A- A+

General Information
for all individuals who have been told they have or may have porphyria

Written by George D. Sweeney, M.B., Ch. B., Ph.D., FRCPC
Prepared for the Canadian Association for Porphyria

Disclaimer
Care has been taken to ensure that the information in this guide is accurate at the time of production. This information is, however, intended for general guidance only. The Canadian Association for Porphyria disclaims for itself and for the author of this guide, all responsibility for any mis-statements or for consequences of actions taken by any person while acting on information contained herein. Physicians and patients must make their own decisions about therapy according to the individual circumstances of each case.

What is porphyria?
There are at least six separate "porphyrias" (diseases of porphyrin chemistry in the body) and you must appreciate that these six disorders are quite separate. Some are relatively unimportant and some can be quite serious. Don't read about "porphyria" in medical dictionaries or encyclopedias because information from such sources is more likely to alarm than to inform you. Usually these sources of information are incomplete, out of date, or both. 

Be sure you understand fully from your doctor which porphyria you are supposed to have.

The main types are listed below:

Acute Intermittent Porphyria (AIP) : often called "Swedish" - because of the high frequency in Sweden

Hereditary Coproporphyria (HCP)

Variegate Porphyria (VP): sometimes called "South African" - where it is relatively common

Erythropoietic Protoporphyria (EPP)

Porphyria Cutanea Tarda (PCT)

Congenital Erythropoietic Porphyria (CEP): exceedingly rare


Of the first three porphyria listed above, acute intermittent porphyria is the most common in Canada. The diagnostic tests for each of these are different, but in each case, patients tend to suffer from "acute attacks", particularly if they take drugs like barbiturates and sulfonamides. 

Porphyria 4, 5 and 6 usually present as skin problems, either a sunburn-like response occurring much faster than usual, or blistering and ulceration of the skin on the back of the hands and other sun-exposed areas, and increased hair growth. Again, the tests to diagnose these are quite different and it is important that you know exactly what it is your doctor has told you you have. Types 2 and 3 can also present skin problems. 

Why are these all "porphyria"?
The red colour in blood is due to the pigment, hemoglobin. This pigment consists of the small molecule called heme, attached to a globin protein about 100 times larger. But it is the heme that gives hemoglobin its colour. Heme, in turn, is also two things joined up: a circle of atoms call "protoporphyrin" with iron in the middle of the circle. So you see that this red pigment in blood comes from a porphyrin. When the body makes porphyrins it uses simple starting material to make the first porphyrin (called uroporphyrin) and then successively changes the porphyrins until it has made protoporphyrin. The sequence of substances involved in making heme is approximately:

To be accurate, uroporphyrin and coproporphyrin should be called uroporphyrinogen and coproporphyrinogen. The shorter terms are used to keep things more simple. 

The reason for listing all these technical names is that these are the substances that laboratories look for in blood, urine or stool when diagnosing porphyria and you may have heard the results of tests using these terms. 

So is porphyrin a blood disease?
No, usually it is not, and it is never confined to the blood and the bone marrow (where blood is made). Pigments like hemoglobin are found in all cells and all cells make the heme these pigments need. Only red blood cells have hemoglobin but all cells have cytochromes (cyto = cell; -crome = colour) which are similar pigments also formed from porphyrins. The liver in particular makes large amounts of cytochrome and some of the important porphyrias are specifically diseases of the liver.

A word about inheritance.
Now we need to move to more specific information about the separate porphyrin diseases. Most porphyrin diseases show "dominant" inheritance; one or two show "recessive" inheritance and there is still argument about some. The diagrams below illustrate the difference between dominant and recessive inheritance: basically, only one parent is needed to transmit via the dominant mode and this parent must be affected. Both parents must carry an abnormal gene to transmit in the recessive mode but neither parent will be affected. There are some exceptions, but they are rare.

With this background, you should now read the material referring to the particular porphyria you may have. 

Back to top