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 > X-Linked Protoporphyria
X-Linked Protoporphyria (XLP)
Disease Category: Porphyrias
A very rare, inherited, metabolic disorder caused by genetic mutations on the X chromosome, characterized by build-up of porphyrins. Porphyrins are substances that bind metals to form complexes, such as the iron found in red blood cells. The hallmark symptom is cutaneous photosensitivity (skin hyperreactivity to light), resulting in swelling and redness of the skin and extreme pain upon exposure. Other symptoms include pseudosclerosis (thickening or hardening) of affected skin, mild anemia (low red blood cell levels), iron deficiency, gallbladder dysfunction, and liver disease.
Research groups studying this disease
Porphyrias Consortium (PC)
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.
7211: Effect of Oral Cimetidine in the Protoporphyrias
Erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) result from genetic defects of heme biosynthesis that cause life-long, painful cutaneous sensitivity to light. The objective of this study is to determine the efficacy and safety of oral cimetidine administration for treatment of the protoporphyrias. Efficacy will be based on protoporphyrin levels, photosensitivity, and quality of life questionnaires.
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.