When I was in school, a patient presented to our clinic with acute exacerbation of his porphyria. Well, I had heard the story that the symptoms of porphyria were close to those of vampirism, so perhaps it was the cause of all the legends about vampires. I went into the room to see the fellow, not sure what I would find. I found a nice, middle aged gentlemen who wanted his awful abdominal pain to go away. He didn't look remotely like Dracula and he didn't try to bite me either. Generally, around this time of year, some program shown on the History Channel or The Discovery Channel will repeat the above story. I, for one, think it is absolute rubbish! And here's why...

For a review, the class of disorders known as porphyrias are inherited or acquired disorders of certain enzymes in the heme biosynthetic pathway. In humans, porphyrins are the main precursors of heme, an essential constituent of hemoglobin, myoglobin, and cytochrome. Deficiency in the enzymes of the porphyrin pathway leads to insufficient production of heme. This is, however, not the main problem; most enzymes—even when less functional—have enough residual activity to assist in heme biosynthesis. The largest problem in these deficiencies is the accumulation of porphyrins, the heme precursors, which are toxic to tissue in high concentrations. The chemical properties of these intermediates determine in which tissue they accumulate, whether they are photosensitive, and how the compound is excreted (in the urine or feces).

If the broken enzyme is made in the liver -- the so called hepatic porphyrias -- the disease primarily affects the nervous system, resulting in abdominal pain, vomiting, acute neuropathy, seizures, and mental disturbances, including hallucinations, depression, anxiety, and paranoia. Cardiac arrhythmias and tachycardia (fast heart rate) may develop as the autonomic nervous system is affected. Pain can be severe and can, in some cases, be both acute and chronic in nature. Constipation is frequently present, as the nervous system of the gut is affected.

If the broken enzyme is in the blood -- the erythropoietic porphyrias -- the disease primarily affects the skin, causing photosensitivity, blisters, itching, and swelling, and increased hair growth on areas such as the forehead. These are the ones that give rise to the vampire legends.

Attacks of the disease can be triggered by drugs (e.g. barbiturates, alcohol, sulfa drugs, oral contraceptives, sedatives, and certain antibiotics), other chemicals, certain foods, and exposure to the sun. Fasting can also trigger attacks.

Now, about the vampires... In 1985 biochemist David Dolphin proposed that the vampires of folklore may actually have been people suffering from porphyria. According to his hypothesis, porphyria victims are extraordinarily sensitive to sunlight. Even mild exposure can cause severe disfigurement. Facial skin may scar, the nose and fingers may fall off, and the lips and gums may become so taut that the teeth project like fangs. To avoid sunlight, people with serious cases of porphyria go out only at night, just like Dracula. (Oh really? My patient walked around every day just like a normal person :) ). Porphyria can be treated with injections of blood products. Centuries ago, porphyria victims might have sought to treat themselves by drinking blood. Garlic contains a chemical that worsens porphyria symptoms, causing sufferers to avoid it. Just like vampires.

Well, first of all, porphyria victims DO NOT crave blood. That's just nonsense. It wouldn't make their symptoms better and anyway, if you drink the blood, it passes into your stomach, where your gastric juices would break down the molecules in the blood that you are missing if you are suffering from porphyria.

Second, there is only one rare form of porphyria which produces the drastic skin changes as described above. Skin problems are indeed a fairly common symptom, but only the rarest form -- congenital erythropoietic porphyria -- causes severe disfigurement. Most people only get skin blistering. Alleged vampires exhumed typically weren't disfigured but appeared as they had in life -- except for being dead, of course!

And lastly, there's never been any concrete evidence that garlic makes porphyria worse, although there are a host of drugs that do.

So, that's my take on the whole porphyria/vampire connection. On the other hand, there is good evidence that some famous people in history really did suffer from porphyria. Probably the best known is England's King George III.

~Faustina