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Porphyrias are rare, mostly inherited disorders resulting from altered activity of specific enzymes in the haem synthesis pathway that lead to accumulation of pathway intermediates. Photocutaneous symptoms occur when excess amounts of photoreactive porphyrins circulate in the blood to the skin, whereas increases in potentially neurotoxic porphyrin precursors are associated with neurovisceral symptoms. Current therapies are suboptimal and their mechanisms are not well established. As described here, emerging therapies address underlying disease mechanisms by introducing a gene, RNA or other specific molecule with the potential to cure or slow progression of the disease. Recent progress in nanotechnology and nanoscience, particularly regarding particle design and formulation, is expanding disease targets. More secure and efficient drug delivery systems have extended our toolbox for transferring specific molecules, especially into hepatocytes, and led to proof-of-concept studies in animal models. Repurposing existing drugs as molecular chaperones or haem synthesis inhibitors is also promising. This review summarizes key examples of these emerging therapeutic approaches and their application for hepatic and erythropoietic porphyrias., (© 2024 The Authors. Liver International published by John Wiley & Sons Ltd.)

Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disease due to the deficient, but not absent, activity of uroporphyrinogen III synthase (UROS), the fourth enzyme in the heme biosynthesis pathway. Biallelic variants in the UROS gene result in decreased UROS enzymatic activity and the accumulation of non-physiologic Type I porphyrins in cells and fluids. Overproduced uroporphyrins in haematopoietic cells are released into the circulation and distributed to tissues, inducing primarily hematologic and dermatologic symptoms. The clinical manifestations vary in severity ranging from non-immune hydrops fetalis in utero to mild dermatologic manifestations in adults. Here, the biochemical, molecular and clinical features of CEP as well as current and new treatment options, including the rescue of UROS enzyme activity by chaperones, are presented., (© 2024 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Congenital erythropoietic porphyria (CEP), also known as pink tooth or Gunther disease, is a rare hereditary disorder caused by an enzyme mutation in the heme biosynthesis pathway, which leads to the accumulation of immature and non-physiological protoporphyrin rings in various tissues. CEP is characterized by sun-exposed bullous skin lesions, hemolytic anemia, red/brown urine, and teeth staining., Case Presentation: We present a unique case of a 10-year-old Asian boy with CEP who presented with recurrent epistaxis, an unusual presentation for this condition. Based on clinical presentation and laboratory findings, including elevated urine uroporphyrin and coproporphyrin I and III levels, microcytic anemia, a higher red cell distribution width (RDW), and a lower platelet count, a thorough assessment and detailed workup resulted in a diagnosis of CEP. The patient underwent a successful splenectomy and recovered without any complications., Conclusion: This case report aims to raise awareness among healthcare professionals about the uncommon and atypical presentation of CEP and its management options., (© 2023. The Author(s).)

Congenital erythropoietic porphyria (CEP), a rare form of porphyria, is caused by a defect in the heme biosynthesis pathway of the enzyme uroporphyrinogen III synthase (UROS). Uroporphyrinogen III synthase deficiency leads to an accumulation of nonphysiological porphyrins in bone marrow, red blood cells, skin, bones, teeth, and spleen. Consequently, the exposure to sunlight causes severe photosensitivity, long-term intravascular hemolysis, and eventually, irreversible mutilating deformities. Several supportive therapies such as strict sun avoidance, physical sunblocks, red blood cells transfusions, hydroxyurea, and splenectomy are commonly used in the management of CEP. Currently, the only available curative treatment of CEP is hematopoietic stem cell transplantation (HSCT). In this article, we present a young girl in which precocious genetic testing enabled early diagnosis and allowed curative treatment with HSCT for CEP at the age of 3 months of age, that is, the youngest reported case thus far.

Congenital erythropoietic porphyria (CEP) is a rare genetic disorder leading to accumulation of uro/coproporphyrin-I in tissues due to inhibition of uroporphyrinogen-III synthase. Clinical manifestations of CEP include bone fragility, severe photosensitivity and photomutilation. Currently there is no specific treatment for CEP, except bone marrow transplantation, and there is an unmet need for treating this orphan disease. Fluorescent porphyrins cause protein aggregation, which led us to hypothesize that uroporphyrin-I accumulation leads to protein aggregation and CEP-related bone phenotype. We developed a zebrafish model that phenocopies features of CEP. As in human patients, uroporphyrin-I accumulated in the bones of zebrafish, leading to impaired bone development. Furthermore, in an osteoblast-like cell line, uroporphyrin-I decreased mineralization, aggregated bone matrix proteins, activated endoplasmic reticulum stress and disrupted autophagy. Using high-throughput drug screening, we identified acitretin, a second-generation retinoid, and showed that it reduced uroporphyrin-I accumulation and its deleterious effects on bones. Our findings provide a new CEP experimental model and a potential repurposed therapeutic.

Clinical severity is heterogeneous among patients suffering from congenital erythropoietic porphyria (CEP) suggesting a modulation of the disease (UROS deficiency) by environmental factors and modifier genes. A KI model of CEP due to a missense mutation of UROS gene present in human has been developed on 3 congenic mouse strains (BALB/c, C57BL/6, and 129/Sv) in order to study the impact of genetic background on disease severity. To detect putative modifiers of disease expression in congenic mice, hematologic data, iron parameters, porphyrin content and tissue samples were collected. Regenerative hemolytic anemia, a consequence of porphyrin excess in RBCs, had various expressions: 129/Sv mice were more hemolytic, BALB/c had more regenerative response to anemia, C57BL/6 were less affected. Iron status and hemolysis level were directly related: C57BL/6 and BALB/c had moderate hemolysis and active erythropoiesis able to reduce iron overload in the liver, while, 129/Sv showed an imbalance between iron release due to hemolysis and erythroid use. The negative control of hepcidin on the ferroportin iron exporter appeared strain specific in the CEP mice models tested. Full repression of hepcidin was observed in BALB/c and 129/Sv mice, favoring parenchymal iron overload in the liver. Unchanged hepcidin levels in C57BL/6 resulted in retention of iron predominantly in reticuloendothelial tissues. These findings open the field for potential therapeutic applications in the human disease, of hepcidin agonists and iron depletion in chronic hemolytic anemia., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disorder characterized by photosensitivity and by hematologic abnormalities in affected individuals. CEP is caused by mutations in the uroporphyrinogen synthase (UROS) gene. In three reported cases, CEP has been associated with a specific X-linked GATA1 mutation. Disease-causing mutations in either gene result in absent or markedly reduced UROS enzymatic activity. This in turn leads to the accumulation of the non-physiologic and photoreactive porphyrinogens, uroporphyrinogen I and coproporphyrinogen I, which damage erythrocytes and elicit a phototoxic reaction upon light exposure. The clinical spectrum of CEP depends on the level of residual UROS activity, which is determined by the underlying pathogenic loss-of-function UROS mutations. Disease severity ranges from non-immune hydrops fetalis in utero to late-onset disease with only mild cutaneous involvement. The clinical characteristics of CEP include exquisite photosensitivity to visible light resulting in bullous vesicular lesions which, when infected lead to progressive photomutilation of sun-exposed areas such as the face and hands. In addition, patients have erythrodontia (brownish discoloration of teeth) and can develop corneal scarring. Chronic transfusion-dependent hemolytic anemia is common and leads to bone marrow hyperplasia, which further increases porphyrin production. Management of CEP consists of strict avoidance of exposure to visible light with sun-protective clothing, sunglasses, and car and home window filters. Adequate care of ruptured vesicles and use of topical antibiotics is indicated to prevent superinfections and osteolysis. In patients with symptomatic hemolytic anemia, frequent erythrocyte cell transfusions may be necessary to suppress hematopoiesis and decrease marrow production of the phototoxic porphyrins. In severe transfection-dependent cases, bone marrow or hematopoietic stem cell transplantation has been performed, which is curative. Therapeutic approaches including gene therapy, proteasome inhibition, and pharmacologic chaperones are under investigation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

The erythropoietic porphyrias are inborn errors of heme biosynthesis with prominent cutaneous manifestations. They include autosomal recessive Congenital Erythropoietic Porphyria (CEP) due to loss-of-function (LOF) mutations in the Uroporphyrinogen III Synthase (UROS) gene, Erythropoietic Protoporphyria (EPP) due to LOF mutations in the ferrochelatase (FECH) gene, and X-Linked Protoporphyria (XLP) due to gain-of-function mutations in the terminal exon of the Aminolevulinic Acid Synthase 2 (ALAS2) gene. During the 11-year period from 01/01/2007 through 12/31/2017, the Mount Sinai Porphyrias Diagnostic Laboratory provided molecular diagnostic testing for one or more of these disorders in 628 individuals, including 413 unrelated individuals. Of these 628, 120 patients were tested for CEP, 483 for EPP, and 331 for XLP, for a total of 934 tests. For CEP, 24 of 78 (31%) unrelated individuals tested had UROS mutations, including seven novel mutations. For EPP, 239 of 362 (66%) unrelated individuals tested had pathogenic FECH mutations, including twenty novel mutations. The IVS3-48 T > C low-expression allele was present in 231 (97%) of 239 mutation-positive EPP probands with a pathogenic FECH mutation. In the remaining 3%, three patients with two different FECH mutations in trans were identified. For XLP, 24 of 250 (10%) unrelated individuals tested had ALAS2 exon 11 mutations. No novel ALAS2 mutations were identified. Among family members referred for testing, 33 of 42 (79%) CEP, 62 of 121 (51%) EPP, and 31 of 81 (38%) XLP family members had the respective family mutation. Mutation-positive CEP, EPP, and XLP patients who had been biochemically tested had marked elevations of the disease-appropriate porphyrin intermediates. These results expand the molecular heterogeneity of the erythropoietic porphyrias by adding a total of 27 novel mutations. The results document the usefulness of molecular testing to confirm the positive biochemical findings in these patients and to identify heterozygous family members., (Copyright © 2018. Published by Elsevier Inc.)

CRISPR-Cas9 is a promising technology for genome editing. Here we use Cas9 nuclease-induced double-strand break DNA (DSB) at the UROS locus to model and correct congenital erythropoietic porphyria. We demonstrate that homology-directed repair is rare compared with NHEJ pathway leading to on-target indels and causing unwanted dysfunctional protein. Moreover, we describe unexpected chromosomal truncations resulting from only one Cas9 nuclease-induced DSB in cell lines and primary cells by a p53-dependent mechanism. Altogether, these side effects may limit the promising perspectives of the CRISPR-Cas9 nuclease system for disease modeling and gene therapy. We show that the single nickase approach could be safer since it prevents on- and off-target indels and chromosomal truncations. These results demonstrate that the single nickase and not the nuclease approach is preferable, not only for modeling disease but also and more importantly for the safe management of future CRISPR-Cas9-mediated gene therapies.

The porphyrias are a group of metabolic disorders resulting from an innate abnormality in haem biosynthesis, and the clinical settings of which vary according to the genetic enzyme abnormality in question. These are genetic disorders with autosomal dominant or recessive inheritance of varying penetrance, and whose clinical expression differs according to the preferential location of haem precursors. Different classifications have been proposed according to genetic inheritance, the enzyme anomaly at issue, and clinical expression. The clinical classification distinguishes between acute porphyria (acute intermittent porphyria, porphyria variegata, hereditary coproporphyria), bullous cutaneous porphyrias (porphyria cutanea tarda, porphyria variegata and hereditary coproporphyria), painful photosensitive acute cutaneous porphyrias (erythropoietic protoporphyria and X-linked dominant protoporphyria), and rare recessive porphyrias (congenital erythropoietic porphyria, Doss porphyria, hepatoerythropoietic porphyria and harderoporphyria). Treatment depends on the clinical expression of the disorder., (Copyright © 2018. Published by Elsevier Masson SAS.)

Loss-of-function mutations in genes for heme biosynthetic enzymes can give rise to congenital porphyrias, eight forms of which have been described. The genetic penetrance of the porphyrias is clinically variable, underscoring the role of additional causative, contributing, and modifier genes. We previously discovered that the mitochondrial AAA+ unfoldase ClpX promotes heme biosynthesis by activation of δ-aminolevulinate synthase (ALAS), which catalyzes the first step of heme synthesis. CLPX has also been reported to mediate heme-induced turnover of ALAS. Here we report a dominant mutation in the ATPase active site of human CLPX, p.Gly298Asp, that results in pathological accumulation of the heme biosynthesis intermediate protoporphyrin IX (PPIX). Amassing of PPIX in erythroid cells promotes erythropoietic protoporphyria (EPP) in the affected family. The mutation in CLPX inactivates its ATPase activity, resulting in coassembly of mutant and WT protomers to form an enzyme with reduced activity. The presence of low-activity CLPX increases the posttranslational stability of ALAS, causing increased ALAS protein and ALA levels, leading to abnormal accumulation of PPIX. Our results thus identify an additional molecular mechanism underlying the development of EPP and further our understanding of the multiple mechanisms by which CLPX controls heme metabolism., Competing Interests: The authors declare no conflict of interest.

Congenital erythropoietic porphyria (CEP) is an inborn error of heme biosynthesis characterized by uroporphyrinogen III synthase (UROS) deficiency resulting in deleterious porphyrin accumulation in blood cells responsible for hemolytic anemia and cutaneous photosensitivity. We analyzed here the molecular basis of UROS impairment associated with twenty nine UROS missense mutations actually described in CEP patients. Using a computational and biophysical joint approach we predicted that most disease-causing mutations would affect UROS folding and stability. Through the analysis of enhanced green fluorescent protein-tagged versions of UROS enzyme we experimentally confirmed these data and showed that thermodynamic instability and premature protein degradation is a major mechanism accounting for the enzymatic deficiency associated with twenty UROS mutants in human cells. Since the intracellular loss in protein homeostasis is in excellent agreement with the in vitro destabilization, we used molecular dynamic simulation to rely structural 3D modification with UROS disability. We found that destabilizing mutations could be clustered within three types of mechanism according to side chain rearrangements or contact alterations within the pathogenic UROS enzyme so that the severity degree correlated with cellular protein instability. Furthermore, proteasome inhibition using bortezomib, a clinically available drug, significantly enhanced proteostasis of each unstable UROS mutant. Finally, we show evidence that abnormal protein homeostasis is a prevalent mechanism responsible for UROS deficiency and that modulators of UROS proteolysis such as proteasome inhibitors or chemical chaperones may represent an attractive therapeutic option to reduce porphyrin accumulation and prevent skin photosensitivity in CEP patients when the genotype includes a missense variant., (© The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Congenital erythropoietic porphyria (CEP) is a rare genetic disease resulting from the remarkable deficient activity of uroporphyrinogen III synthase, the fourth enzyme of the haem biosynthetic pathway. This enzyme defect results in overproduction of the non-physiological and pathogenic porphyrin isomers, uroporphyrin I and coproporphyrin I. The predominant clinical characteristics of CEP include bullous cutaneous photosensitivity to visible light from early infancy, progressive photomutilation and chronic haemolytic anaemia. The severity of clinical manifestations is markedly heterogeneous among patients; and interdependence between disease severity and porphyrin amount in the tissues has been pointed out. A more pronounced endogenous production of porphyrins concomitant to activation of ALAS2, the first and rate-limiting of the haem synthesis enzymes in erythroid cells, has also been reported. CEP is inherited as autosomal recessive or X-linked trait due to mutations in UROS or GATA1 genes; however an involvement of other causative or modifier genes cannot be ruled out., (© 2016 John Wiley & Sons Ltd.)

The GATA family of transcription factors consists of six proteins (GATA1-6) which are involved in a variety of physiological and pathological processes. GATA1/2/3 are required for differentiation of mesoderm and ectoderm-derived tissues, including the haematopoietic and central nervous system. GATA4/5/6 are implicated in development and differentiation of endoderm- and mesoderm-derived tissues such as induction of differentiation of embryonic stem cells, cardiovascular embryogenesis and guidance of epithelial cell differentiation in the adult.

An 18-year-old boy with congenital erythropoietic porphyria and calcific constrictive pericarditis underwent total pericardiectomy. The cause of pericardial calcification could be deposition of porphyrins in the pericardium. Surgical importance of this rare condition is highlighted., (© The Author(s) 2015.)

Routine clinical application of whole exome sequencing remains challenging due to difficulties in variant interpretation, large dataset management, and workflow integration. We describe a tool named ClinLabGeneticist to implement a workflow in clinical laboratories for management of variant assessment in genetic testing and disease diagnosis. We established an extensive variant annotation data source for the identification of pathogenic variants. A dashboard was deployed to aid a multi-step, hierarchical review process leading to final clinical decisions on genetic variant assessment. In addition, a central database was built to archive all of the genetic testing data, notes, and comments throughout the review process, variant validation data by Sanger sequencing as well as the final clinical reports for future reference. The entire workflow including data entry, distribution of work assignments, variant evaluation and review, selection of variants for validation, report generation, and communications between various personnel is integrated into a single data management platform. Three case studies are presented to illustrate the utility of ClinLabGeneticist. ClinLabGeneticist is freely available to academia at http://rongchenlab.org/software/clinlabgeneticist .

Congenital erythropoietic porphyria (CEP) is an autosomal recessive disorder of heme synthesis characterized by reduced activity of uroporphyrinogen III synthase and the accumulation of nonphysiologic isomer I porphyrin metabolites, resulting in ineffective erythropoiesis and devastating skin photosensitivity. Management of the disease primarily consists of supportive measures. Increased activity of 5-aminolevulinate synthase 2 (ALAS2) has been shown to adversely modify the disease phenotype. Herein, we present a patient with CEP who demonstrated a remarkable improvement in disease manifestations in the setting of iron deficiency. Hypothesizing that iron restriction improved her symptoms by decreasing ALAS2 activity and subsequent porphyrin production, we treated the patient with off-label use of deferasirox to maintain iron deficiency, with successful results. We confirmed the physiology of her response with marrow culture studies., (© 2015 by The American Society of Hematology.)

Congenital erythropoietic porphyria (CEP) is a rare genetic disease that is characterized by a severe cutaneous photosensitivity causing unrecoverable deformities, chronic hemolytic anemia requiring blood transfusion program, and by fatal systemic complications. A correct and early diagnosis is required to develop a management plan that is appropriate to the patient's needs. Recently only one case of X-linked CEP had been reported, describing the trans-acting GATA1-R216W mutation. Here, we have characterized two novel X-linked CEP patients, both with misleading hematological phenotypes that include dyserythropoietic anemia, thrombocytopenia, and hereditary persistence of fetal hemoglobin. We compare the previously reported case to ours and propose a diagnostic paradigm for this variant of CEP. Finally, a correlation between phenotype variability and the presence of modifier mutations in loci related to disease-causing gene is described., (© 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Congenital erythropoietic porphyria (CEP) results from a deficiency in uroporphyrinogen III synthase enzyme (UROIIIS) activity that ultimately stems from deleterious mutations in the uroS gene. C73 is a hotspot for these mutations and a C73R substitution, which drastically reduces the enzyme activity and stability, is found in almost one-third of all reported CEP cases. Here, we have studied the structural basis, by which mutations in this hotspot lead to UROIIIS destabilization. First, a strong interdependency is observed between the volume of the side chain at position 73 and the folded protein. Moreover, there is a correlation between the in vitro half-life of the mutated proteins and their expression levels in eukaryotic cell lines. Molecular modelling was used to rationalize the results, showing that the mutation site is coupled to the hinge region separating the two domains. Namely, mutations at position 73 modulate the inter-domain closure and ultimately affect protein stability. By incorporating residues capable of interacting with R73 to stabilize the hinge region, catalytic activity was fully restored and a moderate increase in the kinetic stability of the enzyme was observed. These results provide an unprecedented rationale for a destabilizing missense mutation and pave the way for the effective design of molecular chaperones as a therapy against CEP., (© The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Background: Porphyria is an umbrella term for a group of largely hereditary diseases that are due to defective haem synthesis. The diseases have a varied and partly overlapping range of symptoms and presentations. The commonest forms of porphyria are porphyria cutanea tarda, acute intermittent porphyria and erythropoietic protoporphyria. The purpose of this study is to provide an overview of the prevalence and pathological manifestations of porphyrias in Norway., Material and Method: Information on all patients registered with the Norwegian Porphyria Centre (NAPOS) up to 2012 was used to estimate the prevalence and incidence of porphyrias in Norway. Figures on symptoms, precipitating factors and follow-up routines were obtained from the Norwegian Porphyria Registry, which includes 70% of Norwegians registered with NAPOS as having porphyria., Results: The prevalence of porphyria cutanea tarda was approximately 10 : 100,000 and that of acute intermittent porphyria approximately 4 : 100,000. The total incidence of all porphyrias was approximately 0.5-1 : 100,000 per year. Diagnostic delay, i.e. the time passing between the onset of symptoms and diagnosis, varied from 1-17 years depending on the type of porphyria. There was wide variation in the frequency with which patients with the various types of porphyria went for medical check-ups., Interpretation: The prevalence of acute intermittent porphyria and porphyria cutanea tarda appears to be higher in Norway than in most other countries. Data from the Norwegian Porphyria Registry makes it possible to demonstrate differences in treatment and follow-up of porphyria patients and may be used to initiate necessary measures.

Congenital erythropoietic porphyria (CEP) is a rare autosomal recessive disorder characterized by uroporphyrinogen III synthase (UROS) deficiency resulting in massive porphyrin accumulation in blood cells, which is responsible for hemolytic anemia and skin photosensitivity. Among the missense mutations actually described up to now in CEP patients, the C73R and the P248Q mutations lead to a profound UROS deficiency and are usually associated with a severe clinical phenotype. We previously demonstrated that the UROS(C73R) mutant protein conserves intrinsic enzymatic activity but triggers premature degradation in cellular systems that could be prevented by proteasome inhibitors. We show evidence that the reduced kinetic stability of the UROS(P248Q) mutant is also responsible for increased protein turnover in human erythroid cells. Through the analysis of EGFP-tagged versions of UROS enzyme, we demonstrate that both UROS(C73R) and UROS(P248Q) are equally destabilized in mammalian cells and targeted to the proteasomal pathway for degradation. We show that a treatment with proteasomal inhibitors, but not with lysosomal inhibitors, could rescue the expression of both EGFP-UROS mutants. Finally, in CEP mice (Uros(P248Q/P248Q)) treated with bortezomib (Velcade), a clinically approved proteasome inhibitor, we observed reduced porphyrin accumulation in circulating RBCs and urine, as well as reversion of skin photosensitivity on bortezomib treatment. These results of medical importance pave the way for pharmacologic treatment of CEP disease by preventing certain enzymatically active UROS mutants from early degradation by using proteasome inhibitors or chemical chaperones.

Congenital erythropoietic porphyria (CEP), or Günther's disease, is an inborn error of metabolism produced by a deficiency of uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthesis pathway. This enzymatic defect induces the accumulation of isomer I porphyrins in erythrocytes, skin, and tissues, producing various clinical manifestations. Severe cases are characterized by extreme photosensitivity, causing scarring and mutilations, and by hemolytic anemia, reducing life expectancy. CEP is caused by mutations in the UROS gene, and one of the most severe forms of the disease is associated with a cysteine to arginine substitution at residue 73 of the protein (C73R). CEP has been successfully treated only by the transplantation of hematopoietic precursors. We report the case of a male infant with severe postdelivery symptoms diagnosed with CEP and found to be homozygous for the C73R mutation. He underwent successful allogeneic bone marrow transplantation from a matched unrelated donor at 7 months of age. The hemolytic anemia was corrected and the porphyrin overproduction was significantly reduced. The patient remained asymptomatic after 1 year. This new case confirms that patients with severe CEP can benefit from early postnatal hematopoietic stem cell transplantation., (© 2013 Wiley Periodicals, Inc.)

Congenital erythropoietic porphyria is a rare disorder of heme biosynthesis, resulting from decreased enzymatic activity of uroporphyrinogen III synthase. Clinical manifestations are heterogenous, of variable severity, and with occasional phenotypic-genotypic correlation. A 14-month-old boy developed fever, extensive dermatitis, and reddish colored urine. Anemia, erythrodontia, hepatosplenomegaly, and massive urinary elimination of predominantly type I porphyrins was suggestive of congenital erythropoietic porphyria. Although hemolysis remained mild and compensated, facial and digital mutilation developed indicative of moderate clinical phenotype. Mutational analysis revealed compound heterozygosity of mutant alleles, including a novel mutation (p.Pro190Leu). The child received supportive management and underwent facial reconstruction successfully.

In recent years, important advances have been made in our understanding of the genetics of porphyrias, particularly with respect to erythropoietic protoporphyria (EPP) and congenital erythropoietic porphyria (CEP), 2 forms of erythropoietic porphyria no longer considered to be monogenic. The identification of mutations in genes not previously associated with these disorders as causative factors or modulators of severity has helped to explain the presence of genotypic and phenotypic differences between patients carrying the same mutations. These advances have also led to the identification of causative genetic defects in patients who, based on molecular studies, had no mutations in the uroporphyrinogen III synthase gene UROS (in CEP) or in the ferrochelatase gene FECH (in EPP). Better understanding and characterization of the genetics of porphyrias will allow us to determine genotypic and phenotypic correlations and improve the molecular classification of these diseases, which will have both practical and prognostic implications., (Copyright © 2011 Elsevier España, S.L. and AEDV. All rights reserved.)

Background: Congenital erythropoietic porphyria (CEP) is an autosomal recessive photomutilating porphyria with onset usually in childhood, where haematological complications determine prognosis. Due to its extreme rarity and clinical heterogeneity, management decisions in CEP are often difficult., Objectives: To develop a management algorithm for patients with CEP based on data from carefully characterized historical cases., Methods: A single investigator collated data related to treatments and their outcomes in 29 patients with CEP from the U.K., France, Germany and Switzerland., Results: Six children were treated with bone marrow transplantation (BMT); five have remained symptomatically cured up to 11.5 years post-transplantation. Treatments such as oral charcoal, splenectomy and chronic hypertransfusion were either of no benefit or were associated with complications and negative impact on health-related quality of life. Lack of consistent genotype-phenotype correlation meant that this could not be used to predict disease prognosis. The main poor prognostic factors were early age of disease onset and severity of haematological manifestations., Conclusions: A management algorithm is proposed where every patient, irrespective of disease severity at presentation, should receive a comprehensive, multidisciplinary clinical assessment and should then be reviewed at intervals based on their predicted prognosis, and the rate of onset of complications. A BMT should be considered in those with progressive, symptomatic haemolytic anaemia and/or thrombocytopenia. Uroporphyrinogen III synthase genotypes associated with poor prognosis would additionally justify consideration for a BMT. Rigorous photoprotection of the skin and eyes from visible light is essential in all patients., (© 2012 The Authors. BJD © 2012 British Association of Dermatologists.)

Background: Congenital erythropoietic porphyria (CEP) is an autosomal recessive cutaneous porphyria caused by decreased activity of uroporphyrinogen III synthase (UROS). Its predominant characteristics include bullous cutaneous photosensitivity to visible light from early infancy, progressive photomutilation and chronic haemolytic anaemia. Due to its rarity and genetic heterogeneity, clinical phenotypes are unclear and its impact on health-related quality of life (HRQoL) has not been previously assessed., Objectives: To define comprehensively CEP phenotypes and assess their impact on HRQoL, and to correlate these factors with laboratory parameters., Methods: A single observer assessed patients with CEP from four European countries., Results: Twenty-seven unrelated patients with CEP, aged between 7.6 and 65 years, participated in the study. The patients came from the U.K. (17), France (4), Switzerland (4) and Germany (2). Additional data were obtained for two deceased patients. Newly characterized features of CEP include acute-onset cutaneous and noncutaneous symptoms immediately following sunlight exposure, and pink erythematous facial papules. There was a lack of consistent genotype-phenotype correlation in CEP. The main poor prognostic factors in CEP are the early age of disease onset and haematological complications., Conclusions: CEP is a multisystem disease; cutaneous, ocular, oral and skeletal manifestations also contribute to disease severity and impact on HRQoL, in addition to the haematological complications. The rarity of the disease can lead to delayed diagnosis. The lack of consistent genotype-phenotype correlation in CEP suggests a contribution to phenotype from other factors, such as environment, patients' photoprotective behaviour and genes other than UROS. There is currently an unmet need for multidisciplinary management of patients with CEP., (© 2012 The Authors. BJD © 2012 British Association of Dermatologists.)

Congenital erythropoietic porphyria (CEP) is due to a deficiency in the enzymatic activity of uroporphyrinogen III synthase (UROS); such a deficiency leads to porphyrin accumulation and results in skin lesions and hemolytic anemia. CEP is a candidate for retrolentivirus-mediated gene therapy, but recent reports of insertional leukemogenesis underscore the need for safer methods. The discovery of induced pluripotent stem cells (iPSCs) has opened up new horizons in gene therapy because it might overcome the difficulty of obtaining sufficient amounts of autologous hematopoietic stem cells for transplantation and the risk of genotoxicity. In this study, we isolated keratinocytes from a CEP-affected individual and generated iPSCs with two excisable lentiviral vectors. Gene correction of CEP-derived iPSCs was obtained by lentiviral transduction of a therapeutic vector containing UROS cDNA under the control of an erythroid-specific promoter shielded by insulators. One iPSC clone, free of reprogramming genes, was obtained with a single proviral integration of the therapeutic vector in a genomic safe region. Metabolic correction of erythroblasts derived from iPSC clones was demonstrated by the disappearance of fluorocytes. This study reports the feasibility of porphyria gene therapy with the use of iPSCs., (Copyright © 2012 The American Society of Human Genetics. Published by Elsevier Inc. All rights reserved.)

Porphyrias are rare metabolic hereditary diseases originating from defects in specific enzymes involved in the heme biosynthesis pathway. Congenital erythropoietic porphyria (CEP) is the rarest autosomal recessive porphyria resulting from a deficiency of uroporphyrinogen III cosynthase (UROS), the fourth enzyme in heme biosynthesis. CEP leads to an excessive production and accumulation of type Ι porphyrins in bone marrow, skin and several other tissues. Clinical manifestations are presented in childhood with severe cutaneous photosensitivity, blistering, scarring and deformation of the hands and the loss of eyebrows and eyelashes. Less than 200 cases of CEP have been reported to date. Four CEP patients and their family members were studied for the first time in Iran. A missense mutation in the UROS gene was identified in this family. A, T to C change at nucleotide 34313, leading to a substitution of Leucine by Proline at codon 237, was observed in the homozygous state in these 4 patients and heterozygous state in their parents. Our data from the Iranian population emphasizes the importance of codon 237 alone, given the rarity of this disease. This fact can be taken into consideration in the mutational analysis of UROS. This work emphasizes the advantages of molecular genetic techniques as diagnostic tools for the detection of clinically asymptomatic heterozygous mutation carriers as well as CEP within families.

Previous studies have shown that congenital erythropoietic porphyria (CEP) in cattle is caused by an inherited deficiency of the enzyme uroporphyrinogen III synthase (UROS) encoded by the UROS gene. In this study, we have established the pedigree of an extended Holstein family in which the disease is segregating in a manner consistent with autosomal recessive inheritance. Biochemical analyses demonstrated accumulation of uroporphyrin, thus confirming that it is indeed insufficient activity of UROS which is the cause of the disease. We have therefore sequenced all nine exons of UROS in affected and non-affected individuals without detecting any potential causative mutations. However, a single nucleotide polymorphism (SNP) located within the spliceosome attachment region in intron 8 of UROS is shown to segregate with the disease allele. Our study supports the hypothesis that CEP in cattle is caused by a mutation affecting UROS; however, additional functional studies are needed to identify the causative mutation., (© 2011 The Authors, Animal Genetics © 2011 Stichting International Foundation for Animal Genetics.)

The inborn errors of heme biosynthesis, the porphyrias, are 8 genetically distinct metabolic disorders that can be classified as "acute hepatic," "hepatic cutaneous," and "erythropoietic cutaneous" diseases. Recent advances in understanding their pathogenesis and molecular genetic heterogeneity have led to improved diagnosis and treatment. These advances include DNA-based diagnoses for all the porphyrias, new understanding of the pathogenesis of the acute hepatic porphyrias, identification of the iron overload-induced inhibitor of hepatic uroporphyrin decarboxylase activity that causes the most common porphyria, porphyria cutanea tarda, the identification of an X-linked form of erythropoietic protoporphyria due to gain-of-function mutations in erythroid-specific 5-aminolevulinate synthase (ALAS2), and new and experimental treatments for the erythropoietic prophyrias. Knowledge of these advances is relevant for hematologists because they administer the hematin infusions to treat the acute attacks in patients with the acute hepatic porphyrias, perform the chronic phlebotomies to reduce the iron overload and clear the dermatologic lesions in porphyria cutanea tarda, and diagnose and treat the erythropoietic porphyrias, including chronic erythrocyte transfusions, bone marrow or hematopoietic stem cell transplants, and experimental pharmacologic chaperone and stem cell gene therapies for congenital erythropoietic protoporphyria. These developments are reviewed to update hematologists on the latest advances in these diverse disorders.

Background & Aims: Chronic, progressive hepatobiliary disease is the most severe complication of erythropoietic protoporphyria (EPP) and can require liver transplantation, although the mechanisms that lead to liver failure are unknown. We characterized protoporphyrin-IX (PPIX)-linked hepatobiliary disease in BALB/c and C57BL/6 (Fechm1Pas) mice with mutations in ferrochelatase as models for EPP., Methods: Fechm1Pas and wild-type (control) mice were studied at 12-14 weeks of age. PPIX was quantified; its distribution in the liver, serum levels of lipoprotein-X, liver histology, contents of bile salt and cholesterol phospholipids, and expression of genes were compared in mice of the BALB/c and C57BL/6 backgrounds. The in vitro binding affinity of PPIX for bile components was determined., Results: Compared with mice of the C57BL/6 background, BALB/c Fechm1Pas mice had a more severe pattern of cholestasis, fibrosis with portoportal bridging, bile acid regurgitation, sclerosing cholangitis, and hepatolithiasis. In C57BL/6 Fechm1Pas mice, PPIX was sequestrated mainly in the cytosol of hepatocytes and Kupffer cells, whereas, in BALB/c Fechm1Pas mice, PPIX was localized within enlarged bile canaliculi. Livers of C57BL/6 Fechm1Pas mice were protected through a combination of lower efflux of PPIX and reduced synthesis and export of bile acid., Conclusions: PPIX binds to bile components and disrupts the physiologic equilibrium of phospholipids, bile acids, and cholesterol in bile. This process might be involved in pathogenesis of sclerosing cholangitis from EPP; a better understanding might improve diagnosis and development of reagents to treat or prevent liver failure in patients with EPP., (Copyright © 2011 AGA Institute. Published by Elsevier Inc. All rights reserved.)

Mutations in the uroporphyrinogen III synthase (UROS) gene cause congenital erythropoietic porphyria (CEP), an autosomal-recessive inborn error of erythroid heme biosynthesis. Clinical features of CEP include dermatologic and hematologic abnormalities of variable severity. The discovery of a new type of erythroid porphyria, X-linked dominant protoporphyria (XLDPP), which results from increased activity of 5-aminolevulinate synthase 2 (ALAS2), the rate-controlling enzyme of erythroid heme synthesis, led us to hypothesize that the CEP phenotype may be modulated by sequence variations in the ALAS2 gene. We genotyped ALAS2 in 4 unrelated CEP patients exhibiting the same C73R/P248Q UROS genotype. The most severe of the CEP patients, a young girl, proved to be heterozygous for a novel ALAS2 mutation: c.1757 A > T in exon 11. This mutation is predicted to affect the highly conserved and penultimate C-terminal amino acid of ALAS2 (Y586). The rate of 5-aminolevulinate release from Y586F was significantly increased over that of wild-type ALAS2. The contribution of the ALAS2 gain-of-function mutation to the CEP phenotype underscores the importance of modifier genes underlying CEP. We propose that ALAS2 gene mutations should be considered not only as causative of X-linked sideroblastic anemia (XLSA) and XLDPP but may also modulate gene function in other erythropoietic disorders.

Congenital erythropoietic porphyria is a rare form of porphyria, presenting during the neonatal period or during infancy. Clinical features include photosensitive blistering and severe anemia. Wood's lamp fluorescence of the diaper is a useful screening test. We describe a severely affected neonate with systemic involvement due to a homozygous mutation. Because of ongoing severe hemolytic anemia and severe photosensitivity, bone-marrow transplantation was performed, but the patient ultimately succumbed to chemotherapy-induced lung damage, as well as severe pulmonary hypertension, likely due to his chronic hemolytic anemia., (© 2011 Wiley Periodicals, Inc.)

A single mutation (C73R) in the enzyme uroporphyrinogen III synthase (UROIIIS) is responsible for more than one-third of all of the reported cases of the rare autosomal disease congenital erythropoietic porphyria (CEP). CEP patients carrying this hotspot mutation develop a severe phenotype of the disease, including reduced life expectancy. Here, we have investigated the molecular basis for the functional deficit in the mutant enzyme both in vitro and in cellular systems. We show that a Cys in position 73 is not essential for the catalytic activity of the enzyme but its mutation to Arg speeds up the process of irreversible unfolding and aggregation. In the mammalian cell milieu, the mutant protein levels decrease to below the detection limit, whereas wild type UROIIIS can be detected easily. The disparate response is not produced by differences at the level of transcription, and the results with cultured cells and in vitro are consistent with a model where the protein becomes very unstable upon mutation and triggers a degradation mechanism via the proteasome. Mutant protein levels can be restored upon cell treatment with the proteasome inhibitor MG132. The intracellularly recovered C73R-UROIIIS protein shows enzymatic activity, paving the way for a new line of therapeutic intervention in CEP patients.

Congenital erythropoietic porphyria (CEP) is an autosomal recessive disorder due to the deficient activity of uroporphyrinogen III synthase (UROS). Knock-in mouse models were generated for the common, hematologically severe human genotype, C73R/C73R, and milder genotypes (C73R/V99L and V99L/V99L). The specific activities of the UROS enzyme in the livers and erythrocytes of these mice averaged approximately 1.2%, 11% and 19% of normal, respectively. C73R/C73R mice that survived fetal life to weaning age (~12%) had a severe microcytic hypochromic anemia (hemoglobin 7.9 g/dL, mean cellular volume 26.6 fL, mean cellular hemoglobin content 27.4 g/dL, red cell distribution width 37.7%, reticulocytes 19%) and massively accumulated isomer I porphyrins (95, 183 and 44 μmol/L in erythrocytes, spleen and liver, respectively), but a nearly normal lifespan. In adult C73R/C73R mice, spleen and liver weights were 8.2- and 1.5-fold increased, respectively. C73R/V99L mice were mildly anemic (hemoglobin was 14.0 g/dL and mean cellular hemoglobin was 13.3), with minimally accumulated porphyrins (0.10, 5.54 and 0.58 μmol/L in erythrocytes, spleen and liver, respectively), whereas adult V99L/V99L mice were normal. Of note, even the mildest genotype, V99L/V99L, exhibited porphyria in utero, which disappeared by 2 months of age. These severe and mild mouse models inform therapeutic interventions and permit further investigation of the porphyrin-induced hematopathology, which leads to photo-induced cutaneous lesions. Of significance for therapeutic intervention, these mouse models suggest that only 11% of wild-type activity might be needed to reverse the pathology in CEP patients.

Background: Congenital erythropoietic porphyria (CEP) is a genodermatosis associated uroporphyrinogen III synthase deficit that results in porphyrin accumulation in various organs, particularly the skin. It is the most severe form of porphyria associated with haemolytic anaemia and cutaneous phototoxicity. We report a severe case of CEP treated by allogeneic bone marrow transplantation., Case Report: A one-year-old child presented erythrodontia and scarring on exposed areas. The diagnosis of CEP was confirmed by the decline of uroporphyrinogen III synthase activity. Demonstration of p.Cys73Arg mutation confirmed the severity of the disease. Allogeneic bone marrow transplantation resulted in persistent resolution of clinical signs 25 months after grafting., Discussion: Symptomatic treatment is ineffective in this serious disease associated with early mortality. 11 of the 13 patients treated by allogeneic hematopoietic stem cell graft, including our patient, continued to be asymptomatic an average of seven years after transplantation., Conclusion: This new case confirms the role of allogeneic hematopoietic stem cell grafting in the treatment of congenital erythropoietic porphyria., (Copyright © 2010 Elsevier Masson SAS. All rights reserved.)

Background: Congenital erythropoietic porphyria (CEP) is a severe autosomal recessive disorder characterized by a deficiency in uroporphyrinogen III synthase (UROS), the fourth enzyme of the heme biosynthetic pathway. We recently demonstrated the definitive cure of a murine model of CEP by lentiviral vector-mediated hematopoietic stem cell (HSC) gene therapy. In the perspective of a gene therapy clinical trial, human cellular models are required to evaluate the therapeutic potential of lentiviral vectors in UROS-deficient cells. However, the rare incidence of the disease makes difficult the availability of HSCs derived from patients., Methods: RNA interference (RNAi) has been used to develop a new human model of the disease from normal cord blood HSCs. Lentivectors were developed for this purpose., Results: We were able to down-regulate the level of human UROS in human cell lines and primary hematopoietic cells. A 97% reduction of UROS activity led to spontaneous uroporphyrin accumulation in human erythroid bone marrow cells of transplanted immune-deficient mice, recapitulating the phenotype of cells derived from patients. A strong RNAi-induced UROS inhibition allowed us to test the efficiency of different lentiviral vectors with the aim of selecting a safer vector. Restoration of UROS activity in these small hairpin RNA-transduced CD34(+) cord blood cells by therapeutic lentivectors led to a partial correction of the phenotype in vivo., Conclusions: The RNAi strategy is an interesting new tool for preclinical gene therapy evaluation., (Copyright 2010 John Wiley & Sons, Ltd.)