for vampire folklore. "Although vampires aren't real, there is a real need for innovative therapies to improve the lives of people with porphyrias," said Barry Paw of Boston Children's Hospital, Harvard Medical School. Erythropoietic protoporphyria (EPP), the most common kind of porphyria to occur in childhood, causes people's skin to become very sensitive to light. Prolonged exposure to sunshine can cause 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," Paw said. "Even on a cloudy day, there's enough ultraviolet light to cause blistering and disfigurement of the exposed body parts, ears and nose," Paw added.
Staying indoors during the day and receiving blood transfusions containing sufficient heme levels can help alleviate some of the disorder's symptoms. In ancient times, drinking animal blood and emerging only at night may have achieved a similar effect -- adding further fuel to the legend of vampires. In a study published in the journal Proceedings of the National Academy of Sciences (PNAS), the researchers described a genetic mutation that triggers EPP. It illuminates a novel biological mechanism potentially responsible for stories of " vampires" and identifies a potential therapeutic target for treating EPP. By performing deep gene sequencing on members of a family from Northern France with EPP of a previously unknown genetic signature, Paw's team 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," said Paw, 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 said. Identifying various gene mutations that contribute to porphyria could pave the way for future therapies that could correct the faulty genes responsible for these related disorders, Paw said.