Diseases Studied

The Rare Diseases Clinical Research Network is an NIH-funded research network of 20 active consortia or research groups working to advance treatment for diseases that are rare. Use the search tools on this page to find the diseases we currently study. You can reach out to the indicated consortia or research groups for more information on those diseases and studies underway.

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All Diseases > Variegate Porphyria

Variegate Porphyria (VP)

Disease Category: Porphyrias

A rare, metabolic disorder characterized by deficiency of the enzyme protoporphyrinogen oxidase (PPO), which allows for build-up of porphyrins and porphyrin precursors. Porphyrins are substances that bind metals to form complexes, such as the iron found in red blood cells. Symptoms include abdominal and extremity pain, nausea, vomiting, constipation, bladder dysfunction, convulsions, profound muscle weakness, tachycardia (rapid heartbeat), hypertension (high blood pressure), and cutaneous photosensitivity (skin hyperreactivity to light) resulting in blistering skin lesions, hypertrichosis (excessive hair growth), and discoloration. Risk for developing chronic kidney disease and hepatocellular carcinoma (liver cancer) increases.

Research groups studying this disease

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Porphyrias Consortium (PC)

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The porphyrias are a group of rare metabolic diseases that may present in childhood or adult life and are due to deficiencies of enzymes in the heme biosynthetic pathway. Porphyrias have various symptoms depending on the type, but these can range from neurological symptoms to sun sensitivity. See the descriptions of each type to get more information. The natural history of these disorders is not well described and it is not known why some patients are more severe than others. Therefore, the purpose of this long-term follow-up study is to collect a large group of patients with the different types of porphyria and to provide a better understanding of the natural history of these disorders. The hope is that this information will help in developing new forms of treatment. The research aims are: 1. To study the prevalence of specific indicators of disease severity. To study the effects on quality of life and health of various porphyrias. 2. To determine the relationships between disease severity and various biological characteristics, genetic information, and environmental factors.

The purpose of this study is to collect information on acute porphyria attacks that may have been caused by a medication. Individuals who have tested positive for an acute porphyria, or have been told by a doctor that they may have the disease may join this study. We are particularly interested in the following: (1) Attacks that appeared to be due to a specific medication; (2) Use of a medication that is considered risky in porphyria but caused no problems; and (3) Use of medications for which the safety profile in porphyria is unknown.

The purpose of this study is to establish an independent, public, online database, called the International Porphyria Molecular Diagnostic Database. This Database will have all published, newly identified, and biochemically/clinically verified pathogenic mutations for the eight major porphyrias, as well as a list of genomic variants for each gene from the latest genomic/exonic databases (e.g., GnomAD) that are benign, likely-benign, or unknown. The eight major porphyrias include: Acute Intermittent Porphyria (AIP), due to pathogenic mutations in the Hydroxymethylbilane Synthase (HMBS) gene, Hereditary Coproporphyria (HCP), due to pathogenic mutations in the Coproporphyrinogen Oxidase (CPOX) gene, Variegate Porphyria (VP), due to pathogenic mutations in the Protoporphyrinogen Oxidase (PPOX) gene, Porphyria Cutanea Tarda (PCT) due to pathogenic mutations in the Uroporphyrinogen Decarboxylase (UROD) gene, Erythropoietic Protoporphyria (EPP) due to pathogenic mutations in the Ferrochelatase (FECH) gene, Congenital Erythropoietic Porphyria (CEP) due to pathogenic mutations in the Uroporphyrinogen III Synthase (UROS) gene, X-Linked Protoporphyria (XLP) due to pathogenic mutations in the Aminolevulinic Acid Synthase 2 (ALAS2) gene, and ALA-Dehydrogenase Deficient Porphyria (ADP), due to pathogenic mutations in the ALADehydrogenase (ALAD) gene. Efforts will be directed to verify each published or new mutation in conjunction with the European Porphyria Network (EPNET) by elevated urinary, stool, erythrocyte, or plasma porphyrin precursor levels as well as by specific enzymatic activity, when available, from de-identified patients with the respective clinical manifestations for each porphyria.

Committed to improving the quality of life of the porphyria patient community, relentlessly focused on advancing disease awareness, research, and therapies in all the porphyrias.