Porphyria was a hereditary disease common amongst several British royals, including Mary Queen of Scots, King James I of England, and King George III, among others. It is caused by insufficient production of hemoglobin.
- abdominal pain
- acute neuropathy
- port wine colored urine (see picture—yum!)
Porphyria also causes intense mental disturbances, including hallucinations, depression, anxiety, and paranoia.
Interestingly, it was at one point believed that Porphyria was beyond the development of vampire myths. However, the theory has since been dismissed.