Hereditary Coproporphyria (HCP) is one of eight different types of Porphyria and due to a build up of phorphyrins in the blood. Episodes of symtpoms, including vomiting, confusion, headache, weakness, siezures, and even hallucination, can be triggered by dehydration, hormonal changes (especially in women) and sun exposure. HCP is inherited in an autosommal dominant patter; affected parents have a 50% chance of passing it on with each child. Treatment inlvoves hydration, glucose and even lblood transfusions. Some believe that the origins of vampire stories are based families with this genetic condition.