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Porphyric Red Cells
Published in Ronald L. Nagel, Genetically Abnormal Red Cells, 2019
A new type of porphyria was recognized in 1975 and called hepatoerythropoietic porphyria because it had a clinical resemblance of erythropoietic porphyria and because excess porphyrin production could be demonstrated both in hepatic and erythropoietic tissue.147 A number of cases described as atypical cases of erythropoietic porphyria and erythropoietic protoporphyria probably suffer from hepatoerythropoietic porphyria.12,148,150
Cutaneous Porphyrias
Published in Henry W. Lim, Herbert Hönigsmann, John L. M. Hawk, Photodermatology, 2007
Gillian M. Murphy, Karl E. Anderson
Five types of porphyria can present with identical blistering skin lesions, but are readily differentiated by biochemical testing (Tables 1–3). Defective enzymes associated with these porphyrias have been identified (Fig. 1, Table 4). In three, namely PCT, variegate porphyria (VP) and hereditary coproporphyria (HCP) symptoms usually begin in adult life. HCP and VP can also cause acute neurological symptoms. Cutaneous manifestations of CEP and hepatoerythropoietic porphyria (HEP) are usually much more severe and mutilating and begin in early childhood. However, cases of CEP and HEP with less severe symptoms, sometimes beginning in adulthood, are also well documented.
Givosiran, a novel treatment for acute hepatic porphyrias
Published in Expert Review of Precision Medicine and Drug Development, 2021
Manish Thapar, Sean Rudnick, Herbert L. Bonkovsky
The human porphyrias generally are classified according to the principal sites of overproduction of porphyrins or porphyrin precursors as being either hepatic or erythropoietic. The hepatic porphyrias are further classified as being ‘acute’ or ‘inducible’ (due to up-regulation of ALA synthase-1) or as being ‘chronic.’ The acute designation is used for four relatively rare disorders, all due to inherited defects in normal heme synthesis [ALA dehydratase deficient porphyria (ADP); acute intermittent porphyria (AIP), due to partial deficiency of HMBS; hereditary coproporphyria (HCP), due to partial deficiency of CPOX; and variegate porphyria (VP), due to partial deficiency of PPOX]. When these are biochemically active (elevated ALA and PBG), there is induction of ALA synthase-1 in the liver, as already described, leading to marked overproduction of ALA, and usually also of porphobilinogen (PBG). The chronic hepatic porphyrias comprise two disorders, porphyria cutanea tarda (PCT) and hepatoerythropoietic porphyria (HEP), which, respectively, are due to partial (∼50%) or nearly total (>90%) deficiency of uroporphyrinogen decarboxylase (UROD), the fifth enzyme of the heme synthetic pathway. PCT, the disorder with milder UROD deficiency, occurs mainly in adult men with underlying liver disease, whereas the disorder with severe UROD deficiency is HEP. It is usually manifest in childhood or infancy and continues life-long.
Porphyrias and photosensitivity: pathophysiology for the clinician
Published in Postgraduate Medicine, 2018
Loukas Kakoullis, Stylianos Louppides, Eleni Papachristodoulou, George Panos
Porphyrias manifest with either one or more of these clinical syndromes, depending of the substrates being accumulated. Acute intermittent porphyria (AIP) manifests as acute neurovisceral disease only, hereditary coproporphyria (HCP), and variegate porphyria (VP) combine acute neurovisceral disease with delayed blistering photosensitivity, whereas porphyria cutanea tarda (PCT) and congenital erythropoietic porphyria (CEP) manifest only as delayed blistering photosensitivity. However, it should be noted that photosensitivity in CEP is far more severe and can lead to photomutilation and disfigurement. Immediate and painful photosensitivity characterizes the two forms of protoporphyria, erythropoietic protoporphyria (EPP) and X-linked erythropoietic protoporphyria (XLEPP) [7,9,11]. Finally, an ultra-rare form of porphyria, ALA dehydratase deficiency porphyria (ALADP), manifests with acute neurovisceral disease, but due to the paucity of reported cases (less than 10 cases have been reported [7]), the complete range of its manifestations remains unknown [11], and thus will not be discussed. The main source of heme precursors in AIP, PCT, HCP, and VP is the liver, whereas the bone marrow produces the excess of porphyrins observed in CEP, EPP and XLEPP [7]. In hepatoerythropoietic porphyria, another ultra-rare form of porphyria, both the liver and bone marrow contribute to the excess production of heme precursors [12,13].