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Sharma P, Bhatia P, Singh M, Jamwal M, Pallavelangini S, Das R, Malhotra P, Attri SV, Ducamp S, Fleming MD, Trehan A. Comprehensive Genomic Analysis Identifies a Diverse Landscape of Sideroblastic and Nonsideroblastic Iron-Related Anemias with Novel and Pathogenic Variants in an Iron-Deficient Endemic Setting. J Mol Diagn 2024; 26:430-444. [PMID: 38360212 DOI: 10.1016/j.jmoldx.2024.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Revised: 01/19/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024] Open
Abstract
Inherited iron metabolism defects are possibly missed or underdiagnosed in iron-deficient endemic settings because of a lack of awareness or a methodical screening approach. Hence, we systematically evaluated anemia cases (2019 to 2021) based on clinical phenotype, normal screening tests (high-performance liquid chromatography, α gene sequencing, erythrocyte sedimentation rate, C-reactive protein, and tissue transglutaminase), and abnormal iron profile by targeted next-generation sequencing (26-gene panel) supplemented with whole-exome sequencing, multiplex ligation probe amplification/mitochondrial DNA sequencing, and chromosomal microarray. Novel variants in ALAS2, STEAP3, and HSPA9 genes were functionally validated. A total of 290 anemia cases were screened, and 41 (14%) enrolled for genomic testing as per inclusion criteria. Comprehensive genomic testing revealed pathogenic variants in 23 of 41 cases (56%). Congenital sideroblastic anemia was the most common diagnosis (14/23; 61%), with pathogenic variations in ALAS2 (n = 6), SLC25A38 (n = 3), HSPA9 (n = 2) and HSCB, SLC19A2, and mitochondrial DNA deletion (n = 1 each). Nonsideroblastic iron defects included STEAP3-related microcytic anemia (2/23; 8.7%) and hypotransferrenemia (1/23; 4.3%). A total of 6 of 22 cases (27%) revealed a non-iron metabolism gene defect on whole-exome sequencing. Eleven novel variants (including variants of uncertain significance) were noted in 13 cases. Genotype-phenotype correlation revealed a significant association of frameshift/nonsense/splice variants with lower presentation age (0.8 months versus 9 years; P < 0.01) compared with missense variants. The systematic evaluation helped uncover an inherited iron defect in 41% (17/41) of cases, suggesting the need for active screening and awareness for these rare diseases in an iron-deficient endemic population.
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Affiliation(s)
- Pankaj Sharma
- Pediatric Haematology Oncology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Prateek Bhatia
- Pediatric Haematology Oncology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
| | - Minu Singh
- Pediatric Haematology Oncology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Manu Jamwal
- Department of Haematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Swetha Pallavelangini
- Pediatric Haematology Oncology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Reena Das
- Department of Haematology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Pankaj Malhotra
- Department of Clinical Haematology and Medical Oncology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Savita V Attri
- Pediatric Biochemistry Laboratory, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India
| | - Sarah Ducamp
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts
| | - Mark D Fleming
- Department of Pathology, Boston Children's Hospital, Boston, Massachusetts
| | - Amita Trehan
- Pediatric Haematology Oncology Unit, Department of Pediatrics, Postgraduate Institute of Medical Education and Research, Chandigarh, India.
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Utgés JS, MacGowan SA, Ives CM, Barton GJ. Classification of likely functional class for ligand binding sites identified from fragment screening. Commun Biol 2024; 7:320. [PMID: 38480979 PMCID: PMC10937669 DOI: 10.1038/s42003-024-05970-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 02/23/2024] [Indexed: 03/17/2024] Open
Abstract
Fragment screening is used to identify binding sites and leads in drug discovery, but it is often unclear which binding sites are functionally important. Here, data from 37 experiments, and 1309 protein structures binding to 1601 ligands were analysed. A method to group ligands by binding sites is introduced and sites clustered according to profiles of relative solvent accessibility. This identified 293 unique ligand binding sites, grouped into four clusters (C1-4). C1 includes larger, buried, conserved, and population missense-depleted sites, enriched in known functional sites. C4 comprises smaller, accessible, divergent, missense-enriched sites, depleted in functional sites. A site in C1 is 28 times more likely to be functional than one in C4. Seventeen sites, which to the best of our knowledge are novel, in 13 proteins are identified as likely to be functionally important with examples from human tenascin and 5-aminolevulinate synthase highlighted. A multi-layer perceptron, and K-nearest neighbours model are presented to predict cluster labels for ligand binding sites with an accuracy of 96% and 100%, respectively, so allowing functional classification of sites for proteins not in this set. Our findings will be of interest to those studying protein-ligand interactions and developing new drugs or function modulators.
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Affiliation(s)
- Javier S Utgés
- Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
| | - Stuart A MacGowan
- Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
| | - Callum M Ives
- Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee, Scotland, UK
- Department of Chemistry and Hamilton Institute, Maynooth University, Maynooth, Ireland
| | - Geoffrey J Barton
- Division of Computational Biology, School of Life Sciences, University of Dundee, Dundee, Scotland, UK.
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3
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Thomas B, Visanica S, Poussing S, Gérard D, Perrin J. Is this really thalassemia? Am J Hematol 2023; 98:1814-1815. [PMID: 36932887 DOI: 10.1002/ajh.26913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2023] [Revised: 03/06/2023] [Accepted: 03/09/2023] [Indexed: 03/19/2023]
Affiliation(s)
- Benoit Thomas
- Laboratoire de biologie médicale, UNEOS Metz, Metz, France
| | | | | | - Delphine Gérard
- Hématologie biologique, CHRU Nancy, Vandoeuvre les Nancy, France
| | - Julien Perrin
- Hématologie biologique, CHRU Nancy, Vandoeuvre les Nancy, France
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Van Dijck R, Goncalves Silva AM, Rijneveld AW. Luspatercept as Potential Treatment for Congenital Sideroblastic Anemia. N Engl J Med 2023; 388:1435-1436. [PMID: 37043658 DOI: 10.1056/nejmc2216213] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 04/14/2023]
Affiliation(s)
- Ruben Van Dijck
- Erasmus University Medical Center, Rotterdam, the Netherlands
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Zhou J, Zhang H, Qin Y, Liu T. Severe Microcytic Anemia Caused by Complex Hereditary Spherocytosis and X-Linked Sideroblastic Anemia with Mutations in SPTB and ALAS2 Genes. J Clin Med 2023; 12:jcm12051990. [PMID: 36902777 PMCID: PMC10004689 DOI: 10.3390/jcm12051990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2023] [Revised: 02/17/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
We report a case of severe anemia caused by complex hereditary spherocytosis (HS) and X-linked sideroblastic anemia (XLSA) with two mutations in the spectrin beta (SPTB) and 5-aminolevulinic acid synthase (ALAS2) genes. The proband was a 16-year-old male with severe jaundice and microcytic hypochromic anemia since his childhood. He had more severe anemia requiring erythrocyte transfusion, and had no response to vitamin B6 treatment. Next-generation sequencing (NGS) revealed double heterozygous mutations, one in exon 19 (c.3936G > A:p.W1312X) of the SPTB gene and another in exon 2 (c.37A > G:p.K13E) of the ALAS2 gene, and confirmed again by Sanger sequencing. The mutation of ALAS2 (c.37A > G) is inherited from his asymptomatic heterozygous mother, causing amino acid p.K13E, and the mutation has not yet been reported. The mutation of SPTB (c.3936G > A) is a nonsense mutation, leading to a premature termination codon in exon 19, and the mutation in the SPTB gene is not found in any of his relatives, which indicates a de novo monoallelic mutation. Conclusions: The double heterozygous mutations in the SPTB and ALAS2 genes lead to the joint occurrence of HS and XLSA in this patient, and are implicated in the more severe clinical phenotypes.
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Affiliation(s)
| | | | | | - Ting Liu
- Correspondence: ; Tel.: +86-18980601240
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Iron Metabolism in the Disorders of Heme Biosynthesis. Metabolites 2022; 12:metabo12090819. [PMID: 36144223 PMCID: PMC9505951 DOI: 10.3390/metabo12090819] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 08/26/2022] [Accepted: 08/29/2022] [Indexed: 01/19/2023] Open
Abstract
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.
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Congenital sideroblastic anemia model due to ALAS2 mutation is susceptible to ferroptosis. Sci Rep 2022; 12:9024. [PMID: 35637209 PMCID: PMC9151922 DOI: 10.1038/s41598-022-12940-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 05/18/2022] [Indexed: 11/20/2022] Open
Abstract
X-linked sideroblastic anemia (XLSA), the most common form of congenital sideroblastic anemia, is caused by a germline mutation in the erythroid-specific 5-aminolevulinate synthase (ALAS2) gene. In XLSA, defective heme biosynthesis leads to ring sideroblast formation because of excess mitochondrial iron accumulation. In this study, we introduced ALAS2 missense mutations on human umbilical cord blood-derived erythroblasts; hereafter, we refer to them as XLSA clones. XLSA clones that differentiated into mature erythroblasts showed an increased frequency of ring sideroblast formation with impaired hemoglobin biosynthesis. The expression profiling revealed significant enrichment of genes involved in ferroptosis, which is a form of regulated cell death induced by iron accumulation and lipid peroxidation. Notably, treatment with erastin, a ferroptosis inducer, caused a higher proportion of cell death in XLSA clones. XLSA clones exhibited significantly higher levels of intracellular lipid peroxides and enhanced expression of BACH1, a regulator of iron metabolism and potential accelerator of ferroptosis. In XLSA clones, BACH1 repressed genes involved in iron metabolism and glutathione synthesis. Collectively, defective heme biosynthesis in XLSA clones could confer enhanced BACH1 expression, leading to increased susceptibility to ferroptosis. The results of our study provide important information for the development of novel therapeutic targets for XLSA.
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Taylor JL, Brown BL. Structural basis for dysregulation of aminolevulinic acid synthase in human disease. J Biol Chem 2022; 298:101643. [PMID: 35093382 PMCID: PMC8892079 DOI: 10.1016/j.jbc.2022.101643] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 01/19/2022] [Accepted: 01/20/2022] [Indexed: 01/19/2023] Open
Abstract
Heme is a critical biomolecule that is synthesized in vivo by several organisms such as plants, animals, and bacteria. Reflecting the importance of this molecule, defects in heme biosynthesis underlie several blood disorders in humans. Aminolevulinic acid synthase (ALAS) initiates heme biosynthesis in α-proteobacteria and nonplant eukaryotes. Debilitating and painful diseases such as X-linked sideroblastic anemia and X-linked protoporphyria can result from one of more than 91 genetic mutations in the human erythroid-specific enzyme ALAS2. This review will focus on recent structure-based insights into human ALAS2 function in health and how it dysfunctions in disease. We will also discuss how certain genetic mutations potentially result in disease-causing structural perturbations. Furthermore, we use thermodynamic and structural information to hypothesize how the mutations affect the human ALAS2 structure and categorize some of the unique human ALAS2 mutations that do not respond to typical treatments, that have paradoxical in vitro activity, or that are highly intolerable to changes. Finally, we will examine where future structure-based insights into the family of ALA synthases are needed to develop additional enzyme therapeutics.
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Affiliation(s)
- Jessica L Taylor
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
| | - Breann L Brown
- Department of Biochemistry, Vanderbilt University School of Medicine, Nashville, Tennessee, USA; Center for Structural Biology, Vanderbilt University School of Medicine, Nashville, Tennessee, USA.
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Nzelu D, Shangaris P, Story L, Smith F, Piyasena C, Alamelu J, Elmakky A, Pelidis M, Mayhew R, Sankaran S. X-linked sideroblastic anaemia in a female fetus: a case report and a literature review. BMC Med Genomics 2021; 14:296. [PMID: 34930268 PMCID: PMC8686580 DOI: 10.1186/s12920-021-01146-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 12/08/2021] [Indexed: 01/19/2023] Open
Abstract
Background X-linked sideroblastic anaemia (XLSA) is commonly due to mutations in the ALAS2 gene and predominantly affects hemizygous males. Heterozygous female carriers of the ALAS2 gene mutation are often asymptomatic or only mildly anaemic. XLSA is usually characterized by microcytic erythrocytes (reduced mean corpuscular volume (MCV)) and hypochromia, along with increased red cell distribution width. However, in females with XLSA the characteristic laboratory findings can be dimorphic and present with macrocytic (elevated MCV) in addition to microcytic red cells. Case presentation We report a case of fetal anaemia, presenting in the early third trimester of pregnancy, in a female fetus. Ultrasound findings at 29 weeks were of cardiomegaly, prominent umbilical veins, a small rim of ascites, and mean cerebral artery peak systolic velocity (PSV) value above 1.5 Multiples of the Median (MoM). She underwent non-invasive prenatal testing that determined the rhesus genotype of the fetus to be rhesus B negative. No red blood cell antibodies were reported. Other investigations to determine the underlying cause of fetal anaemia included microarray comparative genomic hybridization, serology to exclude congenital infection and a peripheral blood film and fetal bilirubin to detect haemolysis. The maternal grandmother had a history of sideroblastic anaemia diagnosed at the age of 17 years. The mother had mild macrocytic anaemia with haemoglobin of 10.4 g/dl and MCV of 104 fl. The fetal anaemia was successfully treated with two in utero transfusions (IUTs), and delivery occurred via caesarean section at 37 weeks of gestation. The red cell gene sequencing in both the mother and fetus were heterozygous for an ALAS2 mutation causing in utero manifestations of XLSA. The haemoglobin on discharge to the local hospital at five days of age was 19.1 g/dl. Subsequently, the infant became anaemic, requiring regular 3–4 monthly blood transfusions and demonstrating overall normal development. Her anaemia was unresponsive to pyridoxine. Conclusions This is one of four cases reporting multiple female members presenting with discordant clinical features of XLSA from being entirely asymptomatic to hydropic in utero. Our report is novel in that there are no previous cases in the literature of anaemia in a female fetus heterozygous for ALAS2 mutation.
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Affiliation(s)
- Diane Nzelu
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK
| | - Panicos Shangaris
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK. .,Department of Women and Children's Health, School of Life Course & Population Sciences, Faculty of Life Sciences and Medicine, King's College London, 10th Floor North Wing St Thomas' Hospital, London, SE1 7EH, UK.
| | - Lisa Story
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK.,Department of Women and Children's Health, School of Life Course & Population Sciences, Faculty of Life Sciences and Medicine, King's College London, 10th Floor North Wing St Thomas' Hospital, London, SE1 7EH, UK
| | - Frances Smith
- Viapath at King's College Hospital, Bessemer Wing, Denmark Hill, London, SE5 9RS, UK
| | - Chinthika Piyasena
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK
| | - Jayanthi Alamelu
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK
| | - Amira Elmakky
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK
| | - Maria Pelidis
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK
| | - Rachel Mayhew
- Viapath at King's College Hospital, Bessemer Wing, Denmark Hill, London, SE5 9RS, UK
| | - Srividhya Sankaran
- Guy's & St. Thomas' Hospital NHS Foundation Trust, Westminster Bridge Road, London, SE1 7EH, UK.,Department of Women and Children's Health, School of Life Course & Population Sciences, Faculty of Life Sciences and Medicine, King's College London, 10th Floor North Wing St Thomas' Hospital, London, SE1 7EH, UK
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10
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Juchniewicz P, Piotrowska E, Kloska A, Podlacha M, Mantej J, Węgrzyn G, Tukaj S, Jakóbkiewicz-Banecka J. Dosage Compensation in Females with X-Linked Metabolic Disorders. Int J Mol Sci 2021; 22:ijms22094514. [PMID: 33925963 PMCID: PMC8123450 DOI: 10.3390/ijms22094514] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 04/20/2021] [Accepted: 04/22/2021] [Indexed: 01/19/2023] Open
Abstract
Through the use of new genomic and metabolomic technologies, our comprehension of the molecular and biochemical etiologies of genetic disorders is rapidly expanding, and so are insights into their varying phenotypes. Dosage compensation (lyonization) is an epigenetic mechanism that balances the expression of genes on heteromorphic sex chromosomes. Many studies in the literature have suggested a profound influence of this phenomenon on the manifestation of X-linked disorders in females. In this review, we summarize the clinical and genetic findings in female heterozygotic carriers of a pathogenic variant in one of ten selected X-linked genes whose defects result in metabolic disorders.
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Affiliation(s)
- Patrycja Juchniewicz
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (P.J.); (A.K.); (J.J.-B.)
| | - Ewa Piotrowska
- Department of Molecular Biology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (M.P.); (J.M.); (G.W.); (S.T.)
- Correspondence: ; Tel.: +48-58-523-6040
| | - Anna Kloska
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (P.J.); (A.K.); (J.J.-B.)
| | - Magdalena Podlacha
- Department of Molecular Biology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (M.P.); (J.M.); (G.W.); (S.T.)
| | - Jagoda Mantej
- Department of Molecular Biology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (M.P.); (J.M.); (G.W.); (S.T.)
| | - Grzegorz Węgrzyn
- Department of Molecular Biology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (M.P.); (J.M.); (G.W.); (S.T.)
| | - Stefan Tukaj
- Department of Molecular Biology, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (M.P.); (J.M.); (G.W.); (S.T.)
| | - Joanna Jakóbkiewicz-Banecka
- Department of Medical Biology and Genetics, Faculty of Biology, University of Gdańsk, Wita Stwosza 59, 80-308 Gdańsk, Poland; (P.J.); (A.K.); (J.J.-B.)
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Lira Zidanes A, Marchi G, Busti F, Marchetto A, Fermo E, Giorgetti A, Vianello A, Castagna A, Olivieri O, Bianchi P, Girelli D. A Novel ALAS2 Missense Mutation in Two Brothers With Iron Overload and Associated Alterations in Serum Hepcidin/Erythroferrone Levels. Front Physiol 2020; 11:581386. [PMID: 33281618 PMCID: PMC7689258 DOI: 10.3389/fphys.2020.581386] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/01/2020] [Indexed: 01/19/2023] Open
Abstract
Iron loading anemias are characterized by ineffective erythropoiesis and iron overload. The prototype is non-transfusion dependent ß-thalassemia (NTDT), with other entities including congenital sideroblastic anemias, congenital dyserythropoietic anemias, some hemolytic anemias, and myelodysplastic syndromes. Differential diagnosis of iron loading anemias may be challenging due to heterogeneous genotype and phenotype. Notwithstanding the recent advances in linking ineffective erythropoiesis to iron overload, many pathophysiologic aspects are still unclear. Moreover, measurement of hepcidin and erythroferrone (ERFE), two key molecules in iron homeostasis and erythropoiesis, is scarcely used in clinical practice and of uncertain utility. Here, we describe a comprehensive diagnostic approach, including next-generation sequencing (NGS), in silico modeling, and measurement of hepcidin and erythroferrone (ERFE), in two brothers eventually diagnosed as X-linked sideroblastic anemia (XLSA). A novel pathogenic ALAS2 missense mutation (c.1382T>A, p.Leu461His) is described. Hyperferritinemia with high hepcidin-25 levels (but decreased hepcidin:ferritin ratio) and mild-to-moderate iron overload were detected in both patients. ERFE levels were markedly elevated in both patients, especially in the proband, who had a more expressed phenotype. Our study illustrates how new technologies, such as NGS, in silico modeling, and measurement of serum hepcidin-25 and ERFE, may help in diagnosing and studying iron loading anemias. Further studies on the hepcidin-25/ERFE axis in additional patients with XLSA and other iron loading anemias may help in establishing its usefulness in differential diagnosis, and it may also aid our understanding of the pathophysiology of these genetically and phenotypically heterogeneous entities.
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Affiliation(s)
- Acaynne Lira Zidanes
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
| | - Giacomo Marchi
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
| | - Fabiana Busti
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
| | | | - Elisa Fermo
- Hematology and Pathophysiology of Anemias Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCSS) Ca' Granda Foundation, Policlinico Milano, Milan, Italy
| | | | - Alice Vianello
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
| | - Annalisa Castagna
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
| | - Oliviero Olivieri
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
| | - Paola Bianchi
- Hematology and Pathophysiology of Anemias Unit, Istituto di Ricovero e Cura a Carattere Scientifico (IRCSS) Ca' Granda Foundation, Policlinico Milano, Milan, Italy
| | - Domenico Girelli
- Section of Internal Medicine, Department of Medicine, University of Verona, Verona, Italy.,EuroBloodNet Referral Center for Rare Disorders of Iron Metabolism, University Hospital of Verona, Verona, Italy
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12
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Abu-Zeinah G, DeSancho MT. Understanding Sideroblastic Anemia: An Overview of Genetics, Epidemiology, Pathophysiology and Current Therapeutic Options. J Blood Med 2020; 11:305-318. [PMID: 33061728 PMCID: PMC7524202 DOI: 10.2147/jbm.s232644] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 08/18/2020] [Indexed: 01/19/2023] Open
Abstract
Sideroblastic anemia (SA) consists of a group of inherited and acquired anemias of ineffective erythropoiesis characterized by the accumulation of ring sideroblasts in the bone marrow due to disrupted heme biosynthesis. Congenital sideroblastic anemia (CSA) is rare and has three modes of inheritance: X-linked (XLSA), autosomal recessive (ARCSA), and maternal. Acquired SA is more common and can be a result of myelodysplastic syndromes (MDS) or other, generally reversible causes. The diagnostic approach to SA includes a work-up for reversible causes and genetic testing for CSA based on clinical suspicion, family history and genetic pedigree. The treatment of SA depends on the underlying etiology but remains primarily supportive with vitamin B6 supplementation for select cases of XLSA, thiamine for thiamine-responsive megaloblastic anemia subtype, red blood cell transfusions for symptomatic patients and iron chelation therapy for iron overload. The management of anemia in MDS subtypes with ring sideroblasts remains unique and includes the recently approved erythroid maturation agent, Luspatercept. Although there is currently no curative therapy for CSA, anecdotal reports of hematopoietic stem cell transplant demonstrate remissions in selective, non-syndromic cases. This review summarizes the genetics, pathophysiology, diagnosis and treatment of SA for general practitioners and clinical hematologists.
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Affiliation(s)
- Ghaith Abu-Zeinah
- Division of Hematology and Oncology, Department of Medicine, Weill Cornell Medicine, New York Presbyterian Hospital, New York, NY, USA
| | - Maria T DeSancho
- Division of Hematology and Oncology, Department of Medicine, Weill Cornell Medicine, New York Presbyterian Hospital, New York, NY, USA
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13
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Ravindra N, Athiyarath R, S E, S S, Kulkarni U, N A F, Korula A, Shaji RV, George B, Edison ES. Novel frameshift variant (c.409dupG) in SLC25A38 is a common cause of congenital sideroblastic anaemia in the Indian subcontinent. J Clin Pathol 2020; 74:157-162. [PMID: 32605921 DOI: 10.1136/jclinpath-2020-206647] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Revised: 06/03/2020] [Accepted: 06/05/2020] [Indexed: 01/19/2023]
Abstract
AIMS Congenital sideroblastic anaemias (CSAs) are a group of rare disorders with the presence of ring sideroblasts in the bone marrow. Pathogenic variants are inherited in an autosomal recessive/X-linked fashion. The study was aimed at characterising the spectrum of mutations in SLC25A38 and ALAS2 genes in sideroblastic anaemia patients, exploring the genotype-phenotype correlation and identifying the haplotype associated with any recurrent mutation. PATIENTS AND METHODS Twenty probable CSA patients were retrospectively analysed for genetic variants in ALAS2 and SLC25A38 genes by direct bidirectional sequencing. Real-time PCR was used to quantify gene expression in a case with promoter region variant in ALAS2. Three single nucleotide polymorphisms were used to establish the haplotype associated with a recurrent variant in the SLC25A38 gene. RESULTS Six patients had causative variants in ALAS2 (30%) and 11 had variants in SLC25A38 (55%). The ALAS2 mutated cases presented at a significantly later age than the SLC25A38 cases. A frameshift variant in SLC25A38 (c.409dupG) was identified in six unrelated patients and was a common variant in our population exhibiting 'founder effect'. CONCLUSION This is the largest series of sideroblastic anaemia cases with molecular characterisation from the Indian subcontinent.
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Affiliation(s)
- Niveditha Ravindra
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Rekha Athiyarath
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Eswari S
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Sumithra S
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Uday Kulkarni
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Fouzia N A
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Anu Korula
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Ramachandran V Shaji
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
| | - Biju George
- Department of Haematology, Christian Medical College, Vellore, Tamil Nadu, India
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14
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Bailey HJ, Bezerra GA, Marcero JR, Padhi S, Foster WR, Rembeza E, Roy A, Bishop DF, Desnick RJ, Bulusu G, Dailey HA, Yue WW. Human aminolevulinate synthase structure reveals a eukaryotic-specific autoinhibitory loop regulating substrate binding and product release. Nat Commun 2020; 11:2813. [PMID: 32499479 PMCID: PMC7272653 DOI: 10.1038/s41467-020-16586-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2019] [Accepted: 05/11/2020] [Indexed: 12/12/2022] Open
Abstract
5'-aminolevulinate synthase (ALAS) catalyzes the first step in heme biosynthesis, generating 5'-aminolevulinate from glycine and succinyl-CoA. Inherited frameshift indel mutations of human erythroid-specific isozyme ALAS2, within a C-terminal (Ct) extension of its catalytic core that is only present in higher eukaryotes, lead to gain-of-function X-linked protoporphyria (XLP). Here, we report the human ALAS2 crystal structure, revealing that its Ct-extension folds onto the catalytic core, sits atop the active site, and precludes binding of substrate succinyl-CoA. The Ct-extension is therefore an autoinhibitory element that must re-orient during catalysis, as supported by molecular dynamics simulations. Our data explain how Ct deletions in XLP alleviate autoinhibition and increase enzyme activity. Crystallography-based fragment screening reveals a binding hotspot around the Ct-extension, where fragments interfere with the Ct conformational dynamics and inhibit ALAS2 activity. These fragments represent a starting point to develop ALAS2 inhibitors as substrate reduction therapy for porphyria disorders that accumulate toxic heme intermediates.
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Affiliation(s)
- Henry J Bailey
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Gustavo A Bezerra
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Jason R Marcero
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Siladitya Padhi
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Ltd, Hyderabad, 500081, India
| | - William R Foster
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Elzbieta Rembeza
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7DQ, UK
| | - Arijit Roy
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Ltd, Hyderabad, 500081, India
| | - David F Bishop
- Department of Genetics and Genomics Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Robert J Desnick
- Department of Genetics and Genomics Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, 10029, USA
| | - Gopalakrishnan Bulusu
- TCS Innovation Labs-Hyderabad (Life Sciences Division), Tata Consultancy Services Ltd, Hyderabad, 500081, India
| | - Harry A Dailey
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA
| | - Wyatt W Yue
- Structural Genomics Consortium, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7DQ, UK.
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15
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Peoc'h K, Nicolas G, Schmitt C, Mirmiran A, Daher R, Lefebvre T, Gouya L, Karim Z, Puy H. Regulation and tissue-specific expression of δ-aminolevulinic acid synthases in non-syndromic sideroblastic anemias and porphyrias. Mol Genet Metab 2019; 128:190-197. [PMID: 30737140 DOI: 10.1016/j.ymgme.2019.01.015] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Revised: 01/21/2019] [Accepted: 01/21/2019] [Indexed: 02/07/2023]
Abstract
Recently, new genes and molecular mechanisms have been identified in patients with porphyrias and sideroblastic anemias (SA). They all modulate either directly or indirectly the δ-aminolevulinic acid synthase (ALAS) activity. ALAS, is encoded by two genes: the erythroid-specific (ALAS2), and the ubiquitously expressed (ALAS1). In the liver, ALAS1 controls the rate-limiting step in the production of heme and hemoproteins that are rapidly turned over in response to metabolic needs. Several heme regulatory targets have been identified as regulators of ALAS1 activity: 1) transcriptional repression via a heme-responsive element, 2) post-transcriptional destabilization of ALAS1 mRNA, 3) post-translational inhibition via a heme regulatory motif, 4) direct inhibition of the activity of the enzyme and 5) breakdown of ALAS1 protein via heme-mediated induction of the protease Lon peptidase 1. In erythroid cells, ALAS2 is a gatekeeper of production of very large amounts of heme necessary for hemoglobin synthesis. The rate of ALAS2 synthesis is transiently increased during the period of active heme synthesis. Its gene expression is determined by trans-activation of nuclear factor GATA1, CACC box and NF-E2-binding sites in the promoter areas. ALAS2 mRNA translation is also regulated by the iron-responsive element (IRE)/iron regulatory proteins (IRP) binding system. In patients, ALAS enzyme activity is affected in most of the mutations causing non-syndromic SA and in several porphyrias. Decreased ALAS2 activity results either directly from loss-of-function ALAS2 mutations as seen in X-linked sideroblastic anemia (XLSA) or from defect in the availability of one of its two mitochondrial substrates: glycine in SLC25A38 mutations and succinyl CoA in GLRX5 mutations. Moreover, ALAS2 gain of function mutations is responsible for X-linked protoporphyria and increased ALAS1 activity lead to acute attacks of hepatic porphyrias. A missense dominant mutation in the Walker A motif of the ATPase binding site in the gene coding for the mitochondrial protein unfoldase CLPX also contributes to increasing ALAS and subsequently protoporphyrinemia. Altogether, these recent data on human ALAS have informed our understanding of porphyrias and sideroblastic anemias pathogeneses and may contribute to new therapeutic strategies.
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Affiliation(s)
- Katell Peoc'h
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France.
| | - Gaël Nicolas
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France.
| | - Caroline Schmitt
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France; AP-HP, HUPNVS, Centre Français des Porphyries, Hôpital Louis Mourier, Colombes, France.
| | - Arienne Mirmiran
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France.
| | - Raed Daher
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France.
| | - Thibaud Lefebvre
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France; AP-HP, HUPNVS, Centre Français des Porphyries, Hôpital Louis Mourier, Colombes, France.
| | - Laurent Gouya
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France; AP-HP, HUPNVS, Centre Français des Porphyries, Hôpital Louis Mourier, Colombes, France.
| | - Zoubida Karim
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France.
| | - Hervé Puy
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l'inflammation, Université Paris Diderot, site Bichat, Sorbonne Paris Cité, France, 16 rue Henri Huchard, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France; AP-HP, HUPNVS, Centre Français des Porphyries, Hôpital Louis Mourier, Colombes, France.
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16
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Fouquet C, Le Rouzic M, Leblanc T, Fouyssac F, Leverger G, Hessissen L, Marlin S, Bourrat E, Fahd M, Raffoux E, Vannier J, Jäkel N, Knoefler R, Triolo V, Pasquet M, Bayart S, Thuret I, Lutz P, Vermylen C, Touati M, Rose C, Matthes T, Isidor B, Kannengiesser C, Ducassou S. Genotype/phenotype correlations of childhood‐onset congenital sideroblastic anaemia in a European cohort. Br J Haematol 2019; 187:530-542. [DOI: 10.1111/bjh.16100] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2018] [Accepted: 05/08/2019] [Indexed: 01/19/2023]
Affiliation(s)
| | | | | | | | - Guy Leverger
- CHU de Paris Hôpital Armand Trousseau Paris France
| | | | | | | | - Mony Fahd
- CHU de Paris Hôpital Robert Debré Paris France
| | | | | | - Nadja Jäkel
- Department für Hämatologie Onkologie und Hämostaseologie Leipzig Germany
| | - Ralf Knoefler
- Department of Pediatric Haemostaseology University Hospital Carl Gustav Carus Dresden Germany
| | | | | | | | | | - Patrick Lutz
- CHU de Strasbourg Hôpital de Hautepierre Strasbourg France
| | - Christiane Vermylen
- Université Catholique de Louvain, Cliniques universitaires Saint‐Luc Brussels Belgium
| | | | | | - Thomas Matthes
- Geneva University Hospital, Hematology Service Geneva Switzerland
| | | | - Caroline Kannengiesser
- Assistance Publique des Hôpitaux de Paris, Département de Génétique Hôpital Bichat, Université Paris VII Paris France
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17
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Fujiwara T, Harigae H. Molecular pathophysiology and genetic mutations in congenital sideroblastic anemia. Free Radic Biol Med 2019; 133:179-185. [PMID: 30098397 DOI: 10.1016/j.freeradbiomed.2018.08.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Revised: 08/02/2018] [Accepted: 08/04/2018] [Indexed: 01/19/2023]
Abstract
Sideroblastic anemia is a heterogeneous congenital and acquired disorder characterized by anemia and the presence of ring sideroblasts in the bone marrow. Congenital sideroblastic anemia (CSA) is a rare disease caused by mutations in genes involved in the heme biosynthesis, iron-sulfur [Fe-S] cluster biosynthesis, and mitochondrial protein synthesis. The most prevalent form of CSA is X-linked sideroblastic anemia, caused by mutations in the erythroid-specific δ-aminolevulinate synthase (ALAS2), which is the first enzyme of the heme biosynthesis pathway in erythroid cells. To date, a remarkable number of genetically undefined CSA cases remain, but a recent application of the next-generation sequencing technology has recognized novel causative genes for CSA. However, in most instances, the detailed molecular mechanisms of how defects of each gene result in the abnormal mitochondrial iron accumulation remain unclear. This review aims to cover the current understanding of the molecular pathophysiology of CSA.
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Affiliation(s)
- Tohru Fujiwara
- Department of Hematology and Rheumatology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai 980-8575, Japan
| | - Hideo Harigae
- Department of Hematology and Rheumatology, Tohoku University Graduate School of Medicine, 2-1 Seiryo-cho, Aoba-ku, Sendai 980-8575, Japan.
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18
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Abu-Zeinah G, DeSancho MT, Al-Kawaaz M, Geyer J. Delayed diagnosis of congenital sideroblastic anemia. Semin Hematol 2018; 55:177-178. [PMID: 30502842 DOI: 10.1053/j.seminhematol.2017.09.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Revised: 08/08/2017] [Accepted: 09/30/2017] [Indexed: 01/19/2023]
Affiliation(s)
- Ghaith Abu-Zeinah
- Division of Hematology-Oncology, Department of MedicineWeill Cornell MedicineNew York, NY
| | - Maria T DeSancho
- Division of Hematology-Oncology, Department of MedicineWeill Cornell MedicineNew York, NY.
| | | | - Julia Geyer
- Department of Pathology, Weill Cornell MedicineNew York, NY
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19
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Moreno‐Carralero M, Arrizabalaga‐Amuchastegui B, Sánchez‐Calero‐Guilarte J, Morado‐Arias M, Velasco‐Valdazo A, de‐la‐Iglesia‐Iñigo S, Méndez M, Morán‐Jiménez M. Missense variants in
ALAS
2
gene in five patients. Int J Lab Hematol 2018; 41:e5-e9. [DOI: 10.1111/ijlh.12902] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
| | | | | | - Marta Morado‐Arias
- Servicio de Hematología y Hemoterapia Hospital Universitario La Paz Madrid Spain
| | | | - Silvia de‐la‐Iglesia‐Iñigo
- Servicio de Hematología y Hemoterapia Hospital Universitario Doctor Negrín Las Palmas de Gran Canaria Spain
| | - Manuel Méndez
- Instituto de Investigación Sanitaria Hospital 12 de Octubre (imas12) Madrid Spain
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20
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21
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Iron metabolism in erythroid cells and patients with congenital sideroblastic anemia. Int J Hematol 2017; 107:44-54. [PMID: 29139060 DOI: 10.1007/s12185-017-2368-0] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 11/08/2017] [Indexed: 01/31/2023]
Abstract
Sideroblastic anemias are anemic disorders characterized by the presence of ring sideroblasts in a patient's bone marrow. These disorders are typically divided into two types, congenital or acquired sideroblastic anemia. Recently, several genes were reported as responsible for congenital sideroblastic anemia; however, the relationship between the function of the gene products and ring sideroblasts is largely unclear. In this review article, we will focus on the iron metabolism in erythroid cells as well as in patients with congenital sideroblastic anemia.
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22
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Acute hepatic and erythropoietic porphyrias: from ALA synthases 1 and 2 to new molecular bases and treatments. Curr Opin Hematol 2017; 24:198-207. [PMID: 28118224 DOI: 10.1097/moh.0000000000000330] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE OF REVIEW Many studies over the past decade have together identified new genes including modifier genes and new regulation and pathophysiological mechanisms in inherited inborn diseases of the heme biosynthetic pathway. A new porphyria has been characterized: X-linked protoporphyria and the perspective to have innovative treatment at very short-term became a reality. We will summarize how recent data on both ALAS1 and ALAS2 have informed our understanding of disease pathogenesis with an emphasis on how this information may contribute to new therapeutic strategies. RECENT FINDINGS The development of clinical and biological porphyria networks improved the long-term follow up of cohorts. The ageing of patients have allowed for the identification of novel recurrently mutated genes, and highlighted long-term complications in acute hepatic porphyrias. The treatment of hepatic porphyrias by an RNAi-targeting hepatic ALAS1 is actually tested and may lead to improve the management of acute attacks.In erythropoietic porphyrias, the key role of ALAS2 as a gate keeper of the heme and subsequently hemoglobin synthesis has been demonstrated. Its implication as a modifier gene in over erythroid disorders has also been documented. SUMMARY The knowledge of both the genetic abnormalities and the regulation of heme biosynthesis has increased over the last 5 years and open new avenues in the management of erythropoietic and acute hepatic porphyrias.
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23
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Le Rouzic MA, Fouquet C, Leblanc T, Touati M, Fouyssac F, Vermylen C, Jäkel N, Guichard JF, Maloum K, Toutain F, Lutz P, Perel Y, Manceau H, Kannengiesser C, Vannier JP. Non syndromic childhood onset congenital sideroblastic anemia: A report of 13 patients identified with an ALAS2 or SLC25A38 mutation. Blood Cells Mol Dis 2017; 66:11-18. [PMID: 28772256 DOI: 10.1016/j.bcmd.2017.07.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Revised: 07/18/2017] [Accepted: 07/25/2017] [Indexed: 01/19/2023]
Abstract
The most frequent germline mutations responsible for non syndromic congenital sideroblastic anemia are identified in ALAS2 and SLC25A38 genes. Iron overload is a key issue and optimal chelation therapy should be used to limit its adverse effects on the development of children. Our multicentre retrospective descriptive study compared the strategies for diagnosis and management of congenital sideroblastic anemia during the follow-up of six patients with an ALAS2 mutation and seven patients with an SLC25A38 mutation. We described in depth the clinical, biological and radiological phenotype of these patients at diagnosis and during follow-up and highlighted our results with a review of available evidence and data on the management strategies for congenital sideroblastic anemia. This report confirms the considerable variability in manifestations among patients with ALAS2 or SLC25A38 mutations and draws attention to differences in the assessment and the monitoring of iron overload and its complications. The use of an international registry would certainly help defining recommendations for the management of these rare disorders to improve patient outcome.
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Affiliation(s)
| | | | | | | | | | - Christiane Vermylen
- Université Catholique de Louvain, Cliniques universitaires Saint-Luc, Brussels, Belgium.
| | - Nadja Jäkel
- Department für Hämatologie, Onkologie und Hämostaseologie, Leipzig, Germany.
| | | | - Karim Maloum
- Assistance Publique des Hôpitaux de Paris/Hôpital de la Pitié-Salpêtrière, Paris, France.
| | | | - Patrick Lutz
- CHU de Strasbourg/Hôpital de Hautepierre, Strasbourg, France.
| | - Yves Perel
- CHU de Bordeaux/Hôpital Pellegrin, Bordeaux, France.
| | - Hana Manceau
- INSERM U1149, Centre de Recherche sur l'inflammation CRI, Paris, France.
| | - Caroline Kannengiesser
- INSERM U1149, Centre de Recherche sur l'inflammation CRI, Paris, France; Université Paris Diderot, Site Bichat, Sorbonne Paris Cité, DHU UNITY, Paris, France; Laboratory of Excellence, GR-Ex, Paris, France; Assistance Publique des Hôpitaux de Paris, Département de Génétique, Hôpital Bichat, Paris, France.
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24
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Zhang Y, Zhang J, An W, Wan Y, Ma S, Yin J, Li X, Gao J, Yuan W, Guo Y, Engel JD, Shi L, Cheng T, Zhu X. Intron 1 GATA site enhances ALAS2 expression indispensably during erythroid differentiation. Nucleic Acids Res 2016; 45:657-671. [PMID: 28123038 PMCID: PMC5314798 DOI: 10.1093/nar/gkw901] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2016] [Revised: 09/26/2016] [Accepted: 09/30/2016] [Indexed: 01/19/2023] Open
Abstract
The first intronic mutations in the intron 1 GATA site (int-1-GATA) of 5-aminolevulinate synthase 2 (ALAS2) have been identified in X-linked sideroblastic anemia (XLSA) pedigrees, strongly suggesting it could be causal mutations of XLSA. However, the function of this int-1-GATA site during in vivo development remains largely unknown. Here, we generated mice lacking a 13 bp fragment, including this int-1-GATA site (TAGATAAAGCCCC) and found that hemizygous deletion led to an embryonic lethal phenotype due to severe anemia resulting from a lack of ALAS2 expression, indicating that this non-coding sequence is indispensable for ALAS2 expression in vivo. Further analyses revealed that this int-1-GATA site anchored the GATA site in intron 8 (int-8-GATA) and the proximal promoter, forming a long-range loop to enhance ALAS2 expression by an enhancer complex including GATA1, TAL1, LMO2, LDB1 and Pol II at least, in erythroid cells. However, compared with the int-8-GATA site, the int-1-GATA site is more essential for regulating ALAS2 expression through CRISPR/Cas9-mediated site-specific deletion. Therefore, the int-1-GATA site could serve as a valuable site for diagnosing XLSA in cases with unknown mutations.
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Affiliation(s)
- Yingchi Zhang
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Division of Pediatric Blood Diseases Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Jingliao Zhang
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Division of Pediatric Blood Diseases Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Wenbin An
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Division of Pediatric Blood Diseases Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Yang Wan
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Division of Pediatric Blood Diseases Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Shihui Ma
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Jie Yin
- Department of Cell Biology, Tianjin Key Laboratory of Medical Epigenetics, Tianjin Medical University, Tianjin 300070, China
| | - Xichuan Li
- Department of Immunology, Biochemistry and Molecular Biology, Tianjin Key Laboratory of Medical Epigenetics, Tianjin Medical University, Tianjin 300070, China
| | - Jie Gao
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Weiping Yuan
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Ye Guo
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Division of Pediatric Blood Diseases Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - James Douglas Engel
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Lihong Shi
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China .,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
| | - Tao Cheng
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China .,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China.,Department of Stem Cell & Regenerative Medicine, Peking Union Medical College, Tianjin 300020, China
| | - Xiaofan Zhu
- State Key Laboratory of Experimental Hematology, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China .,Division of Pediatric Blood Diseases Center, Institute of Hematology and Blood Diseases Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Tianjin 300020, China.,Center for Stem Cell Medicine, Chinese Academy of Medical Sciences, Beijing 100730, China
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25
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Rose C, Callebaut I, Pascal L, Oudin C, Fournier M, Gouya L, Lambilliotte A, Kannengiesser C. Lethal ALAS2 mutation in males X-linked sideroblastic anaemia. Br J Haematol 2016; 178:648-651. [PMID: 27292130 DOI: 10.1111/bjh.14164] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christian Rose
- Service d'Oncologie et d'Hématologie, Hôpital Saint Vincent de Paul, Université Catholique de Lille, Lille, France
| | - Isabelle Callebaut
- CNRS UMR7590, Sorbonne Universités, Université Pierre et Marie Curie-Paris6 - MNHN - IRD - IUC, Paris, France
| | - Laurent Pascal
- Service d'Oncologie et d'Hématologie, Hôpital Saint Vincent de Paul, Université Catholique de Lille, Lille, France
| | - Claire Oudin
- Département de génétique, hôpital Bichat, HUPNVS, Paris, France
| | | | - Laurent Gouya
- Inserm U773, Université Paris 7, Faculté de Médecine Denis Diderot, Paris, France
| | - Anne Lambilliotte
- Service d'Hématologie, Département de Pédiatrie, Hôpital Jeanne de Flandres, CHRU, Lille, France
| | - Caroline Kannengiesser
- Département de génétique, hôpital Bichat, HUPNVS, Paris, France.,Inserm U773, Université Paris 7, Faculté de Médecine Denis Diderot, Paris, France
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26
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Méndez M, Moreno‐Carralero M, Morado‐Arias M, Fernández‐Jiménez M, de la Iglesia Iñigo S, Morán‐Jiménez M. Sideroblastic anemia: functional study of two novel missense mutations in ALAS2. Mol Genet Genomic Med 2016; 4:273-82. [PMID: 27247955 PMCID: PMC4867561 DOI: 10.1002/mgg3.202] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Revised: 12/10/2015] [Accepted: 12/12/2015] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND X-linked sideroblastic anemia (XLSA) is a disorder characterized by decreased heme synthesis and mitochondrial iron overload with ringed sideroblasts in bone marrow. XLSA is caused by mutations in the erythroid-specific gene coding 5-aminolevulinate synthase (ALAS2). Anemia in XLSA is extremely variable, characteristically microcytic and hypochromic with poikilocytosis, and the red blood cell distribution width is increased and prominent dimorphism of the red cell population. Anemia in XLSA patients responds variably to supplementation with pyridoxine. METHODS AND RESULTS We report four patients with XLSA and three mutations in ALAS2: c.611G>A (p.Arg204Gln), c.1218G>T (p.Leu406Phe) and c.1499A>G (p.Tyr500Cys). The in silico predictions of three ALAS2 mutations and the functional consequences of two ALAS2 mutations were assessed. We performed in silico analysis of these mutations using ten different softwares, and all of them predicted that the p.Tyr500Cys mutation was deleterious. The in vitro prokaryotic expression showed that the p.Leu406Phe and p.Tyr500Cys mutations reduced the ALAS2 specific activity (SA) to 14% and 7% of the control value, respectively. CONCLUSION In view of the results obtained in this study, a clear relationship between genotype and phenotype cannot be established; clinical variability or severity of anemia may be influenced by allelic variants in other genes or transcription factors and environmental conditions.
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Affiliation(s)
- Manuel Méndez
- Instituto de InvestigaciónHospital 12 de OctubreMadridSpain
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27
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Peoc'h K, Martin-Schmitt C, Talbi N, Deybach JC, Gouya L, Puy H. [Porphyrias and haem related disorders]. Rev Med Interne 2016; 37:173-85. [PMID: 26774916 DOI: 10.1016/j.revmed.2015.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 12/05/2015] [Indexed: 10/22/2022]
Abstract
The hereditary porphyrias comprise a group of eight metabolic disorders of the haem biosynthesis pathway characterised by acute neurovisceral symptoms, skin lesions or both. Each porphyria is caused by abnormal function of a separate enzymatic step resulting in a specific accumulation of haem precursors. Seven porphyrias are the consequence of a partial enzyme deficiency while a gain of function mechanism has been recently characterised in a novel porphyria. Acute porphyrias present with severe abdominal pain, nausea, constipation, confusion and seizure, which may be life threatening. Cutaneous porphyrias can be present with either acute painful photosensitivity or skin fragility and blisters. Rare recessive porphyrias usually manifest in early childhood with either severe chronic neurological symptoms or chronic haemolysis and severe cutaneous photosensitivity. Porphyrias are still underdiagnosed, but once they are suspected, and depending on the clinical presentation, a specific and simple front line test allows the diagnosis in all symptomatic patients. Diagnosis is essential to institute as soon as possible a specific treatment. Screening families to identify presymptomatic carriers is crucial to prevent chronic complications and overt disease by counselling on avoiding potential precipitants.
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Affiliation(s)
- K Peoc'h
- Centre français des porphyries, hôpital Louis-Mourier, Assistance publique-Hôpitaux de Paris (AP-HP), 92701 Colombes, France; U1149/ERL CNRS 8252, centre de recherche sur l'inflammation Paris, Montmartre, université Paris Diderot, site Bichat, Sorbonne Paris Cité, 75004 Paris, France
| | - C Martin-Schmitt
- Centre français des porphyries, hôpital Louis-Mourier, Assistance publique-Hôpitaux de Paris (AP-HP), 92701 Colombes, France; Laboratoire d'excellence, GR-Ex, 75015 Paris, France
| | - N Talbi
- Centre français des porphyries, hôpital Louis-Mourier, Assistance publique-Hôpitaux de Paris (AP-HP), 92701 Colombes, France
| | - J-C Deybach
- Centre français des porphyries, hôpital Louis-Mourier, Assistance publique-Hôpitaux de Paris (AP-HP), 92701 Colombes, France; Laboratoire d'excellence, GR-Ex, 75015 Paris, France
| | - L Gouya
- Centre français des porphyries, hôpital Louis-Mourier, Assistance publique-Hôpitaux de Paris (AP-HP), 92701 Colombes, France; Laboratoire d'excellence, GR-Ex, 75015 Paris, France
| | - H Puy
- Centre français des porphyries, hôpital Louis-Mourier, Assistance publique-Hôpitaux de Paris (AP-HP), 92701 Colombes, France; Laboratoire d'excellence, GR-Ex, 75015 Paris, France.
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28
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Iron metabolism and related genetic diseases: A cleared land, keeping mysteries. J Hepatol 2016; 64:505-515. [PMID: 26596411 DOI: 10.1016/j.jhep.2015.11.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 11/06/2015] [Accepted: 11/09/2015] [Indexed: 12/14/2022]
Abstract
Body iron has a very close relationship with the liver. Physiologically, the liver synthesizes transferrin, in charge of blood iron transport; ceruloplasmin, acting through its ferroxidase activity; and hepcidin, the master regulator of systemic iron. It also stores iron inside ferritin and serves as an iron reservoir, both protecting the cell from free iron toxicity and ensuring iron delivery to the body whenever needed. The liver is first in line for receiving iron from the gut and the spleen, and is, therefore, highly exposed to iron overload when plasma iron is in excess, especially through its high affinity for plasma non-transferrin bound iron. The liver is strongly involved when iron excess is related either to hepcidin deficiency, as in HFE, hemojuvelin, hepcidin, and transferrin receptor 2 related haemochromatosis, or to hepcidin resistance, as in type B ferroportin disease. It is less involved in the usual (type A) form of ferroportin disease which targets primarily the macrophagic system. Hereditary aceruloplasminemia raises important pathophysiological issues in light of its peculiar organ iron distribution.
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29
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Fratz EJ, Clayton J, Hunter GA, Ducamp S, Breydo L, Uversky VN, Deybach JC, Gouya L, Puy H, Ferreira GC. Human Erythroid 5-Aminolevulinate Synthase Mutations Associated with X-Linked Protoporphyria Disrupt the Conformational Equilibrium and Enhance Product Release. Biochemistry 2015; 54:5617-31. [PMID: 26300302 PMCID: PMC4573335 DOI: 10.1021/acs.biochem.5b00407] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Regulation of 5-aminolevulinate synthase (ALAS) is at the origin of balanced heme production in mammals. Mutations in the C-terminal region of human erythroid-specific ALAS (hALAS2) are associated with X-linked protoporphyria (XLPP), a disease characterized by extreme photosensitivity, with elevated blood concentrations of free protoporphyrin IX and zinc protoporphyrin. To investigate the molecular basis for this disease, recombinant hALAS2 and variants of the enzyme harboring the gain-of-function XLPP mutations were constructed, purified, and analyzed kinetically, spectroscopically, and thermodynamically. Enhanced activities of the XLPP variants resulted from increases in the rate at which the product 5-aminolevulinate (ALA) was released from the enzyme. Circular dichroism spectroscopy revealed that the XLPP mutations altered the microenvironment of the pyridoxal 5'-phosphate cofactor, which underwent further and specific alterations upon succinyl-CoA binding. Transient kinetic analyses of the variant-catalyzed reactions and protein fluorescence quenching upon binding of ALA to the XLPP variants demonstrated that the protein conformational transition step associated with product release was predominantly affected. Of relevance is the fact that XLPP could also be modeled in cell culture. We propose that (1) the XLPP mutations destabilize the succinyl-CoA-induced hALAS2 closed conformation and thus accelerate ALA release, (2) the extended C-terminus of wild-type mammalian ALAS2 provides a regulatory role that allows for allosteric modulation of activity, thereby controlling the rate of erythroid heme biosynthesis, and (3) this control is disrupted in XLPP, resulting in porphyrin accumulation.
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Affiliation(s)
- Erica J. Fratz
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
| | - Jerome Clayton
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
| | - Gregory A. Hunter
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
| | - Sarah Ducamp
- Assistance Publique-Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, 178 rue des Renouillers, 92701 Colombes CEDEX, France
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l’inflammation, 16 rue Henri Huchard, 75018, Université Paris Diderot, Site Bichat, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France
| | - Leonid Breydo
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
| | - Vladimir N. Uversky
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
| | - Jean-Charles Deybach
- Assistance Publique-Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, 178 rue des Renouillers, 92701 Colombes CEDEX, France
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l’inflammation, 16 rue Henri Huchard, 75018, Université Paris Diderot, Site Bichat, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France
| | - Laurent Gouya
- Assistance Publique-Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, 178 rue des Renouillers, 92701 Colombes CEDEX, France
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l’inflammation, 16 rue Henri Huchard, 75018, Université Paris Diderot, Site Bichat, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France
| | - Hervé Puy
- Assistance Publique-Hôpitaux de Paris, Centre Français des Porphyries, Hôpital Louis Mourier, 178 rue des Renouillers, 92701 Colombes CEDEX, France
- INSERM U1149, CNRS ERL 8252, Centre de Recherche sur l’inflammation, 16 rue Henri Huchard, 75018, Université Paris Diderot, Site Bichat, 75018 Paris, France; Laboratory of Excellence, GR-Ex, Paris, France
| | - Gloria C. Ferreira
- Department of Molecular Medicine, Morsani College of Medicine, University of South Florida, Tampa, Florida, 33612, USA
- Department of Chemistry, University of South Florida, Tampa, Florida, 33612, USA
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30
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Karim Z, Lyoumi S, Nicolas G, Deybach JC, Gouya L, Puy H. Porphyrias: A 2015 update. Clin Res Hepatol Gastroenterol 2015; 39:412-25. [PMID: 26142871 DOI: 10.1016/j.clinre.2015.05.009] [Citation(s) in RCA: 95] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 05/15/2015] [Accepted: 05/19/2015] [Indexed: 02/08/2023]
Abstract
The hereditary porphyrias comprise a group of eight metabolic disorders of the heme biosynthesis pathway. Each porphyria is caused by abnormal function at a separate enzymatic step resulting in a specific accumulation of heme precursors. Porphyrias are classified as hepatic or erythropoietic, based on the organ system in which heme precursors (δ-aminolevulinic acid [ALA], porphobilinogen and porphyrins) are overproduced. Clinically, porphyrias are characterized by acute neurovisceral symptoms, skin lesions or both. However, most if not all the porphyrias impair hepatic or gastrointestinal function. Acute hepatic porphyrias present with severe abdominal pain, nausea, constipation, confusion and seizure, which may be life threatening, and patients are at risk of hepatocellular carcinoma without cirrhosis. Porphyria Cutanea presents with skin fragility and blisters, and patients are at risk of hepatocellular carcinoma with liver iron overload. Erythropoietic protoporphyria and X-linked protoporphyria present with acute painful photosensitivity, and patients are at risk of acute liver failure. Altogether, porphyrias are still underdiagnosed, but once they are suspected, early diagnosis based on measurement of biochemical metabolites that accumulate in the blood, urine, or feces is essential so specific treatment can be started as soon as possible and long-term liver complications are prevented. Screening families to identify presymptomatic carriers is also crucial to prevent overt disease and chronic hepatic complications.
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Affiliation(s)
- Zoubida Karim
- INSERM U1149 CNRS ERL 8252, centre de recherche sur l'inflammation, 16, rue Henri-Huchard, 75018 Paris, France; Laboratory of excellence, GR-Ex, 24, Boulevard du Montparnasse, 75015 Paris, France
| | - Said Lyoumi
- INSERM U1149 CNRS ERL 8252, centre de recherche sur l'inflammation, 16, rue Henri-Huchard, 75018 Paris, France; Laboratory of excellence, GR-Ex, 24, Boulevard du Montparnasse, 75015 Paris, France; Université Versailles-Saint-Quentin, 55, Avenue de Paris, 78000 Versailles, France
| | - Gael Nicolas
- INSERM U1149 CNRS ERL 8252, centre de recherche sur l'inflammation, 16, rue Henri-Huchard, 75018 Paris, France; Laboratory of excellence, GR-Ex, 24, Boulevard du Montparnasse, 75015 Paris, France
| | - Jean-Charles Deybach
- INSERM U1149 CNRS ERL 8252, centre de recherche sur l'inflammation, 16, rue Henri-Huchard, 75018 Paris, France; Université Versailles-Saint-Quentin, 55, Avenue de Paris, 78000 Versailles, France; Université Paris Diderot, site Bichat, Sorbonne Paris Cité, 75018 Paris, France; Centre français des porphyries, hôpital Louis-Mourier, AP-HP, 92701 Colombes, France
| | - Laurent Gouya
- INSERM U1149 CNRS ERL 8252, centre de recherche sur l'inflammation, 16, rue Henri-Huchard, 75018 Paris, France; Université Versailles-Saint-Quentin, 55, Avenue de Paris, 78000 Versailles, France; Université Paris Diderot, site Bichat, Sorbonne Paris Cité, 75018 Paris, France; Centre français des porphyries, hôpital Louis-Mourier, AP-HP, 92701 Colombes, France
| | - Hervé Puy
- INSERM U1149 CNRS ERL 8252, centre de recherche sur l'inflammation, 16, rue Henri-Huchard, 75018 Paris, France; Université Versailles-Saint-Quentin, 55, Avenue de Paris, 78000 Versailles, France; Université Paris Diderot, site Bichat, Sorbonne Paris Cité, 75018 Paris, France; Centre français des porphyries, hôpital Louis-Mourier, AP-HP, 92701 Colombes, France.
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31
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Ramanujam VMS, Anderson KE. Porphyria Diagnostics-Part 1: A Brief Overview of the Porphyrias. CURRENT PROTOCOLS IN HUMAN GENETICS 2015; 86:17.20.1-17.20.26. [PMID: 26132003 PMCID: PMC4640448 DOI: 10.1002/0471142905.hg1720s86] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Porphyria diseases are a group of metabolic disorders caused by abnormal functioning of heme biosynthesis enzymes and characterized by excessive accumulation and excretion of porphyrins and their precursors. Precisely which of these chemicals builds up depends on the type of porphyria. Porphyria is not a single disease but a group of nine disorders: acute intermittent porphyria (AIP), hereditary coproporphyria (HCP), variegate porphyria (VP), δ-aminolevulinic acid dehydratase deficiency porphyria (ADP), porphyria cutanea tarda (PCT), hepatoerythropoietic porphyria (HEP), congenital erythropoietic porphyria (CEP), erythropoietic protoporphyria (EPP), and X-linked protoporphyria (XLP). Each porphyria results from overproduction of heme precursors secondary to partial deficiency or, in XLP, increased activity of one of the enzymes of heme biosynthesis. Taken together, all forms of porphyria afflict fewer than 200,000 people in the United States. Based on European studies, the most common porphyria, PCT, has a prevalence of 1 in 10,000, the most common acute porphyria, AlP, has a prevalence of ∼1 in 20,000, and the most common erythropoietic porphyria, EPP, is estimated at 1 in 50,000 to 75,000. CEP is extremely rare, with prevalence estimates of 1 in 1,000,000 or less. Only six cases of ADP are documented. The current porphyria literature is very exhaustive and a brief overview of porphyria diseases is essential in order for the reader to better appreciate the relevance of this area of research prior to undertaking biochemical diagnostics procedures. This unit summarizes the current knowledge on the classification, clinical features, etiology, pathogenesis, and genetics of porphyria diseases.
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Affiliation(s)
| | - Karl Elmo Anderson
- Department of Preventive Medicine and Community Health, The University of Texas Medical Branch, Galveston, Texas 77555-1109
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32
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Abstract
Microcytic anemia is the most common form of anemia, characterized by reduced hemoglobin (Hb) synthesis associated with decreased red blood cell volume (MCV). It is a very heterogeneous group of diseases that may be either acquired or inherited. Microcytic hypochromic anemia can result from defects in globin (hemoglobinopathies or thalassemias) or heme synthesis or in iron availability, or acquisition by the erythroid precursors. Diagnosis of microcytic anaemia appears to be important in children/adolescents, especially to set, where possible, a treatment plan on the basis of the etiology and pathogenesis. After excluding the acquired causes of microcytic anemia that represent the most frequent etiology, according to the differential diagnosis, the analysis of genetic causes, mostly hereditary, must be considered. This review will consider acquired and hereditary microcytic anemias due to heme synthesis or to iron metabolism defects and their diagnosis.
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Affiliation(s)
- Mariasole Bruno
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy; CEINGE, Advanced Biotechnologies, Naples, Italy; Department of Medicine, Section of Internal Medicine, University of Verona, AOUI-Policlinico GB Rossi, 37134 Verona, Italy
| | - Luigia De Falco
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy; CEINGE, Advanced Biotechnologies, Naples, Italy
| | - Achille Iolascon
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy; CEINGE, Advanced Biotechnologies, Naples, Italy.
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Chiabrando D, Mercurio S, Tolosano E. Heme and erythropoieis: more than a structural role. Haematologica 2015; 99:973-83. [PMID: 24881043 DOI: 10.3324/haematol.2013.091991] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Erythropoiesis is the biological process that consumes the highest amount of body iron for heme synthesis. Heme synthesis in erythroid cells is finely coordinated with that of alpha (α) and beta (β)-globin, resulting in the production of hemoglobin, a tetramer of 2α- and 2β-globin chains, and heme as the prosthetic group. Heme is not only the structural component of hemoglobin, but it plays multiple regulatory roles during the differentiation of erythroid precursors since it controls its own synthesis and regulates the expression of several erythroid-specific genes. Heme is synthesized in developing erythroid progenitors by the stage of proerythroblast, through a series of eight enzymatic reactions divided between mitochondria and cytosol. Defects of heme synthesis in the erythroid lineage result in sideroblastic anemias, characterized by microcytic anemia associated to mitochondrial iron overload, or in erythropoietic porphyrias, characterized by porphyrin deposition in erythroid cells. Here, we focus on the heme biosynthetic pathway and on human erythroid disorders due to defective heme synthesis. The regulatory role of heme during erythroid differentiation is discussed as well as the heme-mediated regulatory mechanisms that allow the orchestration of the adaptive cell response to heme deficiency.
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Affiliation(s)
- Deborah Chiabrando
- Department of Molecular Biotechnology and Health Sciences and Molecular Biotechnology Center, University of Torino, Italy
| | - Sonia Mercurio
- Department of Molecular Biotechnology and Health Sciences and Molecular Biotechnology Center, University of Torino, Italy
| | - Emanuela Tolosano
- Department of Molecular Biotechnology and Health Sciences and Molecular Biotechnology Center, University of Torino, Italy
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34
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Sankaran VG, Ulirsch JC, Tchaikovskii V, Ludwig LS, Wakabayashi A, Kadirvel S, Lindsley RC, Bejar R, Shi J, Lovitch SB, Bishop DF, Steensma DP. X-linked macrocytic dyserythropoietic anemia in females with an ALAS2 mutation. J Clin Invest 2015; 125:1665-9. [PMID: 25705881 DOI: 10.1172/jci78619] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 01/08/2015] [Indexed: 01/19/2023] Open
Abstract
Macrocytic anemia with abnormal erythropoiesis is a common feature of megaloblastic anemias, congenital dyserythropoietic anemias, and myelodysplastic syndromes. Here, we characterized a family with multiple female individuals who have macrocytic anemia. The proband was noted to have dyserythropoiesis and iron overload. After an extensive diagnostic evaluation that did not provide insight into the cause of the disease, whole-exome sequencing of multiple family members revealed the presence of a mutation in the X chromosomal gene ALAS2, which encodes 5'-aminolevulinate synthase 2, in the affected females. We determined that this mutation (Y365C) impairs binding of the essential cofactor pyridoxal 5'-phosphate to ALAS2, resulting in destabilization of the enzyme and consequent loss of function. X inactivation was not highly skewed in wbc from the affected individuals. In contrast, and consistent with the severity of the ALAS2 mutation, there was a complete skewing toward expression of the WT allele in mRNA from reticulocytes that could be recapitulated in primary erythroid cultures. Together, the results of the X inactivation and mRNA studies illustrate how this X-linked dominant mutation in ALAS2 can perturb normal erythropoiesis through cell-nonautonomous effects. Moreover, our findings highlight the value of whole-exome sequencing in diagnostically challenging cases for the identification of disease etiology and extension of the known phenotypic spectrum of disease.
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MESH Headings
- 5-Aminolevulinate Synthetase/genetics
- 5-Aminolevulinate Synthetase/metabolism
- Adult
- Anemia, Dyserythropoietic, Congenital/genetics
- Anemia, Macrocytic/genetics
- Cells, Cultured
- Erythropoiesis/genetics
- Exome/genetics
- Female
- Genes, Dominant
- Genes, X-Linked
- Genetic Diseases, X-Linked/blood
- Genetic Diseases, X-Linked/genetics
- Hemorrhage/etiology
- Humans
- Iron Overload/etiology
- Male
- Models, Molecular
- Molecular Sequence Data
- Mutation, Missense
- Point Mutation
- Pregnancy
- Pregnancy Complications, Hematologic/genetics
- Protein Binding
- Protein Conformation
- Puerperal Disorders/etiology
- Pyridoxal Phosphate/metabolism
- RNA, Messenger/genetics
- Reticulocytes/metabolism
- X Chromosome Inactivation
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35
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Liu G, Guo S, Kang H, Zhang F, Hu Y, Wang L, Li M, Ru Y, Camaschella C, Han B, Nie G. Mutation spectrum in Chinese patients affected by congenital sideroblastic anemia and a search for a genotype-phenotype relationship. Haematologica 2014; 98:e158-60. [PMID: 24323989 DOI: 10.3324/haematol.2013.095513] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
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Abstract
Sideroblastic anemias (SAs) may be acquired or congenital and share the features of disrupted utilization of iron in the erythroblast, ineffective erythropoiesis, and variable systemic iron overload. Congenital forms can have associated syndromic features or be nonsyndromic, and many of them have mutations in genes encoding proteins involved in heme biosynthesis, iron-sulfur cluster biogenesis, or mitochondrial protein synthesis. The mechanism(s) for the acquired clonal SA is undefined and is under intense study. Precise diagnosis of these disorders rests on careful clinical and laboratory evaluation, including molecular analysis. Supportive treatments usually provide for a favorable prognosis and often for normal survival.
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Affiliation(s)
- Sylvia S Bottomley
- Department of Medicine, University of Oklahoma College of Medicine, 755 Research Park, Suite 427, Oklahoma City, OK 73104, USA.
| | - Mark D Fleming
- Department of Pathology, Boston Children's Hospital, Harvard Medical School, 300 Longwood Avenue, Bader 124.1, Boston, MA 02115, USA
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37
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Chiabrando D, Vinchi F, Fiorito V, Mercurio S, Tolosano E. Heme in pathophysiology: a matter of scavenging, metabolism and trafficking across cell membranes. Front Pharmacol 2014; 5:61. [PMID: 24782769 PMCID: PMC3986552 DOI: 10.3389/fphar.2014.00061] [Citation(s) in RCA: 268] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 03/18/2014] [Indexed: 01/19/2023] Open
Abstract
Heme (iron-protoporphyrin IX) is an essential co-factor involved in multiple biological processes: oxygen transport and storage, electron transfer, drug and steroid metabolism, signal transduction, and micro RNA processing. However, excess free-heme is highly toxic due to its ability to promote oxidative stress and lipid peroxidation, thus leading to membrane injury and, ultimately, apoptosis. Thus, heme metabolism needs to be finely regulated. Intracellular heme amount is controlled at multiple levels: synthesis, utilization by hemoproteins, degradation and both intracellular and intercellular trafficking. This review focuses on recent findings highlighting the importance of controlling intracellular heme levels to counteract heme-induced oxidative stress. The contributions of heme scavenging from the extracellular environment, heme synthesis and incorporation into hemoproteins, heme catabolism and heme transport in maintaining adequate intracellular heme content are discussed. Particular attention is put on the recently described mechanisms of heme trafficking through the plasma membrane mediated by specific heme importers and exporters. Finally, the involvement of genes orchestrating heme metabolism in several pathological conditions is illustrated and new therapeutic approaches aimed at controlling heme metabolism are discussed.
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Affiliation(s)
- Deborah Chiabrando
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Francesca Vinchi
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Veronica Fiorito
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Sonia Mercurio
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
| | - Emanuela Tolosano
- Department of Molecular Biotechnology and Health Sciences, Molecular Biotechnology Center, University of Turin Turin, Italy
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Practice guidelines for the diagnosis and management of microcytic anemias due to genetic disorders of iron metabolism or heme synthesis. Blood 2014; 123:3873-86; quiz 4005. [PMID: 24665134 DOI: 10.1182/blood-2014-01-548776] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
During recent years, our understanding of the pathogenesis of inherited microcytic anemias has gained from the identification of several genes and proteins involved in systemic and cellular iron metabolism and heme syntheses. Numerous case reports illustrate that the implementation of these novel molecular discoveries in clinical practice has increased our understanding of the presentation, diagnosis, and management of these diseases. Integration of these insights into daily clinical practice will reduce delays in establishing a proper diagnosis, invasive and/or costly diagnostic tests, and unnecessary or even detrimental treatments. To assist the clinician, we developed evidence-based multidisciplinary guidelines on the management of rare microcytic anemias due to genetic disorders of iron metabolism and heme synthesis. These genetic disorders may present at all ages, and therefore these guidelines are relevant for pediatricians as well as clinicians who treat adults. This article summarizes these clinical practice guidelines and includes background on pathogenesis, conclusions, and recommendations and a diagnostic flowchart to facilitate using these guidelines in the clinical setting.
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Moon SY, Jun IJ, Kim JE, Lee SJ, Kim HK, Yoon SS. A novel hemizygous I418S mutation in the ALAS2 gene in a young Korean man with X-linked sideroblastic anemia. Ann Lab Med 2014; 34:159-62. [PMID: 24624355 PMCID: PMC3948832 DOI: 10.3343/alm.2014.34.2.159] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2013] [Revised: 09/09/2013] [Accepted: 10/22/2013] [Indexed: 11/19/2022] Open
Affiliation(s)
- Soo Young Moon
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - In-Jae Jun
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Ji-Eun Kim
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Seung Jun Lee
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Hyun Kyung Kim
- Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
| | - Sung-Soo Yoon
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
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40
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The chaperone role of the pyridoxal 5′-phosphate and its implications for rare diseases involving B6-dependent enzymes. Clin Biochem 2014; 47:158-65. [DOI: 10.1016/j.clinbiochem.2013.11.021] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 11/28/2013] [Accepted: 11/30/2013] [Indexed: 02/06/2023]
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Fujiwara T, Harigae H. Pathophysiology and genetic mutations in congenital sideroblastic anemia. Pediatr Int 2013; 55:675-9. [PMID: 24003969 DOI: 10.1111/ped.12217] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Accepted: 08/28/2013] [Indexed: 01/23/2023]
Abstract
Sideroblastic anemias are heterogeneous congenital and acquired disorders characterized by anemia and the presence of ringed sideroblasts in the bone marrow. Congenital sideroblastic anemia (CSA) is a rare disease caused by mutations of genes involved in heme biosynthesis, iron-sulfur [Fe-S] cluster biosynthesis, and mitochondrial protein synthesis. The most common form is X-linked sideroblastic anemia, due to mutations in the erythroid-specific δ-aminolevulinate synthase (ALAS2), which is the first enzyme of the heme biosynthesis pathway in erythroid cells. Other known etiologies include mutations in the erythroid specific mitochondrial transporter (SLC25A38), adenosine triphosphate (ATP) binding cassette B7 (ABCB7), glutaredoxin 5 (GLRX5), thiamine transporter SLC19A2, the RNA-modifying enzyme pseudouridine synthase (PUS1), and mitochondrial tyrosyl-tRNA synthase (YARS2), as well as mitochondrial DNA deletions. Due to its rarity, however, there have been few systematic pathophysiological and genetic investigations focusing on sideroblastic anemia. Therefore, a nationwide survey of sideroblastic anemia was conducted in Japan to investigate the epidemiology and pathogenesis of this disease. This review will cover the findings of this recent survey and summarize the current understanding of the pathophysiology and genetic mutations involved in CSA.
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Affiliation(s)
- Tohru Fujiwara
- Department of Hematology and Rheumatology, Tohoku University Graduate School of Medicine, Sendai, Japan; Molecular Hematology/Oncology, Tohoku University Graduate School of Medicine, Sendai, Japan
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Whatley SD, Badminton MN. Role of genetic testing in the management of patients with inherited porphyria and their families. Ann Clin Biochem 2013; 50:204-16. [PMID: 23605133 DOI: 10.1177/0004563212473278] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The porphyrias are a group of mainly inherited metabolic conditions that result from partial deficiency of individual enzymes in the haem biosynthesis pathway. Clinical presentation is either with acute neurovisceral attacks, skin photosensitivity or both, and is due to overproduction of pathway intermediates. The primary diagnosis in the proband is based on biochemical testing of appropriate samples, preferably during or soon after onset of symptoms. The role of genetic testing in the autosomal dominant acute porphyrias (acute intermittent porphyria, hereditary coproporphyria and variegate porphyria) is to identify presymptomatic carriers of the family specific pathogenic mutation so that they can be counselled on how to minimize their risk of suffering an acute attack. At present the additional genetic factors that influence penetrance are not known, and all patients are treated as equally at risk. Genetic testing in the erythropoietic porphyrias (erythropoietic protoporphyria, congenital erythropoietic porphyria and X-linked dominant protoporphyria) is focused on predictive and preconceptual counselling, prenatal testing and genotype-phenotype correlation. Recent advances in analytical technology have resulted in increased sensitivity of mutation detection with success rates of greater than 90% for most of the genes. The ethical and consent issues are discussed. Current research into genetic factors that affect penetrance is likely to lead to a more refined approach to counselling for presymptomatic gene carriers.
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Affiliation(s)
- S D Whatley
- Department of Medical Biochemistry and Immunology, University Hospital of Wales and Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.
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Kaneko K, Furuyama K, Fujiwara T, Kobayashi R, Ishida H, Harigae H, Shibahara S. Identification of a novel erythroid-specific enhancer for the ALAS2 gene and its loss-of-function mutation which is associated with congenital sideroblastic anemia. Haematologica 2013; 99:252-61. [PMID: 23935018 DOI: 10.3324/haematol.2013.085449] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Erythroid-specific 5-aminolevulinate synthase (ALAS2) is the rate-limiting enzyme for heme biosynthesis in erythroid cells, and a missense mutation of the ALAS2 gene is associated with congenital sideroblastic anemia. However, the gene responsible for this form of anemia remains unclear in about 40% of patients. Here, we identify a novel erythroid-specific enhancer of 130 base pairs in the first intron of the ALAS2 gene. The newly identified enhancer contains a cis-acting element that is bound by the erythroid-specific transcription factor GATA1, as confirmed by chromatin immunoprecipitation analysis in vivo and by electrophoretic mobility shift assay in vitro. A promoter activity assay in K562 human erythroleukemia cells revealed that the presence of this 130-base pair region increased the promoter activity of the ALAS2 gene by 10-15-fold. Importantly, two mutations, each of which disrupts the GATA-binding site in the enhancer, were identified in unrelated male patients with congenital sideroblastic anemia, and the lower expression level of ALAS2 mRNA in bone marrow erythroblasts was confirmed in one of these patients. Moreover, GATA1 failed to bind to each mutant sequence at the GATA-binding site, and each mutation abolished the enhancer function on ALAS2 promoter activity in K562 cells. Thus, a mutation at the GATA-binding site in this enhancer may cause congenital sideroblastic anemia. These results suggest that the newly identified intronic enhancer is essential for the expression of the ALAS2 gene in erythroid cells. We propose that the 130-base pair enhancer region located in the first intron of the ALAS2 gene should be examined in patients with congenital sideroblastic anemia in whom the gene responsible is unknown.
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Abstract
Heme, which is composed of iron and the small organic molecule protoporphyrin, is an essential component of hemoglobin as well as a variety of physiologically important hemoproteins. During erythropoiesis, heme synthesis is induced before, and is essential for, globin synthesis. Although all cells possess the ability to synthesize heme, there are distinct differences between regulation of the pathway in developing erythroid cells and all other types of cells. Disorders that compromise the ability of the developing red cell to synthesize heme can have profound medical implications. The biosynthetic pathway for heme and key regulatory features are reviewed herein, along with specific human genetic disorders that arise from defective heme synthesis such as X-linked sideroblastic anemia and erythropoietic protoporphyria.
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Affiliation(s)
- Harry A Dailey
- Department of Microbiology, Department of Biochemistry and Molecular Biology, Biomedical and Health Sciences Institute, University of Georgia, Athens, GA 30602, USA.
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46
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Ducamp S, Schneider-Yin X, de Rooij F, Clayton J, Fratz EJ, Rudd A, Ostapowicz G, Varigos G, Lefebvre T, Deybach JC, Gouya L, Wilson P, Ferreira GC, Minder EI, Puy H. Molecular and functional analysis of the C-terminal region of human erythroid-specific 5-aminolevulinic synthase associated with X-linked dominant protoporphyria (XLDPP). Hum Mol Genet 2012; 22:1280-8. [PMID: 23263862 DOI: 10.1093/hmg/dds531] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Frameshift mutations in the last coding exon of the 5-aminolevulinate synthase (ALAS) 2 gene were described to activate the enzyme causing increased levels of zinc- and metal-free protoporphyrin in patients with X-linked dominant protoporphyria (XLDPP). Only two such so-called gain-of-function mutations have been reported since the description of XLDPP in 2008. In this study of four newly identified XLDPP families, we identified two novel ALAS2 gene mutations, a nonsense p.Q548X and a frameshift c.1651-1677del26bp, along with a known mutation (delAGTG) found in two unrelated families. Of relevance, a de novo somatic and germinal mosaicism was present in a delAGTG family. Such a phenomenon may explain the high proportion of this mutation in XLDPP worldwide. Enhancements of over 3- and 14-fold in the catalytic rate and specificity constant of purified recombinant XLDPP variants in relation to those of wild-type ALAS2 confirmed the gain of function ascribed to these enzymes. The fact that both p.Q548X and c.1651-1677del26bp are located in close proximity and upstream from the two previously described mutations led us to propose the presence of a large gain-of-function domain within the C-terminus of ALAS2. To test this hypothesis, we generated four additional nonsense mutants (p.A539X, p.G544X, p.G576X and p.V583X) surrounding the human XLDPP mutations and defined an ALAS2 gain-of-function domain with a minimal size of 33 amino acids. The identification of this gain-of-function domain provides important information on the enzymatic activity of ALAS2, which was proposed to be constitutively inhibited, either directly or indirectly, through its own C-terminus.
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Affiliation(s)
- Sarah Ducamp
- AP-HP, Centre Franc¸ais des Porphyries, Hoˆ pital Louis Mourier, 178 rue des Renouillers, 92701 Colombes Cedex,France
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Visconte V, Makishima H, Maciejewski JP, Tiu RV. Emerging roles of the spliceosomal machinery in myelodysplastic syndromes and other hematological disorders. Leukemia 2012; 26:2447-54. [PMID: 22678168 DOI: 10.1038/leu.2012.130] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
Abstract
In humans, the majority of all protein-coding transcripts contain introns that are removed by mRNA splicing carried out by spliceosomes. Mutations in the spliceosome machinery have recently been identified using whole-exome/genome technologies in myelodysplastic syndromes (MDS) and in other hematological disorders. Alterations in splicing factor 3 subunit b1 (SF3b1) were the first spliceosomal mutations described, immediately followed by identification of other splicing factor mutations, including U2 small nuclear RNA auxillary factor 1 (U2AF1) and serine arginine-rich splicing factor 2 (SRSF2). SF3b1/U2AF1/SRSF2 mutations occur at varying frequencies in different disease subtypes, each contributing to differences in survival outcomes. However, the exact functional consequences of these spliceosomal mutations in the pathogenesis of MDS and other hematological malignancies remain largely unknown and subject to intense investigation. For SF3b1, a gain of function mutation may offer the promise of new targeted therapies for diseases that carry this molecular abnormality that can potentially lead to cure. This review aims to provide a comprehensive overview of the emerging role of the spliceosome machinery in the biology of MDS/hematological disorders with an emphasis on the functional consequences of mutations, their clinical significance, and perspectives on how they may influence our understanding and management of diseases affected by these mutations.
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Affiliation(s)
- V Visconte
- Department of Translational Hematology and Oncology Research, Taussig Cancer Institute, Cleveland Clinic, Cleveland, OH, USA
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48
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Kadirvel S, Furuyama K, Harigae H, Kaneko K, Tamai Y, Ishida Y, Shibahara S. The carboxyl-terminal region of erythroid-specific 5-aminolevulinate synthase acts as an intrinsic modifier for its catalytic activity and protein stability. Exp Hematol 2012; 40:477-86.e1. [PMID: 22269113 DOI: 10.1016/j.exphem.2012.01.013] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2010] [Revised: 01/10/2012] [Accepted: 01/18/2012] [Indexed: 01/19/2023]
Abstract
Erythroid-specific 5-aminolevulinate synthase (ALAS2) is essential for hemoglobin production, and a loss-of-function mutation of ALAS2 gene causes X-linked sideroblastic anemia. Human ALAS2 protein consists of 587 amino acids and its carboxyl(C)-terminal region of 33 amino acids is conserved in higher eukaryotes, but is not present in prokaryotic ALAS. We explored the role of this C-terminal region in the pathogenesis of X-linked sideroblastic anemia. In vitro enzymatic activity was measured using bacterially expressed recombinant proteins. In vivo catalytic activity was evaluated by comparing the accumulation of porphyrins in eukaryotic cells stably expressing each mutant ALAS2 tagged with FLAG, and the half-life of each FLAG-tagged ALAS2 protein was determined by Western blot analysis. Two novel mutations (Val562Ala and Met567Ile) were identified in patients with X-linked sideroblastic anemia. Val562Ala showed the higher catalytic activity in vitro, but a shorter half-life in vivo compared to those of wild-type ALAS2 (WT). In contrast, the in vitro activity of Met567Ile mutant was about 25% of WT, while its half-life was longer than that of WT. However, in vivo catalytic activity of each mutant was lower than that of WT. In addition, the deletion of 33 amino acids at C-terminal end resulted in higher catalytic activity both in vitro and in vivo with the longer half-life compared to WT. In conclusion, the C-terminal region of ALAS2 protein may function as an intrinsic modifier that suppresses catalytic activity and increases the degradation of its protein, each function of which is enhanced by the Met567Ile mutation and the Val562Ala mutation, respectively.
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Affiliation(s)
- Senkottuvelan Kadirvel
- Department of Molecular Biology and Applied Physiology, Tohoku University School of Medicine, Sendai, Japan
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49
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Blanchard A, Ea V, Roubertie A, Martin M, Coquart C, Claustres M, Béroud C, Collod-Béroud G. DYT6 dystonia: Review of the literature and creation of the UMD locus-specific database (LSDB) for mutations in the THAP1 gene. Hum Mutat 2011; 32:1213-24. [DOI: 10.1002/humu.21564] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2011] [Accepted: 06/20/2011] [Indexed: 11/12/2022]
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Abstract
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.
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