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Journal of the American Academy of... Dec 2023Erythropoietic protoporphyria and X-linked protoporphyria are rare genetic photodermatoses. Limited expertise with these disorders among physicians leads to diagnostic...
Erythropoietic protoporphyria and X-linked protoporphyria are rare genetic photodermatoses. Limited expertise with these disorders among physicians leads to diagnostic delays. Here, we present evidence-based consensus guidelines for the diagnosis, monitoring, and management of erythropoietic protoporphyria and X-linked protoporphyria. A systematic literature review was conducted, and reviewed among subcommittees of experts, divided by topic. Consensus on guidelines was reached within each subcommittee and then among all members of the committee. The appropriate biochemical and genetic testing to establish the diagnosis is reviewed in addition to the interpretation of results. Prevention of symptoms, management of acute phototoxicity, and pharmacologic and nonpharmacologic treatment options are discussed. The importance of ongoing monitoring for liver disease, iron deficiency, and vitamin D deficiency is discussed with management guidance. Finally, management of pregnancy and surgery and the safety of other therapies are summarized. We emphasize that these are multisystemic disorders that require longitudinal monitoring. These guidelines provide a structure for evidence-based diagnosis and management for practicing physicians. Early diagnosis and management of these disorders are essential, particularly given the availability of new and emerging therapies.
Topics: Humans; Dermatitis, Phototoxic; Genetic Diseases, X-Linked; Liver Diseases; Protoporphyria, Erythropoietic; Practice Guidelines as Topic
PubMed: 36041558
DOI: 10.1016/j.jaad.2022.08.036 -
Dermatologie (Heidelberg, Germany) Jun 2024Porphyrias are predominantly genetic metabolic disorders caused by dysregulation of specific enzymes in porphyrin-heme biosynthesis. The enzymatic dysfunction leads to... (Review)
Review
Porphyrias are predominantly genetic metabolic disorders caused by dysregulation of specific enzymes in porphyrin-heme biosynthesis. The enzymatic dysfunction leads to formation and excretion of intermediate metabolic products in the form of porphyrins and/or their precursors δ‑aminolevulinic acid and porphobilinogen, which have cyto- and tissue-toxic properties. Clinically, porphyrias are extremely diverse, with symptoms ranging from skin changes on light-exposed areas of the body to potentially life-threatening neurovisceral attacks. Biochemical tests in urine, blood and stool are used for diagnosis, which can be supplemented by molecular genetic analyses. Treatment of the various forms of porphyria is complex and often requires close interdisciplinary cooperation between different medical specialties.
PubMed: 38902527
DOI: 10.1007/s00105-024-05370-3 -
Gastroenterology Jan 2024
Topics: Humans; Protoporphyria, Erythropoietic; Photosensitivity Disorders; Abdominal Pain; Protoporphyrins
PubMed: 37579823
DOI: 10.1053/j.gastro.2023.07.028 -
Trends in Molecular Medicine Jun 2024Protoporphyrias are caused by pathogenic variants in genes encoding enzymes involved in heme biosynthesis. They induce the accumulation of a hydrophobic phototoxic... (Review)
Review
Protoporphyrias are caused by pathogenic variants in genes encoding enzymes involved in heme biosynthesis. They induce the accumulation of a hydrophobic phototoxic compound, protoporphyrin (PPIX), in red blood cells (RBCs). PPIX is responsible for painful cutaneous photosensitivity, which severely impairs quality of life. Hepatic elimination of PPIX increases the risk of cholestatic liver disease, requiring lifelong monitoring. Treatment options are scarce and mainly limited to supportive care such as protection from visible light. Here, we review the pathophysiology of protoporphyrias, their diagnosis, and current recommendations for medical care. We discuss new therapeutic strategies, some of which are currently undergoing clinical trials and are likely to radically alter the severity of the disease in the years to come.
PubMed: 38890030
DOI: 10.1016/j.molmed.2024.05.006 -
Blood Jun 2023Erythropoietic protoporphyria (EPP) is an inherited cutaneous porphyria caused by reduced expression of ferrochelatase, the enzyme that catalyzes the final step in heme...
Erythropoietic protoporphyria (EPP) is an inherited cutaneous porphyria caused by reduced expression of ferrochelatase, the enzyme that catalyzes the final step in heme biosynthesis. The resultant accumulation of protoporphyrin IX leads to severe, painful cutaneous photosensitivity, as well as potentially life-threatening liver disease in a small percentage of patients. X-linked protoporphyria (XLP) is clinically similar to EPP but results from increased activity of δ-aminolevulinic acid synthase 2, the first step in heme biosynthesis in the bone marrow, and also causes protoporphyrin accumulation. Although historically the management of EPP and XLP (collectively termed protoporphyria) centered around avoidance of sunlight, novel therapies have recently been approved or are in development, which will alter the therapeutic landscape for these conditions. We present 3 patient cases, highlighting key treatment considerations in patients with protoporphyria, including (1) approach to photosensitivity, (2) managing iron deficiency in protoporphyria, and (3) understanding hepatic failure in protoporphyria.
Topics: Humans; Protoporphyria, Erythropoietic; Ferrochelatase; Liver Diseases; Photosensitivity Disorders; Protoporphyrins; Heme
PubMed: 36898083
DOI: 10.1182/blood.2022018688 -
Metabolites Aug 2022Given its remarkable property to easily switch between different oxidative states, iron is essential in countless cellular functions which involve redox reactions. At... (Review)
Review
Given its remarkable property to easily switch between different oxidative states, iron is essential in countless cellular functions which involve redox reactions. At the same time, uncontrolled interactions between iron and its surrounding milieu may be damaging to cells and tissues. Heme-the iron-chelated form of protoporphyrin IX-is a macrocyclic tetrapyrrole and a coordination complex for diatomic gases, accurately engineered by evolution to exploit the catalytic, oxygen-binding, and oxidoreductive properties of iron while minimizing its damaging effects on tissues. The majority of the body production of heme is ultimately incorporated into hemoglobin within mature erythrocytes; thus, regulation of heme biosynthesis by iron is central in erythropoiesis. Additionally, heme is a cofactor in several metabolic pathways, which can be modulated by iron-dependent signals as well. Impairment in some steps of the pathway of heme biosynthesis is the main pathogenetic mechanism of two groups of diseases collectively known as porphyrias and congenital sideroblastic anemias. In porphyrias, according to the specific enzyme involved, heme precursors accumulate up to the enzyme stop in disease-specific patterns and organs. Therefore, different porphyrias manifest themselves under strikingly different clinical pictures. In congenital sideroblastic anemias, instead, an altered utilization of mitochondrial iron by erythroid precursors leads to mitochondrial iron overload and an accumulation of ring sideroblasts in the bone marrow. In line with the complexity of the processes involved, the role of iron in these conditions is then multifarious. This review aims to summarise the most important lines of evidence concerning the interplay between iron and heme metabolism, as well as the clinical and experimental aspects of the role of iron in inherited conditions of altered heme biosynthesis.
PubMed: 36144223
DOI: 10.3390/metabo12090819 -
Frontiers in Physiology 2022Partial deficiency of the last enzyme of the heme biosynthetic pathway, namely, ferrochelatase (FECH), is responsible for erythropoietic protoporphyria (EPP) in humans....
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.
PubMed: 35309058
DOI: 10.3389/fphys.2022.841050 -
Diagnostics (Basel, Switzerland) May 2022The World Health Organization (WHO) describes "health" as a state of physical, mental, and social well-being and not merely the absence of disease or infirmity.... (Review)
Review
The World Health Organization (WHO) describes "health" as a state of physical, mental, and social well-being and not merely the absence of disease or infirmity. Therefore, a biopsychosocial approach should be considered as an integral part of patients' management. In this review, we summarize the available data starting from 1986 on the biological, psychological, and social aspects of porphyrias in order to provide a useful tool for clinicians about the missing knowledge within this field. Porphyrias are a group of rare metabolic disorders affecting the heme biosynthetic pathway and can be categorized into hepatic and erythropoietic. Here, a total of 20 articles reporting the psychological and the quality of life (QoL) data of porphyria patients affected by acute hepatic porphyrias (AHPs), Porphyria Cutanea Tarda (PCT), and Erythropoietic Protoporphyria (EPP) were analyzed. These 13 articles include reported quantitative methods using questionnaires, while the reaming articles employed qualitative descriptive approaches through direct interviews with patients by psychology professionals. We conclude that the use of questionnaires limits the complete description of all areas of a patient's life compared to a direct interview with specialists. However, only a combined use of these methods could be the best approach for the correct disorder management.
PubMed: 35626348
DOI: 10.3390/diagnostics12051193 -
Journal of Drugs in Dermatology : JDD Mar 2021Afamelanotide (SCENESSE®) is a synthetic analogue of α-melanocyte-stimulating hormone that is FDA-approved to increase pain-free sunlight exposure in adult... (Review)
Review
Afamelanotide (SCENESSE®) is a synthetic analogue of α-melanocyte-stimulating hormone that is FDA-approved to increase pain-free sunlight exposure in adult patients with erythropoietic protoporphyria. Its dual photoprotective and anti-inflammatory effects also make it a promising therapy for other photosensitive dermatologic diseases that are resistant to treatment. The PubMed/MEDLINE and ClinicalTrials.gov databases were searched for literature and ongoing trials describing the use of afamelanotide in treating cutaneous diseases. There is randomized controlled trial (RCT) evidence for the successful use of afamelanotide in several conditions beyond erythropoietic protoporphyria, including polymorphic light eruption and vitiligo. Smaller studies have also demonstrated its efficacy in treating acne vulgaris, Hailey-Hailey disease, and solar urticaria. No serious adverse effects with afamelanotide use have been reported, though diffuse hyperpigmentation is experienced by almost all patients. Larger scale studies are needed to confirm the efficacy of afamelanotide in treating dermatologic conditions beyond erythropoietic protoporphyria, and further research should focus on determining the safety, efficacy, and optimal dosing of afamelanotide for pediatric patients.J Drugs Dermatol. 2021;20(3):290-294. doi:10.36849/JDD.5526.
Topics: Adult; Age Factors; Child; Dermatologic Agents; Dose-Response Relationship, Drug; Humans; Orphan Drug Production; Randomized Controlled Trials as Topic; Skin Diseases; Skin Pigmentation; Treatment Outcome; alpha-MSH
PubMed: 33683075
DOI: 10.36849/JDD.5526 -
Molecular Genetics and Metabolism Nov 20195-Aminolevulinate (ALA) synthase (ALAS), a homodimeric pyridoxal-5'-phosphate (PLP)-dependent enzyme, catalyzes the first step of heme biosynthesis in metazoa, fungi and... (Review)
Review
5-Aminolevulinate (ALA) synthase (ALAS), a homodimeric pyridoxal-5'-phosphate (PLP)-dependent enzyme, catalyzes the first step of heme biosynthesis in metazoa, fungi and α-proteobacteria. In this review, we focus on the advances made in unraveling the mechanism of the ALAS-catalyzed reaction during the past decade. The interplay between the PLP cofactor and the protein moiety determines and modulates the multi-intermediate reaction cycle of ALAS, which involves the decarboxylative condensation of two substrates, glycine and succinyl-CoA. Substrate binding and catalysis are rapid, and product (ALA) release dominates the overall ALAS kinetic mechanism. Interconversion between a catalytically incompetent, open conformation and a catalytically competent, closed conformation is linked to ALAS catalysis. Reversion to the open conformation, coincident with ALA dissociation, defines the slowest step of the reaction cycle. These findings were further substantiated by introducing seven mutations in the16-amino acid loop that gates the active site, yielding an ALAS variant with a greatly increased rate of catalytic turnover and heightened specificity constants for both substrates. Recently, molecular dynamics (MD) simulation analysis of various dimeric ALAS forms revealed that the seven active site loop mutations caused the proteins to adopt different conformations. In particular, the emergence of a β-strand in the mutated loop, which interacted with two preexisting β-strands to form an anti-parallel three-stranded β-sheet, conferred the murine heptavariant with a more stable open conformation and prompted faster product release than wild-type mALAS2. Moreover, the dynamics of the mALAS2 active site loop anti-correlated with that of the 35 amino acid C-terminal sequence. This led us to propose that this C-terminal extension, which is absent in prokaryotic ALASs, finely tunes mammalian ALAS activity. Based on the above results, we extend our previous proposal to include that discovery of a ligand inducing the mammalian C-terminal extension to fold offers a good prospect for the development of a new drug for X-linked protoporphyria and/or other porphyrias associated with enhanced ALAS activity and/or porphyrin accumulation.
Topics: 5-Aminolevulinate Synthetase; Biosynthetic Pathways; Catalysis; Heme; Humans; Kinetics; Molecular Dynamics Simulation; Protein Conformation; Pyridoxal Phosphate; Substrate Specificity
PubMed: 31345668
DOI: 10.1016/j.ymgme.2019.06.003