What causes porphyria?
Most porphyrias are inherited disorders, meaning they are caused by abnormalities in genes passed from parents to children. Scientists have identified the genes for all eight enzymes in the heme pathway. Some forms of porphyria result from inheriting an abnormal gene from one parent. Other forms are due to inheriting two abnormal genes-one from each parent. The risk that members of an affected family will have the disease or transmit it to their children depends on the type of porphyria. One type of porphyria-porphyria cutanea tarda-is most often an acquired disorder. It occurs when factors other than genes cause an enzyme deficiency in the liver.
