Frequency of Two Common HFE Gene Mutations (C282Y and H63D) in a Group of Iranian Patients With Cryptogenic Cirrhosis

Background

The human HFE gene (a key component of iron homeostasis in humans) is involved in hereditary hemochromatosis, a common autosomal recessive genetic disorder that is characterized by excessive intestinal iron absorption and progressive iron overload.

Objectives

In this study, we assessed the frequency of two common forms of hemochromatosis HFE gene mutation (C282Y and H63D) in patients suffering from cryptogenic cirrhosis.

Patients and Methods

One hundred and fifty individuals were included in this study, in which 100 were patients with cryptogenic cirrhosis and 50 were from the normal population. All individuals were examined for common HFE gene mutations by amplification of nucleotide 845 C282Y and 187 H63D alleles and product analysis using the polymerase chain reaction method and restriction enzyme digestion.

Results

No case of either a homozygous or heterozygous C282Y mutation was found. For the H63D mutation, no homozygosity was detected but heterozygosity was detected in 22% of patients and in 28% of the normal population.

Conclusions

Hereditary hemochromatosis is not a major cause of cryptogenic cirrhosis in the Iranian population.     

CYBRD1 as a modifier gene that modulates iron phenotype in HFE p.C282Y homozygous patients

Background

Most patients with hereditary hemochromatosis in the Caucasian population are homozygous for the p.C282Y mutation in the HFE gene. The penetrance and expression of hereditary hemochromatosis differ largely among cases of homozygous p.C282Y. Genetic factors might be involved in addition to environmental factors.

Design and Methods:

In the present study, we analyzed 50 candidate genes involved in iron metabolism and evaluated the association between 214 single nucleotide polymorphisms in these genes and three phenotypic outcomes of iron overload (serum ferritin, iron removed and transferrin saturation) in a large group of 296 p.C282Y homozygous Italians. Polymorphisms were tested for genetic association with each single outcome using linear regression models adjusted for age, sex and alcohol consumption.

Results

We found a series of 17 genetic variants located in different genes with possible additive effects on the studied outcomes. In order to evaluate whether the selected polymorphisms could provide a predictive signature for adverse phenotype, we re-evaluated data by dividing patients in two extreme phenotype classes based on the three phenotypic outcomes. We found that only a small improvement in prediction could be achieved by adding genetic information to clinical data. Among the selected polymorphisms, a significant association was observed between rs3806562, located in the 5''UTR of CYBRD1, and transferrin saturation. This variant belongs to the same haplotype block that contains the CYBRD1 polymorphism rs884409, found to be associated with serum ferritin in another population of p.C282Y homozygotes, and able to modulate promoter activity. A luciferase assay indicated that rs3806562 does not have a significant functional role, suggesting that it is a genetic marker linked to the putative genetic modifier rs884409.

Conclusions

While our results support the hypothesis that polymorphisms in genes regulating iron metabolism may modulate penetrance of HFE-hereditary hemochromatosis, with emphasis on CYBRD1, they strengthen the notion that none of these polymorphisms alone is a major modifier of the phenotype of hereditary hemochromatosis.     

Hereditary Hemochromatosis: Missed Diagnosis or Misdiagnosis?

Background

Hereditary hemochromatosis is a disorder that can cause iron overload and organ damage. Hereditary hemochromatosis is characterized by mutations in the HFE gene. HFE C282Y homozygotes and compound heterozygotes (C282Y/H63D) are at risk of developing manifestations of hemochromatosis. Abnormal iron study results also occur in many liver and hematologic diseases. The aim of this study was to evaluate the accuracy of diagnosis of hereditary hemochromatosis.

Methods

Pertinent clinical and laboratory data, including HFE genotype, were tabulated from the electronic medical records of patients with the International Classification of Diseases 9th Revision code 275, “disorders of iron metabolism,” who were seen at a tertiary referral center between January 2002 and May 2012.

Results

HFE genotyping was obtained in only 373 of 601 patients (62%); 200 were C282Y homozygotes or compound heterozygotes. Of the 173 patients with nonhereditary hemochromatosis genotypes, 53% were misdiagnosed with hereditary hemochromatosis and 38% underwent phlebotomy. In two thirds of these cases, the misdiagnosis was made by a nonspecialist. In the remaining 228 patients who were not genotyped, 80 were diagnosed with hereditary hemochromatosis and 64 were phlebotomized. Of patients misdiagnosed with hemochromatosis, 68% had known liver disease and 5% had a hematologic cause of abnormal iron study results.

Conclusions

Abnormal iron study results in patients with nonhereditary hemochromatosis genotypes commonly lead to a misdiagnosis of hereditary hemochromatosis and inappropriate treatment with phlebotomy. This error often is seen in the setting of elevated iron study results secondary to chronic liver diseases. Furthermore, hereditary hemochromatosis is commonly diagnosed and treated without HFE genotyping. We suggest that phlebotomy centers require a documented HFE genotype before initiating phlebotomy.     

Iron overload in HFE C282Y heterozygotes at first genetic testing: a strategy for identifying rare HFE variants

Background

Heterozygotes for the p.Cys282Tyr (C282Y) mutation of the HFE gene do not usually express a hemochromatosis phenotype. Apart from the compound heterozygous state for C282Y and the widespread p.His63Asp (H63D) variant allele, other rare HFE mutations can be found in trans on chromosome 6.

Design and Methods

We performed molecular investigation of the genes implicated in hereditary hemochromatosis in six patients who presented with iron overload but were simple heterozygotes for the HFE C282Y mutation at first genetic testing. Functional impairment of new variants was deduced from computational methods including molecular modeling studies.

Results

We identified four rare HFE mutant alleles, three of which have not been previously described. One mutation is a 13-nucleotide deletion in exon 6 (c.1022_1034del13, p.His341_Ala345>LeufsX119), which is predicted to lead to an elongated and unstable protein. The second one is a substitution of the last nucleotide of exon 2 (c.340G>A, p.Glu114Lys) which modifies the relative solvent accessibility in a loop interface. The third mutation, p.Arg67Cys, also lies in exon 2 and introduces a destabilization of the secondary structure within a loop of the α1 domain. We also found the previously reported c.548T>C (p.Leu183Pro) missense mutation in exon 3. No other known iron genes were mutated. We present an algorithm at the clinical and genetic levels for identifying patients deserving further investigation.

Conclusions

Our results suggest that additional mutations in HFE may have a clinical impact in C282Y carriers. In conjunction with results from previously described cases we conclude that an elevated transferrin saturation level and elevated hepatic iron index should indicate the utility of searching for further HFE mutations in C282Y heterozygotes prior to other iron gene studies.     

Non-HFE iron overload as a surrogate marker of disease severity in patients of liver cirrhosis

Background

Decompensated liver cirrhosis is an important cause of mortality worldwide. Various modifiable and non-modifiable factors are involved in the pathogenesis of cirrhosis and its complications. This study was aimed to evaluate the association of iron overload and disease severity in patients of liver cirrhosis and its association with HFE gene mutation.

Methods

Forty-nine patients with decompensated liver cirrhosis were recruited. Clinical and laboratory parameters were compared in patients with and without iron overload. C282Y and H63D gene mutation analysis was performed in all patients with iron overload.

Results

Iron overload was found in 20 (40.82 %) patients. A significant positive correlation of transferrin saturation with Child-Turcotte-Pugh (CTP) score (r?=?0.705, p?<?0.001) and model for end-stage liver disease (MELD) score (r?=?0.668, p?<?0.001) was found. Transferrin saturation was also independently associated with high CTP and MELD score on multivariate analysis. Mortality over 3 months was significantly more common in iron-overloaded patients (p?=?0.028). C282Y homozygosity or C282Y/H63D compound heterozygosity was not found in any of the patients with iron overload.

Conclusion

Iron overload was significantly associated with disease severity and reduced survival in patients of decompensated liver cirrhosis.

     

Measurement of serum hepcidin-25 levels as a potential test for diagnosing hemochromatosis and related disorders

Background

Iron overload syndromes include a wide spectrum of genetic and acquired conditions. Recent studies suggest suppressed hepcidin synthesis in the liver to be the molecular basis of hemochromatosis. However, a liver with acquired iron overload synthesizes an adequate amount of hepcidin. Thus, hepcidin could function as a biochemical marker for differential diagnosis of iron overload syndromes.

Methods

We measured serum iron parameters and hepcidin-25 levels followed by sequencing HFE, HJV, HAMP, TFR2, and SLC40A1 genes in 13 Japanese patients with iron overload syndromes. In addition, we performed direct measurement of serum hepcidin-25 levels using liquid chromatography–tandem mass spectrometry in 3 Japanese patients with aceruloplasminemia and 4 Italians with HFE hemochromatosis.

Results

One patient with HJV hemochromatosis, 2 with TFR2 hemochromatosis, and 3 with ferroportin disease were found among the 13 Japanese patients. The remaining 7 Japanese patients showed no evidence for genetic basis of iron overload syndrome. As far as the serum hepcidin-25 was concerned, seven patients with hemochromatosis and 3 with aceruloplasminemia showed markedly decreased serum hepcidin-25 levels. In contrast, 3 patients with ferroportin disease and 7 with secondary iron overload syndromes showed serum hepcidin levels parallel to their hyperferritinemia. Patients with iron overload syndromes were divided into 2 phenotypes presenting as low and high hepcidinemia. These were then associated with their genotypes.

Conclusion

Determining serum hepcidin-25 levels may aid differential diagnosis of iron overload syndromes prior to genetic analysis.     

Analysis of HFE gene mutations (C282Y, H63D, and S65C) in the Ecuadorian population

Type 1 hemochromatosis is a disorder of iron metabolism mostly related to the HFE gene mutations. In the present study, we performed a mutation analysis to determine the frequencies of the HFE gene mutations (C282Y, H63D, and S65C) in DNA samples of 100 healthy Ecuadorian individuals. We used the polymerase chain reaction (PCR) to amplify exons 2 and 4 of the HFE gene and then the restriction fragment length polymorphism (RFLP) method to detect the mutations. The results revealed that the mutations in the normal Ecuadorian population have frequencies of 0.0, 0.035, and 0.04 for C282Y, H63D, and S65C, respectively. We also searched for these mutations in 12 hemochromatosis patients, and the frequencies that we found were 0.0 for C282Y, 0.167 for H63D, and 0.042 for S65C. We found differences [using the chi-square (²) test] in the frequency of the H63D mutation between the control group and the group of hemochromatosis patients (p<0.01). This suggests that in Ecuador, type 1 hemochromatosis is more influenced by the H63D mutation than the other two mutations that we analyzed. Given that in a Caucasian population hereditary hemochromatosis is mostly related to the C282Y mutation, it is possible that the findings for the Ecuadorian population are due to geographical differences between the populations.     

Transferrin receptor-2 gene and non-C282Y homozygous patients with hemochromatosis

More than 80% of the patients affected by hereditary hemochromatosis, a common inherited iron disorder, are homozygotes for the 845G --> A (C282Y) mutation of the HFE gene. However, depending on the population, 10-20% of hereditary hemochromatosis can be linked either to other HFE genotypes, particularly the compound heterozygous state for C282Y and the 187 C --> G (H63D) mutation, or to mutations of new other genes. Recently, Camaschella et al. (Nat. Genet. 25, 14-15, 2000) identified a stop mutation (exon 6 nt 750 C --> T, Y250X) on the transferrin receptor-2 (TFR2) gene in two unrelated Sicilian families with hereditary hemochromatosis. The TFR2 gene is a transferrin receptor gene homologue that seems to be involved in iron metabolism. Moreover, one of the patients described by Camaschella et al. was a H63D homozygote. H63D homozygosity can be associated with various phenotypes from asymptomatic subjects to patients with a typical form of hereditary hemochromatosis. Thus, the Y250X mutation could be the molecular defect responsible for hereditary hemochromatosis in subjects with atypical HFE genotypes. We have searched for the Y250X mutation in 63 unrelated French subjects. Forty-three had a diagnosis of hereditary hemochromatosis based on classical criteria. This group included 12 H63D homozygotes, 3 C282Y heterozygotes, and 3 patients with none of the two most prevalent HFE mutants. These 18 patients had no other HFE sequence change and were subsequently subjected to DNA sequencing of the 15 last exons and flanking sequences of the TFR2 gene. The 25 remaining hereditary hemochromatosis patients who were tested for the Y250X mutant were compound heterozygotes for the C282Y and H63D mutations. Finally, we also tested for this TFR2 mutation 20 H63D homozygotes with milder manifestations of iron overload and no acquired cause of iron overload. None of the 63 tested subjects had the Y250X mutation. Concurrently, none of the 18 hereditary hemochromatosis patients who had their TFR2 gene sequenced had any deleterious mutation. Thus, TFR2 mutations are not responsible for hemochromatosis in non-C282Y homozygous patients of our area.     

Hereditary hemochromatosis: molecular diagnosis and effect of treatment

Hereditary hemochromatosis is a genetic disorder, inherited as an autosomal recessive trait, characterized by iron overload. A single mutation (C282Y) in the HFE gene is found in more than 90% of these patients. We report the case of a 50-year-old man, with clinical symptoms of hemochromatosis, who was found to be homozygous for the C282Y mutation. We present the results of therapeutic phlebotomy after one year of the treatment. Genetic tests were performed on the patient's close relatives and revealed that his son was also homozygous for the C282Y mutation. Early phlebotomy could prevent iron deposition and organ damage in this patient. Genetic determining of the HFE mutations is a useful noninvasive method of diagnosing hereditary hemochromatosis.     

Human leukocyte antigen haplotypes and HFE mutations in Spanish hereditary hemochromatosis and sporadic porphyria cutanea tarda

BACKGROUND AND AIMS: It has been postulated that the HFE C282Y mutation (linked to human leukocyte antigen [HLA]-A3-B7 haplotype) is not only responsible for hereditary hemochromatosis; HLA class I alleles would also contribute to the disease pathogenesis. In addition, H63D mutation linked to HLA-A29-B44 would also be pathogenetic, particularly in the Mediterranean Basin and throughout the world. However, sporadic porphyria cutanea tarda (s-PCT) has also been linked to these HFE mutations. In the present work, we have studied HFE mutations and HLA genes to test these hypotheses. METHODS: C282Y and H63D mutations together with HLA genetic typing have been performed in Spanish hereditary hemochromatosis (n = 98) and PCT (n = 63) patients. The etiologic fraction (delta) has been used to determine the absolute strongest gene linkage to both diseases. RESULTS: The Spanish frequent HLA-A29-B44 haplotype is not significantly associated to the H63D mutations in hereditary hemochromatosis patients (although it is found more frequently in patients than in controls). Sporadic porphyria cutanea tarda patients do not show a significant association to H63D mutations, although it is also more frequent than in controls; however, compound H63D/C282Y subjects seem to bear a significant risk to s-PCT. Allelic C282Y (and not H63D) frequencies show a significant association with s-PCT. CONCLUSIONS: The postulated additional risk of hereditary hemochromatosis given by class I HLA antigens may be secondary to the HFE gene linkage disequilibrium with certain class I alleles or to the existence of other neighboring genetic pathogenetic factors in our Spanish sample.     

HFE mutations in patients with hereditary haemochromatosis in Sweden

Cardoso EMP, Stål P, Hagen K, Cabeda JM, Esin S, De Sousa M, Hultcrantz R (Karolinska Hospital, Stockholm; Huddinge University Hospital, Huddinge; and Karolinska Institute, Stockholm, Sweden; Santo António Hospital; Abel Salazar Institute for Biomedical Sciences, Porto, Portugal). HFE mutations in patients with hereditary haemochromatosis in Sweden. J Intern Med 1998; 243 : 203–8.

Objective

To determine the frequency of mutations (C282Y and H63D) in a newly identified gene HFE in patients with hereditary haemochromatosis (HH) in Sweden.

Design

Molecular genetic analyses of the HFE gene (polymerase chain reaction (PCR) followed by enzyme restriction) were performed in genomic DNA from unrelated patients with a clinical diagnosis of HH and in healthy subjects.

Settings

Patients with HH treated with phlebotomies at Karolinska Hospital and Huddinge Hospital were analyzed.

Subjects

Eighty-seven unrelated patients with HH and 117 healthy controls.

Results

It was found that the HFE C282Y mutation occurs in 94.2% of chromosomes from patients with HH. Eighty patients (92.0%) were homo- zygous for the C282Y mutation and one was heterozygous. Three patients were heterozygous for both C282Y and H63D mutations. One patient was homozygous and one was heterozygous for the H63D mutation. One patient carried normal alleles. In healthy controls, the C282Y mutation occurred in nine subjects (7.7%), all of which were heterozygous. The H63D mutation was found in 28 control subjects, one of which was homozygous.

Conclusions

We found that the majority of patients with HH have the C282Y mutation in the HFE gene. The frequency of the H63D mu- tation was higher in controls than in patients with HH, although in chromosomes at risk the frequency of the H63D mutation was higher in patients.

     

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

Three HFE gene mutations (HFE 845 GA, 187 CG and 193 AT) 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.     

Do all hemochromatosis patients have the same origin? A pilot study of mitochondrial DNA and Y-DNA

BACKGROUND:

Mitochondrial DNA (mtDNA) and Y-DNA analysis have been widely used to predict ancestral origin. Genetic anthropologists predict that human civilizations may have originated in central Africa one to two million years previously. Primary iron overload is not a common diagnosis among indigenous people of northern Africa, but hereditary hemochromatosis is present in approximately one in 200 people in northern Europe. MtDNA analysis has the potential to determine whether contemporary hemochromatosis patients have an ancient ancestral linkage.

METHODS:

DNA was obtained from buccal smears for mtDNA and Y-DNA analysis. Y-DNA analysis included examination of 20 short tandem repeat markers on the Y chromosome. Analysis of mtDNA involved sequencing of the HVR-1 genetic sequence (nucleotides 16001 to 16520) and was compared with the Cambridge Reference Sequence. MtDNA ancestral haplotypes were predicted from the analysis of the HVR-1 sequence.

RESULTS:

Twenty-six male C282Y homozygotes were studied. There were 28 polymorphisms present in the HVR-1 sequence of these participants. The most common polymorphism was present at position 16519 in 15 participants and at position 16311 in eight participants. There were 12 different ancestral haplotypes predicted by mtDNA analysis, with the K haplotype being present in five participants. Y-DNA analysis revealed eight different haplotypes, with R1b being found in 11 of the 26 participants.

CONCLUSION:

Analysis of mtDNA and Y-DNA in 26 hemochromatosis patients suggested that they did not all originate from the same ancestral tribe in Africa. These findings were consistent with the theory that the original hemochromatosis mutation occurred after migration of these ancestral people to central Europe, possibly 4000 years previously.     

Natural History and Outcome of Hepatic Vascular Malformations in a Large Cohort of Patients with Hereditary Hemorrhagic Teleangiectasia

Background

Hereditary hemorrhagic telangiectasia is a genetic disease characterized by teleangiectasias involving virtually every organ. There are limited data in the literature regarding the natural history of liver vascular malformations in hemorrhagic telangiectasia and their associated morbidity and mortality.

Aim

This prospective cohort study sought to assess the outcome of liver involvement in hereditary hemorrhagic telangiectasia patients.

Methods

We analyzed 16 years of surveillance data from a tertiary hereditary hemorrhagic telangiectasia referral center in Italy. We considered for inclusion in this study 502 consecutive Italian patients at risk of hereditary hemorrhagic telangiectasia who presented at the hereditary hemorrhagic telangiectasia referral center and underwent a multidisciplinary screening protocol for the diagnosis of hereditary hemorrhagic telangiectasia. Of the 502 individuals assessed in the center, 154 had hepatic vascular malformations and were the subject of the study; 198 patients with hereditary hemorrhagic telangiectasia and without hepatic vascular malformations were the controls. Additionally, we report the response to treatment of patients with complicated hepatic vascular malformations.

Results

The 154 patients were included and followed for a median period of 44 months (range 12?C181); of these, eight (5.2%) died from VM-related complications and 39 (25.3%) experienced complications. The average incidence rates of death and complications were 1.1 and 3.6 per 100 person-years, respectively. The median overall survival and event-free survival after diagnosis were 175 and 90 months, respectively. The rate of complete response to therapy was 63%.

Conclusions

This study shows that substantial morbidity and mortality are associated with liver vascular malformations in hereditary hemorrhagic telangiectasia patients.     

The role of hemochromatosis susceptibility gene mutations in protecting against iron deficiency in celiac disease

BACKGROUND & AIMS: Celiac disease and hereditary hemochromatosis are common HLA-defined conditions in northwestern Europe. We sought to determine whether there is a genetic relationship between the 2 diseases and if hemochromatosis susceptibility gene (HFE) mutations are protective against iron deficiency in celiac disease. METHODS: Polymerase chain reaction amplification using sequence-specific primers capable of identifying the 2 HFE gene mutations (H63D and C282Y) and the HLA class I and II alleles was used to type 145 white patients with celiac disease and 187 matched controls. Hemoglobin and fasting serum iron levels in celiac patients were measured at diagnosis. RESULTS: HFE gene mutations, H63D or C282Y, were identified in 70 celiac patients (48.3%) and 61 controls (32.6%) (P = 0.004). The C282Y mutation was associated with HLA-A*03 and B*07 alleles in controls and with A*01, A*03, B*08, and DRB1*0301 alleles in celiac patients; the H63D mutation was associated with HLA-A*25 and DRB1*03 alleles in controls and A*29 and DRB1*03 alleles in celiac patients. At diagnosis, celiac patients with the C282Y mutation had higher mean hemoglobin and fasting serum iron levels compared with the HFE wild type (P = 0.0002 and 0.006, respectively). This was not observed with the H63D mutation. CONCLUSIONS: In celiac disease, HFE gene mutations are common and are in linkage disequilibrium with different HLA alleles compared with controls. A disease-specific haplotype that carries C282Y and DQB1*02 is suggested. We propose that HFE gene mutations provide a survival advantage by ameliorating the iron deficiency seen in celiac patients.     

A homozygous HFE gene splice site mutation (IVS5+1 G/A) in a hereditary hemochromatosis patient of Vietnamese origin

The vast majority of Caucasian patients presenting with hereditary hemochromatosis demonstrate a single homozygous missense mutation in the HFE gene (C282Y). The underlying genetic defects in hemochromatosis patients of non-Caucasian origin are largely unknown. A 48-year-old man of Vietnamese origin presented with insulin-dependent diabetes mellitus, tertiary adrenocortical insufficiency, and laboratory results highly indicative of hereditary hemochromatosis. Because the patient was negative for the known HFE gene mutations C282Y, H63D, and S65C HFE, the entire coding region and intron/exon boundaries of the HFE gene was investigated. Sequencing studies identified a homozygous G-to-A transition at position +1 of intron 5 (IVS5+1 G/A). This newly described mutation alters the invariant G at position +1 of the 5' splice site causing altered mRNA splicing and exon skipping with exon 4 being spliced to exon 6. Both heterozygously affected children (age 19 and 20 years) had moderately increased ferritin levels with normal serum iron concentration and transferrin saturation. The newly described mutation was not detected in a control group consisting of 220 Caucasian individuals as verified by allele-specific polymerase chain reaction. We describe for the first time a homozygous HFE splice site mutation (IVS5+1 G/A) in a non-Caucasian patient with hereditary hemochromatosis. Although the absence of this novel HFE gene mutation in Caucasian subjects suggests that the mutation is exclusive to this family, mutation screening in populations of different ethnic background is recommended to precisely define its contribution to hereditary hemochromatosis in non-Caucasian patients.     

Hereditary hemochromatosis

INTRODUCTION: Hereditary hemochromatosis is a fairly common disease in the Caucasian population, with a prevalence estimated at between 1.5 to 3/1,000 inhabitants. Over the past few years, its symptomatology has altered; at present, its clinical aspect with diabetes mellitus, cirrhosis, and darker skin pigmentation only constitutes 10% of new cases of this disease. CURRENT KNOWLEDGE AND KEY POINTS: In 1996, the discovery of the C282Y mutation in the HFE gene radically altered the diagnostic approach to hereditary hemochromatosis. At present, any patient admitted with an isolated case of asthenia, or with arthralgia or hypertransaminasemia should be examined via transferrin-saturation testing: if the transferrin saturation coefficient is > 45%, then the presence of the C282Y mutation should be investigated to confirm the diagnosis of hemochromatosis. A liver biopsy is no longer necessary to establish the diagnosis, but this is still useful in cases of possible cirrhosis, which is the main risk factor for hepatocellular carcinoma. Phlebotomy remains the sole recommended treatment, and should be undertaken in a case-specific manner. Family screening should be carried out for all first-degree relatives for every new case that is diagnosed. FUTURE PROSPECTS AND PROJECTS: The discovery of the HFE gene has permitted hereditary hemochromatosis to be easily differentiated from other forms of hepatic iron overload including a new syndrome, dysmotabolic hepatosiderosis. Casos of homozygotic C282Y without hepatic iron overload have been described, but the clinical outcome of some of these cases requires further study, and adds to the controversy on whether systematic population screening should be made available.     

Prevalence of H63D,S65C,and C282Y hereditary hemochromatosis gene variants in Madeira Island (Portugal)

Hereditary HFE Hemochromatosis is an inherited disorder of iron metabolism that results from mutations in the HFE gene. Almost all patients with hereditary hemochromatosis show a C282Y mutation in homozygosity or in compound heterozygosity with H63D. Also, the mutation S65C has been shown to be associated to a milder iron overload. Since allele and genotype frequencies of these three variants of the HFE gene vary between populations, the determination of their prevalence in Madeira Island will clarify the population susceptibility to hereditary hemochromatosis. One hundred and fifty-four samples from Madeira Island were genotyped for the three most common HFE gene mutations, H63D, C282Y, and S65C, by polymerase chain reaction followed by restriction fragment length polymorphism analysis. Results have shown a prevalence of 20.5%, 0.33%, and 1% for H63D, C282Y, and S65C, respectively. Accordingly to our estimates, both genotypes associated to hereditary hemochromatosis, C282Y homozygotes and C282/H63D compound heterozygotes, could be present in Madeira Island population in 1,648 individuals, which represents 0.65% of the total population.     

Expression of the HFE hemochromatosis gene in a community-based population of elderly women

BACKGROUND AND AIM: Recent studies suggest that the clinical penetrance of associated hereditary hemochromatosis, defined as either the C282Y homozygote or compound heterozygote HFE genotype status, is much lower than previously thought. METHODS: We investigated the clinical penetrance and phenotypic expression of HFE-associated hereditary hemochromatosis in a community-based population of 1352 elderly female subjects with a mean age of 75 years. Serum transferrin saturation and ferritin levels were determined on all subjects bearing a C282Y mutation and a subset of wild-type C282Y subjects. RESULTS: The prevalences of the C282Y homozygous and compound heterozygous HFE genotypes were 0.15% (2/1352) and 2.0% (27/1352), respectively. The observed prevalence of 0.15% for C282Y homozygotes borders on significance (P = 0.054) for deviation from the Hardy-Weinberg population equilibrium calculations, which predict a prevalence of 0.49%, whereas the observed and predicted compound heterozygote prevalences were not significantly different. Clinical symptoms of hemochromatosis were absent in both the C282Y homozygote subjects. Of the compound heterozygous subjects, 2/27 (7%) had elevated serum transferrin saturation and ferritin values; however, clinical symptoms of hemochromatosis were absent in both. Considered as a whole, the compound heterozygous subjects had markedly elevated means for serum iron (19.4 vs 16.0 micromol/L, P = 0.0008), transferrin saturation (34.8% vs 25.2%, P < 0.0001) and ferritin (157 vs 92 microg/L, P = 0.002) compared with the wild-type subjects. CONCLUSION: The C282Y homozygous HFE hereditary hemochromatosis genotype was under-represented in this elderly cohort, whereas the compound heterozygous genotype was not. None of the homozygous or compound heterozygous subjects expressed the phenotype of iron overload disease.     

Genetische Hämochromatose

Among the conditions known as hereditary hemochromatosis, only the autosomal recessive type 1 has any clinical significance. In this case a homozygote point mutation C282Y in the HFE gene leads to increased intestinal iron resorption and over the course of decades to iron deposition and injury to various organs (e.g. liver, pancreas, heart, joints and gonads). In populations of Celtic descent, type 1 hemochromatosis is the most common hereditary metabolic disease. The frequency of homozygote carriers is approximately 0.5% but because of an incomplete penetrance, the frequency of clinical diseases is only approximately 0.1%. The diagnosis of hemochromatosis is based on determination of transferrin saturation and serum ferritin levels, whereby transferrin saturation is more sensitive and specific. The diagnosis can be confirmed with genetic testing. A liver biopsy is only recommended by ferritin values of >1,000 ng/ml to evaluate the degree of liver fibrosis. Therapeutic phlebotomy ensures a normal prognosis if initiated before the occurrence of liver cirrhosis and diabetes. Therefore future efforts should be dedicated to early recognition.