Expression of hepcidin in hereditary hemochromatosis: evidence for a regulation in response to the serum transferrin saturation and to non-transferrin-bound iron

Blood ◽  
2003 ◽  
Vol 102 (1) ◽  
pp. 371-376 ◽  
Author(s):  
Sven G. Gehrke ◽  
Hasan Kulaksiz ◽  
Thomas Herrmann ◽  
Hans-Dieter Riedel ◽  
Karin Bents ◽  
...  
Keyword(s):  
Iron Overload ◽  
Serum Ferritin ◽  
Iron Homeostasis ◽  
Iron Status ◽  
Hereditary Hemochromatosis ◽  
Transferrin Saturation ◽  
Serum Transferrin ◽  
Transcript Levels ◽  
Hepcidin Expression

Abstract Experimental data suggest the antimicrobial peptide hepcidin as a central regulator in iron homeostasis. In this study, we characterized the expression of human hepcidin in experimental and clinical iron overload conditions, including hereditary hemochromatosis. Using quantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we determined expression of hepcidin and the most relevant iron-related genes in liver biopsies from patients with hemochromatosis and iron-stain-negative control subjects. Regulation of hepcidin mRNA expression in response to transferrin-bound iron, non-transferrin-bound iron, and deferoxamine was analyzed in HepG2 cells. Hepcidin expression correlated significantly with serum ferritin levels in controls, whereas no significant up-regulation was observed in patients with hemochromatosis despite iron-overload conditions and high serum ferritin levels. However, patients with hemochromatosis showed an inverse correlation between hepcidin transcript levels and the serum transferrin saturation. Moreover, we found a significant correlation between hepatic transcript levels of hepcidin and transferrin receptor-2 irrespective of the iron status. In vitro data indicated that hepcidin expression is down-regulated in response to non-transferrin-bound iron. In conclusion, the presented data suggest a close relationship between the transferrin saturation and hepatic hepcidin expression in hereditary hemochromatosis. Although the causality is not yet clear, this interaction might result from a down-regulation of hepcidin expression in response to significant levels of non-transferrin-bound iron. (Blood. 2003;102:371-376)

scholarly journals Hereditary hemochromatosis: insights from the Hemochromatosis and Iron Overload Screening (HEIRS) Study

Hematology ◽  
2009 ◽  
Vol 2009 (1) ◽  
pp. 195-206 ◽  
Author(s):  
Gordon D. McLaren ◽  
Victor R. Gordeuk
Keyword(s):  
Iron Overload ◽  
Ethnic Groups ◽  
Serum Ferritin ◽  
Iron Status ◽  
Hereditary Hemochromatosis ◽  
Transferrin Saturation ◽  
Phenotypic Expression ◽  
Inherited Disorders ◽  
Iron Stores ◽  
The Us

Abstract Hemochromatosis comprises a group of inherited disorders resulting from mutations of genes involved in regulating iron metabolism. The multicenter, multi-ethnic Hemochromatosis and Iron Overload Screening (HEIRS) Study screened ~100,000 participants in the US and Canada, testing for HFE mutations, serum ferritin and transferrin saturation. As in other studies, HFE C282Y homozygosity was common in Caucasians but rare in other ethnic groups, and there was a marked heterogeneity of disease expression in C282Y homozygotes. Nevertheless, this genotype was often associated with elevations of serum ferritin and transferrin saturation and with iron stores of more than four grams in men but not in women. If liver biopsy was performed, in some cases because of evidence of hepatic dysfunction, fibrosis or cirrhosis was often found. Combined elevations of serum ferritin and transferrin saturation were observed in non-C282Y homozygotes of all ethnic groups, most prominently Asians, but not often with iron stores of more than four grams. Future studies to discover modifier genes that affect phenotypic expression in C282Y hemochromatosis should help identify patients who are at greatest risk of developing iron overload and who may benefit from continued monitoring of iron status to detect progressive iron loading.

scholarly journals Increased Serum Transferrin Saturation Is Associated with Lower Serum Transferrin Receptor Concentration

1999 ◽  
Vol 45 (12) ◽  
pp. 2191-2199 ◽  
Author(s):  
Anne C Looker ◽  
Mark Loyevsky ◽  
Victor R Gordeuk
Keyword(s):  
Iron Deficiency ◽  
Iron Overload ◽  
Transferrin Receptor ◽  
Iron Status ◽  
Transferrin Saturation ◽  
Reference Interval ◽  
Serum Transferrin ◽  
Reactive Protein ◽  
Serum Transferrin Receptor ◽  
Health And Nutrition

Abstract Background: Serum transferrin receptor (sTfR) concentrations are increased in iron deficiency. We wished to examine whether they are decreased in the presence of potential iron-loading conditions, as reflected by increased transferrin saturation (TS) on a single occasion. Methods: We compared sTfR concentrations between 570 controls with normal iron status and 189 cases with increased serum TS on a single occasion; these latter individuals may be potential cases of iron overload. Cases and controls were selected from adults who had been examined in the third National Health and Nutrition Examination Survey (1988–1994) and for whom excess sera were available to perform sTfR measurements after the survey’s completion. Increased TS was defined as >60% for men and >55% for women; normal iron status was defined as having no evidence of iron deficiency, iron overload, or inflammation indicated by serum ferritin, TS, erythrocyte protoporphyrin, and C-reactive protein. Results: Mean sTfR and mean log sTfR:ferritin were ∼10% and 24% lower, respectively, in cases than in controls (P <0.002). Cases were significantly more likely to have an sTfR value <2.9 mg/L, the lower limit of the reference interval, than were controls (odds ratio = 1.8; 95% confidence interval, 1.04–2.37). Conclusion: Our results support previous studies that suggested that sTfR may be useful for assessing high iron status in populations.

Iron Overload in C282Y Heterozygotes: Identification of New Rare HFE Gene Mutants and a Step Strategy for Diagnosis.

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 1859-1859
Author(s):  
Patricia Aguilar-Martinez ◽  
Severine Cunat ◽  
Fabienne Becker ◽  
Francois Blanc ◽  
Marlene Nourrit ◽  
...  
Keyword(s):  
Iron Overload ◽  
Iron Status ◽  
Hereditary Hemochromatosis ◽  
Genetic Defect ◽  
Transferrin Saturation ◽  
Hfe Gene ◽  
Compound Heterozygous ◽  
Exon 2 ◽  
High Iron ◽  
Iron Parameters

Abstract Introduction: Homozygozity for the p.Cys282Tyr (C282Y) mutation of the HFE gene is the main genotype associated with the common form of adult hereditary hemochromatosis. C282Y carriers do not usually develop iron overload, unless they have additional risk factors such as liver diseases, a dysmetabolic syndrome or an associated genetic defect. The commonest is the compound heterozygous state for C282Y and the widespread p.His63Asp (H63D) variant allele. However, a few rare HFE mutations can be found on the 6th chromosome in trans, some of which are of clinical interest to fully understand the disorder. Patients and Methods: We recently investigated four C282Y carrier patients with unusually high iron parameters, including increased levels of serum ferritin (SF), high transferrin saturation (TS) and high iron liver content measured by MRI. They were males, aged 37, 40, 42, 47 at diagnosis. Two brothers (aged 40 and 42) were referred separately. The HFE genotype, including the determination of the C282Y, H63D and S65C mutations was performed using PCR-RFLP. HFE sequencing was undertaken using the previously described SCA method (1). Sequencing of other genes (namely, HAMP, HJV/HFE2, SLC40A1, TFR2) was possibly performed in a last step using the same method. Results: We identified three rare HFE mutant alleles, two of which are undescribed, in the four studied patients. One patient bore a 13 nucleotide-deletion in exon 6 (c.[1022_1034del13], p.His341_Ala345>LeufsX119), which is predicted to lead to an abnormal, elongated protein. The two brothers had a substitution of the last nucleotide of exon 2 (c.[340G>A], p.Glu114Lys) that may modify the splicing of the 2d intron. The third patient, who bore an insertion of a A in exon 4 (c.[794dupA],p.[trp267LeufsX80]), has already been reported (1). Discussion: A vast majority of C282Y carriers will not develop iron overload and can be reassured. However, a careful step by step strategy at the clinical and genetic levels may allow to correctly identify those patients deserving further investigation. First, clinical examination and the assessment of iron parameters (SF and TS) allow identifying C282Y heterozygotes with an abnormal iron status. Once extrinsic factors such as heavy alcohol intake, virus or a dysmetabolic syndrome have been excluded, MRI is very useful to authenticate a high liver iron content. Second, HFE genotype must first exclude the presence of the H63D mutation. Compound heterozygozity for C282Y and H63D, a very widespread condition in our area, is usually associated with mild iron overload. Third, HFE sequencing can be undertaken and may identify new HFE variants as described here. The two novel mutations, a frameshift modifying the composition and the length of the C terminal end of the HFE protein and a substitution located at the last base of an exon, are likely to lead to an impaired function of HFE in association with the C282Y mutant. However, it is noteworthy that three of the four patients were diagnosed relatively late, after the 4th decade, as it is the case for C282Y homozygotes. Three further unrelated patients are currently under investigation in our laboratory for a similar clinical presentation. Finally, it can be noted that in those patients who will not have a HFE gene mutant identified, analysis of other genes implicated in iron overload must be performed to search for digenism or multigenism. None of our investigated patients had an additional gene abnormality.

Interaction Between Genotypes for HFE and TFR2 Genes Mutations and Iron Status in Brazilian Blood Donors

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 5382-5382
Author(s):  
Rodolfo D Cancado ◽  
Paulo CJL Santos ◽  
Samuel Rostelato ◽  
Cristiane T Terada ◽  
Iris Gonzales ◽  
...  
Keyword(s):  
Serum Ferritin ◽  
Serum Iron ◽  
Blood Donors ◽  
Binding Capacity ◽  
Iron Status ◽  
Hereditary Hemochromatosis ◽  
Transferrin Saturation ◽  
The Body ◽  
Hfe Gene ◽  
Automation System

Abstract Hereditary hemochromatosis (HH) is a disorder characterized by increased intestinal iron absorption, which leads to a progressive accumulation of iron in the body. This iron overload has been associated with mutations in HFE gene (C282Y, H63D and S65C) and other genes. The objectives of this study were to assess the frequencies of functional mutations in HFE and TFR2 genes and to investigate their relationship with the iron status in a sample of blood donors. Blood donors (n=542) were recruited at the Hemocenter of the Santa Casa Hospital, Sao Paulo, Brazil. The genotypes for HFE (C282Y, H63D and S65C) TFR2 (Y250X and Q690P) gene mutations were evaluated by PCR-RFLP. The concentrations of serum iron and total iron-binding capacity (TIBC) were measured by automation system Advia®(Bayer Diagnostics) and serum ferritin by Axsym System®(Abbott Laboratories). The frequencies of HFE 282Y, HFE 63D and HFE 65C alleles were 2.1, 13.6 and 0.6%, respectively. The frequency C282Y allele (2.1%) in Brazilian blood donors is lower than that observed in blood donors from Northern Europe (5.1 to 8.2%, P<0.05). The TFR2 250X and TFR2 690P alleles were not found in these subjects. The iron status was similar between HFE genotypes in women. However, men carrying HFE 282CY genotype had higher serum ferritin and lower TIBC concentrations when compared to the HFE 282CC genotype carriers. HFE 282CY genotype was also associated with higher transferrin saturation in men who donated blood at the first time. Moreover, male donors with HFE 63DD plus 63HD genotypes had higher serum iron and transferrin saturation when compared to those with HFE 63HH genotype. A relationship between HFE CY/HH/SS haplotype and lower TIBC concentrations was also found in men. The HFE 282Y and HFE 65C alleles were rare while the HFE 63D was frequent in blood donors. The mutations in TFR2 gene were not found in this study. The HFE 282Y and HFE 63D alleles were associated with alterations on iron status only in male blood donors.

Lack of Association between Single Nucleotide Polymorphism rs3811647 in the TF Gene and Iron Status in Patients with Iron Deficiency and Control Subjects

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4257-4257
Author(s):  
Gordon D. McLaren ◽  
Catherine A. McCarty ◽  
Marylyn Ritchie ◽  
Stephen Turner ◽  
Victor R. Gordeuk ◽  
...  
Keyword(s):  
Iron Deficiency ◽  
Iron Overload ◽  
Serum Ferritin ◽  
Iron Status ◽  
Minor Allele ◽  
P Value ◽  
Serum Transferrin ◽  
Single Nucleotide ◽  
Multiple Measurements ◽  
Tf Gene

Abstract Abstract 4257 Iron in the plasma is bound to transferrin. The total iron binding capacity (TIBC) represents the maximum amount of iron that can be bound and is directly related to transferrin concentration. TIBC and serum transferrin concentration are increased in iron deficiency and decreased in iron overload. Recently, an association was reported between single nucleotide polymorphisms (SNPs) in the transferrin gene, TF, on chromosome 3q22.1, and serum transferrin levels (Benyamin et al. Am J Hum Genet. 2009;84:60-65). In the current study, we investigated whether the association between SNP rs3811647 in TF and transferrin levels (assessed by measurement of TIBC) is attributable to an effect on regulation of body iron status. The Personalized Medicine Research Project (PMRP) is the largest population-based biobank in the US containing genetic, phenotypic and environmental information on approximately 20,000 people. PMRP is part of the NHGRI-funded eMERGE (www.gwas.net) network. Previously, genotyping was performed on selected PMRP samples with the Illumina Human660W-Quad BeadChip platform. Eligible participants in the current study were 491 white men age ≥ 25 y and 747 white women ≥ 50 y with serum ferritin (SF) values collected between 1985 and 2010. Exclusion criteria included a diagnosis of celiac disease and previous phlebotomy treatment for hemochromatosis. Using TIBC as a marker of serum transferrin for eligible participants having multiple measurements, mean TIBC and median serum ferritin were considered in analyses. Subsets of participants included cases of iron deficiency with multiple measurements of SF ≤ 12 μg/L and iron-replete controls (all measurements of SF > 100 μg/L in men, all SF > 50 μg/L in women). Regression analysis was used to examine the association between outcomes (case-control status, natural log of serum ferritin, TIBC) and each of 54 SNPs, adjusted for gender. These SNPS included three in iron genes (rs3811647 in TF, rs1800562 in HFE, and rs2302591 in FLVCR2) and were selected for analysis on the basis of a GWAS of iron-related measures conducted in a separate study of iron deficient cases and iron-replete controls identified in the Hemochromatosis and Iron Overload Screening (HEIRS) Study. Statistical significance was defined as a SNP showing a p-value for association less than 0.001; the threshold is based on a nominal alpha of 0.05 with Bonferroni multiple test correction for the total number of SNPs analyzed. Genotypes were coded as 0, 1, or 2, indicating the number of copies of the less frequent of the two alleles in the genotype. Values for mean TIBC were analyzed for 1175 individuals (726 women, 449 men); median SF was analyzed for 1143 participants (693 women, 450 men). In the subset analyses, there were 258 cases with iron deficiency and 505 controls. The strongest statistical evidence for association with TIBC was found for SNP rs3811647 in the TF gene (observed p-value = 6.05 × 10-6, adjusted for gender). The minor allele frequency for SNP rs3811647 was 0.34. The regression slope parameter was 14.5, indicating that increasing copies of the minor allele were associated with increasing levels of TIBC. In contrast, there was no significant association with SF (observed p=0.22) or case vs. control status (odds ratio 1.26, observed p=0.21), adjusted for gender. For the C282Y mutation in the HFE gene, increasing copies of the minor allele were associated with decreasing levels of TIBC (observed p-value = 0.002, adjusted for gender). The fact that SNP rs3811647 in the TF gene was associated with TIBC levels but showed no significant association with either serum ferritin or the presence of iron deficiency does not support a role for the SNP in regulation of body iron status. Thus, the SNP may affect TIBC independently of iron status. Elevation of transferrin levels could help withhold iron from microorganisms, conferring protection from infection. Use of TIBC as an index of iron deficiency may be confounded by the existence in the population of the minor allele in the rs3811647 genotype, resulting in elevation of TIBC without a corresponding decrease in body storage iron. Disclosures: No relevant conflicts of interest to declare.

Target TMPRSS6 for the Treatment of Hereditary Hemochromatosis

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. 1047-1047
Author(s):  
Sheri Booten ◽  
Daniel Knox ◽  
Luis Alvarado ◽  
Shuling Guo ◽  
Brett P. Monia
Keyword(s):  
Iron Overload ◽  
Genetic Disorder ◽  
Hereditary Hemochromatosis ◽  
Genetic Defect ◽  
Transferrin Saturation ◽  
Common Mutation ◽  
C282y Mutation ◽  
Iron Storage ◽  
Hepcidin Expression ◽  
Iron Deficient

Abstract Abstract 1047 Hereditary hemochromatosis (HH) is a genetic disorder in which hyperabsorption of dietary iron leads to accumulation of iron in multiple tissues including liver and heart. A common clinical manifestation in HH patients is cirrhosis and hepatocellular carcinoma as a result of iron-mediated injury in liver. The most prevalent genetic defect for HH is the failure to up-regulate hepcidin, a peptide hormone that inhibits the absorption of iron in duodenum and the release of iron from intracellular iron storage such as macrophages. Mutations in a number of genes have been identified as the cause for HH, including hepcidin itself. However, the most common mutation is C282Y mutation in HFE, which is a positive regulator for hepcidin expression. C282Y mutation represents about 85% of the HH population. HFE C282Y HH is an autosomal recessive disease with a ∼50% penetrance. Currently, the only treatment available for iron overload is phlebotomy which will continue throughout the patient's life. Hepcidin is mainly expressed and secreted by the liver and its expression is regulated predominantly at the transcription level. TMPRSS6, a transmembrane serine protease mutated in iron-refractory, iron-deficient anemia, is a major suppressor for hepcidin expression. It's been demonstrated that hepcidin expression is significantly elevated in Tmprss6−/− mice and reduction of TMPRSS6 in Hfe−/− mice could ameliorate the iron overload phenotype (Du et al. Science 2008; Folgueras et al. Blood 2008; Finberg KE et al., Blood, 2011). Using second generation antisense technology, we identified antisense oligonucleotides (ASOs) targeting mouse TMPRSS6 for the treatment of HH. These compounds were first identified through in vitro screens in mouse primary hepatocytes. After 4 weeks of treatment in C57BL/6 mice on normal chow, we observed an 80% to 90% reduction of liver TMPRSS6 mRNA with a subsequent 2–3 fold induction of liver hepcidin mRNA. Serum iron and transferrin saturation levels were reduced by ∼50%. These ASOs are currently being evaluated in a diet-induced iron overload model and an Hfe−/− iron overload model. Our preliminary results demonstrate that targeting TMPRSS6 is a viable approach for the treatment of hereditary hemochromatosis and possibly other iron-loading diseases associated with suppressed hepcidin levels. Disclosures: Booten: Isis Pharmaceuticals: Employment. Knox:Isis Pharmaceuticals: Summer Intern. Alvarado:Isis Pharmaceuticals: Employment. Guo:Isis Pharmaceuticals: Employment. Monia:Isis Pharmaceuticals: Employment.

Role of Magnetic Ressonance Imaging – T2* in Hereditary Hemochromatosis.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2096-2096
Author(s):  
Reijane Alves de Assis ◽  
Fernando Uliana Kay ◽  
Paulo Vidal Campregher ◽  
Gilberto Szarf ◽  
Fabiana Mendes Conti ◽  
...  
Keyword(s):  
Iron Overload ◽  
Serum Ferritin ◽  
Conflicts Of Interest ◽  
Hereditary Hemochromatosis ◽  
Transferrin Saturation ◽  
Laboratory Data ◽  
Surrogate Marker ◽  
Control Group ◽  
Double Mutation ◽  
H63d Mutation

Abstract Abstract 2096 Introduction: Hereditary hemochromatosis (HH) is an autossomic recessive disorder characterized by increased iron absorption. Magnetic resonance imaging – T2* (MRI-T2*) has become a reliable and robust methodology to directly assess the iron burden, with better results in transfusional hemosiderosis compared to indirect methods, such as serum ferritin and transferrin saturation (TS). However, little is known about its role in HH. Objectives: Describe the demographic profile of HH type 1 patients as to the type of the HFE mutation and correlate laboratory parameters to MRI-T2*results. Methods: We collected data from patients with a positive HFE gene mutation who performed abdominal and/or cardiac MRI-T2* in our institution from 2004 to 2011. Images retrieved from the digital archive were analyzed by two blinded independent radiologists using the Thalassemia-Tools software (Cardiovascular Imaging Solutions, London, UK). Laboratory data available within 6 months before or after the MRI study were analyzed using the t-Student test, Exact Fisher's test analysis and multivariate analyses. Results: We analyzed 81 patients, 76 (93%) males and 5 (6.2%) females, with a median age of 48 years (21–80). Liver, pancreatic and splenic MRI-T2*values and LIC calculation were performed in 80 patients, and cardiac T2* assessment in 57 patients. The inter-observer T2* variation coefficient was 5%. Serum ferritin was abnormal in 70 patients (90.9%), while TS was abnormal in 34% of the tests. In our study sample, the H63D mutation was present in 70 patients (86.4%): 11 (13.6%) were homozygous, 59 (72.8%) heterozygous and 7 (8.6%) double heterozygous for C282Y/H63D. Only three patients (3.7%) were homozygous and 6 (7.4%) were heterozygous only for the C282Y mutation. The S65C mutation was detected in heterozygous state in 2 (2.5%) of cases. Two out 57 cases had a positive T2* result and were classified as light cardiac overload (T2*:18.98 e 19.14 ms). Both had the H63D mutation (1 homozygous and 1 heterozygous). Thirty seven out of 80 patients (46.3%) had liver overload in abdominal MRI (T2*: 3.8–11.4ms), being 33 (41.3%) light overload and four (5%) moderate overload (T2*:1.8–3.8ms). We found that 77.8% of patients with liver overload were C282Y carriers, of which 57.2% had double mutation and 40.3% had H63D mutation in hetero or homozigosity. Pancreatic overload was found in 20 patients (25.1%), while 30 patients (37.5%) had splenic overload. There was a slight correlation (r: 0.365) between liver T2* and splenic T2* (p=0.001). The presence of C282Y and H63D mutations was statistically associated with a higher frequency of abnormal liver T2* (p=0.017 and p=0.042, respectively). The H63D mutation was associated with iron accumulation in the liver (p=0,037) and homozygous carriers showed higher levels of liver overload (p=0,038). Conclusion: In our study, serum ferritin was a better surrogate marker for iron overload than ST. In addition, up to 40.3% of patients with H63D mutation had evidence of hepatic iron overload by MRI. These findings differ from the currente literature. The higher RMI positivity might be due to a higher sensitivity to detect lower levels of organic iron. Despite the lack of a control group and laboratory tests or MRI in all the cases studied, our results suggest that RMI-T2* is a promising methodology to guide the therapeutic management of HH patients. The clinical impact of this finding must be investigated in further studies. Disclosures: No relevant conflicts of interest to declare.

Target TMPRSS6 Using Antisense Technology for the Treatment of Hereditary Hemochromatosis and β-Thalassemia

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 481-481 ◽  
Author(s):  
Shuling Guo ◽  
Carla Casu ◽  
Sara Gardenghi ◽  
Sheri Booten ◽  
Andy Watt ◽  
...  
Keyword(s):  
Treatment Group ◽  
Iron Overload ◽  
Hereditary Hemochromatosis ◽  
Iron Concentration ◽  
Transferrin Saturation ◽  
Control Group ◽  
Mrna Levels ◽  
Liver Iron ◽  
Hepcidin Expression ◽  
Antisense Technology

Abstract Abstract 481 Hepcidin, the master regulator of iron homeostasis, is a peptide that is mainly expressed and secreted by the liver. Low levels of hepcidin are associated with increased iron absorption. In conditions in which hepcidin is chronically repressed, such as hereditary hemochromatosis and b-thalassemia, patients suffer from iron overload and very severe pathophysiological sequelae associated with this condition. Hepcidin expression is regulated predominantly at the transcriptional level by multiple factors. TMPRSS6, a transmembrane serine protease mutated in iron-refractory, iron-deficient anemia, is a major suppressor of hepcidin expression. It has been demonstrated that hepcidin expression is significantly elevated in Tmprss6−/− mice and reduction of Tmprss6 expression in hereditary hemochromatosis (Hfe−/−) mice ameliorates the iron overload phenotype (Finberg et al. Nature Genetics, 2008; Du et al. Science 2008; Folgueras et al. Blood 2008; Finberg et al., Blood, 2011). It has also been demonstrated that hepcidin up-regulation using either a hepcidin transgene or Tmprss6−/− significantly improves iron overload and anemia in a mouse model of β-thalassemia intermedia (th3/+ mice) (Gardenghi et al. JCI, 120:4466, 2010; Nai et al. Blood, 119: 5021, 2012). In this report, we have examined whether reduction of Tmprss6 expression using antisense technology is an effective approach for the treatment of hereditary hemochromatosis and β-thalassemia. Second generation antisense oligonucleotides (ASOs) targeting mouse Tmprss6 were identified. When normal male C57BL/6 mice were treated with 25, 50 and 100mg/kg/week ASO for four weeks, we achieved up to >90% reduction of liver Tmprss6 mRNA levels and up to 5-fold induction of hepcidin mRNA levels in a dose-dependent manner. Dose-dependent reductions of serum iron and transferrin saturation were also observed. ASOs were well tolerated in these animals. In Hfe−/− mice (both males and females), ASOs were administrated at 100 mg/kg for six weeks. This treatment normalized transferrin saturation (from 92% in control animals to 26% in treatment group) and significantly reduced serum iron (from >300ug/dl in control group to <150ug/dl in treatment group), as well as liver iron accumulation. Histopathological evaluation and Prussian's Perl Blue staining indicated that iron was sequestered by macrophages, which led to an increase in spleen iron concentration. The mouse model of thalassemia intermedia that we utilized mimics a condition defined as non-transfusion dependent thalassemia (NTDT) in humans. These patients exhibit increased iron absorption and iron overload due to ineffective erythropoiesis and suppression of hepcidin; iron overload is the most frequent cause of morbidity and mortality. Th3/+ animals exhibit ineffective erythropoiesis, characterized by increased proliferation and decreased differentiation of the erythroid progenitors, apoptosis of erythroblasts due to the presence of toxic hemichromes, reticulocytosis and shorter lifespan of red cells in circulation, leading to splenomegaly, extramedullary hematopoiesis and anemia (∼ 8 g/dL; Libani et al, Blood 112(3):875–85, 2008). Five month old th3/+ mice (both males and females) were treated with Tmprss6 ASO for six weeks. In th3/+ mice, ∼85% Tmprss6 reduction led to dramatic reductions of serum transferrin saturation (from 55–63% in control group down to 20–26% in treatment group). Liver iron concentration (LIC) was also greatly reduced (40–50%). Moreover, anemia endpoints were significantly improved with ASO treatment, including increases in red blood cells (∼30–40%), hemoglobin (∼2 g/dl), and hematocrit (∼20%); reduction of splenomegaly (∼50%); decrease of serum erythropoietin levels (∼50%); improved erythroid maturation as indicated by a strong reduction in reticulocyte number (50–70%) and in a normalized proportion between the pool of erythroblasts and enucleated erythroid cells. Hemichrome analysis showed a significant decrease in the formation of toxic alpha-globin/heme aggregates associated with the red cell membrane. This was consistent with a remarkable improvement of the red cell distribution width (RDW) as well as morphology of the erythrocytes. In conclusion, these data demonstrate that targeting TMPRSS6 using antisense technology is a promising novel therapy for the treatment of hereditary hemochromatosis and β-thalassemia. Disclosures: Guo: Isis Pharmaceuticals: Employment. Booten:Isis Pharmaceuticals: Employment. Watt:Isis Pharmaceuticals: Employment. Freier:Isis Pharmaceuticals: Employment. Rivella:Novartis Pharmaceuticals: Consultancy; Biomarin: Consultancy; Merganser Biotech: Consultancy, Equity Ownership, Research Funding; Isis Pharma: Consultancy, Research Funding. Monia:Isis Pharmaceuticals: Employment.

Hereditary Hemochromatosis in an Adult Due to H63D Mutation: The Value of Estimating Iron Deposition By MRI T2* and Dissociation Between Serum Ferritin Concentration and Hepatic Iron Overload

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4891-4891
Author(s):  
Mohamed A. Yassin ◽  
Ashraf T Soliman ◽  
Vincenzo Desanctis ◽  
Sandara Abusamaan ◽  
Ahmed Elsotouhy ◽  
...  
Keyword(s):  
Iron Overload ◽  
Basal Ganglion ◽  
Serum Ferritin ◽  
Normal Values ◽  
Hereditary Hemochromatosis ◽  
Transferrin Saturation ◽  
Iron Deposition ◽  
Ferritin Concentration ◽  
H63d Mutation ◽  
Serum Ferritin Concentration

Abstract Hereditary hemochromatosis (HH) is an autosomal recessive disorder characterized by excessive intestinal absorption of dietary iron, causing iron overload in different organs, especially the liver. Hemochromatosis may not be recognized until later in life. Patients are usually asymptomatic but may present with a variety of signs and symptoms. These include: hyper-pigmented skin, hepatomegaly, arthralgia, diabetes mellitusand/or heart failure/arrhythmia. The risk of HH related morbidity in HFE compound homozygotes patients (H63D /H63D) is considered rare, we report a male patient with H63D mutation who developed impaired glucose tolerance, and high hepatic enzymes due to significant iron accumulation in the liver as well as Parkinsonian-like syndrome due to iron deposition in the basal ganglia. A 40 year old Qatari male was referred for evaluation of a rise in hemoglobin and hematocrit values with normal MCV, total leucocyte and platelet counts. The patient was asymptomatic with normal vital signs, no depigmentation or hepato-splenomegaly. Hematologic findings included a hemoglobin concentration of Hb 16.5 g/dL, hematocrit 53%, mean corpuscular volume (MCV) 93 fL/red cell, leucocyte count of 7200/ μL and a platelet count of 199000/μL. His serum ferritin was 359 μg/l ( normal values: < 336 μg/l), serum iron: 37 μmol/l ( normal values <28.6μmol/l), fasting transferrin saturation: 64% (normal < 50%). A random glucose 6.5 and 6.4 mmol/L (normal values 5.5mmol/L ), A1C of 5,4 %, normal creatinine and electrolytes, alanine aminotransferase (ALT) of 66 U/l (normal < 40U/l), mild elevation of bilirubin 39 umol/l (normal <24umol/l), normal U&E Hepatitis B and C antibodies were negative. OGTT revealed impaired glucose tolerance. Thyroid function, morning serum cortisol, LH and FSH and serum total testosterone concentrations were in the normal range. A diagnosis of polycythemia vera was excluded on the basis of WHO Criteria 2008. The polymerase chain restriction assay was negative for the common mutation (C282Y) but positive for H63 D mutation. Family screening confirmed HH in his brother (homozygous), whereas his mother, two brothers and the sister were carriers (heterozygous). His four offspring were carriers. This suggested an autosomal recessive mode of inheritance. Conventional MRI study showed a normal liver size with diffuse fatty changes and focal areas of fatty sparing with some evidence of iron deposition. Whereas, T2-star (T2*) sequences showed a diffuse and significant decrease in liver signal intensity. A LIC liver concentration of 27 mg Fe/g dry wt was found (normalvalues:< 2 mg Fe/g dry wt; severe iron overload: ≥15 mg Fe/g dry wt). No significant iron deposition in the spleen, heart or pancreas was observed. At the age of 41 years the patient complained of tremors in both hands and arms while sitting or standing still (resting tremor) that improved with hands movements. A brain MRI revealed iron deposition in the basal ganglion. It was concluded that basal ganglionicn iron deposition mediated the neurological decline. Currently, the transferrin saturation and serum ferritin levels are within normal. Discussion: This is the first case of HH secondary to H63 D among an Arab family and the first reported case of Parkinsonism tremors secondary to this mutation. The H63D HFE variant is less frequently associated with HH, but its role in the neurodegenerative diseases has received a great attention. An accurate evaluation of iron overload is necessary to establish the diagnosis of HH and to guide iron chelation in HH by determination of liver iron concentration (LIC) by means of T2* MRI. Although serum ferritin concentration was only mildly increased a significant siderosis in the liver was detected by MRI T2* technique occurred. Liver siderosis was associated with mild impairment of liver function (increased serum ALT and bilirubin ). Conclusion: Our data further confirm that serum ferritin levels are not an accurate measure of total body iron stores in HH. Iron deposition in the liver and basal ganglion occurred despite mild elevation of ferritin. changes in basal ganglion may present by parkinsonian like tremors in these patients Use,T2* MRI should be encouraged in patients with HH for better evaluation of Iron overload and avoidance of Complications since serum ferritin can be misleading in these conditions. Disclosures Yassin: Qatar National research fund: Patents & Royalties, Research Funding. Aldewik:Qatar Ntional Research Fund: Patents & Royalties, Research Funding.

Elevated MCV in Patients with Hereditary Hemochromatosis.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 3733-3733
Author(s):  
Sameh E. Mikhail ◽  
Pradyumna D. Phatak
Keyword(s):  
Serum Ferritin ◽  
Hereditary Hemochromatosis ◽  
Transferrin Saturation ◽  
Serum Transferrin ◽  
Weak Correlation ◽  
The Mean ◽  
Relationship Of ◽  
The Relationship ◽  
Hfe Mutation ◽  
C282y Hfe Mutation

Abstract Background: Previous studies have reported that patients with Hereditary Hemochromatosis have higher red cell volumes than normal controls. The relationship of this abnormality to the degree of iron overload and to HFE genotype has not been systematically studied. Method: We retrospectively compared the mean corpuscular volume (MCV) of patients with Hereditary Hemochromatosis with that of an age-, race- and sex-matched control population from the primary care clinic at our institution. We studied the relationship of MCV at diagnosis with serum transferrin saturation, serum ferritin level, phlebotomy-mobilizable iron stores and HFE genotype in our patients. Results: The study population included 290 patients who were treated for Hereditary Hemochromatosis at our center. 122/290 were homozygous for C282Y; the mean MCV of this group was significantly elevated at 95.2 fL (control group was 89.2 fL; p<0.001) Among all patients with phlebotomy-mobilizable iron greater than four grams, regardless of HFE genotype, the mean MCV was 94.8 fL (significantly greater than control, p<0.001); there was no significant difference between those who are homozygous for the C282Y HFE mutation and those who are not. Among C282Y homozygous individuals, there was no significant correlation between the MCV versus serum transferrin saturation, serum ferritin and phlebotomy-mobilizable iron (r= 0.07, 0.207 and −0.005 respectively). In patients with mobilizable iron greater than four grams who were not C282Y homozygous there was weak correlation between the MCV versus serum transferrin saturation and serum ferritin (r= 0.39 and 0.37 respectively) and no significant correlation versus phlebotomy-mobilizable iron (r= 0.04). Conclusion: Our study confirms the presence of elevated MCV levels in patients with Hereditary Hemochromatosis. The mean MCV was high in both C282Y homozygous individuals as well as those with elevated levels of body iron (>4 g) who were not homozygous for the C282Y HFE mutation. For the most part, the elevated MCV did not correlate with measures of body iron stores although there was a weak correlation with serum transferrin saturation and serum ferritin among iron-loaded individuals who were not homozygous for C282Y. Further studies of the factors that influence MCV in these patients may provide insights into the derangements of iron utilization that may occur in iron overload syndromes.

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