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NORD is very grateful to Karl E. Anderson, MD, FACP, Division of Human Nutrition, Department of Preventive Medicine and Community Health; Director, Porphyria Laboratory & Center, University of Texas Medical Branch, for assistance in the preparation of this report.
Synonyms of Variegate Porphyria
- porphyria variegata
- No subdivisions found.
Variegate porphyria is a rare genetic metabolic disorder characterized by deficient function of the enzyme protoporphyrinogen oxidase (PPO or PPOX). This deficiency is caused by heterozygous mutations in the PPOX gene, and leads to the accumulation of certain chemicals called porphyrins and porphyrin precursors in the body, which, in turn, can potentially result in a variety of symptoms. Specific symptoms can vary greatly from one person to another. Some affected individuals present with skin symptoms, some with neurological symptoms and some with both. Blistering and fragility of sun-exposed skin are the most common skin (cutaneous) symptoms. Common neurological symptoms include abdominal pain, nausea, vomiting, constipation, extremity pain and weakness, anxiety, restlessness and convulsions. Many different PPOX mutations have been identified in different families with variegate porphyria. The genetic mutation in a family is inherited as an autosomal dominant trait, but many individuals who inherit a PPOX mutation do not develop any symptoms (asymptomatic).
Variegate porphyria is one of a group of disorders known as the porphyrias. The porphyrias are characterized by abnormally high levels of porphyrins or porphyrin precursors in the body. Each porphyria is due to a deficiency of a different enzyme. There are eight enzymes in the pathway for making heme, which is a part of hemoglobin and other hemoproteins. There are at least eight types of porphyria. The symptoms associated with the various types of porphyria differ, depending upon the specific enzyme that is deficient. It is important to note that people who have one type of porphyria do not develop any of the other types. Porphyrias are generally classified into two groups: the "hepatic" and "erythropoietic" types. Porphyrins and porphyrin precursors originate in excess amounts from the liver in the hepatic types, and mostly from the bone marrow in the erythropoietic types. Variegate porphyria is a hepatic form of porphyria.
Protoporphyrinogen and coproporphyrinogen accumulate in the liver in variegate porphyria because PPOX is deficient, and become oxidized to protoporphyrin and coproporphyrin, which are transported in the blood plasma and cause the skin to be sensitive to sunlight. The neurological symptoms are associated with accumulation of porphyrin precursors, namely delta-aminolevulinic acid (ALA) and porphobilinogen (PBG).
Organizations related to Variegate Porphyria
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