While the most common symptom of<unk>  is the appearance of skin lesions and blistering, their appearance is not conclusive. Laboratory testing commonly reveals high levels of uroporphyrinogen in the urine, clinically referred to as uroporphyrinogenuria. Additionally, testing for common risk factors such as hepatitis C and hemochromatosis is strongly suggested, as their high prevalence in patients with<unk>  may require additional treatment. If clinical appearance of<unk>  is present, but laboratories are negative, the diagnosis of pseudoporphyria should be seriously considered. Classification Some sources divide<unk>  into two types: sporadic and familial. Other sources include a third type, but this is less common. Type OMIM Description Type I ("sporadic") Type I<unk> , the sporadic form, is indicated by UROD deficiency that is observed only in hepatic cells and nowhere else in the body. Genetically, these individuals will not exhibit deficiency in the UROD gene, although other genetic factors such as HFE deficiency (resulting in hemochromatosis and the buildup of iron in the liver) are thought to play a key role. Typically in these individuals, a variety of risk factors such as alcohol use disorder and Hepatitis C virus infection co-occur to result in the clinical manifestation of<unk> . Type II ("familial") Patients exhibiting Type II<unk>  have a specific deficiency in the UROD gene, passed down in an autosomal dominant pattern. Those possessing this deficiency are heterozygous for the UROD gene. They do not show a complete lack of functional uroporphyrinogen decarboxylase, only a deficient form of the enzyme that is marked by reduced conversion of uroporphyrinogen to coproporphyrinogen. Therefore, the expression of uroporphyrinogen decarboxylase will be reduced throughout the body of these individuals, while it is isolated to the liver in Type I patients. While this genetic deficiency is the main distinction between Type I and Type II<unk> , the risk factors mentioned before are often seen in patients presenting with Type II<unk> . In fact, many people who possess the deficient UROD gene often go their entire lives without having a clinical manifestation of<unk>  symptoms. Type III - The least common is Type III, which is no different from Type I insofar as the patients possess normal UROD genes. Despite this, Type III<unk>  is observed in more than one family member, indicating a genetic component unrelated to the expression of uroporphyrinogen decarboxylase. One study used 74% as the cutoff for UROD activity, with those patients under that number being classified as type II, and those above classified as type III if there was a family history, and type I if there was not. Genetic variants associated with hemochromatosis have been observed in<unk>  patients, which may help explain inherited<unk>  not associated with UROD.
Porphyria cutanea tarda
Prurigo pigmentosa
Phakomatosis pigmentovascularis
Dermatopathia pigmentosa reticularis
Urticaria pigmentosa
Variegate porphyria
Hepatic porphyria
Phakomatosis pigmentokeratotica