Vampire Disease: Life Out of the Sun
What is Vampire Disease?
We’ve all heard of Twilight, the love-story of a sparkling vampire and a teenage girl battling an evil coven of blood-thirsty vampires. Stories involving vampires date back to the 17th century, way before Twilight or Buffy the Vampire Slayer. The history of these blood-sucking creatures is thought to be inspired by a real disorder, vampire’s disease, scientifically known as porphyria.
Porphyrias are a group of rare metabolic disorders, the symptoms of which are akin to the characteristics of a vampire. This disease commonly arises due to a genetic mutation, King George II is believed to have had porphyria, giving rise to his vivid hallucinations and lengthy conversations with the trees in his garden.
However, this blood disorder can also be caused by environmental factors. In the 1950s, 4000 people developed porphyria in Turkey due to eating crops contaminated with a fungicide, hexachlorobenzene, which was later banned.
Aside from the fear of garlic, sufferers of porphyria are extremely sensitive to the sun and can experience severe itching, blisters, and scars when exposed to direct sunlight. Other symptoms of porphyria include the thinness of skin, severe abdominal pain, muscle pain, red-brown urine, red-stained teeth, and insomnia.
The Heme Biosynthesis Pathway
Porphyria arises due to an abnormality in heme biosynthesis, heme is an important component of the oxygen-carrying molecule: haemoglobin. Haemoglobin is found in red blood cells and is made up of 4 globular proteins forming a ring structure called a ‘porphyrin ring’.
The porphyrin ring combined with a metal ion, Fe2+, forms Haemoglobin. The formation of Heme involves 8 enzymatic steps, the dysregulation of one of these enzymes leads to an accumulation of the precursor molecule. The diagram below shows the molecules and enzymes involved in Heme synthesis:
As you can see from the diagram, there are many molecules involved in heme production. If the cell was deficient in the enzyme ferrochelatase, Protoporphyrin IX would not be converted into heme, leading to a build-up of the precursor molecule.
Protoporphyrin IX is not harmful in small amounts, however in high quantities can be very toxic to the cells. It is the build-up of these precursor molecules that results in the symptoms seen in porphyria. Different enzymes in this pathway result in different types of porphyria and thus slightly differing symptoms.
Current & Novel Treatment for Porphyria
Centuries ago, with the lack of therapeutics & advanced medical knowledge, physicians advised patients to drink animal blood to help with their deficiency in heme, further fuelling the myth of vampires. Although drinking blood is largely a thing of the past, there is evidence it may have provided some relief as heme is tough enough to survive digestion.
To this date, heme injections and transfusions along with drugs are available to help manage the symptoms of this disease. However, these behind-the-counter drugs need to be carefully prescribed as they can result in acute attacks. Advice from doctors for porphyria patients involves discontinuing alcohol use, avoiding iron tablets, and staying away from birth control.
Novel treatments are being explored for porphyria as scientists have a better understanding of the genetics of the disease and the biosynthesis pathway. A promising hormone has been studied in clinical trials for the reduction of skin blisters when exposed to sunlight and future treatment could involve enzyme replacement therapy, gene therapy, and stem cell therapy. Much like vampires, patients are advised to stay out of sunlight to avoid painful skin blisters and wear special protective clothing.
To conclude, there is no cure for porphyria, only therapeutics to help manage the symptoms. It turns out that stories of vampires avoiding sunlight and drinking blood is more real than you may have believed 3 mins ago.
