Genetic testing for hemochromatosis: attitudes and acceptability among young and older adults

Hemochromatosis is a genetic disorder of iron overload common in persons of northern European descent. We examined attitudes about testing for hemochromatosis in 118 young adults (YA) (19.7 years +/- 1.9) and 50 older adults (OA) (58.5 years +/- 13.7). Participants read about hemochromatosis and two related tests: transferrin saturation measurement (iron test) and HFE genotyping (HFE test). Interest in each test and attitudes about genetic testing were assessed. More than 80% of all participants were willing to undergo either test, if offered. A majority preferred the iron test because of the information it provides about current health. A majority of participants identified at least one benefit of genetic testing, with improved health through early detection/prevention being most common. YA were more likely to report disadvantages of genetic testing (p < 0.001) and were more concerned about potential negative psychological effects (p < 0.005). OA were more concerned about potential discrimination (p < 0.0001). These findings suggest that young and older adults view genetic testing as beneficial and would accept HFE testing were it offered as part of a screening program.     

Psychosocial impact of genetic testing for hemochromatosis in the HEIRS Study: a comparison of participants recruited in Canada and in the United States

The Hemochromatosis and Iron Overload Screening (HEIRS) Study screened 101,168 participants recruited from primary-care clinics in Canada and the United States. The present study investigated differences in the psychological effects of genetic screening for hemochromatosis (HFE mutation analysis) in participants from each country. Study participants comprised a subset of 2,654 individuals who donated blood for HFE mutation analysis. The initial screening and 1-month post-result questionnaires included measures of General Health, Mental Health (SF-36), and a measure of the percentage of individuals who experienced at least one example of worry in response to the genetic testing. Participants reported similar changes in general health and mental health, regardless of mutation result, or country. Although a significantly lower percentage of Canadian participants than U.S. participants indicated at least one negative emotional response to the genetic testing, greater than 50% of C282Y homozygote participants (the gene mutation most strongly associated with hemochromatosis) from both countries experienced such in response to testing. Thus, although not serious enough to affect individuals' mental or physical health, there was evidence of at least one element of negative emotional response to the genetic testing. These findings suggest that population screening for common HFE mutations associated with hemochromatosis risk has similar psychological effects on Canadian and U.S. individuals, although fewer Canadians may experience a negative response to such testing.     

HFE genotype frequencies in consecutive reference laboratory specimens: comparisons among referral sources and association with initial diagnosis

We quantified HFE genotype frequencies in specimens submitted by physicians grouped by specialty and determined associations of genotypes with initial diagnosis based on phenotyping in patients evaluated at an iron disorders center. Of 526 specimens (519 from Alabama), these "typical" hemochromatosis-associated genotypes were detected: 85 C282Y/C282Y, 50 C282Y/H63D, and 27 H63D/H63D. Respective frequencies of C282Y/C282Y in specimens from an iron disorders center (n = 156), gastroenterologists (n = 147), hematologists/medical oncologists (n = 85), liver transplant surgeons (n = 11), endocrinologists and rheumatologists (n = 9), and "other sources" (n = 7) were greater (p < 0.05) than in population controls. In 44 patients from an iron disorders center initially diagnosed as "presumed hemochromatosis," 27 (61.4%) had C282Y/C282Y, 10 (22.7%) had C282Y/H63D, and 3 (6.8%) had H63D/H63D. C282Y/C282Y was not detected in 48 patients with "abnormality probably not an iron overload disorder." A total of 20.5% of 44 family members of patients had "typical" hemochromatosis-associated HFE genotypes (7.0% controls; p = 0.02). We conclude that most physicians who submitted specimens identify patients by phenotyping who have greater frequencies of "typical" hemochromatosis-associated HFE genotypes than controls, and that HFE mutation testing is useful in detecting hemochromatosis in family members of persons with hemochromatosis or iron overload.     

Screening for hemochromatosis in routine medical care: an evaluation of mean corpuscular volume and mean corpuscular hemoglobin

Our aim was to evaluate the potential utility of mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) to detect hemochromatosis. We computed the accuracy of MCV and MCH cut-off points > or = upper reference limits using data from 94 probands and 132 white controls. Our reference ranges are MCV 80.0-97.0 fL and MCH 26.0-32.0 pg. Sensitivity of MCV was 8.6-48.3% for men and 2.8-44.4% for women (cut-off points > or = 105.0 - > or = 97.0 fL, respectively). Sensitivity of MCH was 33.9-70.7% for men and 19.6-50.0% for women (cut-off points > or = 34.0 - > or = 32.0 pg, respectively). Using MCV and a hemochromatosis frequency typical of many western Caucasian populations (0.005), positive predictive values (PV+) were 2.1-100.0% in men and 4.2-100.0% in women. Using MCH, PV+ were 1.7-8.2% in men and 1.8-6.8% in women. We also calculated PV+ using the hemochromatosis frequency 0.015, which could occur in persons receiving medical care. Using MCV cut-off points > or = 101.0 fL, PV+ were 8.9-100.0% in men and 100.0% in women with maximum sensitivities of 24.1% and 25.0%, respectively. Using MCH testing, PV+ was 21.5% in men (cut-off point > or = 34.0 pg) and 18.2% in women (cut-off point > or = 33.0 pg) with sensitivities of 33.9% and 37.0%, respectively. Using MCV or MCH, sensitivity and PV+ for the HFE genotype C282Y/C282Y were generally greater than for "nonclassical" HFE genotypes. All negative predictive values in our study were > or = 98.5%. We conclude that supranormal values of MCV or MCH could be used to detect hemochromatosis in white persons of western European descent who are receiving routine medical care. Comparisons of MCV, MCH, and transferrin saturation testing and other implications of MCV and MCH testing for hemochromatosis in medical care are discussed.     

Rapid genetic screening for hemochromatosis using automated SSCP-based capillary electrophoresis (SSCP-CE).

Hereditary hemochromatosis (HHC) represents an autosomal recessive disease in which increased iron absorption causes iron overload and irreversible tissue damage. The recently detected association between two point mutations in the HFE gene on chromosome 6p and HHC has made it possible to screen for the disease before the onset of irreversible tissue damage. Conventional genetic testing is based on restriction fragment-length polymorphisms (RFLP) using two endonuclease recognition sites in codon 63 or 282, respectively. In this study, we have adapted single-strand conformation polymorphism analysis for capillary electrophoresis (SSCP-CE) to detect homozygote or heterozygote point mutations. Two HFE gene fragments spanning codons 63 and 282 were amplified by a duplex PCR using genomic DNA from peripheral blood or from tissue sections of paraffin-embedded liver biopsies as template. Thereby, rapid genotyping of both HFE mutations was achieved with a single PCR, omitting the need of further analysis by restriction digest. Eighty-five patients with liver disease and/or suspected iron overload were genotyped using SSCP-CE, and all results were verified by conventional RFLP analysis. In summary, SSCP-CE proved to be a reliable, cost-effective, sensitive and rapid method for genotyping HFE mutations. This method will further facilitate high-throughput genetic screening using capillary array electrophoretic devices.     

Genotype-based screening for hereditary hemochromatosis: II. Attitudes toward genetic testing and psychosocial impact--a report from a German pilot study

In collaboration with the German Sickness Fund (Kaufm?nnische Krankenkasse-KKH), we conducted a pilot study on DNA-based population screening of hereditary hemochromatosis (HH) in Germany. The health insurance organization KKH briefly informed their members about the possibility to participate voluntarily in this pilot project. A total of 5882 KKH members contacted us and received detailed information on the aim of the project and clinical and genetic aspects of HH. Of these individuals, 3961 requested HFE genotyping. After genotype results had been communicated to the participants' general practitioner, we sent a self-administered questionnaire to all homozygous (n = 67) and heterozygous (n = 485) as well as 448 wild-type study participants (sigma = 1000) to assess the psychosocial impact of HFE genotyping. In addition, questionnaires were sent to 8000 randomly selected members of the KKH to investigate their attitude toward genetic testing. Six hundred thirty-one (63.1%) of the test participants and 2141 (26.8%) of the randomly chosen KKH members responded. A total of 59.1% of the members would generally accept predictive genetic testing and 3.7% objected to such tests in principle. Individuals with higher educational status accepted predictive testing significantly more often than individuals with less education. Of the tested individuals, 69.9% thought that participation in the pilot study was probably beneficial for them and 1% (5 heterozygotes and 1 wild-type) thought that it was probably harmful. Of the participants, 94.6% judged their decision to have participated in the pilot study as right and 0.3% (2 heterozygotes) as probably wrong. Only very few of the tested individuals underwent pretest (1 case) or posttest (11 cases) genetic counseling. We conclude that genotype- based screening for HH is generally accepted and was perceived as beneficial. Negative psychosocial consequences are rare and could presumably have been prevented by delivering appropriate pretest and posttest information.     

Hemochromatosis gene sequence deviations in German patients with porphyria cutanea tarda

Patients with porphyria cutanea tarda (PCT) reveal a susceptibility to reversible inactivation of hepatic uroporphyrinogen decarboxylase, which might be triggered by alcohol, hepatitis C virus infection, and iron overload. Inherited factors that may predispose to clinically overt PCT also include sequence deviations in the HFE gene that is mutated in classical hemochromatosis. Here, we studied the prevalence of both common and rare hemochromatosis gene variations in 51 PCT patients and 54 healthy controls of German origin. The frequency of the common HFE gene mutation C282Y was 15.7 % in PCT patients and 2.8 % in healthy control individuals (P < 0.001). By contrast, the frequencies of the common H63D mutation did not differ, and the allele frequencies of the less frequently observed sequence deviations as substitution S65C in the HFE gene and mutation Y250X in the TFR2 gene underlying hemochromatosis type 3 (HFE3) were < 0.02 both in PCT patients and controls. Our results comprise the first molecular studies of both common and rare hemochromatosis gene variants in German PCT patients, indicating a significant role of the C282Y mutation in the pathogenesis of PCT.     

Psychosocial impact of C282Y mutation testing for hemochromatosis

The aim of this study was to investigate the psychological effects of genetic testing for hemochromatosis. Study participants included cases discovered through a population screening study in 5211 voluntary blood donors (n = 25) and patients referred for diagnostic evaluation for hemochromatosis (n = 117). Participants completed questionnaires (Spielberger State-Trait Anxiety Index, Medical Outcomes Survey Short Form 36) before and after genetic testing. A subset of participants from the screening study was also interviewed 1 year after testing (Feelings About Test Results Measure). Additional questions included data on insurance applications, time off from work, and family issues. Anxiety significantly decreased in homozygotes and heterozygotes after genetic testing and remained constant in C282Y mutation-negative cases. Vitality and physical composite scores improved after genetic testing. There were no significant deleterious psychological effects of genetic testing on anxiety and on mental and physical health status. There were no negative effects discovered on insurance or time off work. This study has not demonstrated deleterious effects of genetic testing for hemochromatosis on anxiety, mental health and physical health status, insurance, or time off from work. Genetic testing for hemochromatosis is well accepted and should not be discouraged on the basis of potential adverse psychosocial effects.     

Real-time PCR genotyping using displacing probes

Simple and reliable genotyping technology is a key to success for high-throughput genetic screening in the post-genome era. Here we have developed a new real-time PCR genotyping approach that uses displacement hybridization-based probes: displacing probes. The specificity of displacing probes could be simply assessed through denaturation analysis before genotyping was implemented, and the probes designed with maximal specificity also showed the greatest detection sensitivity. The ease in design, the simple single-dye labeling chemistry and the capability to adopt degenerated negative strands for point mutation genotyping make the displacing probes both cost effective and easy to use. The feasibility of this method was first tested by detecting the C282Y mutation in the human hemochromatosis gene. The robustness of this approach was then validated by simultaneous genotyping of five different types of mutation in the human β-globin gene. Sixty-two human genomic DNA samples with nine known genotypes were accurately detected, 32 random clinical samples were successfully screened and 114 double-blind DNA samples were all correctly genotyped. The combined merits of reliability, flexibility and simplicity should make this method suitable for routine clinical testing and large-scale genetic screening.     

Transferrin saturation phenotype and HFE genotype screening for hemochromatosis and primary iron overload: predictions from a model based on national, racial, and ethnic group composition in central Alabama

There is interest in general population screening for hemochromatosis and other primary iron overload disorders, although not all persons are at equal risk. We developed a model to estimate the numbers of persons in national, racial, or ethnic population subgroups in Jefferson County, Alabama, who would be detected using transferrin saturation (phenotype) or HFE mutation analysis (genotype) screening. Approximately 62% are Caucasians, 37% are African Americans, and the remainder are Hispanics, Asians, or Native Americans. The predicted phenotype frequencies are greatest in a Caucasian subgroup, ethnicity unspecified, which consists predominantly of persons of Scotch and Irish descent (0.0065 men, 0.0046 women), and in African Americans (0.0089 men, 0.0085 women). Frequencies of the HFE genotype C282Y/C282Y > or = 0.0001 are predicted to occur only among Caucasians; the greatest frequency (0.0080) was predicted to occur in the ethnicity-unspecified Caucasian population. C282Y/C282Y frequency estimates were lower in Italian, Greek, and Jewish subgroups. There is excellent agreement in the numbers of the ethnicity-unspecified Caucasians who would be detected using phenotype and genotype criteria. Our model also indicates that phenotyping would identify more persons with primary iron overload than would genotyping in our Italian Caucasian, Hispanic, and African American subgroups. This is consistent with previous observations that indicate that primary iron overload disorders in persons of southern Italian descent and African Americans are largely attributable to non-HFE alleles. Because the proportions of population subgroups and their genetic constitution may differ significantly in other geographic regions, we suggest that models similar to the present one be constructed to predict optimal screening strategies for primary iron overload disorders.     

A primer for predicting risk of disease in HFE-linked hemochromatosis

Since the discovery of the hemochromatosis gene (HFE) in 1996, there has been increasing interest in diagnostic testing for the C282Y and H63D mutations. The high frequency of these two alleles and their incomplete penetrance in homozygotes and compound heterozygotes make genetic counseling for hemochromatosis different from some other autosomal recessive conditions in that parents and children may also be at risk for iron overload, while homozygotes may remain asymptomatic. We provide a guideline for genetic counseling in HFE-linked hemochromatosis based on the genetic probability of inheriting HFE mutations and known information about expression of iron overload in various HFE genotypes. Genetic probabilities were based on allele frequencies derived from large population studies and Hardy-Weinberg equilibrium estimates. Expression of iron overload in those of various genotypes was based on available estimates of serum ferritin from population screening studies. Estimates for the likelihood of clinical iron overload requiring follow-up screening or treatment are provided by gender and genotype. The probability of inheriting HFE mutations and developing iron overload can be estimated in family members of a proband with HFE mutations. Many C282Y homozygotes will not have clinical iron overload. The risk is highest in men and their C282Y homozygous brothers and significantly lower in homozygous women. Iron overload is uncommon in compound heterozygotes and H63D homozygotes.     

Hereditary hemochromatosis in Spain

The C282Y mutation of the HFE gene has been reported as the main cause of hereditary hemochromatosis (HH). Another missense mutation (H63D) has also been detected at an increased frequency in a compound heterozygote state with the C282Y mutation in HH patients. However, these two mutations are not present in all of the HH patients, indicating that other mutations in the HFE gene, or in other loci, should exist. The present study reports the frequencies of the C282Y and H63D mutations in 74 Spanish HH patients and the results of the sequencing analysis of the HFE exons, intron-exon boundaries, and 588 bp of the 5' region in 5 patients negative for the C282Y mutation. We have detected a high frequency of the C282Y mutation (85.1%) in Spanish HH patients, indicating that this mutation is the most common defect associated with the disease in Spain. The screening of the HFE regions in our patients without the C282Y mutation has revealed the presence of five polymorphisms. However, no other pathological mutations have been found. Therefore, further efforts to characterize the unscreened part of the HFE gene or other loci should be taken to identify the potential genetic factors causing HH in the C282Y-negative patients.     

Knowledge, attitudes, and utilization of BRCA1/2 testing among women with early-onset breast cancer

A total of 2,400 questionnaires were mailed to members of two mid-Atlantic breast cancer awareness/support groups to investigate the association between attitudes, knowledge, and use of BRCA1/2 testing among women with early-onset breast cancer. Of the 493 (21%) questionnaires returned, 406 respondents had a diagnosis of breast cancer, of whom 248 were diagnosed prior to age 50 and included in the analyses. Eighty-three percent (206/248) of these women had heard of BRCA1/2 testing and 12.5% (31/248) had undergone BRCA1/2 testing. Among women who had heard of BRCA1/2 testing, women who had been tested were younger (p = 0.03), more likely to have a college education (p = 0.03), more likely to have a family member who had undergone BRCA1/2 testing (p = 0.005), and had greater knowledge, more positive attitudes, and fewer negative attitudes about BRCA1/2 testing (p = 0.02, p = 0.004, and p = 0.004, respectively). In this sample, knowledge regarding BRCA1/2 testing is high, but uptake of genetic testing is low. Lack of information regarding how genetic testing might alter health-care decisions and fear about the genetic testing procedure, its costs, and possible false-positive results are associated with low uptake of genetic testing. Further education regarding these specific points may enhance the use of genetic testing.     

Psychosocial correlates of pregnant women's attitudes toward prenatal maternal serum screening and invasive diagnostic testing: beyond traditional risk status

This study examined whether psychosocial variables predict pregnant women's attitudes toward maternal serum screening and invasive diagnostic testing, beyond the influence of traditional obstetric risk status (based on advanced maternal age, history of genetic disorders, etc.). In a sample of 612 pregnant women (66.5% high risk, 33.5% low risk) we assessed responses to hypothetical scenarios of invasive testing following normal or abnormal maternal serum screening. We also assessed psychosocial variables stemming from the theory of planned behavior (e.g., knowledge, concern for fetus, attitudes toward termination, health locus of control). Overall, two thirds of the women would want serum screening. Follow-up invasive diagnostic testing would be sought by 37.2% of the women after a negative screening, and by 75.0% after a positive screening. As expected, traditional risk status predicted desire for screening and also invasive testing following either a negative or positive screen. Yet, controlling for risk status, many psychosocial variables predicted a women's interest in screening and in invasive testing: more knowledge about prenatal testing, concern about fetal health, willingness to terminate a pregnancy, and an internal or medical profession health locus of control. We conclude that psychosocial variables influence women's desire for screening or invasive testing beyond traditional risk status.     

Genetic hemochromatosis, a Celtic disease: is it now time for population screening?

In populations of northern European ancestry, hereditary hemochromatosis (HH) is tightly linked to mutations within the hemochromatosis gene (HFE gene). Over 93% of Irish HH patients are homozygous for the HFE gene C282Y mutation, providing a reliable diagnostic marker of the disease in this population. However, the prevalence of the C282Y mutation and that of the second HFE gene mutation, H63D, have yet to be determined within the Irish population. The objective of this study was to identify the true prevalence of the genetic form of HH in the Irish population. DNA was extracted from 1002 randomly selected newborn screening cards and analyzed for the C282Y and H63D mutations within the HFE gene. Complete results were obtained from 800 cards. Mutations were identified in 364 (46%) neonates. Eight (1%) neonates were homozygous for C282Y and 8 (1%) were homozygous for H63D. One hundred and fifty-five (19%) neonates were C282Y heterozygous and 226 (28%) were H63D heterozygous. Of these, 33 (4%) carried one copy of both C282Y and H63D mutations, i.e., compound heterozygous. Allele frequencies for C282Y and H63D were 11% and 15%, respectively. The high C282Y allele frequency in the Irish population together with its close linkage to HH indicate that C282Y genotyping is the preferred screening strategy for this disease in Ireland.     

A reverse-hybridization assay for the rapid and simultaneous detection of nine HFE gene mutations

Hereditary hemochromatosis (HH) is a very common autosomal recessive disorder of iron metabolism and frequently associated with mutations in the HFE gene. Molecular genetic testing for HFE mutations is considered valuable for carrier identification, as well as for early diagnosis of the disease, allowing simple treatment by phlebotomy and normal survival of patients. We have developed a reverse-hybridization assay for the routine diagnosis of eight previously described and one novel (E168Q) HFE point mutations. The test is based on multiplex DNA amplification and ready-to-use membrane teststrips, which contain oligonucleotide probes for each wild-type and mutated allele immobilized as an array of parallel lines. The procedure is rapid and accessible to automation on commercially available equipment, and by adding new probes the teststrip can easily be adapted to cover an increasing number of mutations.     

Polymorphisms of hemochromatosis, and alpha-1 antitrypsin genes in Egyptian HCV patients with and without hepatocellular carcinoma

Hereditary hemochromatosis and alpha-1antitrypsin deficiency are genetic diseases characterized by endoplasmic reticulum (ER) stress with subsequent development of liver disease. Our aim was to estimate the frequency of hemochromatosis gene (HFE) mutant alleles (C282Y and H63D) and alpha-1 antitrypsin S/Z variants among Egyptian HCV cirrhotic patients and in hepatocellular carcinoma patients and to evaluate their effects on disease progression. HFE and alpha-1 antitrypsin polymorphisms were characterized in 200 Egyptian patients with HCV infection (100 patients complicated with cirrhosis, 100 patients with HCC) and 100 healthy subjects who had no history of any malignancy. The frequencies of HD genotype of H63D mutation were significantly increased in HCC patients compared to control group and to cirrhosis group. Also, the frequencies of DD genotype were significantly increased In HCC group compared to control group and to cirrhosis group. Our results suggested that Carriers of the D allele of H63D mutation were significantly more likely to develop HCC.     

Hemochromatosis gene variants in three different ethnic populations: effects of admixture for screening programs

Genetic testing for hemochromatosis may have important implications for diagnosis and screening of the disease. However, the relative importance of mutations in the gene for hereditary hemochromatosis, HFE, may vary among populations, when the mutant allele frequencies and their penetrance in a particular genetic and environmental background are taken into account. We present data on the allele and genotype frequencies and population structure of two HFE genetic variants in three different ethnic groups from a highly mixed urban population (S?o Paulo, Brazil). Allele frequencies for both the C282Y and H63D HFE mutations showed significant differences among the studied populations (for the C282Y mutation, Euro-Brazilian 3.7%, admixed 0.7%, Afro-Brazilian 0.5%; and for the H63D mutation, Euro-Brazilian 20.3%, admixed 13.0%, Afro-Brazilian 6.4). The data substantiate a European origin for these mutations. Furthermore, they provide a basis for a more rational strategic planning of population screening programs for the disease.     

Hereditary hemochromatosis: the clinical significance of the S65C mutation

Hereditary hemochromatosis (HH) is a common genetic disease with iron overload in certain organs, especially the liver. Most cases are homozygous for the C282Y mutation in the HFE gene; a few are C282Y heterozygous, compound C282Y/H63D heterozygous, or have no known mutation. A third mutation, S65C, has been associated with HH, but this finding is disputed. We have studied the clinical significance of various genotypes with the S65C mutation. In a population-based screening for HH in 65,238 persons, 613 had high serum transferrin saturation in two blood samples and were invited for HFE genotyping. In 556 persons with complete data sets, we studied the serum ferritin concentration and the risk of being diagnosed with phenotypic HH in the various genotypic groups. The phenotypic diagnosis was given without knowing the genotypic result. Except for the C282Y homozygotes, no differences in median serum ferritin concentrations were found between the various genotypic groups. However, the C282Y/S65C compound heterozygous group had a higher risk of being diagnosed with phenotypic HH than the wild-type group, as did the C282Y homozygous and the C282Y/H63D compound heterozygous groups. When combined with the C282Y mutation, the S65C mutation is associated with an increased risk of being diagnosed with phenotypic HH.     

Mutations in the HFE, TFR2, and SLC40A1 genes in patients with hemochromatosis

Hereditary hemochromatosis causes iron overload and is associated with a variety of genetic and phenotypic conditions. Early diagnosis is important so that effective treatment can be administered and the risk of tissue damage avoided. Most patients are homozygous for the c.845G>A (p.C282Y) mutation in the HFE gene; however, rare forms of genetic iron overload must be diagnosed using a specific genetic analysis. We studied the genotype of 5 patients who had hyperferritinemia and an iron overload phenotype, but not classic mutations in the HFE gene. Two patients were undergoing phlebotomy and had no iron overload, 1 with metabolic syndrome and no phlebotomy had mild iron overload, and 2 patients had severe iron overload despite phlebotomy. The patients' first-degree relatives also underwent the analysis. We found 5 not previously published mutations: c.-408_-406delCAA in HFE, c.1118G>A (p.G373D), c.1473G>A (p.E491E) and c.2085G>C (p.S695S) in TFR2; and c.-428_-427GG>TT in SLC40A1. Moreover, we found 3 previously published mutations: c.221C>T (p.R71X) in HFE; c.1127C>A (p.A376D) in TFR2; and c.539T>C (p.I180T) in SLC40A1. Four patients were double heterozygous or compound heterozygous for the mutations mentioned above, and the patient with metabolic syndrome was heterozygous for a mutation in the TFR2 gene. Our findings show that hereditary hemochromatosis is clinically and genetically heterogeneous and that acquired factors may modify or determine the phenotype.