Synonyms
Disturbance of heme synthesisPorphyria are a series of metabolic diseases in which the structure (synthesis) of a part of the transporter for oxygen in the blood (heme in hemoglobin) is disturbed.
Introduction
In the body, thousands of metabolic steps are carried out by enzymes that enable (catalyze) biochemical reactions. If, either due to hereditary factors or acquired, the functionality of an enzyme is so limited or increased that signs of disease (symptoms) occur, the expert speaks of a metabolic disease. Eight developmental steps are necessary in the formation of heme.
If one of them cannot be carried out in a sufficient form due to enzyme deficiency or defectiveness, porphyria is present. The signs of the disease are then caused by the accumulation and deposition of the substance that should actually be converted in the problematic reaction step. Likewise, a lack of the substances that are subsequently produced can lead to inconvenience.
Porphyrias include erythropoietic protoporphyria, congenital erythropoietic porphyria, porphyria cutanea tarda, acute intermittent porphyria and Doss porphyria. Often porphyrias are inherited, with the majority following a dominant inheritance, which means that at least one parent must also be diseased. In contrast, congenital erythropoietic porphyria, for example, is inherited autosomal-recessively.
In this case, the parents are usually healthy, but often related by blood. Genetic changes in the genetic makeup (mutations), which are not inherited, can also be the cause of porphyria. Thus, 4 out of 5 persons suffering from porphyria cutanea tarda have not inherited it, but have developed it due to genetic mutations.
Porphyrias are also possible without genetic defects. In these cases one speaks of acquired (secondary) porphyrias. They are usually due to poisoning, for example with heavy metals such as lead and mercury, or liver damage caused by alcohol, drugs or environmental toxins such as pesticides or hexachlorobenzene.
Other diseases can also cause secondary pophyria. The most important of these are liver diseases (e.g. hepatitis C), other metabolic diseases (e.g. hemochromatosis), and blood-destroying (hemolytic) forms of anaemia.
