RESUMEN
The conserved enzyme aminolevulinic acid synthase (ALAS) initiates heme biosynthesis in certain bacteria and eukaryotes by catalyzing the condensation of glycine and succinyl-CoA to yield aminolevulinic acid. In humans, the ALAS isoform responsible for heme production during red blood cell development is the erythroid-specific ALAS2 isoform. Owing to its essential role in erythropoiesis, changes in human ALAS2 (hALAS2) function can lead to two different blood disorders. X-linked sideroblastic anemia results from loss of ALAS2 function, while X-linked protoporphyria results from gain of ALAS2 function. Interestingly, mutations in the ALAS2 C-terminal extension can be implicated in both diseases. Here, we investigate the molecular basis for enzyme dysfunction mediated by two previously reported C-terminal loss-of-function variants, hALAS2 V562A and M567I. We show that the mutations do not result in gross structural perturbations, but the enzyme stability for V562A is decreased. Additionally, we show that enzyme stability moderately increases with the addition of the pyridoxal 5'-phosphate (PLP) cofactor for both variants. The variants display differential binding to PLP and the individual substrates compared to wild-type hALAS2. Although hALAS2 V562A is a more active enzyme in vitro, it is less efficient concerning succinyl-CoA binding. In contrast, the M567I mutation significantly alters the cooperativity of substrate binding. In combination with previously reported cell-based studies, our work reveals the molecular basis by which hALAS2 C-terminal mutations negatively affect ALA production necessary for proper heme biosynthesis.
Asunto(s)
5-Aminolevulinato Sintetasa , Anemia Sideroblástica , Humanos , 5-Aminolevulinato Sintetasa/genética , 5-Aminolevulinato Sintetasa/metabolismo , 5-Aminolevulinato Sintetasa/química , 5-Aminolevulinato Sintetasa/deficiencia , Anemia Sideroblástica/genética , Anemia Sideroblástica/metabolismo , Enfermedades Genéticas Ligadas al Cromosoma X/genética , Enfermedades Genéticas Ligadas al Cromosoma X/metabolismo , Mutación con Pérdida de Función , Estabilidad de Enzimas , Hemo/metabolismo , Hemo/química , Porfirias/genética , Porfirias/metabolismo , Modelos Moleculares , Mutación , Protoporfiria EritropoyéticaRESUMEN
ABSTRACT: Among the most common genetic alterations in myelodysplastic syndromes (MDS) are mutations in the spliceosome gene SF3B1. Such mutations induce specific RNA missplicing events, directly promote ring sideroblast (RS) formation, and generally associate with a more favorable prognosis. However, not all SF3B1 mutations are the same, and little is known about how distinct hotspots influence disease. Here, we report that the E592K variant of SF3B1 associates with high-risk disease features in MDS, including a lack of RS, increased myeloblasts, a distinct comutation pattern, and a lack of favorable survival seen with other SF3B1 mutations. Moreover, compared with other hot spot SF3B1 mutations, E592K induces a unique RNA missplicing pattern, retains an interaction with the splicing factor SUGP1, and preserves normal RNA splicing of the sideroblastic anemia genes TMEM14C and ABCB7. These data have implications for our understanding of the functional diversity of spliceosome mutations, as well as the pathobiology, classification, prognosis, and management of SF3B1-mutant MDS.
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Síndromes Mielodisplásicos , Fosfoproteínas , Factores de Empalme de ARN , Empalme del ARN , Factores de Empalme de ARN/genética , Factores de Empalme de ARN/metabolismo , Humanos , Síndromes Mielodisplásicos/genética , Fosfoproteínas/genética , Mutación , Anemia Sideroblástica/genética , Femenino , Pronóstico , Anciano , MasculinoRESUMEN
Myelodysplastic neoplasms (MDS) with ring sideroblasts (RS) are diagnosed via bone marrow aspiration in the presence of either (i) ≥15% RS or (ii) 5-14% RS and an SF3B1 mutation. In the MEDALIST trial and in an interim analysis of the COMMANDS trial, lower-risk MDS-RS patients had decreased transfusion dependency with luspatercept treatment. A total of 6817 patients with suspected hematologic malignancies underwent molecular testing using a next-generation-sequencing-based genetic assay and 395 MDS patients, seen at our centre from 1 January 2018 to 31 May 2023, were reviewed. Of these, we identified 39 evaluable patients as having lower-risk MDS with SF3B1 mutations: there were 20 (51.3%) males and 19 (48.7%) females, with a median age of 77 years (range of 57 to 92). Nineteen (48.7%) patients had an isolated SF3B1 mutation with a mean variant allele frequency of 35.2% +/- 8.1%, ranging from 7.4% to 46.0%. There were 29 (74.4%) patients with ≥15% RS, 6 (15.4%) with 5 to 14% RS, one (2.6%) with 1% RS, and 3 (7.7%) with no RS. Our study suggests that a quarter of patients would be missed based on the morphologic criterion of only using RS greater than 15% and supports the revised 2022 definitions of the World Health Organization (WHO) and International Consensus Classification (ICC), which shift toward molecularly defined subtypes of MDS and appropriate testing.
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Mutación , Síndromes Mielodisplásicos , Fosfoproteínas , Factores de Empalme de ARN , Organización Mundial de la Salud , Humanos , Factores de Empalme de ARN/genética , Masculino , Femenino , Anciano , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/clasificación , Persona de Mediana Edad , Estudios Retrospectivos , Anciano de 80 o más Años , Fosfoproteínas/genética , Anemia Sideroblástica/genéticaRESUMEN
ABSTRACT: Pseudouridine is the most prevalent RNA modification, and its aberrant function is implicated in various human diseases. However, the specific impact of pseudouridylation on hematopoiesis remains poorly understood. Here, we investigated the role of transfer RNA (tRNA) pseudouridylation in erythropoiesis and its association with mitochondrial myopathy, lactic acidosis, and sideroblastic anemia syndrome (MLASA) pathogenesis. By using patient-specific induced pluripotent stem cells (iPSCs) carrying a genetic pseudouridine synthase 1 (PUS1) mutation and a corresponding mutant mouse model, we demonstrated impaired erythropoiesis in MLASA-iPSCs and anemia in the MLASA mouse model. Both MLASA-iPSCs and mouse erythroblasts exhibited compromised mitochondrial function and impaired protein synthesis. Mechanistically, we revealed that PUS1 deficiency resulted in reduced mitochondrial tRNA levels because of pseudouridylation loss, leading to aberrant mitochondrial translation. Screening of mitochondrial supplements aimed at enhancing respiration or heme synthesis showed limited effect in promoting erythroid differentiation. Interestingly, the mammalian target of rapamycin (mTOR) inhibitor rapamycin facilitated erythroid differentiation in MLASA-iPSCs by suppressing mTOR signaling and protein synthesis, and consistent results were observed in the MLASA mouse model. Importantly, rapamycin treatment partially ameliorated anemia phenotypes in a patient with MLASA. Our findings provide novel insights into the crucial role of mitochondrial tRNA pseudouridylation in governing erythropoiesis and present potential therapeutic strategies for patients with anemia facing challenges related to protein translation.
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Eritropoyesis , Células Madre Pluripotentes Inducidas , Mitocondrias , ARN de Transferencia , Animales , Ratones , Humanos , ARN de Transferencia/genética , ARN de Transferencia/metabolismo , Mitocondrias/metabolismo , Mitocondrias/patología , Células Madre Pluripotentes Inducidas/metabolismo , Seudouridina/metabolismo , Anemia Sideroblástica/genética , Anemia Sideroblástica/metabolismo , Anemia Sideroblástica/patología , ARN Mitocondrial/genética , ARN Mitocondrial/metabolismo , Hidroliasas/metabolismo , Hidroliasas/genética , Síndrome MELAS/genética , Síndrome MELAS/patología , Síndrome MELAS/metabolismo , Modelos Animales de EnfermedadAsunto(s)
Deleción Cromosómica , Cromosomas Humanos Par 5 , Mutación , Fosfoproteínas , Factores de Empalme de ARN , Trombocitosis , Humanos , Factores de Empalme de ARN/genética , Trombocitosis/genética , Trombocitosis/diagnóstico , Fosfoproteínas/genética , Cromosomas Humanos Par 5/genética , Anemia Sideroblástica/genética , Anemia Sideroblástica/diagnóstico , Masculino , Femenino , Persona de Mediana Edad , AncianoRESUMEN
The revised 4th edition of the World Health Organization (WHO4R) classification lists myelodysplastic syndromes with ring sideroblasts (MDS-RS) as a separate entity with single lineage (MDS-RS-SLD) or multilineage (MDS-RS-MLD) dysplasia. The more recent International Consensus Classification (ICC) distinguishes between MDS with SF3B1 mutation (MDS-SF3B1) and MDS-RS without SF3B1 mutation; the latter is instead included under the category of MDS not otherwise specified. The current study includes 170 Mayo Clinic patients with WHO4R-defined MDS-RS, including MDS-RS-SLD (N=83) and MDS-RSMLD (N=87); a subset of 145 patients were also evaluable for the presence of SF3B1 and other mutations, including 126 with (87%) and 19 (13%) without SF3B1 mutation. Median overall survival for all 170 patients was 6.6 years with 5- and 10-year survival rates of 59% and 25%, respectively. A significant difference in overall survival was apparent between MDS-RS-MLD and MDS-RS-SLD (P<0.01) but not between MDS-RS with and without SF3B1 mutation (P=0.36). Multivariable analysis confirmed the independent prognostic contribution of MLD (hazard ratio=1.8, 95% confidence interval: 1.1-2.8; P=0.01) and also identified age (P<0.01), transfusion need at diagnosis (P<0.01), and abnormal karyotype (P<0.01), as additional risk factors; the impact from SF3B1 or other mutations was not significant. Leukemia-free survival was independently affected by abnormal karyotype (P<0.01), RUNX1 (P=0.02) and IDH1 (P=0.01) mutations, but not by MLD or SF3B1 mutation. Exclusion of patients not meeting ICC-criteria for MDS-SF3B1 did not change the observations on overall survival. MLD-based, as opposed to SF3B1 mutation-based, disease classification for MDS-RS might be prognostically more relevant.
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Anemia Sideroblástica , Mutación , Síndromes Mielodisplásicos , Fosfoproteínas , Factores de Empalme de ARN , Humanos , Factores de Empalme de ARN/genética , Masculino , Femenino , Anciano , Persona de Mediana Edad , Pronóstico , Anciano de 80 o más Años , Adulto , Fosfoproteínas/genética , Anemia Sideroblástica/genética , Anemia Sideroblástica/diagnóstico , Anemia Sideroblástica/mortalidad , Anemia Sideroblástica/patología , Síndromes Mielodisplásicos/genética , Síndromes Mielodisplásicos/mortalidad , Síndromes Mielodisplásicos/diagnóstico , Síndromes Mielodisplásicos/patología , Ribonucleoproteína Nuclear Pequeña U2/genética , Linaje de la Célula , Adulto JovenRESUMEN
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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Anemia Sideroblástica , Hierro , Humanos , Lactante , Hierro/metabolismo , Mutación , Anemia Sideroblástica/epidemiología , Anemia Sideroblástica/genética , Anemia Sideroblástica/diagnóstico , Genómica , ADN Mitocondrial , Proteínas de Transporte de Membrana/genética , 5-Aminolevulinato Sintetasa/genética , 5-Aminolevulinato Sintetasa/metabolismoRESUMEN
Congenital sideroblastic anemia (CSA) is a group of disorders caused by different genetic mutations that result in low iron utilization and ineffective erythropoiesis. Current treatments are limited, and some patients do not respond to vitamin B6 therapy. Luspatercept is a novel erythropoietic maturation agent approved for adult ß-thalassemia and Myelodysplastic syndromes with ring sideroblasts (MDS-RS) associated with ineffective erythropoiesis. Here we report 2 patients with CSA due to mutations in ALAS2 and SLC25A38 genes who became unresponsive after a period of treatment with vitamin B6 and iron chelators but achieved transfusion independence and a markedly reduced spleen after combination with luspatercept.
Asunto(s)
Receptores de Activinas Tipo II , Anemia Sideroblástica , Enfermedades Genéticas Ligadas al Cromosoma X , Proteínas Recombinantes de Fusión , Adulto , Humanos , 5-Aminolevulinato Sintetasa , Receptores de Activinas Tipo II/efectos adversos , Anemia Sideroblástica/tratamiento farmacológico , Anemia Sideroblástica/genética , Anemia Sideroblástica/congénito , Fragmentos Fc de Inmunoglobulinas/efectos adversos , Proteínas Recombinantes de Fusión/efectos adversos , Vitamina B 6RESUMEN
Sideroblastic anaemia with B-cell immunodeficiency, periodic fever and developmental delay is a recently described, rare syndrome characterised by numerous manifestations underpinned by mutations in transfer RNA nucleotidyltransferase. The pathogenesis arises from mitochondrial dysfunction, with impaired intracellular stress response, deficient metabolism and cellular and systemic inflammation. This yields multiorgan dysfunction and early death in many patients with survivors suffering significant disability and morbidity. New cases, often youths, are still being described, expanding the horizon of recognisable phenotypes. We present a mature patient with spontaneous bilateral hip osteonecrosis that likely arises from the impaired RNA quality control and inflammation caused by this syndrome.
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Amiloidosis , Anemia Sideroblástica , Síndromes de Inmunodeficiencia , Osteonecrosis , Humanos , Anemia Sideroblástica/complicaciones , Anemia Sideroblástica/diagnóstico , Anemia Sideroblástica/genética , Cabeza Femoral , Síndromes de Inmunodeficiencia/complicaciones , Fiebre , InflamaciónRESUMEN
Myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) is a rare disease, which presents with features of myelodysplastic syndromes with ring sideroblasts and essential thrombocythemia, as well as anemia and marked thrombocytosis. SF3B1 and JAK2 mutations are often found in patients, and are associated with their specific clinical features. This study was a retrospective analysis of 34 Japanese patients with MDS/MPN-RS-T. Median age at diagnosis was 77 (range, 51-88) years, and patients had anemia (median hemoglobin: 9.0 g/dL) and thrombocytosis (median platelet count: 642 × 109/L). Median overall survival was 70 (95% confidence interval: 68-not applicable) months during the median follow-up period of 26 (range: 0-91) months. A JAK2V617F mutation was detected in 46.2% (n = 12) of analyzed patients (n = 26), while an SF3B1 mutation was detected in 87.5% (n = 7) of analyzed patients (n = 8). Like those with myelodysplastic syndromes or myeloproliferative neoplasms, patients often received erythropoiesis-stimulating agents and aspirin to improve anemia and prevent thrombosis. This study, which was the largest to describe the real-world characteristics of Japanese patients with MDS/MPN-RS-T, showed that the patients had similar characteristics to those in western countries.
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Anemia Sideroblástica , Síndromes Mielodisplásicos , Enfermedades Mielodisplásicas-Mieloproliferativas , Neoplasias , Trombocitosis , Humanos , Anemia Sideroblástica/genética , Estudios Retrospectivos , Pueblos del Este de Asia , Síndromes Mielodisplásicos/genética , Enfermedades Mielodisplásicas-Mieloproliferativas/genética , Trombocitosis/genética , Neoplasias/complicaciones , Mutación , Factores de Empalme de ARN/genéticaRESUMEN
INTRODUCTION: Congenital sideroblastic anemias (CSAs) are a group of inherited bone-marrow disorders manifesting with erythroid hyperplasia and ineffective erythropoiesis. METHODS: We describe a detailed clinical and genetic characterization of three siblings with CSA. RESULTS: Two of them had limb-girdle myopathy and global developmental delay. The two elder siblings performed allogenic hematopoietic stem-cell transplantation 5 and 3 years prior with stabilization of the hematological features. Exome sequencing in the non-transplanted sibling revealed a novel homozygous nonsense variant in SLC25A38 gene NM_017875.2:c.559C > T; p.(Arg187*) causing autosomal-recessive sideroblastic anemia type-2, and a second homozygous pathogenic previously reported variant in GMPPB gene NM_013334.3:c.458C > T; p.(Thr153Ile) causing autosomal-recessive muscular dystrophy-dystroglycanopathy type B14. With the established diagnosis, hematopoietic stem cell transplantation is now being scheduled for the youngest sibling, and a trial therapy with acetylcholine esterase inhibitors was started for the two neurologically affected patients with partial clinical improvement. CONCLUSION: This family emphasizes the importance of whole-exome sequencing for familial cases with complex phenotypes and vague neurological manifestations.
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Anemia Sideroblástica , Humanos , Anemia Sideroblástica/genética , Anemia Sideroblástica/diagnóstico , Anemia Sideroblástica/patología , Hermanos , Genotipo , Fenotipo , MutaciónRESUMEN
Congenital sideroblastic anemia is characterized by anemia and intramitochondrial iron accumulation in erythroid precursors that form ring sideroblasts. The most common recessive forms are caused by sequence variations in the ALAS2 and SLC25A38 genes. In patients with transfusion-dependent and pyridoxine- resistant severe congenital sideroblastic anemia, hematopoietic stem celltransplantis the only curative option. Herein, we described successful implementations of allogeneic hematopoietic stem cell transplant in 4 Iranian children with congenital sideroblastic anemia. The patients had presented with clinical manifestations of anemia early in life, and the diagnoses of congenital sideroblastic anemia were established through blood tests and bone marrow aspiration. Congenital sideroblastic anemia was further confirmed by the identification of pathogenic variants in SLC25A38 in 2 patients. All 4 patients received allogeneic hematopoietic stem cell transplant with myeloablative conditioning regimen that included busulfan, cyclophosphamide, andrabbit antithymocyte globulin. A combination of cyclosporine A and methotrexate or mycophenolate mofetil was used for graft-versus-host disease prophylaxis. Bone marrow and peripheral blood from sibling or related donors with fully matched human leukocyte antigen profiles were applied. The outcomes of hematopoietic stem celltransplantin patients with congenital sideroblastic anemia were favorable. Three patients achieved full donor chimerism (>95%, 98%, and 100%), and the other patient showed mixed chimerism (75%). All patients remained transfusion independent. Hemato- poietic stem celltransplantis a curative treatmentthat can provide long-term survival for patients with congenital sideroblastic anemia, particularly when used in a timely manner. There remain ongoing challenges in various aspects of hematopoietic stem celltransplantin patients with congenital sideroblastic anemia, which remain to be elucidated.
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Anemia Sideroblástica , Enfermedad Injerto contra Huésped , Trasplante de Células Madre Hematopoyéticas , Niño , Humanos , 5-Aminolevulinato Sintetasa/genética , Anemia Sideroblástica/diagnóstico , Anemia Sideroblástica/genética , Anemia Sideroblástica/congénito , Ciclosporina , Irán , Acondicionamiento PretrasplanteRESUMEN
PURPOSE: Sideroblastic anemia, immunodeficiency, periodic fevers, and developmental delay (SIFD) is an autosomal recessive syndrome caused by biallelic loss-of-function variant of tRNA nucleotidyl transferase 1 (TRNT1). Efficacious methods to treat SIFD are lacking. We identified two novel mutations in TRNT1 and an efficacious and novel therapy for SIFD. METHODS: We retrospectively summarized the clinical records of two patients with SIFD from different families and reviewed all published cases of SIFD. RESULTS: Both patients had periodic fever, developmental delay, rash, microcytic anemia, and B cell lymphopenia with infections. Whole-exome sequencing of patient 1 identified a previously unreported homozygous mutation of TRNT1 (c.706G > A/p.Glu236Lys). He received intravenous immunoglobulin (IVIG) replacement and antibiotics, but died at 1 year of age. Gene testing in patient 2 revealed compound heterozygous mutations (c.907C > G/p.Gln303Glu and c.88A > G/p.Met30Val) in TRNT1, the former of which is a novel mutation. Periodic fever was controlled in the first month after adalimumab therapy and IVIG replacement, but recurred in the second month. Adalimumab was discontinued and replaced with thalidomide, which controlled the periodic fever and normalized inflammatory markers effectively. A retrospective analysis of reported cases revealed 69 patients with SIFD carrying 46 mutations. The male: female ratio was 1: 1, and the mean age of onset was 3.0 months. The most common clinical manifestations in patients with SIFD were microcytic anemia (82.6%), hypogammaglobulinemia/B cell lymphopenia (75.4%), periodic fever (66.7%), and developmental delay (60.0%). In addition to the typical tetralogy, SIFD features several heterogeneous symptoms involving multiple systems. Corticosteroids, immunosuppressants, and anakinra have low efficacy, whereas etanercept suppressed fever and improved anemia in reports. Bone-marrow transplantation can be used to treat severe SIFD, but carries a high risk. In total, 28.2% (20/71) of reported patients died, mainly because of multi-organ failure. Biallelic mutations located in exon1-intron5 lead to more severe phenotypes and higher mortality. Furthermore, 15.5% (11/71) patients survived to adulthood. The symptoms could be resolved spontaneously in five patients. CONCLUSIONS: Thalidomide can control the inflammation of SIFD and represents a new treatment for SIFD.
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Anemia Sideroblástica , Síndromes de Inmunodeficiencia , Linfopenia , Masculino , Humanos , Femenino , Talidomida , Estudios Retrospectivos , Anemia Sideroblástica/diagnóstico , Anemia Sideroblástica/tratamiento farmacológico , Anemia Sideroblástica/genética , Adalimumab , Inmunoglobulinas Intravenosas/uso terapéutico , Síndromes de Inmunodeficiencia/genética , Fiebre/etiología , Fiebre/genética , Mutación/genética , Nucleotidiltransferasas/genéticaRESUMEN
Introduction: Sideroblastic anemia with B cell immunodeficiency, periodic fevers, and developmental delay (SIFD) syndrome is caused by biallelic TRNT1 mutations. TRNT1 gene encodes a CCA-adding tRNA nucleotidyl transferase enzyme. Mutant TRNT1 results in immunodeficiency and anemia in various degrees, accompanied by several organ involvement. Case Presentation: We present here a 15-month old male, demonstrated brittle hair, growth hormone deficiency, recurrent fever, arthritis, recurrent infections, mild anemia, and hypogammaglobulinemia. The patient did not respond to colchicine treatment, and after establishing SIFD diagnosis with the presence of homozygote c.948-949delAAinsGG (p.Lys317Glu) mutation in TRNT1 gene, we commenced monthly intravenous immunoglobulin replacement and weekly subcutaneous etanercept. A rapid resolution of fever episodes and infections occurred after initiation of this treatment regimen. Afterward, both anemia and growth parameters have improved during follow-up. Conclusion: SIFD syndrome should be considered in patients with recurrent fever, arthritis, and growth retardation even in the absence of severe anemia and prominent hypogammaglobulinemia.
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Agammaglobulinemia , Amiloidosis , Anemia Sideroblástica , Artritis , Síndromes de Inmunodeficiencia , Agammaglobulinemia/complicaciones , Agammaglobulinemia/tratamiento farmacológico , Agammaglobulinemia/genética , Amiloidosis/complicaciones , Anemia Sideroblástica/complicaciones , Anemia Sideroblástica/tratamiento farmacológico , Anemia Sideroblástica/genética , Artritis/complicaciones , Niño , Colchicina , Etanercept/uso terapéutico , Fiebre/complicaciones , Fiebre/tratamiento farmacológico , Hormona del Crecimiento , Humanos , Inmunoglobulinas Intravenosas , Síndromes de Inmunodeficiencia/complicaciones , Síndromes de Inmunodeficiencia/genética , Lactante , Masculino , Nucleotidiltransferasas/genética , ARN de TransferenciaRESUMEN
The sideroblastic anemias are a heterogeneous group of inherited and acquired disorders characterized by anemia and the presence of ring sideroblasts in the bone marrow. Ring sideroblasts are abnormal erythroblasts with iron-loaded mitochondria that are visualized by Prussian blue staining as a perinuclear ring of green-blue granules. The mechanisms that lead to the ring sideroblast formation are heterogeneous, but in all of them, there is an abnormal deposition of iron in the mitochondria of erythroblasts. Congenital sideroblastic anemias include nonsyndromic and syndromic disorders. Acquired sideroblastic anemias include conditions that range from clonal disorders (myeloid neoplasms as myelodysplastic syndromes and myelodysplastic/myeloproliferative neoplasms with ring sideroblasts) to toxic or metabolic reversible sideroblastic anemia. In the last 30 years, due to the advances in genomic techniques, a deep knowledge of the pathophysiological mechanisms has been accomplished and the bases for possible targeted treatments have been established. The distinction between the different forms of sideroblastic anemia is based on the study of the characteristics of the anemia, age of diagnosis, clinical manifestations, and the performance of laboratory analysis involving genetic testing in many cases. This review focuses on the differential diagnosis of acquired disorders associated with ring sideroblasts.