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1.
Zhongguo Shi Yan Xue Ye Xue Za Zhi ; 28(4): 1316-1320, 2020 Aug.
Artigo em Chinês | MEDLINE | ID: mdl-32798419

RESUMO

OBJECTIVE: To explore the abnormal hemoglobinopathy in couples of child-bearing age in Chongqing. METHODS: A total of 34 800 subjects of child-bearing age were screened for thalassemia by using capillary electrophoresis from January 2015 to September 2018. PCR-flow cytometry fluorescence hybridization assay was used to detect the common thalassemia gene deletions and mutations. RESULTS: 8 kinds of abnormal hemoglobinopathy were detected in 200 cases from 34 800 subjects of child-bearing age, the detection rate was 0.57% in couples of child-bearing age in Chongqing: Among 200 cases of abnormal hemoglobin pathy, Hb E was found in 90 cases (accounting for 45.0%), and Hb D in 25 cases (accounting for 12.5%). Hb NewYork was found in 25 cases (accounting for 12.5%). HbJ-bangkok was found in 25 cases (accounting for 12.5%), and Hb Q-Thailand in 16 cases (accounting for 8.0%). Hb Hope was detected in 15 cases (accounting for 7.5%). Hb S was detected in 3 cases (accounting for 1.5%). Hb Hasharon was detected in 1 case (accounting for 0.5%). The mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) of Hb E and Hb Q-Thailand were lower than normal reference intervals. CONCLUSION: The detection rate of abnormal hemoglobinopathy in Chongqing is higher than the average level in China. Capillary electrophoresis can effectively screen abnormal hemoglobinopathy, which is great significant for aristogenesis and improvement of population quality.


Assuntos
Hemoglobinopatias , Hemoglobinas Anormais , Talassemia , Criança , China , Eletroforese Capilar , Humanos , Tailândia
2.
Pediatr Endocrinol Rev ; 17(3): 226-234, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32741153

RESUMO

At present, assessment of haemoglobin A1c (HbA1c) is widely used for the diagnosis and monitoring of treatment in diabetes mellitus (DM). However, the HbA1c level is affected by many factors such as those influencing the lifespan of red blood cells and the structure, function and amount of normal HbA. Therefore, the clinical significance of HbA1c assessment in thalassemia patients needs careful consideration, especially in transfusion dependent thalassemia patients (TDT) in whom circulating Hb is that of blood donors. Preliminary reports have documented that HbA1c estimation in efficiently transfused patients seems valuable in diagnosis and monitoring of treatment in DM and other glucose disturbances in TDT patients. Herein, a short review of HbA1c measurement in anemias, blood transfusions and hemoglobinopathies, and the debate of the credibility of Hb A1c assessment in TDT patients is reported.


Assuntos
Talassemia , Transfusão de Sangue , Hemoglobina A Glicada , Hemoglobinopatias , Humanos
6.
Lancet Haematol ; 7(6): e469-e478, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32470438

RESUMO

BACKGROUND: Transfusion-dependent haemoglobinopathies require lifelong iron chelation therapy with one of the three iron chelators (deferiprone, deferasirox, or deferoxamine). Deferasirox and deferiprone are the only two oral chelators used in adult patients with transfusion-dependent haemoglobinopathies. To our knowledge, there are no randomised clinical trials comparing deferiprone, a less expensive iron chelator, with deferasirox in paediatric patients. We aimed to show the non-inferiority of deferiprone versus deferasirox. METHODS: DEEP-2 was a phase 3, multicentre, randomised trial in paediatric patients (aged 1 month to 18 years) with transfusion-dependent haemoglobinopathies. The study was done in 21 research hospitals and universities in Italy, Egypt, Greece, Albania, Cyprus, Tunisia, and the UK. Participants were receiving at least 150 mL/kg per year of red blood cells for the past 2 years at the time of enrolment, and were receiving deferoxamine (<100 mg/kg per day) or deferasirox (<40 mg/kg per day; deferasirox is not registered for use in children aged <2 years so only deferoxamine was being used in these patients). Any previous chelation treatment was permitted with a 7-day washout period. Patients were randomly assigned 1:1 to receive orally administered daily deferiprone (75-100 mg/kg per day) or daily deferasirox (20-40 mg/kg per day) administered as dispersible tablets, both with dose adjustment for 12 months, stratified by age (<10 years and ≥10 years) and balanced by country. The primary efficacy endpoint was based on predefined success criteria for changes in serum ferritin concentration (all patients) and cardiac MRI T2-star (T2*; patients aged >10 years) to show non-inferiority of deferiprone versus deferasirox in the per-protocol population, defined as all randomly assigned patients who received the study drugs and had available data for both variables at baseline and after 1 year of treatment, without major protocol violations. Non-inferiority was based on the two-sided 95% CI of the difference in the proportion of patients with treatment success between the two groups and was shown if the lower limit of the two-sided 95% CI was greater than -12·5%. Safety was assessed in all patients who received at least one dose of study drug. This study is registered with EudraCT, 2012-000353-31, and ClinicalTrials.gov, NCT01825512. FINDINGS: 435 patients were enrolled between March 17, 2014, and June 16, 2016, 393 of whom were randomly assigned to a treatment group (194 to the deferiprone group; 199 to the deferasirox group). 352 (90%) of 390 patients had ß-thalassaemia major, 27 (7%) had sickle cell disease, five (1%) had thalassodrepanocytosis, and six (2%) had other haemoglobinopathies. Median follow-up was 379 days (IQR 294-392) for deferiprone and 381 days (350-392) for deferasirox. Non-inferiority of deferiprone versus deferasirox was established (treatment success in 69 [55·2%] of 125 patients assigned deferiprone with primary composite efficacy endpoint data available at baseline and 1 year vs 80 [54·8%] of 146 assigned deferasirox, difference 0·4%; 95% CI -11·9 to 12·6). No significant difference between the groups was shown in the occurrence of serious and drug-related adverse events. Three (2%) cases of reversible agranulocytosis occurred in the 193 patients in the safety analysis in the deferiprone group and two (1%) cases of reversible renal and urinary disorders (one case of each) occurred in the 197 patients in the deferasirox group. Compliance was similar between treatment groups: 183 (95%) of 193 patients in the deferiprone group versus 192 (97%) of 197 patients in the deferisirox group. INTERPRETATION: In paediatric patients with transfusion-dependent haemoglobinopathies, deferiprone was effective and safe in inducing control of iron overload during 12 months of treatment. Considering the need for availability of more chelation treatments in paediatric populations, deferiprone offers a valuable treatment option for this age group. FUNDING: EU Seventh Framework Programme.


Assuntos
Deferasirox/uso terapêutico , Deferiprona/uso terapêutico , Transfusão de Eritrócitos/métodos , Hemoglobinopatias/tratamento farmacológico , Quelantes de Ferro/uso terapêutico , Sobrecarga de Ferro/tratamento farmacológico , Administração Oral , Adolescente , Agranulocitose/induzido quimicamente , Agranulocitose/epidemiologia , Albânia/epidemiologia , Anemia Falciforme/terapia , Técnicas de Imagem Cardíaca/métodos , Criança , Pré-Escolar , Chipre/epidemiologia , Deferasirox/administração & dosagem , Deferasirox/economia , Deferiprona/administração & dosagem , Deferiprona/economia , Egito/epidemiologia , Transfusão de Eritrócitos/estatística & dados numéricos , Feminino , Ferritinas/sangue , Ferritinas/efeitos dos fármacos , Grécia/epidemiologia , Hemoglobinopatias/terapia , Humanos , Lactente , Quelantes de Ferro/administração & dosagem , Quelantes de Ferro/economia , Sobrecarga de Ferro/sangue , Itália/epidemiologia , Imagem por Ressonância Magnética , Masculino , Cooperação do Paciente , Resultado do Tratamento , Tunísia/epidemiologia , Reino Unido/epidemiologia , Doenças Urológicas/induzido quimicamente , Doenças Urológicas/epidemiologia , Talassemia beta/terapia
10.
PLoS One ; 15(1): e0228258, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31999737

RESUMO

Nationally representative data on the micronutrient status of Ghanaian women and children are very scarce. We aimed to document the current national prevalence of micronutrient deficiencies, anemia, malaria, inflammation, α-thalassemia, sickle cell disease and trait, and under- and over-nutrition in Ghana. In 2017, a two-stage cross-sectional design was applied to enroll pre-school children (6-59 months) and non-pregnant women (15-49 years) from three strata in Ghana: Northern, Middle and Southern Belt. Household and individual questionnaire data were collected along with blood samples. In total, 2123 households completed the household interviews, 1165 children and 973 women provided blood samples. Nationally, 35.6% (95%CI: 31.7,39.6) of children had anemia, 21.5% (18.4,25.0) had iron deficiency, 12.2% (10.1,14.7) had iron deficiency anemia, and 20.8% (18.1,23.9) had vitamin A deficiency; 20.3%(15.2,26.6) tested positive for malaria, 13.9% (11.1,17.3) for sickle trait plus disease, and 30.7% (27.5,34.2) for α-thalassemia. Anemia and micronutrient deficiencies were more prevalent in rural areas, poor households and in the Northern Belt. Stunting and wasting affected 21.4% (18.0,25.2) and 7.0% (5.1,9.5) of children, respectively. Stunting was more common in rural areas and in poor households. Among non-pregnant women, 21.7% (18.7,25.1) were anemic, 13.7% (11.2,16.6) iron deficient, 8.9% (6.7,11.7) had iron deficiency anemia, and 1.5% (0.8,2.9) were vitamin A deficient, 53.8% (47.6,60.0) were folate deficient, and 6.9% (4.8,9.8) were vitamin B12 deficient. Malaria parasitemia in women [8.4% (5.7,12.2)] was lower than in children, but the prevalence of sickle cell disease or trait and α-thalassemia were similar. Overweight [24.7% (21.0,28.8)] and obesity [14.3% (11.5,17.7)] were more common in wealthier, older, and urban women. Our findings demonstrate that anemia and several micronutrient deficiencies are highly present in Ghana calling for the strengthening of Ghana's food fortification program while overweight and obesity in women are constantly increasing and need to be addressed urgently through governmental policies and programs.


Assuntos
Anemia/epidemiologia , Transtornos da Nutrição Infantil/epidemiologia , Hemoglobinopatias/epidemiologia , Malária/epidemiologia , Micronutrientes/deficiência , Adolescente , Adulto , Criança , Pré-Escolar , Feminino , Gana/epidemiologia , Inquéritos Epidemiológicos , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Estado Nutricional , Prevalência , Adulto Jovem
12.
Indian J Med Res ; 150(2): 161-166, 2019 08.
Artigo em Inglês | MEDLINE | ID: mdl-31670271

RESUMO

Background & objectives: Swiss-type hereditary persistence of foetal haemoglobin (HPFH) has been shown to be responsible for the wide range of F cell levels in healthy Thai adults. However, a survey for F cells in healthy Thai adults has not been performed. This study was conducted to determine the F cell distribution in adult Thai blood donors and to assess the possible involvement of ß-thalassaemia and haemoglobin E (HbE) carriers in increased HbF levels. Methods: Thai blood donors (n=375, 205 males and 170 females) were included in the study. Blood samples were collected for measuring haemoglobin (Hb) concentration and haematocrit (Hct) and F cell levels. Hb and Hct levels were determined by automated blood counter, while F cells were quantified by flow cytometric analysis of F cells stained by fluorescein isothiocyanate-conjugated anti γ-globin monoclonal antibody. Finally, F cell levels were compared between blood samples having mean corpuscular volume (MCV ) <80 fl and ≥80 fl as well as between ß-haemoglobinopathies (HbE and ß-thalassaemia carriers) and normal adults. Results: F cell levels varied markedly spanning 0.80-39.2 per cent with a positively skewed distribution. Thirty two per cent of these individuals had F cell levels more than the 4.5 per cent cut-off point. F cell levels in females were significantly higher than those in males (P<0.05). F cell levels in individuals having MCV <80 fl were significantly higher than those having MCV ≥80 fl (P<0.05). ß-haemoglobinopathy (HbE and ß-thalassaemia carriers) had significantly higher F cell levels than normal individuals (P<0.05). Interpretation & conclusions: The present results showed that besides Swiss-type HPFH, the ß-haemoglobinopathy was expected to be involved in increased F cell levels in adult Thais. Thus, influence of ß-haemoglobinopathy must be considered in interpreting F cell levels in area endemic of this globin disorder.


Assuntos
Hemoglobina Fetal/genética , Hemoglobina E/genética , Hemoglobinopatias/genética , Talassemia beta/genética , Adulto , Anemia Falciforme/sangue , Anemia Falciforme/epidemiologia , Anemia Falciforme/genética , Anemia Falciforme/patologia , Doadores de Sangue , Pré-Escolar , Índices de Eritrócitos/genética , Feminino , Hemoglobinopatias/sangue , Hemoglobinopatias/epidemiologia , Hemoglobinopatias/patologia , Heterozigoto , Humanos , Lactente , Recém-Nascido , Masculino , Fenótipo , Tailândia , Talassemia beta/sangue , Talassemia beta/epidemiologia , Talassemia beta/patologia
13.
FP Essent ; 485: 24-31, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31613565

RESUMO

Hemoglobinopathies are genetic disorders that lead to abnormal structure of the hemoglobin molecule. Genetic mutation results in major changes in the hemoglobin structure, with dysfunctions related to changes in shape, oxygen-carrying capacity, or ability to clump together, causing obstruction of the vascular system. Sickle cell disease and beta thalassemia major are two common hemoglobinopathies worldwide. However, they occur infrequently in the United States, with approximately 101,000 individuals affected. Sickle cell disease phenotypically is exhibited in patients with two hemoglobin S genes but the disease broadly includes many other hemoglobin abnormalities. Complications vary according to genotype and include acute pain crisis, vasoocclusive events, and acute chest syndrome. Blood transfusions are a mainstay of therapy. The two main categories of thalassemias are beta thalassemias and alpha thalassemias. Symptoms range from severe to none. The severity depends on how many genes are affected. Patients with the most severe form of beta thalassemia (ie, two affected genes) are categorized as having thalassemia major or transfusion-dependent disease. The primary treatment for beta thalassemia major currently is transfusions, although stem cell transplantation is a potentially curative option.


Assuntos
Anemia Falciforme , Hemoglobinopatias , Talassemia , Talassemia beta , Transfusão de Sangue , Hemoglobinopatias/diagnóstico , Hemoglobinopatias/terapia , Humanos
14.
Hemoglobin ; 43(4-5): 223-228, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31603010

RESUMO

ß-Thalassemia (ß-thal) is a genetic disorder representing a major health problem in Algeria. Our first objective was to determine the allelic frequencies and molecular spectrum of ß-thal mutations in patients with major hemoglobinopathies [ß-thal major (ß-TM) and sickle cell disease] in three provinces of northeast Algeria. Our second objective was to assess if the clinical management of ß-TM patients depended on their region of origin. Our last objective was to assess a population originating from Maghreb, the reliability of the thalassemia severity score (TSS) for patients with homozygous ß-thal. Sanger HBB gene sequencing was performed on 59 patients with sickle cell disease and 60 with ß-TM. For the latter patients, the genetic modifiers of the TSS were genotyped: α-thalassemia (α-thal) deletions and four Hb F-inducing polymorphisms (XmnI, rs1427407 and rs10189857 for BCL11A and rs9399137 for HMIP). Eleven different ß-thal mutations were found but two of them (HBB: c.118C>T and HBB: c.93-21G>A) accounted for about 70.0% of the ß-thal alleles. A relatively high proportion of Hb S (HBB: c.20A>T)/ß-thal genotypes (27.0%) was found in our sickle cell disease cohort where a new frameshift ß0-thal mutation (HBB: c.374dup; p.Pro126Thrfs*15) was identified. No difference was found in the three provinces. Of the 60 ß-TM patients, those with a high or very high TSS were significantly younger at the age of first transfusion, thus assessing the reliability of this scoring system in a Maghrebin cohort. Trends for a lower age of splenectomy and high ferritin levels were also detected for the higher TSS categories.


Assuntos
Índice de Gravidade de Doença , Talassemia beta/genética , Adulto , Argélia/epidemiologia , Anemia Falciforme/genética , Transfusão de Sangue , Feminino , Ferritinas/sangue , Mutação da Fase de Leitura , Genótipo , Hemoglobina Falciforme/genética , Hemoglobinopatias/genética , Humanos , Masculino , Esplenectomia , Talassemia beta/epidemiologia
15.
Biomed Res Int ; 2019: 6857417, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31662988

RESUMO

Consanguinity is a social behavior characterized by the arrangement of marriages between relatives. It coincides generally with the geographic distribution of recessive genetic diseases as it increases the likelihood of homozygosis and, consequently, the incidence of their pathologies in the population. In this pilot study, we assess the effect of inbreeding on the burden of hemoglobinopathies in Northern Morocco. From January 2016 to December 2018, 197 children born in the studied region to three ancestral generations and diagnosed with hemoglobinopathies were subject to investigation. The rate of consanguinity in the parents' generation of children with hemoglobinopathies was 50.25%, with first cousin marriages accounting for 68.69% of consanguineous unions (FI = 0.02). The corresponding rates in the general population, based on a sample of N = 900, were 29.67% and 82.02%, respectively. The marriages between first cousins are the most common among the other types of consanguineous unions. Our study propounds that consanguinity substantially contributes to the hemoglobinopathy burden in the studied region and has changed little over time. Refraining from consanguineous marriages and detecting couples at risk could contribute to the reduction of the incidence of genetic diseases in our country.


Assuntos
Hemoglobinopatias/epidemiologia , Criança , Consanguinidade , Feminino , Humanos , Incidência , Masculino , Casamento , Marrocos/epidemiologia , Projetos Piloto
16.
Hemoglobin ; 43(4-5): 254-257, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31599656

RESUMO

To provide the molecular information on hemoglobinopathies in the Myanmar population, the study was carried out on Myanmar workers in Khon Kaen Province in northeast Thailand. A total of 300 anonymous Myanmar factory workers were randomly recruited during their annual medical checkup. Hemoglobinopathies were identified using hemoglobin (Hb) and DNA analyses. These identified heterozygous α0-thalassemia (α0-thal) [- -SEA (Southeast Asian) deletion] (n = 5, 1.7%), heterozygous α+-thal (n = 103, 34.3%), homozygous α+-thal (n = 12, 4.0%), heterozygous ß-thalassemia (ß-thal) (n = 3, 1.0%), heterozygous ß-thal with homozygous α+-thal (n = 2, 0.7%), double heterozygous ß-thal/α0-thal (n = 1, 0.3%)], heterozygous Hb E (HBB: c.79G>A) with α0-thal/α+-thal (n = 1, 0.3%), heterozygous Hb E (n = 27, 9.0%), heterozygous Hb E with α+-thal (n = 24, 8.0%), homozygous Hb E with α0-thal/α+-thal (n = 1, 0.3%), homozygous Hb E (n = 3, 1.0%) and homozygous Hb E with heterozygous α+-thal (n = 3, 1.0%). No thalassemia defect was found in the remaining 115 subjects (38.4%). Haplotypes associated with Hb E and Hb Dhonburi (or Hb Neapolis) [ß126(H4)Val→Gly, codon 126 (T>G), HBB: c.380T>G] are reported. While the proportions of α0-thal, ß-thal and Hb E are comparable to those described in neighboring countries, a markedly high prevalence of α+-thal (48.6% in total) is unexpected. The molecular information obtained should provide necessary information for diagnostic improvement and planning of a prevention and control program of severe thalassemia in the Myanmar population.


Assuntos
Hemoglobinopatias/genética , Talassemia alfa/etnologia , Hemoglobina E , Hemoglobinopatias/etnologia , Hemoglobinas/análise , Hemoglobinas Anormais , Humanos , Mianmar/etnologia , Prevalência , Análise de Sequência de DNA , Tailândia/epidemiologia
17.
Hemoglobin ; 43(4-5): 249-253, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31581858

RESUMO

This study assessed thalassemia and hemoglobinopathies in a group of the Tay ethnic minority. Participants included 289 women of reproductive-age who enrolled in a pilot screening program for thalassemia conducted at six communities of Thai Nguyen Province, northern Vietnam. Standard procedures including complete blood count (CBC), hemoglobin (Hb) and DNA analyses were performed for all samples. The prevalence of thalassemia in 289 Tay women was 15.6% (gene frequency 0.078) for α0-thalassemia (α0-thal), 10.0% (gene frequency 0.050) for α+-thal, 7.3% (gene frequency 0.036) for ß-thalassemia (ß-thal), 2.4% (gene frequency 0.012) for Hb Constant Spring [Hb CS; α142, Term→Gln, TAA>CAA (α2), HBA2: c.427T>C] and 1.7% (gene frequency 0.009) for Hb E [ß26(B8)Glu→Lys, GAG>AAG; HBB: c.79G>A]. Further analysis of ß-globin gene abnormalities identified four mutations including codons 41/42 (-TCTT) (HBB: c.126_129delCTTT), codon 17 (A>T) (HBB: c.52A>T), codons 71/72 (+A) (HBB: c.216_217insA), and -28 (A>G) (HBB: c.78A>G). The results hint at the remarkably high frequencies of severe forms of thalassemia that indicate a serious public health problem requiring further exploration, and most probably, also intervention within the country.


Assuntos
Hemoglobinopatias/etnologia , Grupos Minoritários , Talassemia/etnologia , Grupos Étnicos , Feminino , Frequência do Gene , Hemoglobinopatias/genética , Hemoglobinas Anormais , Humanos , Programas de Rastreamento , Mutação , Prevalência , Talassemia/genética , Vietnã/epidemiologia , Vietnã/etnologia , Talassemia alfa/etnologia , Talassemia alfa/genética , Globinas beta/genética , Talassemia beta/etnologia , Talassemia beta/genética
18.
Isr Med Assoc J ; 21(8): 546-551, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31474018

RESUMO

BACKGROUND: The Bedouins living in southern Israel are a Muslim-Arab population that is transitioning from a nomadic lifestyle to life in permanent settlements. The population has unique characteristics that could affect hemoglobin A1c (HbA1c) measurements. The objective of this study was to describe the socio-demographic and unique morbidity characteristics of this community and their effect on HbA1c measurements. Consanguinity, especially among cousins in the Bedouin population, results in a high prevalence of autosomal recessive genetic diseases such as thalassemia (underestimate of HbA1c), hemoglobinopathies (underestimate and overestimate), Gilbert's disease, and glucose-6-phosphate dehydrogenase deficiency, an X-linked disorder, which can cause hyperbilirubinemia with an overestimate of HbA1c. Furthermore, nutritional deficiencies, autosomal recessive diseases, high birth rates, parasitic infections, and poverty can all cause high rates of anemia (iron and vitamin B12 deficiencies) that can raise HbA1c levels. Congenital dyserythropoietic anemia is found among Bedouin tribes in the Negev region and can lead to an underestimation of HbA1c levels. Pregnancy can also affect HbA1c levels. Medical teams working in the Bedouin community and in other Muslim populations with similar morbidity characteristics throughout the world should identify patients with medical conditions that can affect HbA1c measurements and be aware of possible measurement alternatives such as fructosamine and glycated albumin.


Assuntos
Anemia/etnologia , Hemoglobina A Glicada/análise , Hemoglobinopatias/etnologia , Desnutrição/etnologia , Complicações na Gravidez/etnologia , Anemia/sangue , Anemia/complicações , Árabes , Feminino , Hemoglobinopatias/sangue , Hemoglobinopatias/complicações , Humanos , Islamismo , Israel/etnologia , Masculino , Desnutrição/sangue , Desnutrição/complicações , Gravidez , Complicações na Gravidez/sangue , Reprodutibilidade dos Testes , Fatores Socioeconômicos
20.
Blood ; 134(20): 1697-1707, 2019 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-31554636

RESUMO

As essential components of hemoglobin, iron and heme play central roles in terminal erythropoiesis. The impairment of this process in iron/heme deficiency results in microcytic hypochromic anemia, the most prevalent anemia globally. Heme-regulated eIF2α kinase, also known as heme-regulated inhibitor (HRI), is a key heme-binding protein that senses intracellular heme concentrations to balance globin protein synthesis with the amount of heme available for hemoglobin production. HRI is activated during heme deficiency to phosphorylate eIF2α (eIF2αP), which simultaneously inhibits the translation of globin messenger RNAs (mRNAs) and selectively enhances the translation of activating transcription factor 4 (ATF4) mRNA to induce stress response genes. This coordinated translational regulation is a universal hallmark across the eIF2α kinase family under various stress conditions and is termed the integrated stress response (ISR). Inhibition of general protein synthesis by HRI-eIF2αP in erythroblasts is necessary to prevent proteotoxicity and maintain protein homeostasis in the cytoplasm and mitochondria. Additionally, the HRI-eIF2αP-ATF4 pathway represses mechanistic target of rapamycin complex 1 (mTORC1) signaling, specifically in the erythroid lineage as a feedback mechanism of erythropoietin-stimulated erythropoiesis during iron/heme deficiency. Furthermore, ATF4 target genes are most highly activated during iron deficiency to maintain mitochondrial function and redox homeostasis, as well as to enable erythroid differentiation. Thus, heme and translation regulate erythropoiesis through 2 key signaling pathways, ISR and mTORC1, which are coordinated by HRI to circumvent ineffective erythropoiesis (IE). HRI-ISR is also activated to reduce the severity of ß-thalassemia intermedia in the Hbbth1/th1 murine model. Recently, HRI has been implicated in the regulation of human fetal hemoglobin production. Therefore, HRI-ISR has emerged as a potential therapeutic target for hemoglobinopathies.


Assuntos
Eritropoese , Hemoglobinopatias/metabolismo , eIF-2 Quinase/metabolismo , Fator 4 Ativador da Transcrição/metabolismo , Anemia Ferropriva/metabolismo , Animais , Heme/metabolismo , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Transdução de Sinais
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