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Microcytosis in Erythropoietic Protoporphyria.

ABSTRACT: Partial deficiency of the last enzyme of the heme biosynthetic pathway, namely, ferrochelatase (FECH), is responsible for erythropoietic protoporphyria (EPP) in humans. This disorder is characterized by painful skin photosensitivity, due to excessive protoporphyrin IX (PPIX) production in erythrocytes. Although several papers report the presence of iron deficiency anemia in about 50% of EPP patients, there is still no a conclusive explanation of the why this occurs. In the present work, we explored hematological indices and iron status in 20 unrelated Italian EPP patients in order to propose a new hypothesis. Our data show that microcytosis is present in EPP patients also in the absence of anemia and iron deficiency with a link between PPIX accumulation and reduced MCV, probably indicating an indirect condition of heme deficiency. Patients studied had a downward shift of iron parameters due to increased hepcidin concentrations only in a state of repleted iron stores. Interestingly, hemoglobin synthesis was not limited by iron supply except in cases with further iron loss, in which concomitantly increased soluble transferrin (Tf) receptor (sTfR) levels were detected. The mechanisms involved in the iron uptake downregulation in EPP remain unclear, and the role of PPIX accumulation in microcytosis.

SUBMITTER: Graziadei G

PROVIDER: S-EPMC8928159 | biostudies-literature | 2022

REPOSITORIES: biostudies-literature

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Microcytosis in Erythropoietic Protoporphyria.

Graziadei Giovanna G Duca Lorena L Granata Francesca F De Luca Giacomo G De Giovanni Anna A Brancaleoni Valentina V Nava Isabella I Di Pierro Elena E

Frontiers in physiology 20220303

Partial deficiency of the last enzyme of the heme biosynthetic pathway, namely, ferrochelatase (FECH), is responsible for erythropoietic protoporphyria (EPP) in humans. This disorder is characterized by painful skin photosensitivity, due to excessive protoporphyrin IX (PPIX) production in erythrocytes. Although several papers report the presence of iron deficiency anemia in about 50% of EPP patients, there is still no a conclusive explanation of the why this occurs. In the present work, we explo ...[more]

PMID: 35309058

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Project description:Erythropoietic protoporphyria (EPP) is an inherited disorder of the haem metabolic pathway characterised by accumulation of protoporphyrin in blood, erythrocytes and tissues, and cutaneous manifestations of photosensitivity. EPP has been reported worldwide, with prevalence between 1:75,000 and 1:200,000. It usually manifests in early infancy upon the first sun exposures. EPP is characterised by cutaneous manifestations of acute painful photosensitivity with erythema and oedema, sometimes with petechiae, together with stinging and burning sensations upon exposure to sunlight, without blisters. These episodes have a variable severity depending on the exposure duration and may result in chronic permanent lesions on exposed skin. As protoporphyrin is a lipophilic molecule that is excreted by the liver, EPP patients are at risk of cholelithiasis with obstructive episodes, and chronic liver disease that might evolve to rapid acute liver failure. In most patients, EPP results from a partial deficiency of the last enzyme of the haem biosynthetic pathway, ferrochelatase, EC 4.99.1.1/FECH (encoded by the FECH gene). EPP appears to be inherited as an autosomal dominant disease, the clinical expression of which is modulated by the presence of the hypomorphic FECH IVS3-48C allele trans, but recessive inheritance with two mutated FECH alleles has also been described. In about 2% of patients, overt disease was recently shown to be caused by gain-of-function mutations in the erythroid-specific aminolevulinic acid synthase 2 (ALAS2/ALAS, EC 2.3.1.27) gene and named X-linked dominant protoporphyria. Diagnosis is established by finding increased levels of protoporphyrin in plasma and red blood cells, and detection of a plasma fluorescence peak at 634 nm. Investigations for hepatic involvement, ferrochelatase activity level, genetic analysis (FECH mutations, presence of the hypomorphic FECH IVS3-48C allele trans and ALAS2 mutations) and family studies are advisable. Differential diagnosis includes phototoxic drug reactions, hydroa vacciniforme, solar urticaria, contact dermatitis, angio-oedema and, in some cases, other types of porphyria. Management includes avoidance of exposure to light, reduction of protoporphyrin levels and prevention of progression of possible liver disease to liver failure. As the major risk in EPP patients is liver disease, a regular follow-up of hepatic involvement is essential. Sequential hepatic and bone marrow transplantation should be considered as a suitable treatment for most severe cases of EPP with hepatic involvement. EPP is a lifelong disorder whose prognosis depends on the evolution of the hepatic disease. However, photosensitivity may have a significant impact on quality of life of EPP patients.

Project description:BackgroundErythropoietic protoporphyria is a severe photodermatosis that is associated with acute phototoxicity. Patients with this condition have excruciating pain and a markedly reduced quality of life. We evaluated the safety and efficacy of an α-melanocyte-stimulating hormone analogue, afamelanotide, to decrease pain and improve quality of life.MethodsWe conducted two multicenter, randomized, double-blind, placebo-controlled trials of subcutaneous implants containing 16 mg of afamelanotide. Patients in the European Union (74 patients) and the United States (94 patients) were randomly assigned, in a 1:1 ratio, to receive a subcutaneous implant containing either afamelanotide or placebo every 60 days (a total of five implants in the European Union study and three in the U.S study). The type and duration of sun exposure, number and severity of phototoxic reactions, and adverse events were recorded over the respective 180-day and 270-day study periods. Quality of life was assessed with the use of validated questionnaires. A subgroup of U.S. patients underwent photoprovocation testing. The primary efficacy end point was the number of hours of direct exposure to sunlight without pain.ResultsIn the U.S. study, the duration of pain-free time after 6 months was longer in the afamelanotide group (median, 69.4 hours, vs. 40.8 hours in the placebo group; P=0.04). In the European Union study, the duration of pain-free time after 9 months was also longer in the afamelanotide group than in the placebo group (median, 6.0 hours vs. 0.8 hours; P=0.005), and the number of phototoxic reactions was lower in the the afamelanotide group (77 vs. 146, P=0.04). In both trials, quality of life improved with afamelanotide therapy. Adverse events were mostly mild; serious adverse events were not thought to be related to the study drug.ConclusionsAfamelanotide had an acceptable side-effect and adverse-event profile and was associated with an increased duration of sun exposure without pain and improved quality of life in patients with erythropoietic protoporphyria. (Funded by Clinuvel Pharmaceuticals and others; ClinicalTrials.gov numbers, NCT01605136 and NCT00979745.).

Project description:The use of iron supplementation for anemia in erythropoietic protoporphyria (EPP) is controversial with both benefit and deterioration reported in single case reports. There is no systematic study to evaluate the benefits or risks of iron supplementation in these patients. We assessed the potential efficacy of oral iron therapy in decreasing erythrocyte protoporphyrin (ePPIX) levels in patients with EPP or X-linked protoporphyria (XLP) and low ferritin in an open-label, single-arm, interventional study. Sixteen patients (≥18 years) with EPP or XLP confirmed by biochemical and/or genetic testing, and serum ferritin ≤30 ng/mL were enrolled. Baseline testing included iron studies, normal hepatic function, and elevated plasma porphyrins and ePPIX levels. Oral ferrous sulfate 325 mg twice daily was administered for 12 months. The primary efficacy outcome was the relative difference in total ePPIX level between baseline and 12 months after starting treatment with iron. Secondary measures included improvement in serum ferritin, plasma porphyrins, and clinical symptoms. Thirteen patients had EPP (8 females, 5 males) and 3 had XLP (all females) and the mean age of participants was 38.8 years (SD 14.5). Ten patients completed all study visits limiting interpretation of results. In EPP patients, a transient increase in ePPIX levels was observed at 3 months in 9 of 12 (75%) patients. Iron was discontinued in 2 of these patients after meeting the protocol stopping rule of a 35% increase in ePPIX. Seven patients withdrew before study end. Ferritin levels increased on iron replacement indicating an improvement in iron status. A decrease in ePPIX was seen in both XLP patients who completed the study (relative difference of 0.67 and 0.5 respectively). No substantial changes in ePPIX were seen in EPP patients at the end of the study (n = 8; median relative difference: -0.21 (IQR: -0.44, 0.05). The most common side effects of iron treatment were gastrointestinal symptoms. Hepatic function remained normal throughout the study. Our study showed that oral iron therapy repletes iron stores and transiently increases ePPIX in some EPP patients, perhaps due to a transient increase in erythropoiesis, and may decrease ePPIX in XLP patients. Further studies are needed to better define the role of iron repletion in EPP. Trial registration: NCT02979249.

Project description:ImportanceAutosomal recessive erythropoietic protoporphyria (EPP) and X-linked protoporphyria (XLP) are rare photodermatoses presenting with variable degrees of painful phototoxicity that markedly affects quality of life. The clinical variability, determinants of severity, and genotype/phenotype correlations of these diseases are not well characterized.ObjectiveTo describe the baseline clinical characteristics, genotypes, and determinants of disease severity in a large patient cohort with EPP or XLP.Design, setting, and participantsA prospective observational study was conducted among patients with confirmed diagnoses of EPP or XLP from November 1, 2010, to December 6, 2015, at 6 academic medical centers of the Porphyrias Consortium of the National Institutes of Health Rare Diseases Clinical Research Network. Detailed medical histories, including history of phototoxicity and treatment, were collected on standardized case report forms. Patients underwent baseline laboratory testing, total erythrocyte protoporphyrin (ePPIX) testing, and molecular genetic testing. Data were entered into a centralized database.Main outcomes and measuresResults of biochemical and genetic tests were explored for association with clinical phenotype in patients with EPP or XLP.ResultsOf the 226 patients in the study (113 female and 113 male patients; mean [SD] age, 36.7 [17.0] years), 186 (82.3%) had EPP with a FECH (OMIM 612386) mutation and the common low-expression FECH allele IVS3-48T>C, and only 1 patient had 2 FECH mutations. Twenty-two patients had XLP (9.7%; 10 male and 12 female patients), and 9 patients (4.0%) had elevated ePPIX levels and symptoms consistent with protoporphyria but no detectable mutation in the FECH or ALAS2 (OMIM 301300) gene. Samples of DNA could not be obtained from 8 patients. Patients' mean (SD) age at symptom onset was 4.4 (4.4) years. Anemia (107 [47.3%]), history of liver dysfunction (62 [27.4%]), and gallstones (53 [23.5%]) were commonly reported. Higher ePPIX levels were associated with earlier age of symptom onset (median ePPIX levels for those who developed symptoms before vs after 1 year of age, 1744 vs 1567 µg/dL; P = .02), less sun tolerance (median ePPIX levels for those reporting symptoms before vs after 10 minutes of sun exposure, 2233 vs 1524 µg/dL; P ≤ .001), and increased risk of liver dysfunction (median ePPIX levels for those with liver dysfunction vs normal liver function, 2016 vs 1510 µg/dL; P = .003). Patients with EPP and FECH missense mutations had significantly lower ePPIX levels than those with other mutations (1462 vs 1702 µg/dL; P = .01). Male patients with XLP had significantly higher ePPIX levels, on average, than did patients with EPP (3574 vs 1669 µg/dL; P < .001). Marked clinical variability was seen in female patients with XLP owing to random X-chromosomal inactivation.Conclusions and relevanceThese data suggest that higher ePPIX levels are a major determinant of disease severity and risk of liver dysfunction in patients with EPP or XLP. These findings provide a framework for clinical monitoring and management of these disorders.

Dataset Information

Microcytosis in Erythropoietic Protoporphyria.

Publications

Microcytosis in Erythropoietic Protoporphyria.

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