Diseases Studied

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.

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.

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.