Population screening for hemochromatosis: a comparison of unbound iron-binding capacity, transferrin saturation, and C282Y genotyping in 5,211 voluntary blood donors

Health Economic Evaluations of Hemochromatosis Screening and Treatment: A Systematic Review

BACKGROUND

Hereditary hemochromatosis (HH) is an autosomal recessive disorder that leads to iron overload and multiorgan failure.

OBJECTIVES

The aim of this systematic review was to provide up-to-date evidence of all the current data on the costs and cost effectiveness of screening and treatment for HH.

METHODS

We searched PubMed, Cochrane Library, National Health Service Economic Evaluation Database (NHSEED), Cost-Effectiveness Analysis Registry (CEA Registry), Health Technology Assessment Database (HTAD), Centre for Reviews and Dissemination (CRD), and Econlit until April 2023 with no date restrictions. Articles that reported cost-utility, cost-description, cost-minimization, cost-effectiveness, or cost-benefit analyses for any kind of management (drugs, screening, etc.) were included in the study. Patients with HH, their siblings, or individuals suspected of having HH were included in the study. All screening and treatment strategies were included. Two authors assessed the quality of evidence related to screening (either phenotype or genotype screening) and treatment (phlebotomy and electrophoresis). Narrative synthesis was used to analyse the similarities and differences between the respective studies.

RESULTS

Thirty-nine papers were included in this study. The majority of the studies reported both the cost of phenotype screening, including transferrin saturation (TS), serum ferritin, and liver biopsy, and the cost of genotype screening (HFE screening, C282Y mutation). Few studies reported the cost for phlebotomy and erythrocytapheresis treatment. Data revealed that either phenotype or genotype screening were cost effective compared with no screening. Treatment studies concluded that erythrocytapheresis might be a cost-effective therapy compared with phlebotomy.

CONCLUSIONS

Economic studies on either the screening, or treatment strategy for HH patients should be performed in more countries. We suggest that cost-effectiveness studies on the role of deferasirox in HH should be carried out as an alternative therapy to phlebotomy.

Hemochromatosis risk genotype is not associated with colorectal cancer or age at its diagnosis

Homozygotes for the higher penetrance hemochromatosis risk allele, HFE c.845G>A (p.Cys282Tyr, or C282Y), have been reported to be at a 2- to 3-fold increased risk for colorectal cancer (CRC). These results have been reported for small sample size studies with no information about age at diagnosis for CRC. An association with age at diagnosis might alter CRC screening recommendations. We analyzed two large European ancestry datasets to assess the association of HFE genotype with CRC risk and age at CRC diagnosis. The first dataset included 59,733 CRC or advanced adenoma cases and 72,351 controls from a CRC epidemiological study consortium. The second dataset included 13,564 self-reported CRC cases and 2,880,218 controls from the personal genetics company, 23andMe. No association of the common hereditary hemochromatosis (HH) risk genotype and CRC was found in either dataset. The odds ratios (ORs) for the association of CRC and HFE C282Y homozygosity were 1.08 (95% confidence interval [CI], 0.91-1.29; p = 0.4) and 1.01 (95% CI, 0.78-1.31, p = 0.9) in the two cohorts, respectively. Age at CRC diagnosis also did not differ by HFE C282Y/C282Y genotype in either dataset. These results indicate no increased CRC risk in individuals with HH genotypes and suggest that persons with HH risk genotypes can follow population screening recommendations for CRC.

ACG Clinical Guideline: Hereditary Hemochromatosis

Hereditary hemochromatosis (HH) is one of the most common genetic disorders among persons of northern European descent. There have been recent advances in the diagnosis, management, and treatment of HH. The availability of molecular diagnostic testing for HH has made possible confirmation of the diagnosis for most patients. Several genotype-phenotype correlation studies have clarified the differences in clinical features between patients with the C282Y homozygous genotypes and other HFE mutation patterns. The increasing use of noninvasive tests such as MRI T2* has made quantification of hepatic iron deposition easier and eliminated the need for liver biopsy in most patients. Serum ferritin of <1,000 ng/mL at diagnosis remains an important diagnostic test to identify patients with a low risk of advanced hepatic fibrosis and should be used routinely as part of the initial diagnostic evaluation. Genetic testing for other types of HH is available but is expensive and generally not useful in most clinical settings. Serum ferritin may be elevated among patients with nonalcoholic fatty liver disease and in those with alcoholic liver disease. These diagnoses are more common than HH among patients with elevated serum ferritin who are not C282Y homozygotes or C282Y/H63D compound heterozygotes. A secondary cause for liver disease should be excluded among patients with suspected iron overload who are not C282Y homozygotes. Phlebotomy remains the mainstay of therapy, but emerging novel therapies such as new chelating agents may have a role for selected patients.

Laboratory methodologies for indicators of iron status: strengths, limitations, and analytical challenges

Biochemical assessment of iron status relies on serum-based indicators, such as serum ferritin (SF), transferrin saturation, and soluble transferrin receptor (sTfR), as well as erythrocyte protoporphyrin. These indicators present challenges for clinical practice and national nutrition surveys, and often iron status interpretation is based on the combination of several indicators. The diagnosis of iron deficiency (ID) through SF concentration, the most commonly used indicator, is complicated by concomitant inflammation. sTfR concentration is an indicator of functional ID that is not an acute-phase reactant, but challenges in its interpretation arise because of the lack of assay standardization, common reference ranges, and common cutoffs. It is unclear which indicators are best suited to assess excess iron status. The value of hepcidin, non-transferrin-bound iron, and reticulocyte indexes is being explored in research settings. Serum-based indicators are generally measured on fully automated clinical analyzers available in most hospitals. Although international reference materials have been available for years, the standardization of immunoassays is complicated by the heterogeneity of antibodies used and the absence of physicochemical reference methods to establish "true" concentrations. From 1988 to 2006, the assessment of iron status in NHANES was based on the multi-indicator ferritin model. However, the model did not indicate the severity of ID and produced categorical estimates. More recently, iron status assessment in NHANES has used the total body iron stores (TBI) model, in which the log ratio of sTfR to SF is assessed. Together, sTfR and SF concentrations cover the full range of iron status. The TBI model better predicts the absence of bone marrow iron than SF concentration alone, and TBI can be analyzed as a continuous variable. Additional consideration of methodologies, interpretation of indicators, and analytic standardization is important for further improvements in iron status assessment.

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.

EMQN best practice guidelines for the molecular genetic diagnosis of hereditary hemochromatosis (HH)

Molecular genetic testing for hereditary hemochromatosis (HH) is recognized as a reference test to confirm the diagnosis of suspected HH or to predict its risk. The vast majority (typically >90%) of patients with clinically characterized HH are homozygous for the p.C282Y variant in the HFE gene, referred to as HFE-related HH. Since 1996, HFE genotyping was implemented in diagnostic algorithms for suspected HH, allowing its early diagnosis and prevention. However, the penetrance of disease in p.C282Y homozygotes is incomplete. Hence, homozygosity for p.C282Y is not sufficient to diagnose HH. Neither is p.C282Y homozygosity required for diagnosis as other rare forms of HH exist, generally referred to as non-HFE-related HH. These pose significant challenges when defining criteria for referral, testing protocols, interpretation of test results and reporting practices. We present best practice guidelines for the molecular genetic diagnosis of HH where recommendations are classified, as far as possible, according to the level and strength of evidence. For clarification, the guidelines' recommendations are preceded by a detailed description of the methodology and results obtained with a series of actions taken in order to achieve a wide expert consensus, namely: (i) a survey on the current practices followed by laboratories offering molecular diagnosis of HH; (ii) a systematic literature search focused on some identified controversial topics; (iii) an expert Best Practice Workshop convened to achieve consensus on the practical recommendations included in the guidelines.

A Systematic Review and Narrative Synthesis of Health Economic Studies Conducted for Hereditary Haemochromatosis

BACKGROUND

Hereditary haemochromatosis (HH) is a common genetic condition amongst people of northern European heritage. HH is associated with increased iron absorption leading to parenchymal organ damage and multiple arthropathies. Early diagnosis and treatment prevents complications. Population screening may increase early diagnosis, but no programmes have been introduced internationally: a paucity of health economic data is often cited as a barrier.

OBJECTIVE

To conduct a systematic review of all health economic studies in HH.

METHODS

Studies were identified through electronic searching of economic/biomedical databases. Any study on HH with original economic component was included. Study quality was formally assessed. Health economic data were extracted and analysed through narrative synthesis.

RESULTS

Thirty-eight studies met the inclusion criteria. The majority of papers reported on costs or cost effectiveness of screening programmes. Whilst most concluded screening was cost effective compared with no screening, methodological flaws limit the quality of these findings. Assumptions regarding clinical penetrance, effectiveness of screening, health-state utility values (HSUVs), exclusion of early symptomatology (such as fatigue, lethargy and multiple arthropathies) and quantification of costs associated with HH were identified as key limitations. Treatment studies concluded therapeutic venepuncture was the most cost-effective intervention.

CONCLUSIONS

There is a paucity of high-quality health economic studies relating to HH. The development of a comprehensive HH cost-effectiveness model utilising HSUVs is required to determine whether screening is worthwhile.

Diagnosis and treatment of hereditary hemochromatosis: an update

Hereditary hemochromatosis is an inherited iron overload disorder caused by inappropriately low hepcidin secretion leading to increased duodenal absorption of dietary iron, most commonly in C282Y homozygous individuals. This can result in elevated serum ferritin, iron deposition in various organs and ultimately end-organ damage, although there is incomplete biochemical and clinical penetrance and variable phenotypic expression of the HFE mutation in hereditary hemochromatosis. An elevated SF >1000 mg/l [corrected] is associated with an increased risk of cirrhosis and mortality in C282Y homozygotes.Conversely, a SF <1000 µg/l is associated with a very low likelihood of cirrhosis, making liver biopsy unnecessary among C282Y homozygotes in the absence of concomitant risk factors for liver disease. Phlebotomy remains the mainstay of treatment and new treatments being studied include erythrocytapheresis and 'mini-hepcidins'. Iron overload is being recognized to play a carcinogenic role in hepatocellular carcinoma and other cancers, possibly supporting iron depletion in these patients.

The diagnostic accuracy of unbound iron binding capacity (UIBC) as a test for empty iron stores

BACKGROUND

Unbound iron binding capacity (UIBC) in serum, which is s-total iron binding capacity (2 times s- transferrin) minus s-iron, may be a more accurate marker of empty iron stores than serum transferrin saturation. Previously we have shown this for healthy females of childbearing age.

METHODS

Now we used receiver operating characteristic (ROC) curve analysis to compare the diagnostic accuracy of s-iron, s-transferrin, s-transferrin saturation and s-UIBC in diagnosing empty iron stores in 29,251 female and 19,652 male outpatients. Empty iron stores were defined as s-ferritin less than 10, 15 or 20 μg/L.

RESULTS

At all definitions of empty iron stores s-UIBC had a better diagnostic accuracy than the other tests in both male and female outpatients, with an area under the ROC curve of 0.85-0.97. Also in subpopulations with elevated s-CRP or low b-hemoglobin s-UIBC was more accurate than the other tests. All tests performed better in males than in females, and generally they were more accurate in adults than in children.

CONCLUSION

When diagnosing empty iron stores calculation of s-UIBC is a better way to utilize the information in s-iron and s-transferrin than the calculation of s-transferrin saturation.

The impact of population-based screening studies on hemochromatosis screening practices

OBJECTIVES

To determine if community population screening studies for hemochromatosis affected HFE genetic screening practices in non-study populations.

METHODS

An audit of all genetic testing for HFE mutations at London Health Sciences Center, London, Ontario, Canada from 1997 to 2010 was performed. The frequency of genetic testing and the frequency of C282Y homozygous cases identified during the years of the London Red Cross (1998-1999) and HEIRS (2000-2005) screening studies were compared with the corresponding frequencies in the specified years outside this range (1997-1998 and 2006-2010).

RESULTS

An increase in HFE gene mutation testing is seen during the London Red Cross study, and the frequency of testing rose further during the HEIRS study. Genetic screening activity continued to increase in the years after publication of the HEIRS study. The proportion of patients with homozygosity for C282Y mutation remained relatively constant despite fluctuations in numbers of persons screened per annum.

CONCLUSIONS

The rise in HFE gene testing among non-study populations during the HH studies could be explained by the Hawthorne effect, a phenomenon referring to the improvement or modification of behavior by a population as a consequence of it being studied. In this case, we postulate that primary care physicians at our center performed more HFE gene tests for their patients as a consequence of being affected by knowledge of the screening studies. Despite a general increase in testing during and after completion of the studies, the total number of hemochromatosis cases (C282Y homozygotes) diagnosed per annum remained relatively constant.

Review article: the iron overload syndromes

BACKGROUND

Iron overload syndromes encompass a wide range of hereditary and acquired conditions. Major developments in the field of genetics and the discovery of hepcidin as a central regulator of iron homeostasis have greatly increased our understanding of the pathophysiology of iron overload syndromes.

AIM

To review advances in iron regulation and iron overload syndrome with special emphasis on hereditary haemochromatosis, the prototype iron overload syndrome.

METHODS

A PubMed search using words such as 'iron overload', 'hemochromatosis', 'HFE', 'Non-HFE', 'secondary iron overload' was undertaken.

RESULTS

Iron overload is associated with significant morbidity and mortality. Sensitive diagnostic tests and effective therapy are widely available and can prevent complications associated with iron accumulation in end- organs. Therapeutic phlebotomy remains the cornerstone of therapy for removal of excess body iron, but novel therapeutic agents including oral iron chelators have been developed for iron overload associated with anaemia.

CONCLUSIONS

Iron overload disorders are common. Inexpensive screening tests as well as confirmatory diagnostic tests are widely available. Increased awareness of the causes and importance of early diagnosis and knowledge of the appropriate use of genetic testing are encouraged. The availability of novel treatments should increase therapeutic options for patients with iron overload disorders.

Evaluating the role of blood collection centers in public health: a status report

Blood centers have a central role in the community through recruitment and donation, and these community interactions enable blood centers to have a critical role in public health. Some public health initiatives are inherent in the blood center, such as providing human immunodeficiency virus educational material, whereas other initiatives have been actively created, such as cardiovascular screening, as a means to increase blood donor rates and increase the blood center's community interaction. These public health initiatives have been inconsistently practiced by blood collection centers over many years. An understanding of the current literature and exploring the potential role of blood centers in public health, while considering cost and value of these programs, are necessary for blood centers to evaluate the value of implementing these programs. The studies do not support a significant improvement in donor health or significant increase in donation rates through these public health initiatives. However, no study published thus far has been comprehensive enough or carried out long enough to adequately evaluate the value of providing health initiatives to donors.

Simultaneous detection of HFE C282Y, H63D and S65C mutations associated with type 1 haemochromatosis using a multiplex luminex bead assay

Type 1 hereditary haemochromatosis (HH) is a common genetic disorder in Caucasoids resulting from mutations in the HFE gene. Routine diagnostic testing for type 1 HH involves genotyping for two of these described HFE mutations, C282Y and H63D. In some cases typing of a third mutation, S65C is also performed. Several techniques have been reported for HFE genotyping and these include polymerase chain reaction (PCR)-sequence-specific primers (SSP), PCR-restriction fragment length polymorphism (RFLP), PCR-sequence-specific oligonucleotide probe (SSOP), real-time PCR followed by melting curve analysis and TaqMan assay. The aim of this study was to develop an alternative method to both conventional PCR and real-time PCR/TaqMan assay to detect all three HFE mutations in a single assay using Luminex technology. DNA controls of known genotypes (n = 109) were used to evaluate this approach. These controls were selected to represent the three possible genotypes (wild type, mutant, heterozygous) for each mutation. Subsequently, blind DNA samples (n = 100) were used to validate this method. This new assay was then compared with current techniques (in-house PCR-SSP and TaqMan assay). Comparison of genotypes obtained with the Luminex method with those previously reported by both in-house PCR-SSP and TaqMan assay showed 100% concordance for both DNA controls and blind DNA samples and no discrepancies were observed. Allelic frequency for C282Y, H63D and S65C mutations were 22%, 16% and 2%, respectively. We report here a high-throughput, accurate and robust multiplex luminex bead assay for routine clinical testing of C282Y, H63D and S65C mutations in the HFE gene.

Impact of gene patents and licensing practices on access to genetic testing for hereditary hemochromatosis

Hereditary hemochromatosis is an iron metabolism disorder that leads to excess iron buildup, especially in the heart, liver, and pancreas. Mutations in the HFE gene are the single most common cause of hereditary hemochromatosis, which can be treated effectively if diagnosed early. Patents cover the HFE gene, related proteins, screening methods, and testing kits. Most initial testing for hereditary hemochromatosis is biochemical, but HFE deoxyribonucleic acid testing or genotyping is used to confirm a diagnosis of inherited hemochromatosis. Concerns over patents covering HFE testing emerged in 2002, when scholars argued that exclusive licensing and the patent-enabled sole provider model then in place led to high prices and limited access. Critics of the sole provider model noted that the test was available at multiple laboratories before the enforcement of patents. By 2007, however, Bio-Rad Limited, acquired the key intellectual property and sublicensed it widely. In part because of broad, nonexclusive licensing, there are now multiple providers and testing technologies, and research continues. This case study illustrates how both changes in intellectual property ownership and evolving clinical utility of HFE genetic testing in the last decade have effected the licensing of patents and availability of genetic testing.

EASL clinical practice guidelines for HFE hemochromatosis

Iron overload in humans is associated with a variety of genetic and acquired conditions. Of these, HFE hemochromatosis (HFE-HC) is by far the most frequent and most well-defined inherited cause when considering epidemiological aspects and risks for iron-related morbidity and mortality. The majority of patients with HFE-HC are homozygotes for the C282Y polymorphism [1]. Without therapeutic intervention, there is a risk that iron overload will occur, with the potential for tissue damage and disease. While a specific genetic test now allows for the diagnosis of HFE-HC, the uncertainty in defining cases and disease burden, as well as the low phenotypic penetrance of C282Y homozygosity poses a number of clinical problems in the management of patients with HC. This Clinical Practice Guideline will therefore, focus on HFE-HC, while rarer forms of genetic iron overload recently attributed to pathogenic mutations of transferrin receptor 2, (TFR2), hepcidin (HAMP), hemojuvelin (HJV), or to a sub-type of ferroportin (FPN) mutations, on which limited and sparse clinical and epidemiologic data are available, will not be discussed. We have developed recommendations for the screening, diagnosis, and management of HFE-HC.

Hemochromatosis gene status as a risk factor for Barrett's esophagus

Conditions causing high iron levels, such as hemochromatosis, are proposed risk factors for esophageal adenocarcinoma. Although this hypothesis is supported by animal models, no human data currently exist. We conducted a case-control study of persons with a new Barrett's esophagus diagnosis (cases), persons with gastroesophageal reflux disease (GERD) (without Barrett's esophagus), and population controls. Subjects completed detailed examinations and assays for hemochromatosis mutations and serum iron stores. We evaluated 317 cases, 306 GERD patients, and 308 population controls. There was no significant association between Barrett's esophagus and any hemochromatosis gene defect (odds ratio [OR] = 1.32, 95% confidence interval [CI]: 0.95-1.84), a moderate or severe mutation (OR = 1.54, 95% CI: 0.94-2.52), or a severe mutation (C282Y homozygote or C282Y/H63D heterozygote; OR = 0.77, 95% CI: 0.24-2.48) compared with the population controls. As expected, gene defects were associated with increased iron stores. We can conclude from our findings that Barrett's esophagus was not associated with hemochromatosis gene defects, although we cannot exclude small effects.

Results communication and patient education after screening for possible hemochromatosis and iron overload: experience from the HEIRS Study of a large ethnically and linguistically diverse group

PURPOSE

We assessed the effectiveness of educational interventions for conveying clinical findings and information about hereditary hemochromatosis (HH) and iron overload (IO) to individuals evaluated clinically after initial screening for HH/IO with serum ferritin (SF) concentration, transferrin saturation (TS), and HFE genotyping.

METHODS

A questionnaire mailed to 2300 cases and controls 1 month after a letter summarizing clinical findings measured understanding of results and recommendations, knowledge of HH/IO, and satisfaction with information received.

RESULTS

Of 1622 (70.5%) participants completing relevant items, 83.6% were satisfied with receiving initial screening results by mail, 93.4% found information clear and easy to understand, 89.2% generally felt they got enough information, but 47.5% still had questions. C282Y/C282Y homozygosity with normal TS/SF predicted the best understanding of genetic results. Many with no mutations thought relatives were at risk. Iron levels created most confusion, and a third incorrectly recalled treatment recommendations. Having any abnormal result, lower education, older age, and being non-white, and/or non-English speaking predicted lower understanding.

CONCLUSIONS

Combining genotypic and phenotypic screening for HH/IO creates additional difficulties in communicating results-particularly to those with low health literacy. Explaining aberrant iron TS and SF levels and low-risk genotypes, follow-up recommendations, and risk to relatives will need creative, culturally appropriate strategies.

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.

Hereditary hemochromatosis screening: effect of mutation penetrance and prevalence on cost-effectiveness of testing algorithms

Screening for hereditary hemochromatosis, although largely discussed, is not yet implemented in clinical practice. We evaluated the cost-effectiveness of 165 hemochromatosis population-screening algorithms involving two or three of several screening tests by developing a computer program that simulates all possible screening scenarios. Input data comprised government estimates of health services data and costs and a virtual population with user-defined demographic characteristics (including variable HFE mutation frequencies and penetrance values). We show that when C282Y homozygote prevalence is set at 3:1000, population screening appears cost-effective when penetrance of the biochemical phenotype is >0.70. When only hepatocellular carcinoma and cirrhosis are considered as the cost-driving complications, population-based screening is not significantly more cost-efficient than no screening, but life expectancy of individuals identified with hereditary hemochromatosis and treated is still improved by 7 years. Among the 165 screening algorithms tested in 91 different virtual populations of one million individuals, biochemical tests usually perform better as the initial test than genetic testing. Indeed, the genetic testing is most cost-effective as the final confirmatory test. Finally, for most combinations of prevalence and penetrance of HFE, one screening algorithm--unbound iron-binding capacity + transferrin saturation--appeared robust enough to be always within the top 5 most cost-effective strategies.

The H63D variant in the HFE gene predisposes to arthralgia, chondrocalcinosis and osteoarthritis

OBJECTIVES

To investigate the relation between the HFE C282Y and H63D variants with arthralgia and joint pathology in the population-based Rotterdam Study.

METHODS

From a cohort of 7983 people aged 55 years and over, 2095 randomly drawn subjects were genotyped for C282Y and H63D variants. We compared the frequency of arthralgia, and the presence of chondrocalcinosis, osteophytes, joint space narrowing and radiographic osteoarthritis in hand, hip and knee joints, and Heberden's nodes in carriers of HFE variants with that in non-carriers.

RESULTS

Overall, there was a significantly higher frequency of arthralgia (odds ratio 1.6; 95% CI 1.0 to 2.6), oligoarthralgia (2.3; 1.2 to 4.4) and Heberden's nodes (2.0; 1.1 to 3.8) in H63D homozygotes compared with non-carriers. In subjects aged 65 years or younger, H63D homozygotes had significantly more often polyarthralgia (3.1; 1.3 to 7.4), chondrocalcinosis in hip or knee joints (4.7; 1.2 to 18.5), and more hand joints with osteophytes (6.1+/-1.0 vs 4.4+/-0.3), space narrowing (2.8+/-0.5 vs 1.0+/-0.1), radiographic osteoarthritis (4.4+/-0.7 vs 2.0+/-0.2) and Heberden's nodes (3.1; 1.3 to 12.8) than non-carriers. We found no relation of arthralgia or joint pathology to C282Y, but compound heterozygotes had a significantly higher frequency of arthralgia (2.9; 1.0 to 9.3), chondrocalcinosis in hip joints (6.5; 1.8 to 22.3), and an increased number of osteophytes in knee (6.9+/-1.2, n = 5 vs 2.4+/-0.1) joints at a later age (>65 years).

CONCLUSIONS

The HFE H63D variant may explain, at least in part, the prevalence of arthralgia in multiple joints sites, chondrocalcinosis, and hand osteoarthritis in the general population.

The diversity of liver diseases among outpatient referrals for an elevated serum ferritin

BACKGROUND

The aim of the present study was to examine the diversity of liver diseases in outpatients referred because of elevated serum ferritin.

METHODS

A retrospective review was performed of outpatient referrals for serum ferritin elevations made to a tertiary care centre liver clinic between 1999 and 2005. Information regarding serum ferritin, transferrin saturation, liver biopsy, liver iron concentration and final diagnosis was extracted. Patients were stratified into two groups based on ferritin concentration: ferritin concentration 300 microg/L to 1000 microg/L, and ferritin concentration greater than 1000 microg/L.

RESULTS

A total of 482 charts were reviewed, of which 119 (25%) had ferritin concentrations greater than 1000 microg/L. HFE-linked hemochromatosis, nonalcoholic steatohepatitis and alcohol-related liver disease were the top three diagnoses. HFE-linked hemochromatosis accounted for 28% to 42% of the diagnoses in all subgroups. The percentage of patients diagnosed with HFE-linked hemochromatosis was similar in the ferritin 300 microg/L to 1000 microg/L and the ferritin greater than 1000 microg/L groups (P = 0.067). Among patients with ferritin greater than 1000 microg/L, 63% underwent a liver biopsy. Of those with an elevated liver iron concentration (greater than 35 micromol/g dry weight), 71% had a transferrin saturation greater than 50% (88% of C282Y homozygotes and 43% of non-C282Y homozygotes). In non-C282Y homozygotes with an elevated serum ferritin concentration greater than 1000 microg/L, 64% did not have iron overload on liver biopsy.

CONCLUSION

HFE-linked hemochromatosis accounted for less than one-half of the diagnoses in an outpatient population referred for elevated ferritin, suggesting a need to search further for an alternate cause.

Review article: the modern diagnosis and management of haemochromatosis

Haemochromatosis is the most common genetic disease in populations of European ancestry. Despite estimates based on genetic testing in Caucasian populations of 1 in 227, many physicians consider haemochromatosis to be a rare disease. The diagnosis can be elusive because of the non-specific nature of the symptoms. Of all the symptoms, liver disease has the most consistent relationship to haemochromatosis and the prognosis of haemochromatosis is most closely linked to the degree of iron overload. With the discovery of the HFE gene in 1996, comes new insights into the pathogenesis of the disease and new diagnostic strategies. However, a growing number of new iron-related genes have been discovered and linked to other iron overload syndromes.

Hemochromatosis: genetics and pathophysiology

A number of genetic disorders can result in the accumulation of excess iron in the body. These causes of hereditary hemochromatosis include defects in genes encoding HFE, transferrin receptor 2, ferroportin, hepcidin, and hemojuvelin. Hepcidin, with its cognate receptor, ferroportin, has emerged as a central regulator of iron homeostasis; all of the known causes of hemochromatosis appear to prevent this system from functioning normally. The most common form of primary hemochromatosis is that caused by C282Y mutation of the HFE gene. This mutation is most prevalent among Northern Europeans. Although the frequency of the homozygous genotype is approximately 5 per 1000, the disease itself is quite rare because the clinical penetrance of the genotype is very low.

Frequency of common HFE variants in the Saudi population: a high throughput molecular beacon-based study

Background

Hereditary Hemochromatosis (HH) is an autosomal recessive disorder highlighted byiron-overload. Two popular mutations in HFE, p.C282Y and p.H63D, have been discovered and found to associate with HH in different ethnic backgrounds. p.C282Y and p.H63D diagnosis is usually made byrestriction enzyme analysis. However, the use of this technique is largelylimited to research laboratories because they are relativelyexpensive, time-consuming, and difficult to transform into a high throughput format.

Methods

Single nucleotide variations in target DNA sequences can be readily identified using molecular beacon fluorescent probes. These are quenched probes with loop and hairpin structure, and they become fluorescent upon specific target recognition. We developed high throughput homogeneous real-time PCR assays using molecular beacon technology, to genotype p.C282Y and p.H63D variants. Representative samples of different genotypes for these variants were assayed by restriction enzyme analysis and direct sequencing as bench mark methods for comparison with the newly developed molecular beacon-based real-time PCR assay.

Results

Complete concordance was achieved by all three assay formats. Homozygotes (mutant and wildtype) and heterozygotes were readily differentiated by the allele specific molecular beacons as reported by the associated fluorophore in the real-time assay developed in this study. Additionally, these assays were used in a high throughput format to establish the allele frequency of C282Y and H63D in Saudis for the first time.

Conclusion

These assays may be reliably applied as a diagnostic test or large scale method for population screening.

Reverse cascade screening of newborns for hereditary haemochromatosis: a model for other late onset diseases?

BACKGROUND

Genetic testing can determine those at risk for hereditary haemochromatosis (HH) caused by HFE mutations before the onset of symptoms. However, there is no optimum screening strategy, mainly owing to the variable penetrance in those who are homozygous for the HFE Cys282Tyr (C282Y) mutation. The objective of this study was to identify the majority of individuals at serious risk of developing HFE haemochromatosis before they developed life threatening complications.

METHODS

We first estimated the therapeutic penetrance of the C282Y mutation in people living in la Somme, France, using genetic, demographic, biochemical, and follow up data. We examined the benefits of neonatal screening on the basis of increased risk to relatives of newborns carrying one or two copies of the C282Y mutation. Between 1999 and 2002, we screened 7038 newborns from two maternity hospitals in the north of France for the C282Y and His63Asp (H63D) mutations in the HFE gene, using bloodspots collected on Guthrie cards. Family studies and genetic counselling were undertaken, based on the results of the baby's genotype.

FINDINGS

In la Somme, we found that 24% of the adults homozygous for the C282Y mutation required at least 5 g iron to be removed to restore normal iron parameters (that is, the therapeutic penetrance). In the reverse cascade screening study, we identified 19 C282Y homozygotes (1/370), 491 heterozygotes (1/14) and 166 compound heterozygotes (1/42) in 7038 newborns tested. The reverse cascade screening strategy resulted in 80 adults being screened for both mutations. We identified 10 previously unknown C282Y homozygotes of whom six (four men and two women) required venesection. Acceptance of neonatal screening was high; parents understood the risks of having HH and the benefits of early detection, but a number of parents were reluctant to take the test themselves. Neonatal screening for HH is straightforward. Reverse cascade screening increased the efficiency of detecting affected adults with undiagnosed haemochromatosis. This strategy allows almost complete coverage for HH and could be a model for efficient screening for other late onset genetic diseases.

Hemocromatosis hereditaria: estudio fenotípico de una población española

BACKGROUND AND OBJECTIVE

Hereditary hemochromatosis (HH) displays an important phenotypic variability and is a disease influenced by many factors.

PATIENTS AND METHOD

We included 88 patients with HH. Main clinical and laboratory data were analyzed, and the influence of 6 variables on intensity of iron overload was evaluated.

RESULTS

In 38.6% (95% confidence interval [CI], 28.5-49.6%) patients, none of the typical symptoms of the disease was observed. 30,9% (95% CI, 21.7-41.7%) showed abnormalities of the glucose metabolism. We detected an increase in sideremia in 75.0% patients (CI 95%, 64.4-83.3%), transferrin saturation index (TSI) in 95.4% (CI 95%, 88.1-98.5%) and ferritin in 93.2% (CI 95%, 85.1-97.1%) of patients. In addition, we observed increased values of GPT and alkaline phosphatase in an appreciable percentage of patients. Ferritin was significantly higher in men (1329.4 [913.2] ng/ml vs 656.6 [644.5] ng/ml; p < 0.001), and in those older than 45 years (1293.9 [1006.9] ng/ml vs 868.9 [642.8] ng/ml; p = 0.023] and in not blood donors (1205.2 [926.8] vs 524.8 [365.9] ng/ml; p < 0.001). TSI was 81.9% (19.6) in C282Y homozygotes and 65.7% (19.2) in the rest of HFE genotypes (p = 0.002). Differences of TSI with regard to sex, age or status of blood donor were not detected. Sideremia was significantly higher in patients infected by virus C (251.8 [24.4] microg/dl vs 182.8 [45.8] microg/dl; p = 0.001).

CONCLUSIONS

HH patients have a noticeable phenotypic variability, and for that reason clinical symptoms are only orientative for the diagnosis. The relationship between HH and glucose metabolism should be investigated further. Iron parameters can be influenced by age, sex, HFE genotype, blood donation, alcohol intake and hepatitis C virus infection.

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.

Mutations in the hereditary haemochromatosis gene HFE in professional endurance athletes

BACKGROUND

Hereditary haemochromatosis, a disease that affects iron metabolism, progresses with a greater or lesser tendency to induce iron overload, possibly leading to severe organ dysfunction. Most elite endurance athletes take iron supplements during their active sporting life, which could aggravate this condition.

OBJECTIVE

To determine the prevalence and discuss potential clinical implications of mutations of HFE (the gene responsible for hereditary haemochromatosis) in endurance athletes.

METHODS

Basal concentrations of iron, ferritin, and transferrin and transferrin saturation were determined in the period before competition in 65 highly trained athletes. Possible mutations in the HFE gene were evaluated in each subject by extracting genomic DNA from peripheral blood. The restriction enzymes SnaBI and BclI were used to detect the mutations 845G-->A (C282Y) and 187C-->G (H63D).

RESULTS

Our findings indicate a high prevalence of HFE gene mutations in this population (49.2%) compared with sedentary controls (33.5%). No association was detected in the athletes between mutations and blood iron markers.

CONCLUSIONS

The findings support the need to assess regularly iron stores in elite endurance athletes.

Common heterozygous hemochromatosis gene mutations are risk factors for inflammation and fibrosis in chronic hepatitis C

BACKGROUND

Chronic hepatitis C is frequently associated with increased hepatic iron stores. It remains controversial whether heterozygous mutations of hemochromatosis genes affect fibrosis progression. Therefore our aim was to assess associations between HFE mutations and hepatic inflammation and stage of fibrosis in German hepatitis C patients.

METHODS

Liver biopsies from 166 patients were scored for inflammatory activity (A0-4) and hepatic fibrosis (F0-4). Gene mutations were determined by LightCycler, restriction fragment length polymorphism analysis, or direct sequencing.

RESULTS

The frequencies of common HFE mutations C282Y and H63D are 4.2% and 21.3%, whereas the recently described S65C substitution and the Y250X mutation in the transferrin receptor 2 gene are very rare. In regression analysis, heterozygous carriers of C282Y or H63D mutations display significantly (P < 0.05) higher inflammatory activities and more advanced fibrosis than patients without mutations. For C282Y heterozygous patients, the odds ratios for marked inflammatory activity (A2-4) and advanced liver fibrosis or cirrhosis (F2-4) are 4.9 and 4.6, respectively, compared with patients carrying homozygous wild-type alleles. C282Y mutations are associated with significantly (P < 0.05) increased serum iron and aminotransferase levels, whereas H63D heterozygotes display higher transferrin saturation, serum iron, and ferritin concentrations compared to wild-type (P < 0.01).

CONCLUSIONS

Common heterozygous hemochromatosis mutations are associated with higher grades of inflammation and more severe hepatic fibrosis. Our findings support a role of HFE mutations as primary risk factors for fibrogenesis and disease progression in chronic hepatitis C.

Review article: targeted screening for hereditary haemochromatosis in high-risk groups

Patients with hereditary haemochromatosis are at risk for significant morbidity from iron overload as well as reduced life-expectancy once cirrhosis is established. Although inexpensive, sensitive screening tests and effective therapy are available, there is continued debate regarding the utility of screening for this condition because of recent data suggesting that the homozygous haemochromatosis mutation (C282Y) is associated with low penetrance and mild expressivity when identified in population screening studies. In this review, we examine the published data related to general population screening for haemochromatosis, as well as the evidence for screening selected 'high-risk' populations. We also suggest possible screening strategies based on the available evidence.

Multigenic control of hepatic iron loading in a murine model of hemochromatosis

BACKGROUND & AIMS

Hereditary hemochromatosis is a common disorder of iron homeostasis characterized by increased dietary iron absorption and progressive iron accumulation, mainly in the liver. Most patients are homozygous for the C282Y mutation in the HFE gene. However, not all individuals carrying the hemochromatosis-predisposing genotype in the general population become iron loaded. Genetic modifiers have been shown to influence disease penetrance, but their number and chromosomal locations remain unknown, and their identification is hampered by complex interactions with environmental factors. To circumvent these difficulties, we used 2 strains of mice made deficient for the Hfe gene that strongly differ in their propensity to develop hepatic iron loading.

METHODS

To localize the loci controlling hepatic iron loading in this murine model of hemochromatosis, we produced 1028 mice by an F2 intercross between the C57BL/6 and DBA/2 Hfe-deficient strains. We selected the 276 mice that contributed the most to the total linkage information for genotyping with 145 microsatellite markers.

RESULTS

We mapped 4 modifier loci on chromosomes 7, 8, 11, and 12, with logarithm of odds scores of 14.47, 12.96, 6.04, and 6.72, respectively, in regions containing several genes recently shown to exert important roles in the regulation of iron metabolism.

CONCLUSIONS

Our data provide a clear demonstration of the polygenic pattern of hepatic iron loading inheritance in Hfe-deficient mice. Examination of candidate genes residing at the loci identified in this study and genetic analysis of the syntenic chromosomal regions in humans may provide important insight into the heterogeneous disease presentation observed among HFE C282Y homozygotes.

Haemochromatosis-associated HFE genotypes in English blood donors: age-related frequency and biochemical expression

BACKGROUND/AIMS

There are limited data on the frequency and biochemical expression of the haemochromatosis-associated mutations C282Y and H63D in healthy people.

METHODS

We genotyped (bi-directional PCR amplification of specific alleles method) and performed serum iron studies in randomly selected English male blood donors (<4 previous units donated) in four age bands <30, 30-40, 40-50 and >50 years.

RESULTS

In 6261 subjects, frequency of C282Y homozygosity (+/+) was 0.3%, C282Y/H63D compound heterozygosity (+/-) 2.0%, and H63D and C282Y heterozygosity +/-, 21.7 and 10.4%, respectively. Genotype distribution was within Hardy-Weinberg equilibrium in each age band. C282Y +/- frequency fell from 11.7% in subjects <30 years to 8.2% in subjects >50 (Chi2 7.19; P<0.005). No such trend was seen for C282Y +/+. In C282Y +/+ subjects, median serum ferritin was 247 (range 60-2449) microg/l and exceeded >500 microg/l in only two of 18 subjects. Compared to wild/wild (-/-) subjects, C282Y and H63D +/- subjects had slightly higher serum iron and lower unsaturated iron binding concentrations, similar overall serum ferritin values but higher serum ferritin values in subjects who had previously donated blood.

CONCLUSIONS

C282Y +/+ shows limited biochemical expression and no trend towards age-related attrition. C282Y and H63D +/- may protect against iron deficiency.

Natural history of the C282Y homozygote for the hemochromatosis gene (HFE) with a normal serum ferritin level

BACKGROUND & AIMS

The discovery of a genetic test for hereditary hemochromatosis has identified many individuals who are homozygous for the C282Y mutation of the HFE gene with a normal transferrin saturation and serum ferritin level. The long-term prognosis, rate of iron accumulation, and surveillance guidelines for these individuals are unknown.

METHODS

To determine the degree of iron accumulation over time, an updated serum ferritin level was obtained in patients initially identified as homozygous for the C282Y mutation with a normal serum ferritin level.

RESULTS

Twenty-two asymptomatic untreated C282Y homozygotes with a normal serum ferritin level were identified, 10 through population screening, 9 through pedigree analysis, and 3 through a general medical work-up. There were 18 women (4 postmenopausal) and 4 men with a median age of 46 years, range 28-76 years. The median follow-up interval was 4 years, range 2-23 years. The serum ferritin levels of 20 of 22 patients remained below the upper limit of normal during the follow-up period. A decline in serum ferritin level was observed in 13 of 22 patients. Three patients had an increase in serum ferritin level of greater than 50%, with only 1 male patient exceeding the upper limit of normal by having a serum ferritin level increase from 295 to 344 microg/L during a 3-year period.

CONCLUSIONS

In C282Y homozygotes with a normal ferritin level at the time of diagnosis, 20 of 22 patients failed to show any significant increase in serum ferritin level during a median follow-up of 4 years. This has clinical and economic implications for follow-up and surveillance of this selected population.

HFE genotype and transferrin saturation in the United States

PURPOSE

Examine the penetrance (defined by high transferrin saturation [TS]) of C282Y and H63D in the U.S. population.

METHODS

5171 participants from the Third National Health and Nutrition Examination Survey, 1992 to 1994.

RESULTS

77.1% (95% confidence interval [CI], 2.3, 95.1) of men and 51.9% (95% CI, 0, 84.2) of women with C282Y homozygosity had high TS. The associations of H63D homozygosity with high TS were stronger in people aged 50 years or older than in younger persons. Among Mexican-Americans, simple H63D heterozygosity was associated with high TS.

CONCLUSIONS

The associations between HFE genotype and high TS may vary by sex, age, and ethnic group.

Haptoglobin type neither influences iron accumulation in normal subjects nor predicts clinical presentation in HFE C282Y haemochromatosis: phenotype and genotype analysis

In the UK, 90% of patients with hereditary haemochromatosis (HH) are homozygous for HFE C282Y, as are one in 150 people in the general population. However, only a minority of these will develop clinical haemochromatosis. Iron loss modifies iron accumulation but so may other genetic factors. Haptoglobin (Hp) exists as three major types (Hp 1-1, Hp 2-1 or Hp 2-2) and binds free plasma haemoglobin. In men, Hp 2-2 has been shown to be associated with increased macrophage iron accumulation and serum ferritin concentration. Furthermore, the frequency of Hp 2-2 was shown to be increased in patients with HH. We determined Hp types by phenotyping and genotyping 265 blood donor control subjects and 173 subjects who were homozygous for HFE C282Y. The latter group included 66 blood donors lacking clinical features suggestive of haemochromatosis and without a known family history, and 68 patients presenting clinically with haemochromatosis. Hp 2-2 frequencies did not differ in control subjects and C282Y homozygotes. Hp 2-2 was not a risk factor for disease development in HH. To investigate the relationship between iron accumulation and haptoglobin type, we determined transferrin saturation and serum ferritin concentration in 192 male, first-time blood donors aged 20-40 years who lacked both HFE C282Y and H63D. Transferrin saturation and serum ferritin concentrations did not vary with Hp type.

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.

HFE mutations and chronic hepatitis C: H63D and C282Y heterozygosity are independent risk factors for liver fibrosis and cirrhosis

BACKGROUND/AIMS

The impact of heterozygous HFE mutations on the course of chronic hepatitis C and iron indices was studied.

METHODS

Ferritin, transferrin saturation (TS), serum iron, C282Y and H63D mutations were determined in 401 patients with chronic hepatitis C virus (HCV) infection and 295 healthy controls. Liver histologies were available in 217 and HCV genotypes in 339 patients.

RESULTS

Allele frequencies of the C282Y and H63D mutation did not differ between HCV patients and healthy controls (6.95 vs. 6.2%; 14.75 vs. 16.4%; n.s.). HFE heterozygous HCV patients had higher ferritin (349+/-37 vs. 193+/-15 microg/l; P<0.0005), TS (38+/-2 vs. 32+/-1%; P<0.0005), serum iron (144+/-6 vs. 121+/-3 microg/dl; P<0.0005), semiquantitative liver iron staining (0.26+/-0.07 vs. 0.09+/-0.03; P<0.006) and fibrosis scores (1.9+/-0.2 vs. 1.4+/-0.1; P<0.003) compared to HFE wildtypes. By multivariate regression analysis odds ratios for liver cirrhosis were 5.9 (confidence interval (CI) 1.6-22.6; P<0.009) for C282Y heterozygotes and 2.9 (CI 1.0-8.4; P<0.05) for H63D heterozygotes compared to HFE wildtypes. Considering all HFE heterozygous HCV patients, odds ratios of 3.6 (CI 1.4-9.3; P<0.009) for cirrhosis and 3.1 (CI 1.3-7.3; P<0.009) for fibrosis were calculated.

CONCLUSIONS

C282Y or H63D heterozygosity is an independent risk factor for liver fibrosis and cirrhosis in HCV infected individuals. Screening for HFE mutations should be considered in HCV infection.

A targeted approach significantly increases the identification rate of patients with undiagnosed haemochromatosis

OBJECTIVE

To determine the optimal means of identifying patients with undiagnosed haemochromatosis.

DESIGN

Case-control study where cases are defined by the presence of specific clinical diagnoses or symptoms.

SETTING

Primary care patients were recruited from three Oxfordshire practices and secondary care patients were recruited from those patients attending specialist clinics in Amiens University Hospital.

SUBJECTS

A total of 569 patients recruited via hospital clinics and 60 primary care patients (recruited from 4022 consultations) presenting with the following haemochromatosis associated conditions, diabetes, arthralgia/chronic fatigue, osteoporosis or arthropathy were studied. The control group, a total of 991 healthy volunteers, were recruited through a Health Appraisal Centre. Patients and controls were included in the study if they or their family members had not previously been diagnosed with hereditary haemochromatosis.

MAIN OUTCOME MEASURES

Serum ferritin concentration, transferrin saturation (Tsat) and presence of HFE mutations, C282Y and H63D. The check-up in controls consisted of a questionnaire, clinical examination, biochemical tests and screening for the presence of the C282Y and H63D mutations.

RESULTS

Patient groups presenting with unstable diabetes or chronic fatigue and arthralgia together with a raised serum ferritin concentration showed an enrichment in the haemochromatosis-associated genotype HH/YY, odds ratio (OR) = 40.1, confidence interval (CI) = 8.0-202.1 and OR = 103, CI = 22.9-469.7, respectively.

CONCLUSION

Patients presenting to hospital clinics with haemochromatosis associated conditions should be screened biochemically for iron overload. Only those with a serum ferritin >300 microg L-1 or Tsat >40% should subsequently go on to be genotyped for HFE mutations. The patients at greatest risk of having undiagnosed haemochromatosis are those presenting with unstable diabetes, or fatigue and/or arthralgia in the absence of any other explanation.

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.

Gender-specific phenotypic expression and screening strategies in C282Y-linked haemochromatosis: a study of 9396 French people

Most features of C282Y-linked haemochromatosis support the implementation of population screening of the disorder in Caucasians. However, the penetrance of C282Y homozygosity is poorly documented and the strategy for population screening remains debated. Nine thousand three hundred and ninety-six subjects (3367 men, aged 25-40 years, and 6029 women, aged 35-50 years), attending three Health Appraisal Centres, were genotyped and assessed with respect to clinical and biochemical signs of haemochromatosis. Discriminant, logistic regression and graphic analysis were used to predict homozygosity. Results were validated in 135 homozygotes detected through other family and population studies. Fifty-four subjects (10 men and 44 women) were homozygous for C282Y. All men had abnormal iron status and most had mild clinical symptoms compatible with haemochromatosis. Identification of all homozygous men required a transferrin saturation (TS) threshold of 50% in the study group (90% specificity) and of 40% in the validation group. Homozygous women differed clinically from non-homozygotes for the presence of distal arthralgias only (18%vs 6%, P < 0.03). Thirteen (29%) were iron-deficient (serum ferritin < 13 micro g/l) and undetectable by biochemical tests. Although the population studied was not fully representative of the general population, our data strongly suggests that, in young men, large-scale screening for C282Y homozygosity is justified and can be achieved by using TS prescreening. However, in premenopausal women, large-scale screening remains to be justified with respect to the natural history of haemochromatosis and should be directly genotypic.

Unsaturated iron binding capacity and transferrin saturation are equally reliable in detection of HFE hemochromatosis

OBJECTIVE

Unsaturated iron binding capacity (UIBC) has been proposed as an inexpensive alternative to transferrin saturation for detection of hereditary hemochromatosis. The aim of this study was to compare, in a hospital referral clinic, the reliability of transferrin saturation and UIBC for detection of subjects who have inherited HFE (HLA-asociated iron overload) genotypes predisposing to iron overload.

METHODS

Serum transferrin saturation, UIBC, and ferritin were tested in 110 consecutive subjects. Optimum thresholds were determined from receiver operating characteristic curves.

RESULTS

Of 110 subjects, 44 carried significant HFE mutations (C282Y/C282Y or C282Y/H63D). In genetically predisposed subjects with biochemical expression, the optimum threshold for transferrin saturation was 43%, giving a sensitivity of 0.88 and specificity 0.95. For UIBC, the optimum threshold was 143 microg/dL (25.6 micromol/L), giving a sensitivity of 0.91 and specificity of 0.95. In patients referred with a family history or clinical suspicion of hemochromatosis, transferrin saturation and UIBC were highly reliable predictors of genotype. In patients referred for investigation of abnormal liver enzymes without a known family history of hemochromatosis, a normal transferrin saturation or normal UIBC was highly reliable in excluding hemochromatosis.

CONCLUSIONS

Transferrin saturation and UIBC have equal reliability in ability to predict hemochromatosis. UIBC should be considered as an alternative to transferrin saturation in detection of hemochromatosis.

Hepatocellular carcinoma: predisposing conditions and precursor lesions

The global incidence of HCC is rising; in the United States, its rise is in parallel to that of cirrhosis due to the HCV and obesity epidemics. The lack of adequate treatment for advanced HCC mandates both prevention and early detection of these lesions. The limitations of currently available histopathologic evaluations, serologic markers, and radiographic imaging modalities in detecting HCC and its precursors have been outlined in this review. Refinements of all of these may lead to better HCC detection, earlier intervention, and successful treatment. Randomized controlled trials are necessary to evaluate the most efficacious and cost-effective approach to screening.

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.

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.