"Born to the Purple: the Story of Porphyria" & "New Light on Medicine" Scientific American (www.sciam.com) December 16, 2002.
A medical explanation for vampires and werewolves? Food for thought about photosensitive in plants and animals, and the relationship between these two Kingdoms.
The porphyrias are a family of metabolic disorders, all of which involve abnormalities of the body's heme-building pathway. Heme is a component of the oxygen transport molecule, hemoglobin, and is assembled in a series of eight steps. If any one step fails, due to genetic or environmental causes, intermediate products of earlier steps in the sequence (porphyrin intermediates) may build up to toxic levels in the body.
Apart from leading to port-wine colored urine, porphyrin intermediates may accumulate in the skin. The presence of unmodified porphyrins in the skin is usually not a problem, but these molecules are related to chlorophyll (the plant pigment that absorbs the energy of sunlight in photosynthesis), and can be similarly excited by exposure to sunlight.
The nature and severity of symptoms varies with the specific disorder, but if left untreated include: trances, seizures, and hallucinations (the affliction of "Mad" King George III of Britain); photosensitivity leading to blisters and burns with exposure to sunlight (condition claimed for the children in "The Others"); slow healing associated with scaring and abnormal hair growth (hirsutism on the face); and even disfigurement of the facial features by erosion and scaring, giving an appearance expected for "the undead." Such red blood cells as are produced may be abnormal and rupture, leading to hemolytic anemia.
Garlic as well as sunlight may exacerbate symptoms and discomfort; phlebotomy (drawing blood and so removing heme intermediates from circulation) can help, as might (in theory) drinking blood--as the heme pigment can survive digestion and be absorbed from the intestine. Modern treatment, however, uses transfusions of blood or heme to relieve the symptoms of an attack.
A medical explanation for vampires and werewolves? Food for thought about photosensitive in plants and animals, and the relationship between these two Kingdoms.
The porphyrias are a family of metabolic disorders, all of which involve abnormalities of the body's heme-building pathway. Heme is a component of the oxygen transport molecule, hemoglobin, and is assembled in a series of eight steps. If any one step fails, due to genetic or environmental causes, intermediate products of earlier steps in the sequence (porphyrin intermediates) may build up to toxic levels in the body.
Apart from leading to port-wine colored urine, porphyrin intermediates may accumulate in the skin. The presence of unmodified porphyrins in the skin is usually not a problem, but these molecules are related to chlorophyll (the plant pigment that absorbs the energy of sunlight in photosynthesis), and can be similarly excited by exposure to sunlight.
The nature and severity of symptoms varies with the specific disorder, but if left untreated include: trances, seizures, and hallucinations (the affliction of "Mad" King George III of Britain); photosensitivity leading to blisters and burns with exposure to sunlight (condition claimed for the children in "The Others"); slow healing associated with scaring and abnormal hair growth (hirsutism on the face); and even disfigurement of the facial features by erosion and scaring, giving an appearance expected for "the undead." Such red blood cells as are produced may be abnormal and rupture, leading to hemolytic anemia.
Garlic as well as sunlight may exacerbate symptoms and discomfort; phlebotomy (drawing blood and so removing heme intermediates from circulation) can help, as might (in theory) drinking blood--as the heme pigment can survive digestion and be absorbed from the intestine. Modern treatment, however, uses transfusions of blood or heme to relieve the symptoms of an attack.

