This document provides information about porphyria, a group of rare inherited or acquired disorders affecting enzymes involved in heme production. It discusses how legends of vampires and werewolves may have originated from symptoms of severe porphyria cases. The types of porphyria that affect the nervous system or skin are described. Notable historical figures believed to have had porphyria are mentioned. The mechanism of heme synthesis and how deficiencies cause porphyria are explained. The main types of porphyria are outlined along with their associated symptoms. Diagnosis involves blood, urine, and stool tests, while treatment depends on the type but may include medications, injections, phlebotomies, or avoiding triggers.