Research progress of iron metabolism in phenotype modification of β-thalassemia / 中华医学遗传学杂志

β-thalassemia is a type of inherited hemolytic anemia caused by decreased globin production due to defect of the HBB gene. The pathogenesis of the disease is imbalance of α/β globin chains. The excess of α-globin chains will form hemichromes which can damage red blood cell membranes and lead to hemolysis, ineffective erythropoiesis, and secondary iron overload. Iron overload in turn can cause complications such as growth retardation, liver cirrhosis, cardiac insufficiency, and aggravate the disease phenotype. In recent decades, genes participating in iron metabolism have been discovered, and the mechanism of iron metabolism in the development of thalassemia has gradually been elucidated. Subsequently, by manipulating the expression of key genes in iron metabolism such as hepcidin and transferrin receptor, researchers have revealed that iron restriction can improve ineffective hematopoiesis and iron overload, which may provide a potential approach for the treatment of thalassemia. This article reviews the progress of research on iron metabolism-related genes and related pathways in β-thalassemia.

Differences in Hepatic Expression of Iron, Inflammation and Stress-Related Genes in Patients with Nonalcoholic Steatohepatitis

Abstract: Nonalcoholic fatty liver disease (NAFLD) is the most common cause of chronic liver disease worldwide. We have previously shown that hepatic reticuloendothelial system (RES) iron deposition is associated with an advanced degree of nonalcoholic steatohepatitis (NASH) in humans. In this study, we aimed to determine differentially expressed genes related to iron overload, inflammation and oxidative stress pathways, with the goal of identifying factors associated with NASH progression. Seventy five patients with NAFLD were evaluated for their biochemical parameters and their liver tissue analyzed for NASH histological characteristics. Gene expression analysis of pathways related to iron homeostasis, inflammation and oxidative stress was performed using real-time PCR. Gene expression was compared between subjects based on disease status and presence of hepatic iron staining. We observed increased gene expression of hepcidin (HAMP) (2.3 fold, p = 0.027), transmembrane serine proteinase 6 (TMPRSS6) (8.4 fold, p = 0.003), signal transducer and activator of transcription 3 (STAT3) (5.5 fold, p = 0.004), proinflammatory cytokines; IL-1β (2.7 fold, p = 0.046) and TNF-α (3.8 fold, p = 0.001) in patients with NASH. TMPRSS6, a negative regulator of HAMP, is overexpressed in patients with NASH and HIF1α (hypoxia inducible factor-1) is downregulated. NAFLD patients with hepatic iron deposition exhibited higher hepcidin expression (3.1 fold, p = 0.04) but lower expression of cytokines. In conclusion, we observed elevated hepatic HAMP expression in patients with NASH and in NAFLD patients who had hepatic iron deposition, while proinflammatory cytokines displayed elevated expression only in patients with NASH, suggesting a regulatory role for hepcidin in NAFL to NASH transition and in mitigating inflammatory responses.

Hemocromatose hereditária / Hereditary hemochromatosis

A hemocromatose é um distúrbio autossômico recessivo ou dominante que ocorre devido ao aumento inapropriado da absorção de ferro pela mucosa gastrointestinal, resultando no armazenamento excessivo desse elemento no fígado, pâncreas, coração, articulações e gônadas. Afeta a populaçãocaucasiana, com prevalência de até um em 200 descendentes da população nórdica ou celta. O diagnóstico se faz por critérios clínicos, bioquímicos (ferritina, saturação da transferrina, etc.), genéticos epor imagem (ressonância magnética, tomografia e ultrassom).

Hemochromatosis is a disorder autosomal recessive or dominant that occurs inappropriate due to the increased absorption of iron by the gastrointestinal mucosa resulting in excessive storage of this element in the liver, pancreas, heart, joints and gonads. It affects the caucasian population with a prevalence reaching up to 1 in 200 people descendants of the population nordic or celtic. The diagnosis is made by clinical criteria, biochemical (ferritin, transferrin saturation of and so on), genetic and by image (magnetic resonance, tomography and ultrasound).

Hfe mutations add iron overload in patients with alcoholic liver disease

Context Alcoholic liver disease (ALD) is generally associated with iron overload, which may contribute to its pathogenesis, through increased oxidative stress and cellular damage. There are conflicting reports in literature about hemochromatosis (HFE) gene mutations and the severity of liver disease in alcoholic patients. Objectives To compare the prevalence of mutations in the hemochromatosis (HFE) gene between patients with ALD and healthy controls; to assess the relation of HFE mutations with liver iron stores and liver disease severity. Methods Liver biopsy specimens were obtained from 63 ALD patients (during routine treatment) and 52 healthy controls (during elective cholecystectomy). All individuals underwent routine liver function tests and HFE genotyping (to detect wild-type sequences and C282Y, H63D, S65C, E168Q, E168X, V59M, H63H, P160delC, Q127H, Q283P, V53M and W164X mutations). Associations between HFE mutations and risk of excessive liver iron stores, abnormal serum ferritin, liver fibrosis, or necroinflammatory activity were assessed by multivariate logistic regression analysis. Results ALD patients had significantly higher serum ferritin and transferrin saturation than controls (both P<0.05), but the distribution of HFE mutations was similar between the two groups. For ALD patients, the odds ratio for having at least one HFE mutation and excessive liver iron stores was 17.23 (95% confidence interval (CI): 2.09-142.34, P = 0.008). However, the presence of at least one HFE mutation was not associated with an increased risk of liver fibrosis or necroinflammatory activity. Active alcohol ingestion showed the strongest association to increased serum ferritin (OR = 8.87, 95% CI: 2.11-34.78, P = 0.003). Conclusions ALD patients do not present with a differential profile of HFE mutations from healthy controls. In ALD patients, however, ...

Contexto A doença hepática alcoólica (DHA) está geralmente associada à sobrecarga de ferro, que pode contribuir para a sua patogênese, através do aumento do estresse oxidativo e dano celular. As descrições existentes na literatura sobre a associação entre mutações HFE e a gravidade da DHA nem sempre são concordantes. Objetivos Comparar a prevalência de mutações HFE entre um grupo de pacientes com DHA e uma população de controle. Avaliar a relação entre mutações HFE e os depósitos de ferro hepático. Avaliar se a presença dessas mutações está associada com a gravidade da DHA. Métodos Compararam-se 63 pacientes com DHA que efetuaram biopsia hepática com 52 controles saudáveis. A genotipagem HFE (wild type, C282Y, H63D, S65C, E168Q, E168X, V59M, H63H, P160delC, Q127H, Q283P, V53M, W164X) e uma avaliação laboratorial de rotina (incluindo cinética do ferro) foram feitos em todos os indivíduos. Realizou-se regressão logística multivariada nos casos para avaliar se a presença de mutações HFE estava relacionada com risco aumentado de depósitos de ferro hepático aumentados, ferritina sérica anormal, fibrose hepática significativa ou atividade necroinflamatória. Resultados Os pacientes apresentaram ferritina sérica e saturação da transferrina mais elevadas que os controles, mas não existiram diferenças significativas na distribuição de mutações HFE entre pacientes e controles. Considerando apenas os pacientes, o risco relativo de estes apresentarem pelo menos uma mutação HFE e depósitos de ferro hepático significativos foi de 17.23 (CI 95% 2.09-142.34, P = 0.008). Contudo, a presença ...

Hemocromatose hereditária relacionada ao gene HFE / Hereditary hemochromatosis HFE gene related

A Hemocromatose Hereditária (HH) é a desordem hereditária mais comum em caucasianos. Mais de 90% dos casos de HH resultam da simples substituição do aminoácido Cisteína pela Tirosina no gene HFE. Essa mutação causa uma doença recessiva que resulta no acúmulo tissular de ferro. O mecanismo através do qual o HFE influencia a homeostase do ferro nas células e no corpo permanece obscuro. A doença é subdiagnosticada na população em geral devido à inespecificidade de sua apresentação clínica. O prognóstico envolve a detecção precoce da doença e a terapêutica adequada utilizando a flebotomia em fase oportuna. Essa revisão descreve os conceitos atuais a respeito das manifestações clínicas, fisiopatologia, prognóstico e tratamento da Hemocromatose Hereditária relacionada ao gene HFE.

Hereditary hemochromatosis (HH) is the most common inherited disorder in caucasians. Over 90% of the cases of HH result from a single mutation of a Cys to Tyr in the HFE gene. This mutation causes a recessive disease resulting in iron acumulation in selected tissues. The mechanism by which HFE influences iron homeostasis in cells and in the body remains elusive. The disease is underdiagnosed in general population due to inespecific clinical manifestations. Prognosis is related to early diagnostic and correct treatment using pheblotomy. This review describe the current concepts concerning the clinical features, pathophisiology, prognosis and treatment of HFE-related hemochromatosis hereditary.

Hemocromatose hereditária: associação entre as mutações no gene HFE e o estado de ferro em doadores de sangue e pesquisa de mutações nos genes HFE, HJV, HAMP, TFR2 e SLC40A1 em pacientes com sobrecarga de ferro primária / Hereditary hemochromatosis: relationship between HFE gene mutations and iron status in blood donors and HFE, HJV, HAMP, TFR2 and SLC40A1 gene sequencing in primary iron overload patients

A hemocromatose hereditária é caracterizada pelo aumento da absorção intestinal de ferro, acarretando progressivo acúmulo no organismo. Os objetivos foram: 1- determinar as frequências das mutações p.C282Y, p.H63D e p.S65C no gene HFE e avaliar os efeitos nas concentrações dos parâmetros do ferro em doadores de sangue; 2- pesquisar mutações nos genes: 2.1- HFE, 2.2- HJV e HAMP, 2.3- TFR2 e SLC40A1, em pacientes portadores de sobrecarga de ferro primária. Participaram 542 doadores de sangue provenientes do Hemocentro da Santa Casa de São Paulo. Foram incluídos 51 pacientes que apresentavam saturação de transferrina ≥ 50% (para mulheres) e ≥ 60% (para homens) e ausência de causas secundárias. Os genótipos para as mutações nos genes HFE foram avaliados pela PCR-RFLP. Foi realizado sequenciamento direto bidirecional para cada éxon dos genes, utilizando o sequenciador Genetic Analizer 3500XL®. Nos doadores de sangue, as frequências dos alelos HFE 282Y, HFE 63D e HFE 65C foram 2,1, 13,6 e 0,6%, respectivamente. Os homens que doaram pela primeira vez, portadores do genótipo HFE 282CY, apresentaram maiores valores de saturação de transferrina; e também os portadores dos genótipos HFE 63DD e 63HD apresentaram maiores concentrações de ferritina sérica, em relação aos de genótipo selvagem. Para os pacientes, 72,5% (37/51) apresentaram ao menos 1 alteração no gene HFE e 11 foram identificados como homozigotos para a mutação p.C282Y. Uma mutação não descrita na literatura (p.V256I) foi identificada no gene HFE e a modelagem molecular (análises de ligação e estrutural) detectou que a mutação não reduziu a afinidade entre as proteínas HFE e β2-microglobulina. No sequenciamento dos éxons dos genes HJV e HAMP foram identificadas as alterações já descritas: HJV p.E302K, HJV p.A310G, HJV p.G320V e HAMP p.R59G. Para o gene TFR2, foram identificados 3 polimorfismos já descritos (p.A75V, p.A617A e p.R752H). No gene SLC40A1 foram observados 6 polimorfismos (rs13008848, rs11568351...

Hereditary hemochromatosis (HH) is characterized by increased intestinal iron absorption, which leads to a progressive accumulation of iron in the body. The aims were: 1- to assess the frequency of HFE gene mutations (p.C282Y, p.H63D and p.S65C) and to identify their relationship to iron status in blood donors; 2- to search in primary iron overload patients: 2.1- HFE, 2.2- HJV and HAMP, 2.3- TFR2 and SLC40A1 gene mutations. Blood donors (n=542) were recruited from Hemocentro of Santa Casa Hospital, Sao Paulo, Brazil. The study included 51 patients with transferrin saturation ≥ 50% (women) and ≥ 60% (men) and absence of secondary causes. The genotypes for HFE mutations were evaluated by PCR-RFLP. Subsequent bidirectional sequencing for each gene was performed using the Genetic Analizer sequencer 3500XL®. The frequencies of HFE 282Y, HFE 63D and HFE 65C alleles were 2.1, 13.6 and 0.6% in blood donors, respectively. The first time male donors carrying heterozygous genotype for the p.C282Y mutation had higher transferrin saturation values; and men carrying HFE 63DD and 63HD genotypes had higher serum ferritin concentrations when compared to the wild genotype. Thirtyseven (72.5%) out of the 51 patients presented at least one HFE mutation and 11 were identified as homozygous for the mutation p.C282Y. One novel mutation (p.V256I) in the HFE gene was indentified and molecular modeling (free energy and structural analysis in silico) showed that p.V256I mutation did not reduce the affinity binding between HFE and β2-microglobulin. Sequencing in the HJV and HAMP genes revealed HJV p.E302K, HJV p.A310G, HJV p.G320V and HAMP p.R59G alterations. Sequencing in the TFR2 gene observed 3 polymorphisms (p.A75V, p.A617A e p.R752H); and sequencing in the SLC40A1 gene identified 6 polymorphisms (rs13008848, rs11568351, rs11568345, rs11568344, rs2304704 e rs11568346) and 1 p.G204S non-described mutation. The conclusions were: 1- for blood donors, the presence of HFE 282Y and...

Haemochromatosis gene mutation H63D is a risk factor for iron overload in Egyptian beta- thalassemic children

Iron overload is the main cause of morbidity and mortality in patients with beta-thalassemia. The aim of this study was to evaluate the prevalence of genetic markers [HFE mutations C282Y and H63D] among Egyptian beta-thalassemic Children and its effect on their iron status. 59 beta-thalassemic children attending the pediatric hematology clinic in Menoufiya University Hospital [23 thalassemia major, 23 thalassemia intermedia and13 thalassemia trait] with 50 apparently healthy, Egyptian children [control group] were screened for the prevalence of these two mutations by digestion of PCR products [RFLP]. Serum ferritin level was measured by ELISA. Neither carrier status for the C282Y allele nor homozygous status for the H63D allele were detected in any of the thalassemic children or the 50 controls. The H63D heterozygous state was detected in 15 [25.4%] thalassemic patients with an allele frequency of 12.71% and in 11 [22%] controls with an allele frequency of 11%. with no significant difference between the thalassemic groups and the controls. The prevalence of carriers for the H63D mutation was 26.1% with an allele frequency of 13.04% in patients with either beta- thalassemia major or intermedia, while in beta- thalassemia trait the prevalence of this mutation was 23.1% with an allele frequency of 11.54%. There were significant higher levels of the mean yearly serum ferritin in both beta-thalassemia major and intermedia patients who are heterozygotes for the H63D mutation compared to those without this mutation. The mean serum ferritin levels were positively correlated with the age of the patients. On the other hand, the prevalence of iron -induced complications was not statistically different between patients carrying or not carrying this mutation [among TM and TI]. There is no difference in the prevalence of H63D mutation between beta-thalassemic patients and the normal children and the presence of a heterozygous H63D status and older age are two risk factors for iron overload in Egyptian beta-thalassemic children. RFLP= Restriction Fragment Length Polymorphism, HCV=Hepatitis C Virus, ALT = Alanine aminotransferase, AST =Aspartate aminotransferase

Analysis of HFE gene mutations and HLA-A alleles in Brazilian patients with iron overload

CONTEXTO E OBJETIVO: Hemocromatose é um distúrbio hereditário comum do metabolismo do ferro e uma das causas mais importantes de sobrecarga de ferro. O objetivo foi analisar a presença das mutações C282Y, H63D e S65C no gene HFE e dos alelos HLA-A em um grupo de pacientes brasileiros com sobrecarga de ferro e correlacionar o genótipo com variáveis clínicas e laboratoriais. TIPO DE ESTUDO E LOCAL: Estudo prospectivo, na Disciplina de Hematologia e Oncologia. Faculdade de Ciências Médicas da Santa Casa de Misericórdia de São Paulo. MÉTODOS: Estudamos 35 pacientes com sobrecarga de ferro atendidos em nosso ambulatório entre janeiro de 2001 e dezembro de 2003. Ferro sérico, ferritina sérica e capacidade total de ligação de ferro foram determinados por técnicas convencionais. As mutações C282Y, H63D e S65C do gene HFE e a determinação dos alelos HLA-A foram realizadas por reação de polimerase em cadeia (PCR). RESULTADOS: Vinte e seis dos 35 pacientes (74%) apresentavam pelo menos uma das mutações analisadas do gene HFE. Entre esses, cinco (14%) com genótipo C282Y/C282Y, 4 (11%) C282Y/H63D, 1 (3%) H63D/H63D, 6 (17%) C282Y/WT e 10 (29%) H63D/WT. Não foi encontrado nenhum paciente com a mutação S65C e 9 (26%) pacientes não apresentavam nenhuma das três mutações do gene HFE. Quatro dos 5 pacientes com genótipo C282Y/C282Y (80%) e 3 dos 4 pacientes C282Y/H63D (75%) eram HLA A*03. CONCLUSÃO: Análise das mutações do gene HFE constitui um importante procedimento na identificação de pacientes com hemocromatose hereditária, particularmente em pacientes com sobrecarga de ferro.

Hereditary hemochromatosis in a Brazilian university hospital in São Paulo State (1990-2000)

Hereditary hemochromatosis (HH) is the most common genetic disease among individuals of European descent. Two mutations (845G-->A, C282Y and 187C-->G, H63D) in the hemochromatosis gene (HFE gene) are associated with HH. About 85-90% of patients of northern European descent with HH are C282Y homozygous. The prevalence of HH in the Brazilian population, which has a very high level of racial admixture, is unknown. The aims of the present study were to identify individuals with diagnostic criteria for HH among patients with a body iron overload attended at the university hospital of the Faculty of Medicine of Ribeirao Preto from 1990 to 2000, and to evaluate the prevalence of HFE mutations. We screened first-degree relatives for HFE mutations. Four of 72 patients (three men and one woman, mean age 47 years) fulfilled the criteria for HH. HFE mutations were studied in three patients [two C282Y homozygotes (patients 1 and 2) and one H63D heterozygote]. Patient 1 had four children (all C282Y heterozygotes with no iron overload) and seven brothers and sisters: two sisters (66 and 76 years old) were C282Y homozygotes and both had an iron overload (a liver biopsy in one showed severe iron deposits), one sister (79 years old) was a compound heterozygote with no iron overload, one brother (78 years old) was a C282Y heterozygote with no iron overload, two individuals were H63D heterozygotes (one brother, 49 years old, obese, with a body iron overload and abnormal liver enzymes - a biopsy showed non-alcoholic steatohepatitis, and one 70-year-old sister with no iron overload). Patient 2 had two children (22 and 24 years old who were C282Y heterozygotes with no iron overload) but no brothers or sisters. These results showed that HH was uncommon among individuals attended at our hospital, although HFE mutations were found in all patients. Familial screening is valuable for the early diagnosis of individuals at risk since it allows treatment to be initiated before the onset of the clinical manifestations of organ damage associated with HH

Del 11(q23) as a prognostic factor of iron overload in refractory anemia with ringed sideroblasts

We present the case of a patient with MDS RARS subtype with loss of part of the long arm of chromosome 11 del 11(q23). This a cytogenetic abnormality that occurs in 7 percent to 20 percent of RARS cases not related to poor prognosis. It seems that this deletion is a marker of iron overload in MDS.