Porphyrias are a group of metabolic disorders caused by a disturbance in the synthesis Synthesis Polymerase Chain Reaction (PCR) of heme. In most cases, porphyria is caused by a hereditary enzyme defect. The disease patterns differ depending on the affected enzyme, and the variants of porphyria can be clinically differentiated between acute and nonacute forms. Patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship with porphyria present with photosensitive skin Skin The skin, also referred to as the integumentary system, is the largest organ of the body. The skin is primarily composed of the epidermis (outer layer) and dermis (deep layer). The epidermis is primarily composed of keratinocytes that undergo rapid turnover, while the dermis contains dense layers of connective tissue. Skin: Structure and Functions eruptions and sometimes systemic symptoms such as abdominal pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways and neuropathy Neuropathy Leprosy. Porphyrias are managed by avoiding triggers Triggers Hereditary Angioedema (C1 Esterase Inhibitor Deficiency), such as sun exposure and consumption of alcohol. When flares occur, therapy is targeted toward symptomatic relief.
Last updated: 31 May, 2022
Porphyrias are due to enzymatic defects in heme biosynthesis Biosynthesis The biosynthesis of peptides and proteins on ribosomes, directed by messenger RNA, via transfer RNA that is charged with standard proteinogenic amino acids. Virology:
|Form of porphyria||Defective enzyme|
|Porphyria cutanea tarda||Uroporphyrinogen III decarboxylase|
|Acute intermittent porphyria||Porphobilinogen Porphobilinogen Heme Metabolism deaminase|
|X-linked X-linked Genetic diseases that are linked to gene mutations on the X chromosome in humans or the X chromosome in other species. Included here are animal models of human X-linked diseases. Common Variable Immunodeficiency (CVID) protoporphyria||δ-Aminolevulinic acid synthase 2|
|Congenital Congenital Chorioretinitis erythropoietic porphyria||Uroporphyrinogen III synthase Uroporphyrinogen III synthase An enzyme that catalyzes the cyclization of hydroxymethylbilane to yield uroporphyrinogen III and water. It is the fourth enzyme in the 8-enzyme biosynthetic pathway of heme, and is encoded by uros gene. Heme Metabolism|
|Hereditary coproporphyria||Coproporphyrinogen oxidase Coproporphyrinogen oxidase An enzyme that catalyzes the oxidative decarboxylation of coproporphyrinogen III to protoporphyrinogen IX by the conversion of two propionate groups to two vinyl groups. It is the sixth enzyme in the 8-enzyme biosynthetic pathway of heme, and is encoded by cpo gene. Heme Metabolism|
|Variegate porphyria||Protoporphyrinogen oxidase Protoporphyrinogen oxidase A membrane-bound flavoenzyme that catalyzes the oxygen-dependent aromatization of protoporphyrinogen IX (protogen) to protoporphyrin IX (proto IX). It is the last enzyme of the common branch of the heme and chlorophyll pathways in plants. Heme Metabolism|
|Erythropoietic protoporphyria||Ferrochelatase Ferrochelatase A mitochondrial enzyme found in a wide variety of cells and tissues. It is the final enzyme in the 8-enzyme biosynthetic pathway of heme. Ferrochelatase catalyzes ferrous insertion into protoporphyrin IX to form protoheme or heme. Heme Metabolism|
Most commonly, porphyrias are due to an inherited enzyme defect within the heme biosynthesis Biosynthesis The biosynthesis of peptides and proteins on ribosomes, directed by messenger RNA, via transfer RNA that is charged with standard proteinogenic amino acids. Virology pathway. They may rarely be acquired later in life:
Clinical presentation depends on the pattern of organ involvement.
The diagnosis of porphyrias is typically made using specialized blood tests.
There is no known cure for porphyria.
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