The reaction catalyzed by UroD 20% of cases of<unk>  are inherited in an autosomal dominant pattern. Inherited mutations in the UROD gene cause about 20% of cases (the other 80% of cases do not have mutations in UROD, and are classified as sporadic). UROD makes an enzyme called uroporphyrinogen III decarboxylase, which is critical to the chemical process that leads to heme production. The activity of this enzyme is usually reduced by 50% in all tissues in people with the inherited form of the condition. Nongenetic factors such as excess iron or partially genetic factors such as alcohol use disorder and others listed above can increase the demand for heme and the enzymes required to make heme. The combination of this increased demand and reduced activity of uroporphyrinogen decarboxylase disrupts heme production and allows byproducts of the process to accumulate in the body, triggering the signs and symptoms of<unk> . The HFE gene makes a protein that helps cells regulate the absorption of iron from the digestive tract and into the cells of the body. Certain mutations in the HFE gene cause hemochromatosis (an iron overload disorder). People who have these mutations are also at an increased risk of developing<unk> . In the 20% of cases where<unk>  is inherited, it is inherited in an autosomal dominant pattern, which means one copy of the altered gene is sufficient to decrease enzyme activity and cause the signs and symptoms of the disorder. Other While inherited deficiencies in uroporphyrinogen decarboxylase often lead to the development of<unk> , there are a number of risk factors that can both cause and exacerbate the symptoms of this disease. One of the most common risk factors observed is infection with the Hepatitis C virus. One review of a collection of<unk>  studies noted Hepatitis C infection in 50% of documented cases of<unk> . Additional risk factors include alcohol use disorder, excess iron (from iron supplements as well as cooking on cast iron skillets), and exposure to chlorinated cyclic hydrocarbons and Agent Orange. It can be a paraneoplastic phenomenon. Exacerbating factors * Alcohol * Estrogen * Iron * Hepatitis C virus
Porphyria cutanea tarda
Prurigo pigmentosa
Phakomatosis pigmentovascularis
Dermatopathia pigmentosa reticularis
Urticaria pigmentosa
Variegate porphyria
Hepatic porphyria
Phakomatosis pigmentokeratotica