1. Porphyria

Is this disease the source of the vampire legend? Porphyria is a disease which causes extreme sensitivity to sunlight, an aversion to highly acidic foods (such as garlic) and causes the gums to recede, giving the appearance of sharp fangs. Starting to sounds familiar? Some experts believe porphyria offers an explanation to the legend of the vampire, with symptoms that are very similar to what is described in folklore.

If left untreated, people afflicted with porthyria are said to go mad; in fact it has been theorised that King George III (also known as the ‘mad king’) suffered from a type of porthyria. People who suffer from the condition can now be treated with regular blood transfusions however they will retain their vampiric appearance; although I think they’d appreciate it if you didn’t try to steak them in the heart.