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Cézard C, Rabbind Singh A, Le Gac G, Gourlaouen I, Ferec C, Rochette J. Phenotypic expression of a novel C282Y/R226G compound heterozygous state in HFE hemochromatosis: molecular dynamics and biochemical studies. Blood Cells Mol Dis 2013; 52:27-34. [PMID: 23953397 DOI: 10.1016/j.bcmd.2013.07.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 06/28/2013] [Accepted: 07/05/2013] [Indexed: 11/15/2022]
Abstract
Most adults affected with hereditary hemochromatosis are homozygous for a single point mutation of HFE (p.Cys282Tyr). Apart from the compound heterozygous state for the p.Cys282Tyr mutant and the widespread p.His63Asp variant allele, other rare HFE mutations can be found in trans and may have clinical impact. In the present report we describe the structural and functional consequences of a new mutation, namely the p.Arg226Gly which was inherited in trans with the p.Cys282Tyr allele in a patient affected with a mild iron overload. Because the R226G substitution is located in the vicinity of the normal Cys225S-S282Cys disulfide bond we initially investigated the structure of the variant by molecular dynamics techniques in order to estimate the effect of the mutation on the global structure of HFE domain α3. We found that the solvation free energy, hydrophobicity and formation of salt bridges are slightly modified with the global secondary structure of the α3 domain being conserved. In a previous paper, we demonstrated that the Q283P substitution leads to the loss of the normal Cys225S-S282Cys disulfide bridge. Similar to the Q283P substitution, the R226G substitution does not substitute a residue directly involved in the formation of the disulfide bridge. However, unlike the p.Gln283Pro variant which destroyed the normal disulfide bridge, the R226G mutation does not affect the normal Cys225S-S282Cys bridge. Furthermore based on cell line studies we clearly show that the mutation does not prevent cell surface localization, β2-microglobulin association and binding to transferrin receptor 1. This new compound heterozygous phenotype is very close to those of the C282Y/H63D compound heterozygous patients who display the biochemical hemochromatosis phenotype but with lower body iron stores than C282Y homozygotes. Our results do not exclude unknown genetic and/or metabolic factors that may act synergistically to increase the ferritin level.
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Affiliation(s)
- Christine Cézard
- Laboratoire des Glucides, CNRS FRE 3517, Université de Picardie Jules Verne, Amiens 80037 Cedex 1, France
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Deugnier Y, Lainé F, Le Lan C, Bardou-Jacquet E, Jouanolle AM, Brissot P. Hémochromatoses et autres surcharges hépatiques en fer. ACTA ACUST UNITED AC 2011. [DOI: 10.1016/s1155-1976(11)40364-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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Lim FL, Dooley JS, Roques AW, Grellier L, Dhillon AP, Walker AP. Hepatic iron concentration, fibrosis and response to venesection associated with the A77D and V162del "loss of function" mutations in ferroportin disease. Blood Cells Mol Dis 2007; 40:328-33. [PMID: 18160317 DOI: 10.1016/j.bcmd.2007.11.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Revised: 11/13/2007] [Accepted: 11/16/2007] [Indexed: 12/13/2022]
Abstract
Ferroportin disease is an autosomal dominant form of hemochromatosis associated with siderosis in cells of the mononuclear phagocyte system and, to varying degrees, in hepatocytes. Ferroportin was investigated as a candidate gene in two pedigrees with hyperferritinaemia and siderosis in mononuclear phagocytes. The entire ferroportin coding region was sequenced and hepatic iron concentration, histology and response to treatment were determined. The results were compared with previously reported cases. The A77D mutation was detected in patient 1, his father (patient 2) and his brother (patient 3), who had portal fibrosis. The V162del mutation was detected in patient 4, who developed anemia after the third weekly venesection. While the disease is rare, A77D and V162del are the most common ferroportin mutations in Caucasians. The spectrum of clinical expression of these two mutations was reviewed in all cases described to date. These mutations were associated with fibrosis in about a third of cases. For A77D and V162del, this analysis confirms that the threshold hepatic iron concentration for development of fibrosis may be higher than for classical hemochromatosis. These two mutations, which both decreased iron export in cell culture studies, give rise to similar patterns of clinical expression and morbidity, although the highest hepatic iron concentrations have been observed with A77D. It is important for clinicians to consider ferroportin disease in cases where there are features of iron overload unrelated to HFE, autosomal dominant inheritance and/or iron deposition in mononuclear phagocytes.
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Affiliation(s)
- Francesca L Lim
- Centre for Molecular Medicine, Department of Medicine, The Rayne Institute, University College London, 5 University Street, London, WC1E 6JF, UK
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Corder EH, Beaumont H. Susceptibility groups for Alzheimer's disease (OPTIMA cohort): Integration of gene variants and biochemical factors. Mech Ageing Dev 2007; 128:76-82. [PMID: 17116317 DOI: 10.1016/j.mad.2006.11.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Information on gene variants and blood levels (APOE, BCHE-K, TF-C2, HFE-D, HFE-Y, ACE I/D, AR1; homocysteine, folate and vitamin B(12)) is available for participants in the Oxford Project to Investigate Memory and Ageing (OPTIMA) cohort (n=575). This information identified four risk sets for Alzheimer's disease (AD) using grade of membership analysis (GoM). Graded membership scores that relate individuals to each set are automatically generated. Sets I and III had low intrinsic risk. Set II had high intrinsic risk associated with multiple gene variants, e.g., APOE44/34. Set IV also had high intrinsic risk demonstrating low folate and B(12) levels. Membership in the high intrinsic risk sets was summed, coded as either close versus not close (>or=0.80 versus <0.80) and input into logistic models to predict relative risk: close resemblance multiplied risk 80-fold for possible AD before age 65 and 55-fold for probable or definite AD at ages 65-74. These findings implicate both biochemical and genetic factors in the risk for AD and further support dietary supplementation with folate and vitamin B(12) as a potential means to delay the onset of AD and/or its rate of progression.
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King C, Barton DE. Best practice guidelines for the molecular genetic diagnosis of Type 1 (HFE-related) hereditary haemochromatosis. BMC MEDICAL GENETICS 2006; 7:81. [PMID: 17134494 PMCID: PMC1684250 DOI: 10.1186/1471-2350-7-81] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 08/15/2006] [Accepted: 11/29/2006] [Indexed: 11/17/2022]
Abstract
Background Hereditary haemochromatosis (HH) is a recessively-inherited disorder of iron over-absorption prevalent in Caucasian populations. Affected individuals for Type 1 HH are usually either homozygous for a cysteine to tyrosine amino acid substitution at position 282 (C282Y) of the HFE gene, or compound heterozygotes for C282Y and for a histidine to aspartic acid change at position 63 (H63D). Molecular genetic testing for these two mutations has become widespread in recent years. With diverse testing methods and reporting practices in use, there was a clear need for agreed guidelines for haemochromatosis genetic testing. The UK Clinical Molecular Genetics Society has elaborated a consensus process for the development of disease-specific best practice guidelines for genetic testing. Methods A survey of current practice in the molecular diagnosis of haemochromatosis was conducted. Based on the results of this survey, draft guidelines were prepared using the template developed by UK Clinical Molecular Genetics Society. A workshop was held to develop the draft into a consensus document. The consensus document was then posted on the Clinical Molecular Genetics Society website for broader consultation and amendment. Results Consensus or near-consensus was achieved on all points in the draft guidelines. The consensus and consultation processes worked well, and outstanding issues were documented in an appendix to the guidelines. Conclusion An agreed set of best practice guidelines were developed for diagnostic, predictive and carrier testing for hereditary haemochromatosis and for reporting the results of such testing.
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Affiliation(s)
- Caitriona King
- National Centre for Medical Genetics, Our Lady's Children s Hospital, Crumlin, Dublin 12, Ireland
| | - David E Barton
- National Centre for Medical Genetics, Our Lady's Children s Hospital, Crumlin, Dublin 12, Ireland
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Abstract
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.
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Affiliation(s)
- Ernest Beutler
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
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Cadet E, Capron D, Gallet M, Omanga-Léké ML, Boutignon H, Julier C, Robson KJH, Rochette J. Reverse cascade screening of newborns for hereditary haemochromatosis: a model for other late onset diseases? J Med Genet 2006; 42:390-5. [PMID: 15863667 PMCID: PMC1736060 DOI: 10.1136/jmg.2004.027284] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
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.
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Affiliation(s)
- E Cadet
- Department of Medical Genetics and UMR-INERIS, Centre Hospitalo-Universitaire et Faculté de Médecine, 3 rue des Louvels, 80036, Amiens, France
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Abstract
Elucidation of the molecular pathways of iron transport through cells and its control is leading to an understanding of genetic iron loading conditions. The general phenotype of haemochromatosis is iron accumulation in liver parenchymal cells, a raised serum transferrin saturation and ferritin concentration. Four types have been identified: type 1 is the common form and is an autosomal recessive disorder of low penetrance strongly associated with mutations in the HFE gene on chromosome 6(p21.3); type 2 (juvenile haemochromatosis) is autosomal recessive, of high penetrance with causative mutations identified in the HFE2 gene on chromosome 1 (q21) and the HAMP gene on chromosome 19 (q13); type 3 is also autosomal recessive with mutations in the TfR2 gene on chromosome 3 (7q22); type 4 is an autosomal dominant condition with heterozygous mutations in the ferroportin 1 gene. In type 4, iron accumulates in both parenchymal and reticuloendothelial cells and the transferrin saturation may be normal. There are also inherited neurodegenerative conditions associated with iron accumulation. The current research challenges include understanding the central role of the HAMP gene (hepcidin) in controlling iron absorption and the reasons for the variable penetrance in HFE type 1.
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Affiliation(s)
- Mark Worwood
- Department of Haematology, University of Wales College of Medicine, Cardiff CF14 4XN, Wales, UK.
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Robson KJH, Lehmann DJ, Wimhurst VLC, Livesey KJ, Combrinck M, Merryweather-Clarke AT, Warden DR, Smith AD. Synergy between the C2 allele of transferrin and the C282Y allele of the haemochromatosis gene (HFE) as risk factors for developing Alzheimer's disease. J Med Genet 2004; 41:261-5. [PMID: 15060098 PMCID: PMC1735734 DOI: 10.1136/jmg.2003.015552] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND There is evidence that iron may play a role in the pathology of Alzheimer's disease (AD). There may be genetic factors that contribute to iron deposition resulting in tissue damage thus exacerbating AD. METHODS We have genotyped 269 healthy elderly controls, 191 cases with definite or probable AD, and 69 with mild cognitive impairment (MCI) from the OPTIMA cohort. RESULTS We have examined the interaction between the C2 variant of the transferrin (TF) gene and the C282Y allele of the haemochromatosis (HFE) gene as risk factors for developing AD. Our results showed that each of the two variants was associated with an increased risk of AD only in the presence of the other. Neither allele alone had any effect. Carriers of both variants were at 5 times greater risk of AD compared with all others. The interaction was significant by logistic regression (p = 0.014) and by synergy factor analysis (p = 0.015, synergy factor = 5.1). Further, carriers of these two alleles plus apolipoprotein E epsilon4 (APOE4) were at still higher risk of AD: of the 14 tri-carriers of the three variants, identified in this study, 12 had AD and two MCI. CONCLUSION We suggest that the combination of TF C2 and HFE C282Y may lead to an excess of redox-active iron and the induction of oxidative stress in neurones, which is exacerbated in carriers of APOE4. Since 4% of Northern Europeans carry the two iron-related variants and since iron overload is a treatable condition, these results merit replication.
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Affiliation(s)
- K J H Robson
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, Headington, Oxford OX3 9DS, UK.
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Livesey KJ, Wimhurst VLC, Carter K, Worwood M, Cadet E, Rochette J, Roberts AG, Pointon JJ, Merryweather-Clarke AT, Bassett ML, Jouanolle AM, Mosser A, David V, Poulton J, Robson KJH. The 16189 variant of mitochondrial DNA occurs more frequently in C282Y homozygotes with haemochromatosis than those without iron loading. J Med Genet 2004; 41:6-10. [PMID: 14729817 PMCID: PMC1757237 DOI: 10.1136/jmg.2003.008805] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
BACKGROUND Patients with hereditary haemochromatosis (HH) are usually homozygous for the C282Y mutation in the HFE gene. They have variable expression of iron overload and present with a variety of complications, including liver disease, diabetes, arthropathy, fatigue, and cardiomyopathy. The mitochondrial 16189 variant is associated with diabetes, dilated cardiomyopathy, and low body fat at birth, and might contribute to genetic predisposition in further multifactorial disorders. The objective of this study was to determine the frequency of the 16189 variant in a range of patients with haemochromatosis, who had mutations in the HFE gene. METHODS Blood DNA was analysed for the presence of the 16189 variant in British, French, and Australian C282Y homozygotes and controls, with known iron status, and in birth cohorts. RESULTS The frequency of the mitochondrial 16189 variant was found to be elevated in individuals with haemochromatosis who were homozygous for the C282Y allele, compared with population controls and with C282Y homozygotes who were asymptomatic (42/292 (14.4%); 102/1186 (8.6%) (p = 0.003); and 2/64 (3.1%) (p = 0.023), respectively). CONCLUSIONS Iron loading in C282Y homozygotes with HH was exacerbated by the presence of the mitochondrial 16189 variant.
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Affiliation(s)
- K J Livesey
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, Oxford, UK
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Emery J, Rose P, Harcourt J, Livesey K, Merryweather-Clarke A, Pointon JJ, Robson K. Pilot study of early diagnosis of hereditary haemochromatosis through systematic case finding in primary care. Public Health Genomics 2004; 5:262-5. [PMID: 14960881 DOI: 10.1159/000066689] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES To test the feasibility of adopting and evaluating a systematic case-finding approach to the early diagnosis of hereditary haemochromatosis (HHC) in primary care, and to estimate the prevalence of presenting conditions for which HHC testing could be offered. METHODS Systematic identification of, and genotyping for, C282Y and H63D mutations in patients presenting in primary care with possible symptoms of HHC during a 4-week period to 1 of 14 doctors in Oxfordshire. RESULTS From a total of 4,022 consultations, 169 (4.2%; 95% CI: 3.6-4.8) adult patients had possible symptoms of HHC. Of these, 88 (2.2%; 95% CI: 1.7-2.6) were aged 25-70 and were offered genotyping for HHC, of whom 60 agreed to be tested. There were no C282Y homozygotes (0%; 95% CI: 0-6.0), no C282Y/H63D compound heterozygotes (0%; 95% CI: 0-6.0), 2 H63D homozygotes with normal iron indices (3.3%%; 95% CI: 0.4-11.5) and 3 C282Y heterozygotes (5.0%; 95% CI: 1.0-13.9). CONCLUSIONS This study raises doubts about a case-finding approach to early diagnosis of HHC in primary care. The non-specific nature and high prevalence of possible symptoms of HHC in primary care mean that many patients would require testing to identify a single case. Whether this offers a more cost-effective alternative to population screening requires further study.
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Affiliation(s)
- Jon Emery
- General Practice & Primary Care Research Unit, University of Cambridge, Institute of Public Health, Cambridge, UK.
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Pointon JJ, Viprakasit V, Miles KL, Livesey KJ, Steiner M, O'Riordan S, Hien TT, Merryweather-Clarke AT, Robson KJH. Hemochromatosis gene (HFE) mutations in South East Asia: a potential for iron overload. Blood Cells Mol Dis 2003; 30:302-6. [PMID: 12737949 DOI: 10.1016/s1079-9796(03)00041-x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Hereditary hemochromatosis (HH) is an autosomal recessive disease caused by mutations in the HFE gene that mainly affects populations of European descent. Recently a novel mutation (IVS5+1 G-->A) has been described in a Vietnamese patient with HH that was not detected in a European control population. We have developed a novel method to screen for this mutation based on restriction enzyme digestion of a PCR product using a modified forward primer. We have screened 314 Vietnamese people from several ethnic groups and 154 people from Thailand for this mutation and have detected two heterozygotes in the Vietnamese subjects (allele frequency 0.003). Analysis of these heterozygotes indicates that the mutation is on the same haplotype as that found in the original proband. Screening for the widely distributed HFE mutation, H63D, gave an allele frequency of 0.049 in the Vietnamese subjects and 0.032 in the subjects from Thailand. This is the first report of H63D allele frequencies in these populations. We suggest that the presence of the IVS5+1 G-->A and H63D mutations should be considered when investigating iron overload in Vietnamese patients and those of mixed origin as co-inheritance of both mutations is likely to be a risk factor for iron overload.
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Affiliation(s)
- Jennifer J Pointon
- MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, Headley Way, Headington, Oxford OX3 9DS, United Kingdom.
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Cadet E, Capron D, Perez AS, Crépin SN, Arlot S, Ducroix JP, Dautréaux M, Fardellone P, Leflon P, Merryweather-Clarke AT, Livesey KJ, Pointon JJ, Rose P, Harcourt J, Emery J, Sueur JM, Feyt R, Robson KJH, Rochette J. A targeted approach significantly increases the identification rate of patients with undiagnosed haemochromatosis. J Intern Med 2003; 253:217-24. [PMID: 12542563 DOI: 10.1046/j.1365-2796.2003.01094.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
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.
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Affiliation(s)
- E Cadet
- Services de Génétique Médicale, CHU d'Amiens, Faculté de Médecine & Université Jules Verne de Picardie, 3 rue des Louvels, 80036 Amiens, France
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Deugnier Y, Jouanolle AM, Chaperon J, Moirand R, Pithois C, Meyer JF, Pouchard M, Lafraise B, Brigand A, Caserio-Schoenemann C, Mosser J, Adams P, Le Gall JY, David V. Gender-specific phenotypic expression and screening strategies in C282Y-linked haemochromatosis: a study of 9396 French people. Br J Haematol 2002; 118:1170-8. [PMID: 12199803 DOI: 10.1046/j.1365-2141.2002.03718.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
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.
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Affiliation(s)
- Yves Deugnier
- Service des Maladies du Foie and INSERM U522, Rennes, France.
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Abstract
BACKGROUND Hereditary hemochromatosis is the most common autosomal recessive disorder in populations of northern European descent. ISSUES Many experts consider hemochromatosis to be an almost ideal disease for population screening because it essentially fulfills almost all the criteria for screening proposed by the WHO. However, others disagree and suggest that more data are required particularly with regard to the natural history and penetrance of the disease. There is also disagreement about the best diagnostic/screening test for the disease and the performance of these tests in the context of screening. Other concerns are the variability and lack of standardization in screening test measurements, the selection of screening threshold values and the identification of false positive cases. The advent of a genetic test for the condition has brought other worries with regard to informed consent and the ethical, legal and social implications of screening particularly in relation to medical and general discrimination. Other important issues include compliance, cost effectiveness and the evidence that screening has lessened the burden of disease in the community. CONCLUSIONS At the present time, we believe that further data regarding both the exact disease burden and the outcomes of screening studies particularly in the general community are required before widespread population screening is introduced.
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Affiliation(s)
- Mark A McCullen
- Department of Gastroenterology and Hepatology, Princess Alexandra Hospital, Ipswich Road, Woolloongabba, Brisbane, Queensland 4102, Australia
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Camaschella C, De Gobbi M, Roetto A. Hereditary hemochromatosis: progress and perspectives. ACTA ACUST UNITED AC 2001. [DOI: 10.1046/j.1468-0734.2000.00022.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Román R, Colomer A, Erill N, Puig X, Guix M. [Importance of 5569G/A polymorphism in intron 4 of HFE gene in the diagnosis of hereditary hemochromatosis]. Med Clin (Barc) 2001; 117:690-1. [PMID: 11730630 DOI: 10.1016/s0025-7753(01)72225-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
BACKGROUND The presence of the 5569A polymorphism may lead to misdiagnosis of patients susceptible of hereditary hemochromatosis (HH). For that reason, samples containing the Cys282Tyr mutation were revised and the frequency of this polymorphism in our environment was assessed. PATIENTS AND METHOD Twenty samples were retested and 56 controls were included. The study was performed by PCR-RFLP. RESULTS The diagnosis was confirmed in 8 cases susceptible of error. However, an amplification deficiency of normal alleles was detected in 2 heterozygous (17%). The allelic frequency of the 5569A polymorphism in the control population was 14.3%. CONCLUSIONS Although misdiagnosis was not committed, we recommend changing to any primer that does not include the 5569G/A polymorphism in the study of HH.
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Affiliation(s)
- R Román
- BIOPAT, Biopatologia Molecular, Grup Assistència, Hospital de Barcelona, Barcelona, Spain
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19
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Jackson HA, Carter K, Darke C, Guttridge MG, Ravine D, Hutton RD, Napier JA, Worwood M. HFE mutations, iron deficiency and overload in 10,500 blood donors. Br J Haematol 2001; 114:474-84. [PMID: 11529872 DOI: 10.1046/j.1365-2141.2001.02949.x] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
People with genetic haemochromatosis (GH) accumulate iron from excessive dietary absorption. In populations of northern European origin, over 90% of patients are homozygous for the C282Y mutation of the HFE gene. While about 1 in 200 people in the general population have this genotype the proportion who develop clinical haemochromatosis is not known. The influence of HFE genotype on iron status was investigated in 10 556 blood donors. The allele frequencies of the C282Y and H63D mutations were 8.23% and 15.3% respectively. Heterozygosity for C282Y occurred in 1 in 7.9 donors, for H63D in 1 in 4.2 donors, and 1 in 42 were compound heterozygotes. Homozygosity for H63D occurred in 1 in 42 donors and 1 in 147 (72) were homozygous for C282Y. Mean values increased for transferrin saturation (TS) and serum ferritin (sFn), and decreased for unsaturated iron binding capacity (UIBC) in the order: donors lacking the mutations, H63D heterozygotes, C282Y heterozygotes, H63D homozygotes, compound heterozygotes and C282Y homozygotes, but serum ferritin (sFn) concentrations were no higher in H63D heterozygotes and C282Y heterozygous women than in donors lacking mutations. The percentage of donors failing the screening test for anaemia or of those with sFn < 15 microg/l did not differ among the genotype groups. C282Y and H63D heterozygotes and donors homozygous for H63D were at no greater risk of iron accumulation than donors lacking mutations, of whom 1 in 1200 had both a raised TS and sFn. The risk was higher for compound heterozygotes (1 in 80, P = 0.003) and for C282Y homozygotes (1 in 5, P < 0.0001). There was no correlation between sFn and either age or donation frequency in C282Y homozygotes. None of the 63 C282Y homozygous donors interviewed showed physical signs of overload or were aware of relatives with haemochromatosis. The Welsh Blood Service collects blood from about 140 000 people each year including an estimated 950 who are homozygous for HFE C282Y. They are probably healthy and unaware of any family history of iron overload.
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Affiliation(s)
- H A Jackson
- Department of Haematology, University of Wales College of Medicine and University Hospital of Wales, Cardiff, UK
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20
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Abstract
Abstract
Background: Hereditary hemochromatosis is an inherited disorder of iron metabolism that is characterized by excessive iron deposition in major organs of the body. Chronic increased iron absorption leads to multiorgan dysfunction. Since the discovery of the gene responsible for the majority of cases, research has progressed rapidly to identify the gene product, the effects of mutations, and the implications for different populations. The protein product of the HFE gene is a transmembrane glycoprotein, termed HFE, that modulates iron uptake. Mutations in the HFE protein compromise its function and produce disease symptoms. Two mutations, C282Y and H63D, have been linked to the majority of disease cases.
Approach: We reviewed the recent literature for the molecular basis of hereditary hemochromatosis. Genotypic information was combined with biochemical and clinical phenotypic information to achieve a better understanding of the disease mechanism.
Content: This review provides a comprehensive discussion of known mutations in the HFE gene and their phenotypic expression. Diagnostic criteria using molecular genetic techniques in conjunction with traditional biochemical tests are provided. Current methods and limitations of molecular testing are examined in detail. A strategy for population screening and an algorithm for diagnosis that incorporates molecular testing are presented. Treatment by therapeutic phlebotomy and the use of blood obtained from hemochromatosis patients are discussed.
Summary: Although the disease mechanism has not been completely elucidated, phenotypic and penetrance data are becoming available. Controversy still exists concerning the role of genetic testing in diagnosis and population screening.
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Affiliation(s)
- Elaine Lyon
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT 84132
| | - Elizabeth L Frank
- Department of Pathology, University of Utah Health Sciences Center, Salt Lake City, UT 84132
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21
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Pointon JJ, Wallace D, Merryweather-Clarke AT, Robson KJ. Uncommon mutations and polymorphisms in the hemochromatosis gene. GENETIC TESTING 2001; 4:151-61. [PMID: 10953955 DOI: 10.1089/10906570050114867] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder of iron metabolism. Iron absorption from the gut is inappropriately high, resulting in increasing iron overload. The hemochromatosis gene (HFE) was identified in 1996 by extensive positional cloning by many groups over a period of about 20 years. Two missense mutations were identified. Homozygosity for one of these, a substitution of a tyrosine for a conserved cysteine (C282Y), has now clearly been shown to be associated with HH in 60-100% of patients. The role of the second mutation, the substitution of an aspartic acid for a histidine (H63D), is not so clear but compound heterozygotes for both these mutations have a significant risk of developing HH. Here we review other putative mutations in the HFE gene and document a number of diallelic polymorphisms in HFE introns.
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Affiliation(s)
- J J Pointon
- MRC Molecular Haematology Unit, Institute Molecular Medicine, Headington, Oxford, UK.
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22
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Beutler E, Gelbart T. Large-scale screening for HFE mutations: methodology and cost. GENETIC TESTING 2001; 4:131-42. [PMID: 10953952 DOI: 10.1089/10906570050114830] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Large-scale detection of mutations at the DNA level requires the development of cost-effective methods for the screening of thousands of samples. Hemochromatosis is an appropriate testing ground for the development of such technologies, and we report the methods that we have developed to screen large numbers of samples using equipment available in most laboratories. We are able to examine DNA samples for two mutations in the HFE gene at a cost of only slightly over $8 per sample, a cost that includes overhead and the approximately 40 hr per week of technician time required to perform the studies. The technologies involved in mutation analysis are evolving rapidly and ultimately more highly automated, lower-cost technologies may become available. At present, however, we find the methodology described to be very suitable for large-scale, low-cost mutation screening.
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Affiliation(s)
- E Beutler
- The Scripps Research Institute, Department of Molecular and Experimental Medicine, La Jolla, CA 92037, USA.
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23
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Merryweather-Clarke AT, Pointon JJ, Jouanolle AM, Rochette J, Robson KJ. Geography of HFE C282Y and H63D mutations. GENETIC TESTING 2001; 4:183-98. [PMID: 10953959 DOI: 10.1089/10906570050114902] [Citation(s) in RCA: 228] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder causing inappropriate dietary iron absorption that affects North Europeans. HH is associated with the C282Y mutation of the HFE gene, and the H63D mutation to a lesser degree. Both mutations are abundant in Europe, with H63D also appearing in North Africa, the Middle East, and Asia. Emigration from Europe over the past 500 years has introduced C282Y and H63D to America, Australia, New Zealand, and South Africa in an essentially predictable fashion. The distinctive characteristics of the population genetics of HH are the confined racial distribution and high frequency in North European peoples. C282Y frequencies in North Europeans are typically between 5% and 10%, with homozygotes accounting for between 1/100 and 1/400 of these populations. The scarcity of the C282Y mutation in other populations accounts for the lack of HH in non-Europeans.
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24
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Pointon JJ, Merryweather-Clarke AT, Carella M, Robson KJ. Detection of C282Y and H63D in the HFE gene. GENETIC TESTING 2001; 4:115-20. [PMID: 10953949 DOI: 10.1089/10906570050114803] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The gene for hemochromatosis was identified in 1996 and two mutations were found. Homozygosity for one of these, C282Y, is associated with hemochromatosis in a high percentage of patients. Genetic analysis of patient DNA is, therefore, a very useful tool to aid and confirm diagnosis and to screen asymptomatic relatives of patients to identify those at risk of developing this common, easily treated disease.
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Affiliation(s)
- J J Pointon
- MRC Molecular Haematology Unit, Institute Molecular Medicine, Headington, Oxford, UK.
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25
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Abstract
Hemochromatosis is a common autosomal recessive condition found in the homozygous state in 1/200-1/400 people of northern-, central-, and western-European origin. It causes increased iron storage, which may lead to liver cirrhosis, liver cancer, heart disease, arthritis, and diabetes in many but not all affected adults, with a higher frequency in males. The condition is easily treated by repeated venesections without side effects but is frequently overlooked. Population screening of adults using iron indices alone or combined with DNA testing has therefore been recommended, but a consensus conference in 1997 recommended that such screening be deferred, owing to uncertainty regarding the extent of clinical disease that may develop in individuals detected by such programs. There was also concern that DNA screening results might be used for discrimination in insurance and occupational settings. Screening family members of patients with evidence of definite iron loading, however, is accepted by all observers. Because serious complications may be overlooked, a more aggressive stance toward case detection in the adult population has been advocated by some observers, realizing that unnecessary treatment might occur. Because additional information regarding the spectrum of clinical disease in homozygotes in now accumulating, a consensus conference in the near future is suggested to consider appropriate policies.
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26
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Thorstensen K, Kvitland M, Asberg A, Hveem K. 5569G/A polymorphism of the HFE gene: no implications for C282Y genotyping in a hemochromatosis screening study of 65,238 individuals. GENETIC TESTING 2001; 4:147-9. [PMID: 10953954 DOI: 10.1089/10906570050114858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
In a previous hemochromatosis screening study including a total of 65,238 individuals, 566 persons were genotyped for the C282Y and the H63D mutations. Of these, a total of 433 samples (298 homozygous C282Y and 135 homozygous wild type) were reanalyzed to investigate if the potential presence of the newly described 5569G/A polymorphism had confounded the genotyping results for the C282Y mutation. Genotyping with a polymorphism-insensitive primer pair yielded no samples that altered their genotype. By utilizing the polymorphism-sensitive primer pair and elevated annealing temperatures, 133 samples previously genotyped as heterozygous C282Y were reanalyzed to verify the presence of the polymorphism in the population studied. Out of a total of 266 chromosomes, we found the polymorphism present in 9 chromosomes, yielding an allele frequency of 0.034 in this particular subpopulation. In one of the samples, the polymorphism was present on the same DNA strand as the C282Y mutation. We conclude that in the population studied, the 5569 G/A polymorphism is present, but its presence had no implications for the outcome of the previous genotyping. Nevertheless, we recommend that C282Y genotyping by restriction endonuclease digestion of PCR products in the future should utilize a primer pair that is not influenced by the 5569G/A polymorphism.
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Affiliation(s)
- K Thorstensen
- Department of Clinical Chemistry, Trondheim University Hospital, Norway.
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27
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Jeffrey GP, Adams PC. Pitfalls in the genetic diagnosis of hereditary hemochromatosis. GENETIC TESTING 2001; 4:143-6. [PMID: 10953953 DOI: 10.1089/10906570050114849] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The widespread use of the genotype assay that identifies the common C282Y mutation in the HFE gene has allowed an earlier diagnosis to be made in many subjects. A significant number of these patients may have no evidence of phenotypic disease and have a normal serum ferritin level. This phenomenon is more common when the genotype assay is used to screen populations rather than higher-risk groups such as family members of a proband with hereditary hemochromatosis. Moreover, patients with significant iron overload may be wild type for the C282Y mutation and have no other demonstrable mutation of the HFE gene. The HFE genotype assay has recently been found to give a false-positive C282Y homozygous result in half of the subjects in one population screening study due to the presence of a single nucleotide polymorphism (SNP) that interfered with primer binding in the PCR assay. The problem may be overcome by using alternate primers. A number of other groups have confirmed the finding but in a much smaller number of subjects, whereas others found that their assays were not affected by the SNP. The use of the HFE genotype assay as the sole diagnostic criterion for hereditary hemochromatosis is not recommended. The genotype assay should be used as an adjunct to the established methods of demonstrating iron overload and be viewed as a predictor of either the presence of iron overload or the subsequent development of iron overload during an individual's lifetime.
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Affiliation(s)
- G P Jeffrey
- Faculty of Medicine and Dentistry, University of Western Australia, and Sir Charles Gairdner Hospital, Nedlands, Perth.
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28
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Roa S, Martín-Oterino JA, Rodríguez RE, García-Berrocal B, Sánchez-Rodríguez A, González-Sarmiento R. [Analysis of the HFE gene in a large Spanish kindred with hereditary hemochromatosis]. Med Clin (Barc) 2001; 116:100-3. [PMID: 11181289 DOI: 10.1016/s0025-7753(01)71736-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
BACKGROUND Hereditary hemochromatosis (HH) is an inborn error of iron metabolism that is inherited as an autosomal recessive trait. Recently, it has been shown that the HFE gene, located telomeric to HLA-A on chromosome 6 is mutated in most patients with HH. Moreover, the phenotypic expression of hereditary hemochromatosis is influenced by sex and environmental agents such as alcohol and dietary iron intake. SUBJECTS AND METHOD We have studied 40 subjects from a family some of which members have HH. DNA was obtained from nucleated peripheral blood cells, and exons 2 and 4 and intron 5 of the HFE gene were amplified by PCR and digested with specific restriction enzymes. RESULTS Analysis of the HFE gene revealed that 29 members of the family carry some of the three HFE mutations (C282Y, H63D and S65C). Nevertheless, only those homozygous for the C282Y mutation develop HH. In this family, the allele 187G of exon 2 mutation is cosegregated with the allele IVS5-47 A in intron 5. CONCLUSIONS Analysis of the HFE gene in the members of a large Spanish kindred, living in the same geographical area, shows that only those homozygous for the C282Y mutation develop hemochromatosis.
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Affiliation(s)
- S Roa
- Unidad de Medicina Molecular. Departamento de Medicina
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29
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Andrikovics H, Kalmár L, Bors A, Fandl B, Petri I, Kalász L, Tordai A. Genotype Screening for Hereditary Hemochromatosis among Voluntary Blood Donors in Hungary. Blood Cells Mol Dis 2001; 27:334-41. [PMID: 11358395 DOI: 10.1006/bcmd.2001.0384] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hereditary hemochromatosis (HH) is a common genetic disorder. Although it is inherited in an autosomal recessive manner, heterozygous individuals are believed to be protected against iron deficiency. Screening to estimate the prevalence of HH was frequently performed among blood donors, not considering that carriers of the HH gene mutations may be present in higher proportion in this population. To examine the allele frequencies of the HH gene (HFE) point mutations, C282Y and H63D genotyping was carried out in 996 consecutive, first-time, and regular Hungarian blood donors by PCR-RFLP techniques. Iron parameters of the first-time donors and the identified C282Y heterozygotes and age, gender, and number of previous blood donation-matched wild-type donors were also determined. We were not able to demonstrate a significant increase in the frequency of C282Y and H63D alleles among regular blood donors, compared to first-time blood donors. However, there was a trend of higher C282Y allele frequency among women with higher number of previous blood donations (2.2 +/- 1.5% in female blood donors with 0-8 previous blood donations compared to 4.8 +/- 2.3% in women with more than 8 previous blood donations, P = 0.06). No detectable phenotypic differences were observed in serum iron, ferritin, and transferrin saturation values between C282Y wild-type and heterozygous groups. However, the single identified C282Y homozygous male (age 21) showed definite signs of iron overload. Our observations suggest that the protective effect of C282Y heterozygosity against iron deficiency may be less significant than other environmental (e.g., iron-rich diet) or genetic factors.
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Affiliation(s)
- H Andrikovics
- National Institute of Hematology and Immunology, Budapest, Hungary
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30
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Yu S, Fimmel A, Fung D, Trent RJ. Polymorphisms in the CAG repeat--a source of error in Huntington disease DNA testing. Clin Genet 2000; 58:469-72. [PMID: 11149616 DOI: 10.1034/j.1399-0004.2000.580607.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Five of 400 patients (1.3%), referred for Huntington disease DNA testing, demonstrated a single allele on CAG alone, but two alleles when the CAG + CCG repeats were measured. The PCR assay failed to detect one allele in the CAG alone assay because of single-base silent polymorphisms in the penultimate or the last CAG repeat. The region around and within the CAG repeat sequence in the Huntington disease gene is a hot-spot for DNA polymorphisms, which can occur in up to 1% of subjects tested for Huntington disease. These polymorphisms may interfere with amplification by PCR, and so have the potential to produce a diagnostic error.
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Affiliation(s)
- S Yu
- Department of Molecular and Clinical Genetics, Royal Prince Alfred Hospital, Camperdown NSW, Australia
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31
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Burke W, Imperatore G, McDonnell SM, Baron RC, Khoury MJ. Contribution of different HFE genotypes to iron overload disease: a pooled analysis. Genet Med 2000; 2:271-7. [PMID: 11399207 DOI: 10.1097/00125817-200009000-00001] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
PURPOSE To determine the contribution of the C282Y and H63D mutations in the HFE gene to clinical expression of hereditary hemochromatosis. METHODS Pooled analysis of 14 case-control studies reporting HFE genotype data, to evaluate the association of different HFE genotypes with iron overload. In addition, we used data from the pooled analysis and published data to estimate the penetrance of the C282Y/C282Y genotype. RESULTS Homozygosity for the C282Y mutation carried the largest risk for iron overload (OR = 4383, 95% CI 1374 to >10,000) and accounted for the majority of hemochromatosis cases (attributable fraction (AF) = 0.73). Risks for other genotypes were much smaller: OR = 32 for genotype C282Y/H63D (95% CI 18.5 to 55.4, AF = 0.06); OR = 5.7 for H63D/H63D (95% CI 3.2 to 10.1, AF = 0.01); OR = 4.1 for C282Y heterozygosity (95% CI 2.9 to 5.8, with heterogeneity in study results, making this association uncertain); and OR = 1.6 for H63D heterozygosity (95% CI 1 to 2.6, AF = 0.03). Estimates of penetrance for the C282Y/C282Y genotype were highly sensitive to estimates of the prevalence of iron overload disease. At a prevalence of 2.5 per 1000 or less, penetrance of the C282Y/C282Y genotype is unlikely to exceed 50%. Penetrance of other HFE genotypes is much lower. CONCLUSIONS C282Y homozygosity confers the highest risk for iron overload but the H63D mutation is also associated with increased risk. Our data indicate a gradient of risk associated with different HFE genotypes and thus suggest the presence of other modifiers, either genetic or environmental, that contribute to the clinical expression of hemochromatosis.
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Affiliation(s)
- W Burke
- Department of Medical History and Ethics, University of Washington, Seattle, Washington 98195, USA.
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32
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Beutler E, Gelbart T. A common intron 3 mutation (IVS3 -48c-->g) leads to misdiagnosis of the c.845G-->A (C282Y) HFE gene mutation. Blood Cells Mol Dis 2000; 26:229-33. [PMID: 10950943 DOI: 10.1006/bcmd.2000.0300] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amplification of the region of the HFE gene that contains the c.845G-->A (C282Y) mutation is usually performed using one amplimer that binds to a sequence in intron 3 and another that binds to a sequence in intron 4. Previously, a mutation that interferes with efficient binding to the intron 4 site has been described. We now find that another common mutation in intron 3, IVS3 -48c-->g, prevents binding of the amplimer to that site. This polymorphism occurs at a gene frequency of 0.128 in the African-American population and at a frequency of only 0.006 in the European population. DNA samples heterozygous for the IVS3 -48c-->g polymorphism and C282Y were undistinguishable from samples homozygous for the C282Y mutation when they were examined by allele-specific oligonucleotide hybridization (ASOH) and showed only a weak normal band when examined by electrophoresis following restriction endonuclease digestion. Although the polymorphism occurs in a DNA sequence almost identical to the intron 3 splice donor site, we found no evidence of alternative splice forms. Moreover, serum iron, transferrin saturation, and serum ferritin levels were normal in subjects heterozygous for the polymorphism. It appears, therefore, that the main importance of this polymorphism is that it may lead to misdiagnosis of heterozygotes for the C282Y mutation as homozygotes. We therefore recommend exonic amplimers that avoid sites that contain polymorphisms and that can be multiplexed for detection of the c.187C-->G (H63D) and c.845G-->A (C282Y) mutations.
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Affiliation(s)
- E Beutler
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, California 92037, USA.
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33
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Gottschalk R, Seidl C, Schilling S, Braner A, Seifried E, Hoelzer D, Kaltwasser JP. Iron-overload and genotypic expression of HFE mutations H63D/C282Y and transferrin receptor Hin6I and BanI polymorphism in german patients with hereditary haemochromatosis. EUROPEAN JOURNAL OF IMMUNOGENETICS : OFFICIAL JOURNAL OF THE BRITISH SOCIETY FOR HISTOCOMPATIBILITY AND IMMUNOGENETICS 2000; 27:129-34. [PMID: 10940080 DOI: 10.1046/j.1365-2370.2000.00215.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Gene variations of HFE, a HLA-class I like molecule, are highly associated with hereditary haemochromatosis (HH). Functional as well as molecular studies of the HFE protein have indicated that the molecule is involved in iron metabolism and that the HFE gene variations observed among HH patients affect its interaction with the transferrin receptor (TfR). In the present study, we have therefore analysed the relationship between the HFE gene variants, C282Y and H63D, and body iron status among 85 German HH patients. In addition, two TfR gene polymorphism, TfR-Hin6I and TfR-BanI, were typed that have been reported to define ethnically distinct haplotypes. As controls we used 251/159 healthy German blood donors. Seventy-eight (92%) patients were C292Y homozygous, the H63D mutation was present in five (6%) patients with none of the patients being H63D homozygous. Serum transferrin, transferrin saturation and liver iron content were determined prior to therapeutic intervention. Among C282Y homozygous patients serum ferritin levels (2294 +/- 3174 vs. 463 +/- 224 microg L-1, P < 0.0001) and transferrin saturation (86 +/- 18% vs. 62 +/- 25%, P = 0.048) were elevated significantly compared with C282Y and/or H63D heterozygous patients. In addition, the liver iron content (291 +/- 165 vs. 138 +/- 95 micromol g-1, P = 0.028) and liver iron index (6.4 +/- 2.8 vs. 3.2 +/- 2.3, P = 0.019) were increased among C282Y homozygotes compared with C282Y heterozygotes. In contrast, no difference was observed between patients and controls regarding the distribution of TfR-Hin6I and TfR-BanI alleles. These data indicate that the iron intake is higher among C282Y homozygous patients compared with C282Y heterozygous or C282Y/H63D compound heterozygous individuals and supports the functional role of the HFE protein in iron metabolism whereas the TfR gene variants seem to have no influence on iron uptake.
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Affiliation(s)
- R Gottschalk
- Department of Internal Medicine III, J-W Goethe University, Frankfurt/ Main, Germany
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34
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Press RD. Iron beware: a common HFE gene polymorphism may prevent the accurate molecular diagnosis of homozygous hemochromatosis in low-risk, but not high-risk groups. Hepatology 2000; 31:540-2. [PMID: 10655286 DOI: 10.1002/hep.510310243] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/07/2022]
Affiliation(s)
- R D Press
- Dept of Pathology, Oregon Health Sciences University Portland, OR, USA
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35
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Trent RJ, Le H, Yu B, Young G, Bowden DK. DNA testing for haemochromatosis: diagnostic, predictive and screening implications. Pathology 2000. [DOI: 10.1080/pat.32.4.274.279] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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