The Porphyria reference article from the English Wikipedia on 24-Apr-2004 (provided by Fixed Reference: snapshots of Wikipedia from wikipedia.org)

Porphyria

The porphyrias are inherited or acquired disorders of specific enyzmes in the heme biosynthetic pathway. They are broadly classified as hepatic porphyrias or erythropoetic porphyrias, based on the site of the overproduction and accumulation of the porphyrins (or their chemical precursors).

Porphyrin is used to make heme, the part of blood that carries oxygen. Heme also gives blood its color. Any circulating porphyrin the body does not use is excreted in urine and stool. When the body produces and excretes too much porphyrin, as happens with porphyria, not enough heme remains to keep a person healthy.

The hepatic porphyrias primarily affect the nervous system, resulting in abdominal pain, neuropathy, seizures, and mental disturbances, including hallucinations, depression, anxiety, and paranoia.

The erythropoeitic porphyrias primarily affect the skin, causing photosensitivity, blisters, itching, and swelling.

In some forms of porphyria, accumulated heme precursors excreted in the urine may change its color to a reddish or purple hue.

Attacks of the disease can be triggered by drugs (barbiturates, tranquilizers, birth control pills, sedatives), chemicals, certain foods, and exposure to the sun.

Porphyria is diagnosed through tests on blood, urine, and stool. It can be treated with medicines to relieve symptoms, a drug called hemin (which is like heme), or a high-carbohydrate diet.

There are eight enzymes in the heme biosynthetic pathway: the first and the last three are in the mitochondria, while the other four are in the cytosol.

1. δ-aminolevulinate (ALA) synthase
2. δ-aminolevulinate (ALA) dehydratase
3. hydroxymethylbilane (HMB) synthase
4. uroporphyrinogen (URO) synthase
5. uroporphyrinogen (URO) decarboxylase
6. coproporphyrinogen (COPRO) oxidase
7. protoporphyrinogen (PROTO) oxidase
8. ferrochelastase

the hepatic porphyrias are:

• ALA dehydratase deficiency
• acute intermittent porphyria (AIP): a deficiency in HMB synthase
• hereditary coproporphyria (HCP): a deficiency in COPRO oxidase
• variegate porphyria (VP): a deficiency in PROTO oxidase
• porphyria cutanea tarda (PCT): a deficiency in URO decarboxylase

the erythropoetic porphyias are:

• X-linked sideroblastic anemia (XLSA): a deficiency in ALA synthase
• congenital erythropoietic porphyria (CEP): a deficiency in URO synthase
• erythropoietic protoporphyria (EPP): a deficiency in ferrochelatase

Table of contents

1 Mixt porphyria 2 Popular misconception 3 External link

Mixt porphyria

The mixt one, or porphyria variegata, combine the signs of the acute with the one of the skin. From teen when the sickness appear it evolve to worsen the neuropsychics signs and death can happen by reaching the bulb. It's mostly people living in South Africa from a single ancestor from the Netherlands, Berrit Janisz, who emigrated in the XVIIe century.

Popular misconception

Porphyria has been speculatively linked with the vampirism myth, based on a number of superficial resemblances between the symptoms of the porphyrias and vampire folklore. These fancies are based on a misunderstanding of the nature of porphyria. Porphyria is also inadequate as an explanation for werewolf beliefs.

External link

• Debunking the association of porphyria with vampirism

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