Frequency and biochemical expression of C282Y/H63D hemochromatosis (HFE) gene mutations in the healthy adult population in Italy

Interventions for hereditary haemochromatosis: an attempted network meta-analysis

BACKGROUND

Hereditary haemochromatosis is a genetic disorder related to proteins involved in iron transport, resulting in iron load and deposition of iron in various tissues of the body. This iron overload leads to complications including liver cirrhosis (and related complications such as liver failure and hepatocellular carcinoma), cardiac failure, cardiac arrhythmias, impotence, diabetes, arthritis, and skin pigmentation. Phlebotomy (venesection or 'blood letting') is the currently recommended treatment for hereditary haemochromatosis. The optimal treatment of hereditary haemochromatosis remains controversial.

OBJECTIVES

To assess the comparative benefits and harms of different interventions in the treatment of hereditary haemochromatosis through a network meta-analysis and to generate rankings of the available treatments according to their safety and efficacy. However, we found only one comparison. Therefore, we did not perform the network meta-analysis and we assessed the comparative benefits and harms of different interventions using standard Cochrane methodology.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, Science Citation Index Expanded, World Health Organization International Clinical Trials Registry Platform, and randomised clinical trials registers to March 2016 to identify randomised clinical trials on treatments for hereditary haemochromatosis.

SELECTION CRITERIA

We included only randomised clinical trials (irrespective of language, blinding, or publication status) in participants with hereditary haemochromatosis. We excluded trials which included participants who had previously undergone liver transplantation. We considered any of the various interventions compared with each other or with inactive treatment.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. We calculated the odds ratio (OR) and rate ratio with 95% confidence intervals (CI) using both fixed-effect and random-effects models with RevMan 5 based on available-participant analysis. We assessed risk of bias according to Cochrane, controlled risk of random errors with Trial Sequential Analysis, and assessed the quality of the evidence using GRADE.

MAIN RESULTS

Three trials with 146 participants met the inclusion criteria of this review. Two parallel group trials with 100 participants provided information on one or more outcomes. The remaining trial was a cross-over trial, with no usable data for analysis. All the trials were at high risk of bias. Overall, all the evidence was of very low quality. All three trials compared erythrocytapheresis (removal of red cells only, instead of whole blood) versus phlebotomy. Two of the trials shared the same first author. The mean or median age in the three trials ranged from 42 to 55 years. None of the trials reported whether the included participants were symptomatic or asymptomatic or a mixture of both. Two trials were conducted in people who were haemochromatosis treatment-naive. The trial that provided most data for this review excluded people with malignancy, heart failure, and serious cardiac arrhythmias. We found no trials assessing iron-chelating agents.Only one of the trials with 38 participants reported no short-term mortality and no serious adverse events at the end of the short-term follow-up (eight months). Two trials reported the proportion of people with adverse events: 10/49 (20.4%) in the erythrocytapheresis group versus 11/51 (21.6%) in the phlebotomy group. One of these two trials provided data on adverse event rates (42.1 events per 100 participants with erythrocytapheresis versus 52.6 events per 100 participants with phlebotomy). There was no evidence of differences in the proportion of people with adverse events and the number of adverse events (serious and non-serious) between the groups (proportion of people with adverse events: OR 0.93, 95% CI 0.36 to 2.43; participants = 100; trials = 2; number of adverse events: rate ratio 0.80, 95% CI 0.32 to 2.03; participants = 38; trial = 1). There was no difference between the groups regarding short-term health-related quality of life (mean difference (MD) 1.00, 95% CI -10.80 to 12.80; participants = 38; trials = 1). This outcome was measured using EQ-VAS (range: 0 to 100 where a higher score indicates better health-related quality of life). None of the trials reported mortality beyond one year, health-related quality of life beyond one year, liver transplantation, decompensated liver disease, cirrhosis, hepatocellular carcinoma, diabetes, or cardiovascular complications during the long-term follow-up.The two trials that provided data for this review were funded by parties with no vested interest in the results; the source of funding of the third trial was not reported.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to determine whether erythrocytapheresis is beneficial or harmful compared with phlebotomy. Phlebotomy has less equipment requirements and remains the treatment of choice in people with hereditary haemochromatosis who require blood letting in some form. However, it should be noted that there is no evidence from randomised clinical trials that blood letting in any form is beneficial in people with hereditary haemochromatosis. Having said this, a trial including no treatment is unlikely to be conducted. Future trials should compare different frequencies of phlebotomy and erythrocytapheresis versus phlebotomy with and without different iron-chelating agents compared with each other, and with placebo. Such trials should include long-term follow-up of participants (e.g. using national record linkage databases) to determine whether treatments are beneficial or harmful in terms of clinical outcomes such as deaths, health-related quality of life, liver damage and its consequences, heart damage and its consequences, and other outcomes that are of importance to people with hereditary haemochromatosis.

Haplotype Analysis of Hemochromatosis Gene Polymorphisms in Chronic Hepatitis C Virus Infection: A Case Control Study

Background

Chronic hepatitis C virus (HCV) infection is frequently associated with elevated serum iron markers. Polymorphisms in the hemochromatosis (HFE) genes are responsible for iron accumulation in most cases of hemochromatosis, and may play a role in HCV infection.

Objectives

We aimed to assess the prevalence of HFE gene polymorphisms in a group of Iranian HCV-infected patients, and to explore the association of these polymorphisms with HCV infection.

Patients and Methods

HFE gene polymorphisms were examined in a total of 69 HCV patients and 69 healthy controls using polymerase chain reaction and restriction fragment length polymorphism techniques. Haplotype and diplotype analyses were performed using PHASE software.

Results

In a recessive analysis model of the His63Asp (H63D) locus (HH vs. HD + DD), the HH genotype was more common in patients compared to controls (adjusted P = 0.012; OR = 6.42 [95% CI: 1.51 - 27.33]). Also, in a recessive analysis model of the Cys282Tyr (C282Y) locus (CC vs. CY + YY), the CC genotype was more frequent in patients compared to controls (adjusted P = 0.03; OR = 5.06 [95% CI: 1.13 - 22.06]). In addition, there was a significant association between the HC haplotype and the HCDC diplotype and HCV infection.

Conclusions

Polymorphism in the hemochromatosis gene may confer some degree of risk for HCV infection, and individuals carrying the H and C alleles may be susceptible to this disease; however, a larger sample of HCV patients and healthy individuals may be necessary to further illustrate the role of these polymorphisms in HCV.

The evolutionary adaptation of the C282Y mutation to culture and climate during the European Neolithic

OBJECTIVES

The C282Y allele is the major cause of hemochromatosis as a result of excessive iron absorption. The mutation arose in continental Europe no earlier than 6,000 years ago, coinciding with the arrival of the Neolithic agricultural revolution. Here we hypothesize that this new Neolithic diet, which originated in the sunny warm and dry climates of the Middle East, was carried by migrating farmers into the chilly and damp environments of Europe where iron is a critical micronutrient for effective thermoregulation. We argue that the C282Y allele was an adaptation to this novel environment.

MATERIALS AND METHODS

To address our hypothesis, we compiled C282Y allele frequencies, known Neolithic sites in Europe and climatic data on temperature and rainfall for statistical analysis.

RESULTS

Our findings indicate that the geographic cline for C282Y frequency in Europe increases as average temperatures decrease below 16°C, a critical threshold for thermoregulation, with rainy days intensifying the trend.

DISCUSSION

The results indicate that the deleterious C282Y allele, responsible for most cases of hemochromatosis, may have evolved as a selective advantage to culture and climate during the European Neolithic.

Association Studies of HFE C282Y and H63D Variants with Oral Cancer Risk and Iron Homeostasis Among Whites and Blacks

Background: Polymorphisms in the hemochromatosis (HFE) gene are associated with excessive iron absorption from the diet, and pro-oxidant effects of iron accumulation are thought to be a risk factor for several types of cancer. Methods: The C282Y (rs1800562) and H63D (rs1799945) polymorphisms were genotyped in 301 oral cancer cases and 437 controls and analyzed in relation to oral cancer risk, and serum iron biomarker levels from a subset of 130 subjects. Results: Individuals with the C282Y allele had lower total iron binding capacity (TIBC) (321.2 ± 37.2 µg/dL vs. 397.7 ± 89.0 µg/dL, p = 0.007) and higher percent transferrin saturation (22.0 ± 8.7 vs. 35.6 ± 22.9, p = 0.023) than wild type individuals. Iron and ferritin levels approached significantly higher levels for the C282Y allele (p = 0.0632 and p = 0.0588, respectively). Conclusions: Iron biomarker levels were elevated by the C282Y allele, but neither (rs1800562) nor (rs1799945) was associated with oral cancer risk in blacks and whites.

Diagnostic utility of HFE variants in Spanish patients: association with HLA alleles and role in susceptibility to acute lymphoblastic leukemia

Two single nucleotide polymorphisms (SNPs) in the Human Hemochromatosis (HFE) gene, C282Y and H63D, are the major variants associated to altered iron status and it is well known that these mutations are in linkage disequilibrium with certain Human Leukocyte Antigen (HLA)-A alleles. In addition, the C282Y SNP has been previously suggested to confer susceptibility to acute lymphoblastic leukemia (ALL). We have aimed to assess the diagnosis utility of these polymorphisms in a population of Spanish subjects with suspicion of hereditary iron overload and to evaluate the effect of their associations with HLA-A alleles on the susceptibility to ALL. Both the 63DD [OR=4.31 (1.7-11.2)] and 282YY (p for trend=0.02) genotypes were more frequently found among subjects with suspicion of iron overload than among controls. 282YY carriers displayed significantly higher transferrin saturation index (TSI) values (p<0.001) as well as serum iron (p=0.01) and ferritin (p=0.01) levels. In addition, transferrin levels were lower in these subjects (p=0.01). Likewise, patients who were carriers of the compound heterozygous diplotype (282CY/63HD) showed significantly higher TSI and serum iron and ferritin concentrations. The H63D SNP did not significantly affect the analytical parameters measured. All 282YY carriers and 69.2% of compound heterozygotes showed an altered biochemical index. The frequencies of the HFE SNPs in ALL pediatric patients were lower than those found in controls, whereas the HLA-A*24 allele was significantly overrepresented in the patients group [OR=3.76 (1.9-7.3)]. No HFE-HLA-A associations were found to modulate the ALL risk. These results suggest that it may be useful to test for both HFE H63D and C282Y polymorphisms in patients with iron overload, as opposed to just genotyping for the C282Y SNP, which is customary in some healthcare centers. These HFE variants and their associations with HLA-A alleles were not observed to be relevant for the susceptibility to ALL in our population.

Prevalence of 845G>A HFE mutation in Slavic populations: an east-west linear gradient in South Slavs

AIM

To compare A allele frequencies of the 845G>A mutation of 10 Slavic populations in central, eastern, and southern Europe between each other and with other European populations.

METHODS

The 845G>A mutation from the DNA of 400 Polish neonates collected in 2005-2006 was analyzed by polymerase chain reaction-restriction fragment length polymorphism. The data were compared with reports from other countries.

RESULTS

We identified 381 GG homozygotes, 18 GA heterozygotes, and 1 AA homozygote. The 845A allele frequency was 2.5%, which makes the summary figure for Poland from this and previous studies 3.5%. The average prevalence for Poland and other West Slavic countries was 3.6%, similar to Russia (inhabited by the East Slavs, 3.5%). The average prevalence in South Slavic countries was 2.2%, gradually decreasing from 3.6% in Slovenia to 0% in Bulgaria, with a longitudinal linear gradient (adjusted R(2)=0.976, P<0.001).

CONCLUSIONS

The West and East Slavs, together with Finland, Estonia, Germany, Austria, Hungary, Slovenia, and Croatia, form a group with 845A allele frequencies between 3% and 4%. In the South Slavs, there is a gradual decline in the prevalence of 845A allele from northwest to southeast, with a surprisingly exact east-west linear gradient.

An MBL2 haplotype and ABCB4 variants modulate the risk of liver disease in cystic fibrosis patients: a multicentre study

BACKGROUND

Cystic fibrosis is the most common lethal recessive disorder among Caucasians. Over 1500 mutations have been identified in cystic fibrosis transmembrane conductance regulator disease-gene so far. A large variability of the clinical phenotype has been observed both in cystic fibrosis patients bearing the same genotype, and in affected sibpairs. Thus, genes inherited independently from cystic fibrosis transmembrane conductance regulator could modulate the clinical expression of cystic fibrosis.

METHODS

We analysed some putative modifier genes of liver cystic fibrosis phenotype (serpin 1, hemochromatosis, transferrin receptor 2, ferroportin 1, mannose binding lectin and adenosine triphospate-binding cassette subfamily B member 4) in 108 unrelated cystic fibrosis patients with and without liver involvement.

RESULTS

HYPD mannose binding lectin haplotype was significantly (p<0.05) more frequent in cystic fibrosis patients with liver disease versus those without liver disease. This haplotype already related to a more severe pulmonary cystic fibrosis phenotype, is associated to a reduced MBL immunological activity. The c.834-66G>T variant of adenosine triphospate-binding cassette subfamily B member 4 gene was significantly (p<0.05) less frequent in cystic fibrosis patients with liver disease as compared to those with no liver disease.

CONCLUSIONS

The HYPD mannose binding lectin haplotype may predispose a subgroup of cystic fibrosis patients to a more severe liver involvement impairing the local defence mechanisms whereas the c.834-66G>T adenosine triphospate-binding cassette subfamily B member 4 variant may enhance the activity of the protein and thus exert a protective effect toward liver disease.

Reduced serum hepcidin levels in patients with chronic hepatitis C

BACKGROUND/AIMS

Patients with chronic hepatitis C (CHC) often have increased liver iron, a condition associated with reduced sustained response to antiviral therapy, more rapid progression to cirrhosis, and development of hepatocellular carcinoma. The hepatic hormone hepcidin is the major regulator of iron metabolism and inhibits iron absorption and recycling from erythrophagocytosis. Hepcidin decrease is a possible pathophysiological mechanism of iron overload in CHC, but studies in humans have been hampered so far by the lack of reliable quantitative assays for the 25-amino acid bioactive peptide in serum (s-hepcidin).

METHODS

Using a recently validated immunoassay, we measured s-hepcidin levels in 81 untreated CHC patients and 57 controls with rigorous definition of normal iron status. All CHC patients underwent liver biopsy with histological iron score.

RESULTS

s-hepcidin was significantly lower in CHC patients than in controls (geometric means with 95% confidence intervals: 33.7, 21.5-52.9 versus 90.9, 76.1-108.4 ng/mL, respectively; p<0.001). In CHC patients, s-hepcidin significantly correlated with serum ferritin and histological total iron score, but not with s-interleukin-6. After stratification for ferritin quartiles, s-hepcidin increased significantly across quartiles in both controls and CHC patients (chi for trend, p<0.001). However, in CHC patients, s-hepcidin was significantly lower than in controls for each corresponding quartile (analysis of variance, p<0.001).

CONCLUSIONS

These results, together with very recent studies in animal and cellular models, indicate that although hepcidin regulation by iron stores is maintained in CHC, the suppression of this hormone by hepatitis C virus is likely an important factor in liver iron accumulation in this condition.

Serum ferritin as a predictor of treatment outcome in patients with chronic hepatitis C

OBJECTIVES

Antiviral treatment in chronic hepatitis C (CHC) involves ribavirin, a hemolytic agent. We planned a prospective study to evaluate whether drug-induced iron perturbation is clinically relevant as it relates to therapeutic outcome.

METHODS

Iron variables were sequentially assessed in 206 CHC patients undergoing antiviral therapy and were correlated with pretreatment iron status and histology, hemolysis, and therapeutic outcome.

RESULTS

At week 1 of therapy, serum iron (SI), transferrin saturation (TS), and serum ferritin (SF) increased markedly in all patients. All iron parameters correlated with hemolysis up to week 4; this correlation was lost for SF at later time points. SF rise during treatment was inversely related to baseline SF and iron deposits in hepatic mesenchymal/Kupffer cells. Both baseline SF and mesenchymal iron significantly correlated with fibrosis at multivariate analysis (P=0.015 and 0.008, respectively). Interestingly, baseline SF, despite good specificity (89%), had low sensitivity in predicting siderosis (25%). During therapy, SI, TS, and hemolysis parameters did not correlate with sustained virological response (SVR), whereas SF rise became an independent predictor of therapeutic response: a 2.5-fold increase of SF at week 12 associated with higher likelihood of SVR (odds ratio 1.91, P=0.032). Accordingly, lack of mesenchymal iron deposits at the baseline biopsy correlated with SVR (odds ratio 3.02, P=0.043).

CONCLUSIONS

In CHC, SF is a useful marker for assessing disease duration and progression before starting treatment and for predicting therapeutic response while on therapy. SF rise during antiviral therapy is largely independent of hemolysis and likely indicates activation of macrophages in response to antivirals.

Prevalence of H63D, S65C and C282Y hereditary hemochromatosis gene mutations in Slovenian population by an improved high-throughput genotyping assay

BACKGROUND

Hereditary hemochromatosis (HH) is a common genetic disease characterized by excessive iron overload that leads to multi-organ failure. Although the most prevalent genotype in HH is homozygosity for C282Y mutation of the HFE gene, two additional mutations, H63D and S65C, appear to be associated with a milder form of HH. The aim of this study was to develop a high-throughput assay for HFE mutations screening based on TaqMan technology and to determine the frequencies of HFE mutations in the Slovenian population.

METHODS

Altogether, 1282 randomly selected blood donors from different Slovenian regions and 21 HH patients were analyzed for the presence of HFE mutations by an in-house developed real-time PCR assay based on TaqMan technology using shorter non-interfering fluorescent single nucleotide polymorphism (SNP)-specific MGB probes. The assay was validated by RFLP analysis and DNA sequencing.

RESULTS

The genotyping assay of the H63D, S65C and C282Y mutations in the HFE gene, based on TaqMan technology proved to be fast, reliable, with a high-throughput capability and 100% concordant with genotypes obtained by RFLP and DNA sequencing. The observed frequency of C282Y homozygotes in the group of HH patients was only 48%, others were of the heterogeneous HFE genotype. Among 1282 blood donors tested, the observed H63D, S65C and C282Y allele frequency were 12.8% (95% confidence interval (CI) 11.5-14.2%), 1.8% (95% CI 1.4-2.5%) and 3.6% (95% CI 3.0-4.5%), respectively. Approximately 33% of the tested subjects had at least one of the three HH mutations, and 1% of them were C282Y homozygotes or compound heterozygotes C282Y/H63D or C282Y/S65C, presenting an increased risk for iron overload disease. A significant variation in H63D allele frequency was observed for one of the Slovenian regions.

CONCLUSION

The improved real-time PCR assay for H63D, S65C and C282Y mutations detection is accurate, fast, cost-efficient and ready for routine screening and diagnostic procedures. The genotype frequencies in the Slovenian population agree with those reported for the Central European populations although some deviations where observed in comparison with other populations of Slavic origin. Regional distribution of the mutations should be considered when planning population screening.

An open population screening study for HFE gene major mutations proves the low prevalence of C282Y mutation in Central Italy

BACKGROUND

The C282Y mutation in the HFE gene is responsible for most cases of hereditary haemochromatosis.

AIM

To investigate the allele frequency of HFE mutations and the associations between mutations and cases of iron overload or liver diseases in an open population of Central Italy.

METHODS

A total of 502 individuals over 8 years of age, comprising 203 males and 299 females, who were residents in Arsita (a small town in Central Italy), were assayed for: C282Y, H63D and S65C mutations of the HFE gene by TaqMan probes; body mass index, serum ferritin, transferrin saturation, transaminases, GGT, glucose, insulin, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, HBV and HCV serum markers. Information was obtained on alcohol intake. Liver ultrasound was performed in 334 (67%) subjects.

RESULTS

The allele frequencies for C282Y, H63D and S65C were 2%, 15%, and 0.01%, respectively. C282Y/wt was found in 19 subjects (4%), H63D/wt in 127 (25%), H63D/H63D in 11 (2%) and S65C/wt in one (2.0 per thousand). No homozygosity for C282Y or compound mutation (C282Y/H63D) was found in the study population, but 27 subjects (5%) had TfSat >45% (including 10 subjects with high serum ferritin). Overall, 49 subjects (9.8%) were HCV-RNA-positive. Logistic regression analysis indicated that male gender (P = 0.000) and hepatic steatosis (P = 0.017) were independent variables correlating to a high serum ferritin.

CONCLUSION

C282Y HFE mutation is less frequent in Central Italy than in Northern Italy.

Prevalence of the hemochromatosis gene mutation in patients with nonalcoholic steatohepatitis and correlation with degree of liver fibrosis

BACKGROUND

Nonalcoholic steatohepatitis is a chronic liver disease with a high prevalence in the general population and a potential to evolve into cirrhosis. It is speculated that iron overload could be associated with liver injury and unfavorable progress in affected patients.

AIMS

To evaluate the prevalence of mutation of the hemochromatosis gene (HFE) in patients with nonalcoholic steatohepatitis and to correlate it with histological findings in liver specimens.

PATIENTS AND METHODS

Twenty-nine patients with nonalcoholic steatohepatitis were evaluated. The presence of mutation in the hemochromatosis gene (C282Y and H63D) was tested in all patients and its result was evaluated in relation to hepatic inflammatory activity, presence of fibrosis, and iron overload in the liver. The control group was composed of 20 patients with normal liver function tests and 20 patients infected with the hepatitis C virus, with elevated serum levels of aminotransferases and with chronic hepatitis as shown by biopsy.

RESULTS

Mutation of the hemochromatosis gene (C282Y and/or H63D) was diagnosed in 16 (55.2%) patients with nonalcoholic steatohepatitis, in 12 (60%) patients with hepatitis C and in 8 (40%) patients with no liver disease. No association was found between the presence of mutation and inflammatory activity, nor with the presence of fibrosis in patients with nonalcoholic steatohepatitis. An association was found between the presence of mutation and the occurrence of iron overload in liver, but there was no association between liver iron and the occurrence of fibrosis.

CONCLUSIONS

The findings suggest that iron does not play a major role in the pathogenesis and progression of nonalcoholic steatohepatitis, and routine tests of the hemochromatosis gene mutation in these patients should not be recommended.

Individuals homozygous for the H63D mutation have significantly elevated iron indexes

Our objective was to assess the iron indexes of patients with one or more mutations of the HFE gene with a specific interest in studying the effect of the H63D/H63D genotype. Eight hundred twenty subjects who underwent HFE mutational testing for C282Y and H63D mutations were retrospectively identified. Data collected included age, gender, HFE genotype, and values for serum ferritin, iron saturation, aspartate aminotransferase (AST), and alanine aminotransferase (ALT). Compared to the Wild/Wild genotype (0.34 +/- 0.17), genotypes H63D/C282Y (0.44 +/- 0.14 P < 0.01), H63D/H63D (0.51 +/- 0.21 P < 0.01), and C282Y/C282Y (0.64 +/- 0.20 P < 0.01) had significantly higher transferrin saturation levels and were independent predictors of higher iron saturation in multivariate regression analysis. Compared to the Wild/Wild genotype, no abnormal HFE genotypes had significantly higher ferritin levels, although the genotype H63D/H63D was an independent predictor of higher serum ferritin (P = 0.02) in regression analysis. There was no significant difference in the proportion of patients with abnormally elevated AST (P = 0.64) or ALT (P = 0.80) between groups. H63D homozygotes have elevated transferrin saturation compared to the Wild genotype, comparable to that of C282Y homozygotes and compound heterozygotes. The clinical significance of this finding is unclear but warrants further study.

Frequency of the C282Y and H63D mutations of the hemochromatosis gene (HFE) in a cohort of 1,000 neonates in Madrid (Spain)

For centuries in Europe, population movements have contributed to ethnic groups, cultures, and consequently, inheritance mixing. There are certain genetic diseases such as hereditary hemochromatosis whose distribution is directly related to the population movements. The objective of the present investigation was to determine the C282Y and H63D mutation frequency of the HFE gene in a cohort study of 1,000 neonates in the Community of Madrid (Spain), thus contributing to the HFE gene mutations distribution research in Europe and establishing the origin of the mutations in Spain. The allelic frequency of C282Y mutation was 1.7% (CI 95% 1.1-2.3) and the H63D allele was present in 16.4% of chromosomes (CI 95% 14.8-18). In Spain, the presence of C282Y mutation and its distribution could be due more to Celtic than to Viking legacy, whereas it is assumed that the one in relation to the H63D variant occurred in the Basque Country during the Paleolithic Period.

Mutation analysis of the HFE gene associated with hereditary hemochromatosis in a Venezuelan sample

The frequency of the C282Y, H63D and S65C alleles of the HFE gene was determined in a sample of the Venezuelan population. Two new sets of primers were tested for amplifying the regions mapping these mutations, and genotyping was performed by restriction fragment length polymorphism (RFLP). DNA sequencing was used to validate the RFLP analysis. Serum ferritin levels were also determined. Two hundred and fourteen individuals were tested, extracting DNA from whole blood cells (n=177) or from serum (n=37). The frequency of heterozygous subjects was 3.7, 18.2 and 1.7% for the C282Y, H63D and S65C mutations, respectively, and the allele frequencies were 0.019+/-0.01 for C282Y, 0.119+/-0.016 for H63D and 0.009+/-0.005 for S65C. The results suggest that the admixture of native populations with subjects of South European origin might have had an important role in the diffusion of HFE alleles in Venezuela. C282Y homozygous subjects were not found in this study. No HFE genotype studied here was associated with a significant elevation of serum ferritin concentrations, except for C282Y/H63D compound heterozygote found in one asymptomatic male. This finding supports the theory that the H63D mutation could be involved in alterations of iron parameters when inherited together with C282Y. Our results indicate that C282Y homozygotes will be rarely detected. Performance of HFE mutation analysis in individuals with high iron determinations would be recommended.

HFE gene mutations in susceptibility to childhood leukemia: HuGE review

The hereditary hemochromatosis (HHC) gene, HFE on chromosome 6p21.3, encodes a protein involved in iron homeostasis. HFE mutations have low penetrance with a mild effect on serum iron levels. Animal, twin, and population studies have shown that carrier state for C282Y can increase iron levels. A proportion of heterozygotes show slightly elevated serum iron levels. Increased serum iron has been suggested to increase the risk for oxidative damage to DNA. Epidemiologic studies established a correlation between iron levels and cancer risk. Case-control studies have reported associations between HFE mutations C282Y/H63D and several cancers, some of which in interaction with the transferrin receptor gene TFRC or dietary iron intake. Increased cancer risk in C282Y carriers is likely due to higher iron levels in a multifactorial setting. In childhood acute lymphoblastic leukemia (ALL), there is an association of C282Y with a gender effect in two British populations. No association has been found in acute myeloblastic leukemia and Hodgkin disease in adults. The childhood leukemia association possibly results from elevated intracellular iron in lymphoid cells increasing the vulnerability to DNA damage at a critical time window during lymphoid cell development. Interactions of HFE with environmental and genetic factors, most of which are recognized, may play a role in modification of susceptibility to leukemia conferred by C282Y. Given the population frequency of C282Y and the connection between iron and cancer, clarification of the mechanism of HFE associations in leukemia and cancer will have strong implications in public health.

Frequency and clinical expression of HFE gene mutations in a Spanish population of subjects with abnormal iron metabolism

Three HFE gene mutations (HFE 845 G-->A, 187 C-->G and 193 A-->T) are the most common mutations related to hereditary haemochromatosis (HH). The genotype for these mutations was analysed in 359 Spanish individuals with altered iron metabolism and iron overload. Various biochemical parameters were measured in serum samples from 96 of these individuals, and the effect of the genotype on these parameters was studied. Allele frequencies were 12.95% for the HFE C282Y variant, 28.97% for the HFE H63D variant and 0.69% for the HFE S65C variant, calculated in a total of 718 chromosomes. Multiple comparisons analysis showed very significant differences (p=0.001) in transferrin saturation index (TSI) between the HFE C282Y variant homozygous and control (ten healthy volunteers) groups. Highly significant (p=0.0001) and significant (p=0.005) differences in serum ferritin values were found between the HFE C282Y variant homozygous and control groups and between compound (HFE C282Y/H63D variant) heterozygous and control groups, respectively. Very significant differences (p=0.001) in serum iron values were observed between the HFE C282Y variant homozygous and control groups. TSI and serum ferritin values detected most HFE C282Y variant homozygotes and are recommended to facilitate the clinical diagnosis of HH.

Serum iron levels and hepatic iron overload in nonalcoholic steatohepatitis and chronic viral hepatitis

Our objective was to determine the effect of serum iron levels and hepatic iron overload on hepatocellular damage in nonalcoholic steatohepatitis (NASH) and to compare this with chronic viral hepatitis. Twenty-five patients who had elevated transaminase levels on at least two occasions, without any evidence of viral and autoimmune hepatitis and diabetes, without a history of significant alcohol use, and with a liver biopsy consistent with NASH were enrolled in the study. Twenty-five patients with chronic viral hepatitis (13 patients with chronic hepatitis C and 12 with chronic hepatitis B) who were not under any antiviral treatment were taken as controls. Metabolic factors were studied in the NASH and chronic hepatitis groups. Biopsy specimens were stained with hematoxylin-eosin, and the grade of steatosis and the stage of fibrosis were evaluated as I, II, or III, I being mild and III being severe. Iron overload in the hepatic tissue was studied by Prussian blue staining. Serum ALT, AST, ALP, GGT, globulin, and ferritin levels were comparable in both steatohepatitis and chronic viral hepatitis groups. However, patients with chronic hepatitis had a lower albumin level and a higher serum iron level, with higher transferrin saturation. Among patients with NASH, mild, moderate, and severe steatosis was found in 7, 10, and 8 patients, respectively. Inflammatory infiltration was grade I in 24 patients and grade III in 1 patient. Fibrosis was mild in 12 patients and 13 patients had no fibrosis. Among patients with chronic viral hepatitis, inflammatory infiltration of grade I was seen in 11 patients, grade II in 11 patients, and grade III in 3 patients. Fibrosis was mild in 9 patients, moderate in 13 patients, and severe in 2 patients; 1 patient had no fibrosis. Compared to patients with NASH, those with chronic viral hepatitis cases had more severe inflammatory infiltration and fibrosis (P < 0.01). While five patients with chronic viral hepatitis had mild iron overload, patients with NASH had no hepatic paranchymal iron overload. Neither NASH nor chronic viral hepatitis revealed a relationship between hepatic iron overload and disease activity. This suggests that the iron overload actually may be a result of hemachromatosis gene mutation. The absence of hepatic parenchymal iron overload in the NASH group and only mild iron accumulation in the chronic hepatitis group may be explained by a lower frequency of the gene mutation in our country.

Soluble transferrin receptor and mutations in hemochromatosis and transferrin genes in a general Catalan population

BACKGROUND

The measurement of soluble transferrin receptor (sTfR) has been proposed as a valuable marker of erythropoietic activity and iron status. However, the possibility that mutations in HFE and/or transferrin genes have a direct effect on this parameter has not been sufficiently investigated. The present report addresses this point in the general population.

METHODS

Serum sTfR, ferritin, iron and transferrin, as well as the H63D and the C282Y polymorphisms of the HFE gene and the TF C1/C2 polymorphism of the transferrin gene, were analysed in 348 subjects.

RESULTS

We observed significant and independent associations of serum sTfR with sex (2.68+/-1.27 mg/L in men vs. 2.25+/-1.33 in women; P=0.002), H63D polymorphism (2.61+/-1.34 in wild type homozygotes vs. 2.28+/-1.25 in carriers of one or two mutated alleles; P=0.009), and serum iron concentration (r=-0.17; P=0.002).

CONCLUSION

The H63D mutation of the HFE gene has a moderate but significant influence on sTfR concentration in the general population, the presence of one or two mutated alleles being associated with an average of 0.27 mg/L less sTfR than nonmutated homozygotes.

Analysis of hemochromatosis gene mutations in 52 consecutive patients with polycythemia vera

A literature review reports increased erythrocyte indices [hemoglobin concentration, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin (MCH), MCH concentration] in subjects with hereditary hemochromatosis (HH). We, therefore, screened 52 consecutive patients with polycythemia vera for 12 HH gene mutations, comparing iron status and red cell parameters between patients positive or negative for HH gene mutations. Our results support the evidence that there is no association between these two conditions.

Heterozygous beta-thalassemia and homozygous H63D hemochromatosis in a child: an 18-year follow-up

At age of 3.2 years routine blood analysis showed the presence of a beta-thalassemic trait with unexpected high level of serum iron and high transferrin saturation. Hematological follow-up confirmed the moderate degree of anemia and persisting high levels of iron indices throughout the years with a progressive increase of serum ferritin. At the age of 19 years the patient was diagnosed homozygous for HC63D HFE. The patient referred by us confirm the possibility of precocious alteration of iron indices in patients with heterozygosity for beta-thalassemia inherited together with HFE mutations. This observation suggests that any children with thalassemic trait with increased transferrin saturation and/or serum ferritin might be investigated for the presence of the hemocromatosis genes in order to detect the disease before any clinical manifestation and even before organ iron loading.

Analysis of HFE and TFR2 gene mutations in patients with acute leukemia

There are increasing evidences regarding the association between iron overload and extra-hepatic malignancies. We studied the prevalence of 12 hereditary hemochromatosis (HH) gene mutations (C282Y, V53M, V59M, H63D, H63H, S56C, Q127H, E168Q, E168X, W169X and Q283P in the HFE gene and Y250X in the TFR2 gene) and its correlation with the iron status in 82 adult patients with acute leukemia (AL); 48 patients (58.5%) were affected by acute myeloid leukemia (AML) and 34 patients (41.5%) by acute lymphoblastic leukemia (ALL); 27 patients (32.9%) had at least one HH gene mutation (6 heterozygous for C282Y, 6 homozygous for H63D, 13 heterozygous for H63D and 2 heterozygous for S56C). Mean serum ferritin levels at diagnosis were increased (822.5+/-811.4 microg/L). However, there was no difference between patients positive or negative for the HH gene mutations. Similarly, we did not observe any statistically significant difference as far as iron status between AML and ALL patients. Our study does not support the evidence of an association between hemochromatosis gene mutations and iron overload in AL patients.

Efficacy and safety of phlebotomy to reduce transfusional iron overload in adult, long-term survivors of acute leukemia

BACKGROUND

Transfusional iron overload is a frequent finding in long-term survivors of acute leukemia (AL). Only a few studies have reported the results of iron depletion therapy in this category of patients.

STUDY DESIGN AND METHODS

Between January 1996 and July 2003, 26 consecutive adult patients who achieved complete remission of AL and developed transfusional iron overload underwent a weekly phlebotomy program at our transfusion center. Serum ferritin levels and transferrin saturation were monitored during the iron depletion therapy and the follow-up period. These AL patients were also checked for the presence of 12 hereditary hemochromatosis (HH) gene mutations.

RESULTS

After a mean follow-up of 57.8 months, therapeutic phlebotomy (mean number of units collected, 36.6) was effective in reducing mean ferritin concentration and transferrin saturation from 1726.9 to 93.0 mg per L and from 54.7 to 23.3 percent, respectively. The presence of a HH gene mutation did not influence initial iron status or response to treatment. The phlebotomy program was well tolerated and no adverse events were recorded during or after collection. In three cases the time between phlebotomies was increased because of patient's poor compliance or low Hb levels.

CONCLUSION

Our study shows that phlebotomies are a safe and effective method for reducing iron over-load in multiply transfused long-term AL survivors with secondary hemochromatosis.

Genotipo y expresión fenotípica de la hemocromatosis hereditaria en España

INTRODUCTION

The prevalence of C282Y homozygosity in patients with hereditary hemochromatosis (HH) has been reported to be markedly lower in the Mediterranean Basin than in northern Europe. In Spain, the available data are contradictory and limited to small series in specific regions. The objective of this study is to determine the prevalence of the 2 main HFE gene mutations in a large series of unrelated Spanish patients with HH from different geographical origins.

PATIENTS AND METHOD

The criteria for HH diagnosis were: repeat serum transferrin saturation index (> 45% plus C282Y homozygosity and/or hepatic iron index (> 1.9 of dry liver weight in non-cirrhotic patients or (> 4.1 in patients with liver cirrhosis. Cases in related individuals were excluded. Demographic data, clinical expression, iron parameters and HFE gene mutations (C282Y and H63D) were assessed in 222 patients.

RESULTS

A total of 83.3% of patients were C282Y homozygous and 5% were compound heterozygous (C282Y/H63D). No significant differences in phenotypic expression or in the frequency of C282Y homozygosity were observed between patients born in the North and South of Spain.

CONCLUSION

The genotypic and phenotypic expression of HH in Spain is very similar to that reported in Northern Europe. Thus, the genetic heterogeneity described in some Southern European regions cannot be considered a common feature to all countries of the Mediterranean Basin.

Contribution of the H63D mutation in HFE to murine hereditary hemochromatosis

Hereditary hemochromatosis (HH) is an autosomal recessive disease characterized by iron accumulation in several organs, followed by organ damage and failure. The C282Y mutation in the HFE gene explains 80-90% of all diagnosed cases of HH in populations of northwestern European ancestry. Targeted disruption of the mouse Hfe gene (or introduction of the murine mutation analogous to the C282Y human mutation) produces a murine model of HH. Another mutation in the HFE gene, H63D, is more prevalent than C282Y. However, the physiological consequences of the H63D mutation (as well as C282Y/H63D compound heterozygosity) on iron homeostasis are less well established. To evaluate the phenotypic consequences of the C282Y/H63D and H63D/H63D genotypes, we produced H67D (corresponding to H63D in humans) and C294Y (corresponding to C282Y in humans) knock-in mice. H67D homozygous mice, C294Y homozygous mice, and H67D/C294Y compound heterozygous mice each demonstrated hepatic iron loading. Even on a standard diet, by 10 weeks of age, hepatic iron levels in mice of these three genotypes were significantly higher than those of wild-type littermates. The relative severity of hepatic iron loading was C294Y/C294Y > C294Y/H67D > H67D/H67D. We conclude that the H67D allele, when homozygous or combined with a more consequential mutation like C294Y, leads to hepatic iron loading. These observations indicate that the H67D mutation leads to partial loss of Hfe function and can contribute to murine HH.

Frequency of HFE gene mutations in Iranian beta-thalassaemia minor patients

OBJECTIVES

Beta-thalassaemia minor (BTM) alone does not lead to iron overload, however, some gene modifiers and acquired causes are reported. When it is inherited together with a mutation in the HFE (HLA-H) gene associated with hereditary haemochromatosis, iron overload may ensue. To analyse the relationship between iron status and HFE mutations in Iranian BTM patients, we compared the frequency of the C282Y and H63D HFE mutations and ferritin level in a group of BTM patients from the National Thalassaemia Transfusion and Care Centre with that of healthy individuals.

PATIENTS AND METHODS

Ninety-three (56 females) documented BTM cases and 104 (54 females) controls were enrolled in the study. Serum ferritin level was measured in all subjects by immuno-radiometric assay and HFE genotypes were determined using restriction fragment length polymorphism analysis of PCR-amplified HFE gene fragment.

RESULTS

Eighteen (19.4%) BTM patients vs. 12 (11.5%) controls were H63D heterozygotes, while there were three (3.2%) cases and three (2.9%) controls with H63D homozygosity. All three C282Y mutations were found in BMT patients with one of them being a compound heterozygote. A significant difference was observed in the total number of HFE mutations in favour of BTM patients over the controls (P < 0.05, OR = 2.064). The H63D and C282Y allele frequencies were 12.9 and 1.61 in patients and 8.65 and 0 in controls, respectively. The mean ferritin level in cases with HFE mutations showed no significant difference from that of the patients without mutations (P > 0.05).

CONCLUSIONS

Our results suggest that HFE mutations C282Y and H63D are more frequent in Iranian BTM patients than in the normal population, causing no significant changes in serum ferritin level.

Evidence that the Cys282Tyr mutation of the HFE gene originated from a population in Southern Scandinavia and spread with the Vikings

Hereditary hemochromatosis has been recognized as a clinical disorder for more than 100 years. The common form of the disorder is caused by the Cys282Tyr mutation (C282Y) of the HFE gene. Hereditary hemochromatosis affects predominantly people of Northern European origin. The C282Y mutation probably occurred on a single chromosome carrying the ancestral hemochromatosis haplotype, which subsequently was spread by emigration and the founder effect. It has been estimated that the C282Y mutation appeared 60-70 generations ago. It was initially suggested that the ancestral C282Y mutation occurred within the Celtic group of peoples. However, we hypothesize that the distribution of the C282Y mutation in Europe is more consistent with an origin among the Germanic Iron Age population in Southern Scandinavia. From this area, the mutation could later be spread by the migratory activities of the Vikings. The aim of the present study was to evaluate the validity of these two hypotheses. Several arguments are in favor of the 'Viking hypothesis': first, the highest frequencies (5.1-9.7%) of the C282Y mutation are observed in populations in the Northern part of Europe, i.e. Denmark, Norway, Sweden, Faeroe Islands, Iceland, Eastern part of England (Danelaw) and the Dublin area, all Viking homelands and settlements. Second, the highest allele frequencies are reported among populations living along the coastlines. Third, the frequencies of the C282Y mutation decline from Northern to Southern Europe. Intermediate allele frequencies (3.1-4.8%) are seen in the populations in Central Europe, which is the original Celtic homeland. Low allele frequencies (0-3.1%) are recognized in populations in Southern Europe and the Mediterranean.

Prevalence of HFE mutations in upper Northern Italy: study of 1132 unrelated blood donors

BACKGROUND

In the Italian general population, prevalence of C282Y is lower than in Northern European countries. We hypothesised a higher prevalence of C282Y in Northern than in Central and Southern Italy. We previously identified a nonsense mutation (W169X) in haemochromatosis probands originating from a Northern Italian region (Brianza).

AIM

To define the prevalence of HFE mutations in that region. Subjects and methods. A total of 1132 unrelated blood donors from the Blood Banks of Monza and Merate were investigated for C282Y, H63D, S65C and W169X mutations by PCR-restriction assays. A total of 300 were also tested for rare HFE and TFR2 mutations by reverse-hybridization test strips.

RESULTS

Two C282Y homozygotes, eight C282Y/H63D compound heterozygotes, 27 H63D homozygotes and one W169X heterozygote were found. The allele frequencies of C282Y, H63D, S65C, and W169X were 3.2, 13.4, 1.3, and 0.04%, respectively.

CONCLUSIONS

Our results confirm the existence of a decreasing frequency of C282Y allele from upper to lower Northern Italy. This difference is probably related to the larger Celtic component of upper Northern Italian populations in which screening studies for haemochromatosis may even be cost effective. W169X, due to its severity, should be looked for in all haemochromatosis patients of Northern ancestry with an incomplete HFE genotype.

Frequency of hemochromatosis C282Y and H63D mutations in Sardinia

Hereditary hemochromatosis (HH) is one of the most common autosomal recessive disorders of iron metabolism among Caucasians, and it is associated with C282Y mutation of the HFE gene in populations of Celtic origins. A second mutation, H63D, shows a very high widespread frequency, although its role in iron metabolism is still inconclusive. There are no data on the frequencies of these two mutations in Sardinia, an island in the Mediterranean sea that has not been invaded by Celtic peoples. We examined 836 chromosomes from Sardinian subjects and tested for the mutation by restriction enzyme digestion of PCR products. Among the 836 analyzed chromosomes, we found a C282Y allele frequency of 0.0036 and an H63D allele frequency of 0.173. These data could explain the observed rarity of HH in Sardinia. The high allele frequency of H63D and the rarity of HH in Sardinia is suggestive that this mutation is not a major contributor to this disease.

Population screening for hemochromatosis: a study in 5370 Spanish blood donors

BACKGROUND/AIMS

Hereditary hemochromatosis is associated with homozygosity for C282Y mutation in the HFE gene, elevated serum transferrin saturation and excess iron deposits throughout the body. We conducted a population-based study in Spain to asses the prevalence of the HFE mutations and their effect on iron parameters.

METHODS

We screened 5370 blood donors for the C282Y and H63D HFE mutations by allele-specific polymerase chain reaction. Serum iron, serum ferritin and transferrin saturation were also measured.

RESULTS

We have found eight (five men and three women) blood donors who are C282Y homozygotes (0.15%) and 74 C282Y/H63D compound heterozygotes (1.38%). Four out of the eight C282Y homozygotes, all men, had high serum ferritin and transferrin saturation values. No woman was detected with both iron parameters increased. Only one of the 74 C282Y/H63D compound heterozygotes showed elevated serum ferritin and transferrin saturation values (penetrance 1.35%). Serum ferritin and transferrin saturation were significantly higher in C282Y homozygous men as compared with the rest of the genotypes.

CONCLUSIONS

The C282Y/C282Y genotype frequency in Spain is 1 in 1004. The C282Y/C282Y genotype is clearly associated with an increase in iron parameters. Biochemical expression of the disease was found in 80% of the C282Y/C282Y men.

Public health aspects of genetic screening for hereditary haemochromatosis in Australia

Hereditary haemochromatosis (HH) is an inherited disorder of iron absorption. It meets several of the key public health principles for population-based screening and is considered to be a test-case for public health genetics. However, there has been relatively little debate in the public health or wider community regarding the merits of population-based genetic screening for HH. Genetic susceptibility to HH occurs in about 1:200 people and although mortality is low (age-standardised rate 2.75/million), there are potentially serious clinical manifestations of iron overload. Regular venesection is a simple and effective treatment for early stage iron overload. DNA-based testing is available and iron overload may be identified using serum transferrin saturation and ferritin tests. However, there are important gaps in knowledge relevant to screening for HH. The limited data on penetrance of HFE genotypes, and thus the uncertain probability that genetically susceptible individuals will develop clinically significant disease, is a major impediment to population-based genetic screening. Clinical evidence supports treating early-stage disease but no randomised controlled trials of the effectiveness of screening in reducing the burden of disease have been conducted. In addition, the natural history of early stages of HH and factors that may modify progression are unclear. Two intemational consensus panels on HH concluded that there is insufficient evidence for population-based screening at present. We present recommendations to advance the debate on screening for HH in Australia.

Genetics of haemochromatosis

After identification of the hereditary haemochromatosis gene HFE, and receipt of confirmation that most patients with the condition were homozygous for a single, founder mutation (C282Y), most assumed that C282Y would be a prevalent, highly penetrant mutation in a gene that plays a key part in the regulation of iron absorption and of whole-body iron homoeostasis. With carrier rates of between 10% and 15%, and a homozygote frequency of about one-in-150 in people of northern European descent, C282Y is certainly prevalent. However, it is not highly penetrant. The pronounced variation in phenotype in individuals with the same gene mutation has prompted the search for modifier genes at other loci, and for environmental factors that might affect expression of the condition. Progress in our understanding of how HFE regulates the absorption of dietary iron has been slow, but much can be learnt from the study of the rare instances of haemochromatosis that involve mutations in newly-identified iron-metabolism genes, such as TFR2--a transferrin receptor isoform--and ferroportin1/Ireg1/mtp1--an intestinal iron transporter. The availability of definitive information on penetrance and the identity of genetic modifiers will aid the debate on whether population screening for haemochromatosis should be undertaken or whether alternative strategies should be implemented to improve early detection.

Frequency of the HFE gene mutations in five Italian populations

Genetic hemochromatosis is an autosomal recessive disorder characterized by iron overload and a variety of clinical manifestations such as liver cirrhosis and arthropathy. It is the most common genetic disease of northern European populations. The principal gene responsible for hereditary hemochromatosis, designated HFE, is located on chromosome 6 in the HLA region. The single point mutation 845A, changing cysteine at position 282 to tyrosine (C282Y), in this gene has been identified as the main genetic basis of hereditary hemochromatosis. Two other mutations, 187G, a histidine to aspartate at amino acid 63 (H63D), and 193T, a serine to cysteine at amino acid 65 (S65C), appear to be associated with milder forms of hereditary hemochromatosis. There is a high prevalence of the C282Y mutation in northern European populations, whereas in those of the Mediterranean basin the prevalence seems low and almost absent in Far East countries. This mutation seems usually to occur on the ancestral haplotype 7.1. Accordingly, a Celtic origin of this mutation has been suggested. The aim of this study was to determine the frequency of HFE gene mutations in five geographic regions in Italy. Samples were tested for C282Y, H63D, and S65C mutations of the HFE gene according to methods of each laboratory and the results were standardized with the exchange of typed samples between the different laboratories. In addition, C282Y-positive DNA samples were typed for D6S105 allele 8 and HLA-A3 by ARMS-PCR. We have found that the allele frequency of the C282Y mutation decreases from northeast Italy (Friuli, 6%) to northwest Italy (Piedmont, 4.8%) and to central Italy (Emilia-Romagna, 1.7%). However, this mutation is lacking in the two regions of the Mediterranean basin's center (Sicily and Sardinia). Accordingly, a significant difference in the frequency of the mutation was observed between these Italian regions (P = 0.07 x 10(-3)). In contrast, no difference was observed in allele frequency of H63D in the five Italian regions. Finally, as regards the S65C mutation a very low frequency was observed in Friuli, Emilia-Romagna, and Sardinia, whereas in Sicily and Piedmont we have not found this mutation. In conclusion, these data are consistent with the hypothesis that the C282Y mutation occurred in Caucasian populations of Celtic origin, whereas the H63D mutation is more ancient as demonstrated by the ubiquitous distribution.

Increased serum ferritin is common in men with essential hypertension

OBJECTIVES

Insulin-resistance-associated hepatic iron overload syndrome (IRHIO) is characterized by high serum ferritin and presence of metabolic alterations that are part of insulin-resistance syndrome (IRS). Thus, clinical conditions characterized by a high prevalence of IRS may also be characterized by a high prevalence of IRHIO.

DESIGN AND METHODS

We studied 88 consecutive patients with essential hypertension, 62 patients with IRHIO and 102 healthy normotensive controls. Hemochromatosis, other conditions able to induce secondary iron overload or serum ferritin increase unrelated to body iron stores were excluded. Iron indices, metabolic profiles and hepatic tests in hypertensive with or without increased serum ferritin and in IRHIO with and without hypertension were studied. Metabolic variables, serum iron indices, liver function tests and hepatic ultrasound data were analysed. Data were compared by non-parametric tests.

RESULTS

In men with hypertension, increased serum ferritin was more frequent than in controls (21 versus 0%, P = 0.001). Hypertensive men with increased serum ferritin had more frequent and pronounced metabolic alterations than those with normal serum ferritin, the metabolic abnormalities and serum ferritin being frequently positively correlated. In hypertensive men with increased serum ferritin, metabolic and iron data were similar to those of IRHIO patients with hypertension.

CONCLUSIONS

In males, hypertension is characterized by a higher prevalence of increased iron stores and metabolic abnormalities that are part of the IRHIO syndrome. This finding may have clinical implications due to the increased risk of IRHIO patients to develop hepatic cirrhosis and also for the role of iron in early atherogenesis.

Hemochromatosis gene in leukemia and lymphoma

The gene causing hereditary hemochromatosis (HH), HFE is an HLA class I-like gene with no known immunological function but indirectly related to the immune functions because of its role in iron transport. It is located 6.5 Mb telomeric to HLA-A. The most common mutation of HFE, C282Y, has a Celtic origin and most patients with HH are homozygous for it in Northern European populations. While there is an enormously increased risk for hepatocellular cancer in hemochromatosis that is attributed to the toxic effects of iron, the risk for extra-hepatic cancers is also increased slightly. Recent studies have found genetic associations between several cancers and C282Y but only in the presence of a particular allele of the transferrin receptor gene. This suggests that the increased cancer risk is more likely due to the effects of iron. In childhood acute lymphoblastic leukemia (ALL), however, there is a strong association of C282Y with a gender effect in two different Celtic populations. This association does not require homozygosity for C282Y or an interaction with the transferrin receptor gene, and is male-specific. The other HFE mutation H63D does not confer increased risk to childhood ALL. Acute myeloblastic leukemia and Hodgkin's disease in adults do not have an association with HFE. Its male-specificity, occurrence in childhood and the lack of a gene-dosage effect suggest that the C282Y association in childhood ALL may reflect the involvement of another HLA-linked gene in leukemia susceptibility.

Physiology of iron transport and the hemochromatosis gene

Iron is essential for fundamental cell functions but is also a catalyst for chemical reactions involving free radical formation, potentially leading to oxidative stress and cell damage. Cellular iron levels are therefore carefully regulated to maintain an adequate substrate while also minimizing the pool of potentially toxic "free iron." The main control of body iron homeostasis in higher organisms is placed in the duodenum, where dietary iron is absorbed, whereas no controlled means of eliminating unwanted iron have evolved in mammals. Hereditary hemochromatosis, the prototype of deregulated iron homeostasis in humans, is due to inappropriately increased iron absorption and is commonly associated to a mutated HFE gene. The HFE protein is homologous to major histocompatibility complex class I proteins but is not an iron carrier, whereas biochemical and cell biological studies have shown that the transferrin receptor, the main protein devoted to cellular uptake of transferrin iron, interacts with HFE. This review focuses on recent advances in iron research and presents a model of HFE function in iron metabolism.

Autosomal-dominant hemochromatosis is associated with a mutation in the ferroportin (SLC11A3) gene

Hemochromatosis is a progressive iron overload disorder that is prevalent among individuals of European descent. It is usually inherited in an autosomal-recessive pattern and associated with missense mutations in HFE, an atypical major histocompatibility class I gene. Recently, we described a large family with autosomal-dominant hemochromatosis not linked to HFE and distinguished by early iron accumulation in reticuloendothelial cells. Through analysis of a large pedigree, we have determined that this disease maps to 2q32. The gene encoding ferroportin (SLC11A3), a transmembrane iron export protein, lies within a candidate interval defined by highly significant lod scores. We show that the iron-loading phenotype in autosomal-dominant hemochromatosis is associated with a nonconservative missense mutation in the ferroportin gene. This missense mutation, converting alanine to aspartic acid at residue 77 (A77D), was not seen in samples from 100 unaffected control individuals. We propose that partial loss of ferroportin function leads to an imbalance in iron distribution and a consequent increase in tissue iron accumulation.

Autosomal-dominant hemochromatosis is associated with a mutation in the ferroportin (SLC11A3) gene

Hemochromatosis is a progressive iron overload disorder that is prevalent among individuals of European descent. It is usually inherited in an autosomal-recessive pattern and associated with missense mutations in HFE, an atypical major histocompatibility class I gene. Recently, we described a large family with autosomal-dominant hemochromatosis not linked to HFE and distinguished by early iron accumulation in reticuloendothelial cells. Through analysis of a large pedigree, we have determined that this disease maps to 2q32. The gene encoding ferroportin (SLC11A3), a transmembrane iron export protein, lies within a candidate interval defined by highly significant lod scores. We show that the iron-loading phenotype in autosomal-dominant hemochromatosis is associated with a nonconservative missense mutation in the ferroportin gene. This missense mutation, converting alanine to aspartic acid at residue 77 (A77D), was not seen in samples from 100 unaffected control individuals. We propose that partial loss of ferroportin function leads to an imbalance in iron distribution and a consequent increase in tissue iron accumulation.