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Frequency of the HFE C282Y and H63D mutations in Danish patients with clinical haemochromatosis initially diagnosed by phenotypic methods
European Journal of Haematology
Abstract
To assess the frequency of the C282Y and H63D mutations on the HFE gene in Danish patients with clinical hereditary haemochromatosis initially diagnosed by phenotypic methods.
In the period 1950-1985, an epidemiological survey in Denmark identified 179 patients with clinical idiopathic haemochromatosis diagnosed by phenotypic methods (serum transferrin saturation, serum ferritin, liver biopsy and mobilisable body iron stores). In 32 unrelated patients, frozen blood samples were available for genetic analysis. In a subsequent series of 26 unrelated Danish patients, a phenotypic diagnosis of clinical idiopathic haemochromatosis was made before blood samples were taken for HFE genotyping. The total series consisted of 58 patients (40 men and 18 women) with a median age of 60 yrs (range 18-74). HFE genotyping was performed by the polymerase chain reaction (PCR) technique.
Among the patients, 55 of 58 (94.8%) were C282Y/C282Y homozygous. One 63-year-old woman (1.7%) was compound C282Y/H63D heterozygous. Two women (3.4%), aged 42 and 43 yrs were negative for both the C282Y and the H63D mutation.
In the Danish population, homozygosity for the C282Y mutation appears to be the prevailing cause of clinically overt genetic haemochromatosis. This finding has implications both for the evaluation of patients with iron overload disorders and for the strategy in future population screening surveys.
... The frequency of the C282Y mutation is highest among people in Northern Europe, i.e., Scandinavia, and displays a decreasing gradient from Northern to Southern Europe. In Danish patients with clinical hereditary hemochromatosis , the prevalence of C282Y homozygosity is 96% [8], stressing the major importance of this mutation in hereditary iron overloading disorders. Genetic studies in Danes [9, 10, 11] have shown an allele frequency of the C282Y mutation of 5.7% (Table 2). ...
... probably due to the small number of subjects tested [18] (Table 2). The frequency of C282Y/ H63D compound heterozygotes was similar to the frequency in Danes [8]. This is the first report of the S65C mutation in Faroese subjects. ...
... Due to the relative isolation, the coefficient of consanguinity is probably high in the Faroese population [26] , which might contribute to propagate the C282Y mutation. There is a discrepancy between the high frequency of the C282Y mutation and the low incidence of clinical hemochromatosis [8, 10]. According to our results, in the Faroe population, approximately 1 in 156 persons should be C282Y homozygous. ...
The aim of the study was to assess the frequencies of the hereditary hemochromatosis HFE mutations C282Y, H63D, and S65C in the population in the Faroe Islands. The series comprised 200 randomly selected blood donors of Faroese heritage. The frequency of the C282Y, H63D, and S65C mutations on the HFE gene was assessed by genotyping using the polymerase chain reaction (PCR) technique and calculated from direct allele counting. We found no C282Y homozygous subjects; 28 (14.0%) subjects were C282Y heterozygous and four subjects were C282Y/H63D compound heterozygous (2.0%). The C282Y allele frequency was 8.0% (95% CI 5.3-10.7%). The series contained three (1.5%) H63D homozygous subjects and 60 (30.0%) H63D heterozygous subjects. The H63D allele frequency was 17.5% (95% CI 13.8-21.2%). There were four (2.0%) S65C heterozygous subjects. The S65C allele frequency was 1.0% (95% CI 0.3-2.5%). The frequency of the C282Y mutation is high in Faroese blood donors, being close to and not significantly different from the frequencies reported in other Scandinavian countries: Denmark 5.7%, Norway 6.6%, Iceland 5.1%, and Sweden 6.1%. The frequency of the H63D mutation in Faroese subjects is significantly higher than the frequency in Denmark 12.8% (p=0.007), Iceland 10.9% (p=0.003), and Sweden 12.4% (p=0.015), but not from the frequency in Norway 11.2% (p=0.063). The frequency of the S65C mutation in Faroese subjects is not significantly different from the frequencies in Denmark 1.5% and Sweden 1.6%. Screening of larger groups of the Faroese population for HFE mutations especially C282Y should be considered in order to establish the penetrance.
... The most prevalent variants of genetic hemochromatosis in populations of northwestern European ancestry are caused by mutations (C282Y, H63D, S65C) in the HFE-gene located on chromosome 6, and designated HFE-hemochromatosis [1,2]. C282Y and H63D are the most common mutations and homozygosity for C282Y (C282Y/C282Y) is the predominant cause for the disorder in 93-95% of all the diagnosed cases [1][2][3][4]. The frequency of C282Y/C282Y homozygosity in the population ranges from 0.4% in Denmark [3,4] to 0.6% in England [5] and 0.8% in Ireland [6]. ...
... C282Y and H63D are the most common mutations and homozygosity for C282Y (C282Y/C282Y) is the predominant cause for the disorder in 93-95% of all the diagnosed cases [1][2][3][4]. The frequency of C282Y/C282Y homozygosity in the population ranges from 0.4% in Denmark [3,4] to 0.6% in England [5] and 0.8% in Ireland [6]. ...
More than 20,000 Danes out of a population of 5 million are predisposed to developing the hereditary iron overload disease genetic hemochromatosis, where too much iron is absorbed from the daily diet. Over the years, the excess iron causes damage to many vital organs, e.g., the heart, liver, pancreas, and joints. The current treatment consists of regular, repeated blood lettings, which remove the excess iron and prevent organ damage. Since the surplus iron comes from the diet, it must be logical to try to limit the iron intake by an appropriate change in diet. This article by Dr. Nils Thorm Milman reviews on a systematic and scientifically based basis the factors that are important for iron absorption and gives recommendations for dietary compositions that reduce iron absorption.
... Among the mutations that have been reported, the prevalence of C282Y/C282Y genotype is 0?30 % among non-Hispanic whites, 0?06 % among non-Hispanic blacks and 0?03 % among Mexican-Americans, with no gender differences (2) . The C282Y homozygote genotype is most closely associated with HH, presenting in 67-95 % of clinically diagnosed HH cases (1)(2)(3)(4)(5)(6) . ...
... However, the severity of the disease varies greatly. It is well established that the majority of homozygotes will have increased transferrin saturation and serum ferritin (SF) (3,(12)(13)(14)(15)(16) , but the percentage of homozygotes who will develop clinical symptoms is still unclear. Factors influencing the progress of the disease remain poorly understood. ...
To quantify the role of dietary Fe in total body Fe (TBI) accumulation among homozygotes for the HFE gene associated with haemochromatosis.
A Monte Carlo model was built to simulate Fe accumulation based on findings from human feeding experiments and national dietary surveys. A hypothetical cohort of 1000 homozygotes with starting age 25 years was used in 39-year simulations. The impact of reducing dietary Fe intake on Fe accumulation was tested.
In the baseline model without any dietary intervention, by age 64, the percentage of males with TBI > 10 g, >15 g and >20 g was 93.2%, 49.6% and 14.7%, respectively. When the Fe intake of individuals in the cohort was reduced to < or =200% of the recommended dietary allowance (RDA), the corresponding percentages were 92.0%, 40.5% and 10.2%, respectively. The corresponding figures were 91.0%, 40.0% and 9.3% for Fe defortification and 70.3%, 21.3% and 4.1% when Fe intake was capped at 100% RDA. Similar trends were seen with sexes combined, although the impact of interventions was less. Sensitivity analysis revealed that the rate of Fe accumulation and the impact of dietary interventions are highly dependent on assumptions concerning Fe absorption rates.
Variation in Fe intake as currently observed in the USA contributes to variation in Fe accumulation among homozygotes, when continued over an extended period. Lifelong dietary habits and national fortification policy can affect the rate of Fe accumulation, although the magnitude of the effect varies by gender, the TBI level of interest and factors affecting the Fe absorption rate.
... The frequency of the C282Y mutation is highest among people in Northern Europe, e.g., Scandinavia, and displays a decreasing gradient from Northern to Southern Europe [6]. The prevalence of homozygosity for the C282Y mutation in a series of Danish patients with clinical hereditary hemochromatosis is 96% [7], stressing the importance of this mutation in hereditary iron overloading disorders in subjects of Danish heritage. In Danes, there is good agreement between the genetically determined C282Y homozygosity frequency of 0.36% and the phenotypically determined hemochromatosis frequency of 0.37% (using serum transferrin saturation and serum ferritin) in Danish male blood donors [8]. ...
... d, Scotland, England, and the Jersey Islands. The frequency of C282Y/H63D compound heterozygosity (1.44%) was similar to the frequency of 1.42% found in the Copenhagen study [12] and not significantly different from the frequency of 1.72% in a series of Danish patients with clinical hemochromatosis initially diagnosed by phenotypic methods (p=0.57) [7]. Also, it was not significantly different from the frequency in the Faroese population (2.0%) (p=0.54) [19]. We have hypothesized that the C282Y mutation originated among the population in Southern Scandinavia and was spread to other parts of Northern Europe by the Vikings around 700–1050 A.D. [6]. Around the turn of the first millenniu ...
The aim of the study was to assess the frequency of the C282Y and H63D mutations of the hemochromatosis gene (HFE) in ethnic Danes. The series comprised 2501 subjects (1284 men) of Danish heritage who were drawn at random from the Census Registry in age cohorts of 30, 40, 50, and 60 years. The frequency of the C282Y and H63D mutations was assessed on blood samples by genotyping using a polymerase chain reaction (PCR) technique. The HFE genotype distribution was in Hardy-Weinberg equilibrium (p=0.85). C282Y mutation: 9 subjects (0.36%) were homozygous and 265 subjects (10.6%) were heterozygous. H63D mutation: 40 subjects (1.6%) were homozygous and 584 subjects (23.4%) were heterozygous. C282Y/H63D compound heterozygosity was found in 36 subjects (1.4%). The C282Y allele frequency was 5.7% [95% confidence interval (CI) 5.0-6.3%] and the H63D allele frequency was 13.3% (95% CI 12.3-14.2%). In conclusion, the C282Y frequency is relatively high in the Danes, being close to the frequency in other Scandinavian countries, i.e., Iceland 5.1%, the Faroe Islands 6.6%, and Sweden 5.7%, but significantly lower than in Norway 6.6% (p=0.02). Also, the H63D frequency in Danes is close to and not significantly different from the frequency in Iceland 10.9%, Norway 11.2%, and Sweden 12.4%, but significantly lower than in the Faroe Islands 15.4% (p=0.046).
... Homozygosity for a particular gene means that the two alleles of the gene present on both homologous chromosomes are identical. Homozygosity for the HFE-C282Y mutation (C282Y/C282Y) is the leading cause of preclinical and clinical haemochromatosis in ethnic Danes, where more than 95% of the patients have this mutation [7]. Heterozygosity for a particular gene means that the two alleles of the gene present on both homologous chromosomes are not identical, i.e., the cells contain two different alleles, one mutant and one wild-type allele. ...
Objective:
To provide an overview of nutrients and compounds, which influence human intestinal iron absorption, thereby making a platform for elaboration of dietary recommendations that can reduce iron uptake in patients with genetic haemochromatosis.
Design:
Review. Setting. A literature search in PubMed and Google Scholar of papers dealing with iron absorption.
Results:
The most important promoters of iron absorption in foods are ascorbic acid, lactic acid (produced by fermentation), meat factors in animal meat, the presence of heme iron, and alcohol which stimulate iron uptake by inhibition of hepcidin expression. The most important inhibitors of iron uptake are phytic acid/phytates, polyphenols/tannins, proteins from soya beans, milk, eggs, and calcium. Oxalic acid/oxalate does not seem to influence iron uptake. Turmeric/curcumin may stimulate iron uptake through a decrease in hepcidin expression and inhibit uptake by complex formation with iron, but the net effect has not been clarified.
Conclusions:
In haemochromatosis, iron absorption is enhanced due to a decreased expression of hepcidin. Dietary modifications that lower iron intake and decrease iron bioavailability may provide additional measures to reduce iron uptake from the foods. This could stimulate the patients' active cooperation in the treatment of their disorder and reduce the number of phlebotomies.
... Among the HH related genotypes, we found that 7.4% were C282Y homozygotes, 6.3% were C282Y/H63D compound heterozygotes, 5.7% were H63D homozygotes, and 0.6% were C282Y/S65C compound heterozygotes. These findings differed from those reported for a similar population of patients in northern Europe, where over 90% of patients with HH were either C282Y homozygotes or C282Y/H63D compound heterozygotes [8][9][10][11][12]. However, our findings were consistent with data reported for other similar populations of patients in southern Europe, where approximately one-third of the patients did not carry either a C282Y or a H63D mutation [13][14][15][16][17][18][19]. ...
Hereditary hemochromatosis (HH) is a common autosomal recessive disorder in populations of European descent. It is characterized by a variable prevalence of mutations in the hemochromatosis gene (HFE) in different countries and a complex relationship between the HFE genotype and the HH phenotype. Genetic analysis has not been conducted in Croatian patients with iron overload. The aim of this study was to determine whether HFE mutations, C282Y, H63D, and S65C were correlated with clinical and biochemical parameters in Croatian patients with suspected HH.
Clinical examination, biochemical analysis, and genotyping were performed in 175 patients suspected of having HH. The control group consisted of 350 healthy blood donors.
Among the patients, 20% had genotypes related to HH--7.4% were homozygous for C282Y, 6.3% were compound heterozygous for C282Y and H63D, 5.7% were homozygous for H63D, and 0.6% was compound heterozygous for C282Y and S65C. The allelic frequencies were 14.6% for C282Y mutation, 23.7% for H63D mutation, and 1.4% for S65C mutation. A comparison of the clinical and laboratory profiles of patients revealed that C282Y homozygotes had higher frequencies of all clinical symptoms and higher levels of biochemical parameters than others. The C282Y/H63D compound heterozygotes and H63D homozygotes were found to be clinically important, despite the fact that they were associated with less severe disease.
Our results show that HFE mutations are responsible for only about 20% of Croatian patients with suspected HH. Screening with biochemical methods and HFE genotyping may be not sufficient for diagnoses in the Croatian population.
... The biochemical prevalence of HH in Denmark has been estimated to 0.37-0.46%[8] and 94.8% of diagnosed HH-patients are homozygous for the HFE C282Y polymorphism[9]. Iron plays a variety of roles in cellular function and variations in iron content could play a pathophysiological role in several heart diseases due to interference in oxidation-reduction reactions and cellular proliferation [10]. ...
It is believed that hereditary hemochromatosis (HH) might play a role in cardiac disease (heart failure (HF) and ischemia). Mutations within several genes are HH-associated, the most common being the HFE gene. In a large cohort of HF patients, we sought to determine the etiological role and the prognostic significance of HFE genotypes.
We studied 667 HF patients (72.7% men) with depressed systolic function, enrolled in a multicentre trial with a follow-up period of up to 5 years. All were genotyped for the known HFE variants C282Y, H63D and S65C.
The genotype and allele frequencies in the HF group were similar to the frequencies determined in the general Danish population. In multivariable analysis mortality was not predicted by C282Y-carrier status (HR 1.2, 95% CI: 0.8-1.7); H63D-carrier status (HR 1.0, 95% CI: 0.7-1.3); nor S65C-carrier status (HR 1.2, 95% CI: 0.7-2.0). We identified 27 (4.1%) homozygous or compound heterozygous carriers of HFE variants. None of these carriers had a clinical presentation suggesting hemochromatosis, but hemoglobin and ferritin levels were higher than in the rest of the cohort. Furthermore, a trend towards reduced mortality was seen in this group in univariate analyses (HR 0.4, 95% CI: 0.2-0.9, p = 0.03), but not in multivariate (HR 0.5, 95% CI: 0.2-1.2).
HFE genotypes do not seem to be a significant contributor to the etiology of heart failure in Denmark. HFE variants do not affect mortality in HF.
... The frequency displays a decreasing gradient from Northern to Southern Europe and from Western to Eastern Europe [16]. The prevalence of homozygosity for the C282Y variant in a series of ethnic Danish patients with clinical genetic haemochromatosis was 96% [17], stressing the importance of this variant in hereditary iron overloading disorders in subjects of Danish heritage. In Danes, there is good agreement between the genetic frequency of C282Y homozygosity of 0.36% in the present study and the phenotypic (using serum transferrin saturation and serum ferritin) frequency of~0.37% in male blood donors [6]. ...
The objective was to assess the frequencies of haemochromatosis (HFE) gene mutations or variants C282Y, H63D and S65C in ethnic Danes. This is a prospective epidemiologic population study. A cohort of 6,020 Danish men aged 30-50 years was screened for HFE C282Y (c845G-->A), H63D (c187C-->G) and S65C (c193A-->T) gene variants, assessed on saliva or blood samples by restriction fragment length polymorphism (RFLP) analysis. The C282Y gene variant allele was present in 5.6%, H63D in 12.8% and S65C in 1.8% of the chromosomes. In the entire series, we observed 1.4% H63D/C282Y, 0.1% S65C/C282Y and 0.4% H63D/S65C compound heterozygotes. The C282Y allele frequency in Denmark is of similar order as reported in other Scandinavian countries: Iceland 5.1%, Faeroe Islands 6.6%, Norway 6.8% and Sweden 5.8%. Also, the H63D frequency in Denmark is close to the frequencies in other Scandinavian countries: Iceland 10.9%, Faeroe Islands 15.2%, Norway 11.4% and Sweden 12.1%.
A practical, clinically-oriented handbook of iron overload disorders giving a compact guide to normal iron metabolism, iron-related pathobiology, and the diagnosis and management of heritable and acquired iron overload disorders. Many of these disorders were discovered and characterized only in the last decade, and are unmentioned or inadequately described in most texts. Written by clinicians for clinicians, this handbook summarizes information on diverse iron overload conditions, including their history, signs, symptoms, physical examination findings, genetics, genotype-phenotype correlations, pathophysiology, differential diagnosis and treatment. Most physicians, regardless of specialty, encounter patients with systemic or organ-specific iron overload conditions. This book contains essential information for practising adult and pediatric medical specialists in the fields of hematology, gastroenterology, hepatology, rheumatology, endocrinology, diabetology, neurology, oncology, dermatology and internal medicine. Pathologists, pharmacologists, geneticists, genetic counselors and epidemiologists will also find substantial, up-to-date sections in this handbook that are pertinent to their respective fields of interest.
A practical, clinically-oriented handbook of iron overload disorders giving a compact guide to normal iron metabolism, iron-related pathobiology, and the diagnosis and management of heritable and acquired iron overload disorders. Many of these disorders were discovered and characterized only in the last decade, and are unmentioned or inadequately described in most texts. Written by clinicians for clinicians, this handbook summarizes information on diverse iron overload conditions, including their history, signs, symptoms, physical examination findings, genetics, genotype-phenotype correlations, pathophysiology, differential diagnosis and treatment. Most physicians, regardless of specialty, encounter patients with systemic or organ-specific iron overload conditions. This book contains essential information for practising adult and pediatric medical specialists in the fields of hematology, gastroenterology, hepatology, rheumatology, endocrinology, diabetology, neurology, oncology, dermatology and internal medicine. Pathologists, pharmacologists, geneticists, genetic counselors and epidemiologists will also find substantial, up-to-date sections in this handbook that are pertinent to their respective fields of interest.
Hereditary hemochromatosis with the homozygous C282Y HFE mutation (HH-282H) is a genetic condition which causes iron overload (IO) and elevated reactive oxygen species (ROS) secondary to the IO. Interestingly, even after successful iron removal therapy, HH-282H subjects demonstrate chronically elevated ROS. Raised ROS are also associated with the development of multiple cardiovascular diseases and HH-282H subjects may be at risk to develop these complications. In this narrative review, we consider HH-282H subjects as a clinical model for assessing the contribution of elevated ROS to the development of cardiovascular diseases in subjects with fewer confounding clinical risk factors as compared to other disease conditions with high ROS. We identify HH-282H subjects as a potentially unique clinical model to assess the impact of chronically elevated ROS on the development of cardiovascular disease and to serve as a clinical model to detect effective interventions for anti-ROS therapy.
This paper outlines the Danish aspects of HFE-hemochromatosis, which is the most frequent genetic predisposition to iron overload in the five million ethnic Danes; more than 20,000 people are homozygous for the C282Y mutation and more than 500,000 people are compound heterozygous or heterozygous for the HFE-mutations. The disorder has a long preclinical stage with gradually increasing body iron overload and eventually 30% of men will develop clinically overt disease, presenting with symptoms of fatigue, arthralgias, reduced libido, erectile dysfunction, cardiac disease and diabetes. Subsequently the disease may progress into irreversible arthritis, liver cirrhosis, cardiomyopathy, pancreatic fibrosis and osteoporosis. The effective standard treatment is repeated phlebotomies, which in the preclinical and early clinical stages ensures a normal survival rate. Early detection of the genetic predisposition to the disorder is therefore important to reduce the overall burden of clinical disease. Population screening seems to be cost-effective and should be considered.
To evaluate DNA testing for detecting hereditary haemochromatosis (HHC) in subgroups of patients suspected of having the disorder and in family members of those diagnosed with HHC.
Major electronic databases, searched from inception to April 2007.
A systematic review was undertaken using a priori methods and a de novo model developed to assess costs and consequences of DNA testing.
Eleven studies were identified for estimating the clinical validity of genotyping for the C282Y mutation for the diagnosis of HHC. No clinical effectiveness studies meeting the inclusion criteria were identified. Two North American cost-effectiveness studies of reasonable quality were identified but their generalisability to the UK is not clear. Three cohort studies met the inclusion criteria for the review of psychosocial aspects. All had methodological limitations and their generalisability is difficult to determine. The clinical sensitivity of C282Y homozygosity for HHC ranged from 28.4% to 100%, or from 91.3% to 92.4% when considering only the most relevant studies. Clinical specificity ranged from 98.8% to 100%. One study found that gene testing was a cost-effective method of screening relatives of patients with haemochromatosis, whereas the other found that genotyping the spouse of a homozygote was the most cost-efficient strategy. Genetic testing for haemochromatosis appears to be well accepted, is accompanied by few negative psychosocial outcomes and may lead to reduced anxiety. The de novo economic model showed that, in people suspected of having haemochromatosis, the DNA strategy is cost saving compared with the baseline strategy using liver biopsy (cost saved per case detected 123 pounds), largely because of the reduction in liver biopsies. For family testing of siblings the DNA strategy is not cost saving because of the costs of the DNA test (additional cost per case detected 200 pounds). If the cost of the test were to reduce from 100 pounds to 60 pounds, the DNA strategy would be the cheaper one. For family testing of offspring the DNA test strategy is cheaper than the baseline biochemical testing strategy (cost saved per case detected 7982 pounds). Sensitivity analyses showed that the conclusions in each case are robust across all reasonable parameter values.
The preferred strategy in practice is DNA testing in conjunction with testing iron parameters when there is clear clinical indication of risk for haemochromatosis because of biochemical criteria or when there is familial risk for HHC. Access to genetic testing and centralisation of test provision in expert laboratories would lower the cost of testing, improve the cost-effectiveness of the strategy and improve the quality of information provided to clinicians and patients.
Hereditary haemochromatosis is a disease that affects iron metabolism and leads to iron overload. Homozygosity for the H63D mutation is associated with increased transferrin saturation (TS) and ferritin levels. Our objective was to find out if the homozygosity of H63D mutation was the primary cause of iron overload.
We studied 45 H63D homozygotes (31 males and 14 females) with biochemical iron overload and/or clinical features of haemochromatosis. The simultaneous detection of 18 known HFE, TFR2 and FPN1 mutations and sequencing of the HAMP gene were performed to rule out the possible existence of genetic modifier factors related with iron overload.
Values of biochemical iron overload, measured as percentage TS and serum ferritin concentration (SF), in our H63D homozygotes were significantly higher in patients than in controls: TS 55 +/- 15% vs. 35 +/- 15% and SF 764 (645-883) microg/L vs. 115 (108-123) microg/L for patients and controls, respectively. These H63D homozygotes presented extreme hyperferritinaemia and no additional mutations in HFE, TFR2, FPN1 and HAMP genes were detected.
The lack of additional mutations in our H63D homozygotes suggests that this genotype could be the primary cause of iron overload in these patients. Despite our results, we cannot entirely discount the possibility that one or more genetic modifier factor exists, simply because we were unable to find it, although there was a precedent in the HFE gene. Genetic modifier factors have been described for C282Y mutations in the HFE gene, but at the present time they have never been reported in H63D homozygotes.
Tight linkage between the hemochromatosis locus and the HLA region permits determination of genotype in members of hemochromatosis pedigrees. To determine if simple laboratory measures of iron metabolism could predict the affected genotype without the need for HLA typing, we studied seven measures of iron metabolism: serum iron concentration, total iron-binding capacity, per cent saturation of transferrin, serum ferritin concentration, deferoxamine-induced urinary iron excretion and hepatic iron concentration evaluated by both chemical and histological methods. Discriminant analysis showed a per cent saturation of transferrin above 62% to be the best simply-measured indicator of the affected genotype: homozygosity is accurately predicted in 92% of the cases. The logarithmic transform of serum ferritin concentration was only 71% accurate. Pedigree analysis estimated the frequency of the hemochromatosis gene at 0.069 +/- 0.020 with a recombination probability of 0.015 +/- 0.015 with the HLA region. This corresponds to a heterozygote frequency of 0.13 and a disease frequency of 0.005.
Hereditary haemochromatosis (HH), which affects some 1 in 400 and has an estimated carrier frequency of 1 in 10 individuals of Northern European descent, results in multi-organ dysfunction caused by increased iron deposition, and is treatable if detected early. Using linkage-disequilibrium and full haplotype analysis, we have identified a 250-kilobase region more than 3 megabases telomeric of the major histocompatibility complex (MHC) that is identical-by-descent in 85% of patient chromosomes. Within this region, we have identified a gene related to the MHC class I family, termed HLA-H, containing two missense alterations. One of these is predicted to inactivate this class of proteins and was found homozygous in 83% of 178 patients. A role of this gene in haemochromatosis is supported by the frequency and nature of the major mutation and prior studies implicating MHC class I-like proteins in iron metabolism.
The DNA of 147 patients of European origin clinically diagnosed with idiopathic hemochromatosis and 193 controls was examined for mutations of the HLA-H gene at nt 845 and nt 187. One hundred twenty-one (82.3%) of the hemochromatosis patients were homozygous and 10 (6.8%) heterozygous for the 845A (C282Y) mutation. All of the homozygous patients were also homozygous for nt 187C, and all 845A heterozygotes had at least one copy of 187C. Thus, the nt 845 and nt 187 mutations were in complete linkage disequilibrium; nt 187 was a C on all chromosomes with the 845A mutation. Eight of the 10 heterozygotes for 845A were heterozygous for 187G(H63D). The excess of heterozygotes at both nt 187 and nt 845 suggested either the presence of as yet undiscovered mutations existing in trans with 845A and in linkage disequilibrium with 187G, or that the 187G itself is a deleterious mutation, which in concert with the 845A can give rise to hemochromatosis. None of the 193 normal controls were homozygous for 845A and 29/193 (15%) were heterozygous for 845A. Although 47/193 (24.3%) of normal controls were heterozygous for the 187G mutation only two of these carried the 845A mutation. If the 187G mutation complemented the 845A mutation with high penetrance in causing hemochromatosis, then the population frequency of the two genes would require that a high proportion of patients with hemochromatosis be heterozygous for 845A and 187G. Instead, the frequency of homozygotes for the 845A mutation was much higher than that of the 845A/187G genotype. Based on our data, the penetrance of the 845A/187G genotype is only 1.5% and based on the data of Feder et al. only 0.5%. In contrast, the penetrance of the homozygous 845A/845A genotype seems to be very high. Thus, screening for this genotype should be very useful.
The gene whose alteration causes hereditary hemochromatosis (HFE according to the international nomenclature) was, more than 20 years ago, shown to map to 6p21.3. It has since escaped all efforts to identify it by positional cloning strategies. Quite recently, a gene named HLA-H was reported as being responsible for the disease. Two missense mutations, Cys282Tyr (C282Y) and His63Asp (H63D), were observed, but no proof was produced that the gene described is the hemochromatosis gene. To validate this gene as the actual site of the alteration causing hemochromatosis, we decided to look for the two mutations in 132 unrelated patients from Brittany. Our results indicate that more than 92% of these patients are homozygous for the C282Y mutation, and that all 264 chromosomes but 5 carry either mutation. These findings confirm the direct implication of HLA-H in hemochromatosis.
The prevalence of hereditary hemochromatosis in Norway is one of the highest reported in the world. However, the clinical presentation in patients with hemochromatosis in Norway seems to be different compared with recent studies elsewhere. The aim of this study was to investigate patients with hemochromatosis in one community hospital in Norway and to study the prevalence of the C282Y mutation.
One hundred and twenty patients were consecutively admitted to one medical department in Oslo. Serum transferrin and ferritin concentrations were measured in all patients, and a percutaneous liver biopsy was obtained in 108 of 120 (90%) patients. Stainable iron (Perls stain) in hepatocytes was graded from 0 to 4+ and fibrosis from 1 to 4. Genotyping for the C282Y and H63D mutation in the HFE gene was performed by PCR-RFLP.
Forty-eight (40%) of the patients suffered from tiredness and astenia and 29 (24%) had typical arthropathy. Only 5 of 105 (4.5%) had biopsy confirmed cirrhosis and 5 had diabetes mellitus. Patients referred from a blood bank had significantly less symptoms and signs compared with other patients. Twenty-one of 120 (17.5%) patients were C282Y mutation negative. Seventeen (81%) of these patients (16 women and 1 man) had a history of extensive oral iron intake lasting from 5 to 50 years. When excluding those with extensive oral iron intake (n = 17), 92 of 103 (89%) were homozygous for the C282Y mutation, 7 (7%) were heterozygous including 3 compound heterozygous and 4 (4%) were mutation negative.
Only a minority of our patients with hemochromatosis had a far advanced disease at the time of diagnosis (less than 5% had cirrhosis) and hemochromatosis in a majority of the C282Y mutation negative patients was associated with excessive oral iron intake for several years.
First considered as a polymorphism of the HFE gene, the H63D mutation is now widely recognised as a haemochromatosis associated allele. But few H63D homozygotes with clinical manifestations of hereditary haemochromatosis (HH) have been reported. Concurrently, an increasing number of genes have been shown to interact with HFE in iron metabolism.
To describe the clinical expression of iron overload (IO) associated with H63D homozygosity, and search for potential genetic modifiers (within the HFE or other genes) that could explain the variability of the phenotypes.
We retrospectively analysed the clinical phenotype of 56 H63D homozygotes referred for a personal or family history of IO. For each subject we examined intragenic HFE haplotypes and transferrin receptor (TfR) gene polymorphisms and searched for the Y250X mutation on the TFR2 gene. Additionally, we sequenced the HFE gene of H63D homozygotes with HH.
Fifty of 56 subjects had biological and/or clinical abnormalities of iron metabolism. Up to two thirds of patients (n=34) had no acquired cause of IO. Among these, 12 had a phenotypic diagnosis of HH. In the iron loaded group there was a strong prevalence of male patients. No correlation was found between the potential genetic modifiers and phenotypes. No additional mutation of HFE was identified.
The variable phenotypes associated with H63D homozygosity do not appear to be linked to other HFE mutations, to the TFR2 Y250X mutation, or to HFE or TfR gene intragenic polymorphisms. The exact role of H63D homozygosity in IO and HH needs to be further investigated in unselected populations.
Hereditary hemochromatosis (HH) is a very common disorder characterized by iron overload and multi-organ damage. Several genes involved in iron metabolism have been implicated in the pathology of HH (refs. 1-4). We report that a mutation in the gene encoding Solute Carrier family 11, member A3 (SLC11A3), also known as ferroportin, is associated with autosomal dominant hemochromatosis.
Hemochromatosis is a progressive iron overload disorder that is prevalent among individuals of European descent. It is usually inherited in an autosomal-recessive pattern and associated with missense mutations in HFE, an atypical major histocompatibility class I gene. Recently, we described a large family with autosomal-dominant hemochromatosis not linked to HFE and distinguished by early iron accumulation in reticuloendothelial cells. Through analysis of a large pedigree, we have determined that this disease maps to 2q32. The gene encoding ferroportin (SLC11A3), a transmembrane iron export protein, lies within a candidate interval defined by highly significant lod scores. We show that the iron-loading phenotype in autosomal-dominant hemochromatosis is associated with a nonconservative missense mutation in the ferroportin gene. This missense mutation, converting alanine to aspartic acid at residue 77 (A77D), was not seen in samples from 100 unaffected control individuals. We propose that partial loss of ferroportin function leads to an imbalance in iron distribution and a consequent increase in tissue iron accumulation.
The object was to analyze, in a nationwide survey, the incidence and course of hereditary hemochromatosis in relation to the degree of iron overload and the presence of organ damage. The study included 179 Danish Caucasian patients with clinically overt hemochromatosis diagnosed between 1948 and 1985. A cohort of 158 patients was followed for a median of 8.5 years (range: 0.2-29.5). From 1951 to 1975, the yearly relative incidence rate was constant: 0.58/100,000 persons >20 years of age. From 1981 to 1985, the yearly relative incidence rate rose to 1.40/100,000 persons >20 years of age. Survival was reduced in the entire series when compared with a matched control population ( p<0.0001). There was a steady increase in survival from 1948 to 1985 ( p<0.002). Survival was significantly reduced in patients with liver cirrhosis and/or diabetes mellitus ( p<0.01). In contrast, survival in patients without cirrhosis or diabetes was similar to rates expected. Survival in patients with arthropathy was higher than in patients without joint affection ( p<0.004). Patients adequately treated with phlebotomy ( n=66) had a higher survival than inadequately treated patients ( n=62; p<0.0001). Adequately treated patients with cirrhosis and/or diabetes had better survival than inadequately treated patients with similar organ damage ( p<0.001). The main causes of death were hepatic failure due to cirrhosis (32.0%) and cirrhosis with liver cancer (23.1%). Sharpened diagnostic awareness has improved early diagnosis and increased the diagnostic frequency of clinical hemochromatosis. Adequate phlebotomy treatment was the major determinant of survival and markedly improved prognosis. Early detection and treatment of this common iron overload disorder is crucial and can completely prevent any excess mortality caused by hemochromatosis.
We describe a family with autosomal dominant inheritance of increased body iron stores characterized by raised serum ferritin concentration and normal transferrin saturation. Liver biopsy showed iron deposition in Kupffer cells without fibrosis. The clinical features of HFE-related hemochromatosis were absent, as were the Cys282Tyr and His63Asp mutations. Venesection therapy was poorly tolerated, suggesting a defect in iron release from reticuloendothelial stores. A 3-base pair deletion in exon 5 of the ferroportin 1 gene (SLC11A3) predicting Val162 deletion was found in affected members, but not in unaffected individuals or in 100 control subjects. Consensus structural predictions of the transmembrane helices showed that the deletion is in the extracellular loop between the third and fourth predicted transmembrane helices and lies within a spatial cluster of other known ferroportin 1 mutations. These results indicate that this extracellular cluster is functionally important for iron transport, and its disruption leads to iron overload.
Hemochromatosis is a common disorder characterized by excess iron absorption and accumulation of iron in tissues. Usually hemochromatosis is inherited in an autosomal recessive pattern and is caused by mutations in the HFE gene. Less common non-HFE-related forms of hemochromatosis have been reported and are caused by mutations in the transferrin receptor 2 gene and in a gene localized to chromosome 1q. Autosomal dominant forms of hemochromatosis have also been described. Recently, 2 mutations in the ferroportin1 gene, which encodes the iron transport protein ferroportin1, have been implicated in families with autosomal dominant hemochromatosis from the Netherlands and Italy. We report the finding of a novel mutation (V162del) in ferroportin1 in an Australian family with autosomal dominant hemochromatosis. We propose that this mutation disrupts the function of the ferroportin1 protein, leading to impaired iron homeostasis and iron overload.
Hereditary hemochromatosis (HH) is classically associated with a Cys282Tyr (C282Y) mutation of the HFE gene. Non-C282Y HH is a heterogeneous group accounting for 15% of HH in Northern Europe. Pathogenic mutations of the transferrin receptor 2 (TfR2) gene have been identified in 4 Italian pedigrees with the latter syndrome. The goal of this study was to perform a mutational analysis of the TfR2 and HFE genes in a cohort of non-C282Y iron overload patients of mixed ethnic backgrounds. Several sequence variants were identified within the TfR2 gene, including a homozygous missense change in exon 17, c2069 A-->C, which changes a glutamine to a proline residue at position 690. This putative mutation was found in a severely affected Portuguese man and 2 family members with the same genotype. In summary, pathologic TfR2 mutations are present outside of Italy, accounting for a small proportion of non-C282Y HH.
Hereditary hemochromatosis (HH) is a common autosomal recessive genetic disorder of iron metabolism. The HFE candidate gene encoding an HLA class I-like protein involved in HH was identified in 1996. Two missense mutations have been described: C282Y, accounting for 80% to 90% of HH chromosomes, and H63D, which is associated with a milder form of the disease representing 40% to 70% of non-C282Y HH chromosomes. We report here on the analysis of C282Y, H63D, and the 193A→T substitution leading to the S65C missense substitution in a large series of probands and controls. The results confirm that the C282Y substitution was the main mutation involved in hemochromatosis, accounting for 85% of carrier chromosomes, whereas the H63D substitution represented 39% of the HH chromosomes that did not carry the C282Y mutation. In addition, our screening showed that the S65C substitution was significantly enriched in probands with at least one chromosome without an assigned mutation. This substitution accounted for 7.8% of HH chromosomes that were neither C282Y nor H63D. This enrichment of S65C among HH chromosomes suggests that the S65C substitution is associated with the mild form of hemochromatosis.
Background:
The diagnosis of genetic haemochromatosis (GH) before iron overload has developed is difficult. However a convincing candidate gene for GH, HFE (previously HLA-H), has been described recently.
Aims:
To determine the prevalence of the haemochromatosis associated HFE mutations C282Y and H63D in United Kingdom affected and control populations.
Methods:
The prevalence of the HFE C282Y and H63D mutations was determined by polymerase chain reaction amplification and restriction enzyme digestion in a cohort of 115 well characterised patients with GH and 101 controls from the United Kingdom.
Results:
One hundred and five of 115 (91%) patients with GH were homozygous for the C282Y mutation. Only one of 101 (1%) controls was homozygous for the C282Y mutation and this individual currently shows evidence of iron overload. Two of five patients who did not have either of the two described mutations of HFE had early onset iron overload (ages 16 and 24). One had a family history of cardiac failure and the second was subsequently hospitalised due to cardiac failure. These are the first phenotypic observations for patients without either C282Y or H63D mutation of HFE.
Conclusion:
This simple genetic test promises to be a highly effective tool in the diagnosis of GH.
Hemochromatosis type 4 is an atypical hemochromatosis characterized by dominant inheritance, increased serum ferritin, normal transferrin saturation, and prevalent iron deposition in the reticuloendothelial (RE) cells rather than in hepatocytes. Heterozygous missense mutations of the iron export
To compare haemoglobin concentrations in Greenlanders and Danes.
Haemoglobin was measured in a population survey in 1993-1994 comprising 234 indigenous Greenlandic individuals (115 men) aged 19-82 yr. and in Copenhagen County 1983-1984 comprising 2804 Caucasian Danes (1444 men) aged 30-60 yr. The Greenlandic participants were residents in the capital Nuuk (n=70), the town Ilulissat (n=74), and four settlements in the Uummannaq district (n=90). The significance of differences was assessed by Student's t-test, and the xi2-test. Correlations were assessed by Spearman's correlation coefficient (rs).
Greenlanders: Haemoglobin levels were not correlated with age or consumption of traditional foods, and were not significantly different in the three residential areas. Mean haemoglobin was higher in men, 146+/-9.6 (SD) g/L, than in women, 132+/-9.6 g/L (p<0.0001). Mean haemoglobin in iron-replete men with serum ferritin >32 microg/L (n=104) was 146+/-9.3 g/L, and in iron-replete women (n=68) 133+/-10.4 g/L (p<0.0001). The 5th percentile for haemoglobin in iron-replete men was 133 g/L (8.3 mmol/L) and in women 118 g/L (7.3 mmol/L). The prevalence of iron deficiency anaemia (i.e. ferritin <13 microg/L and Hb <5th percentile for iron-replete men and women) was 0% in men, 2.78% in women < or =50 yr of age and 0% in women >50 yr of age. Danes: Mean haemoglobin in men was 154+/-10.0 g/L and in women 138+/-10.4 g/L (p<0.0001). Haemoglobin in iron-replete men (n=1379) (i.e. serum ferritin >32 microg/L) was 154+/-10.7 g/L, and in iron-replete women (n=1003) 140+/-9.6 g/L (p<0.0001). Mean haemoglobin was lower in premenopausal than in postmenopausal women (p<0.0001). The 5th percentile for haemoglobin in iron-replete men was 137 g/L (8.5 mmol/L) and in women 124 g/L (7.7 mmol/L). The prevalence of iron deficiency anaemia (i.e. ferritin <13 microg/L and Hb <5th percentile for iron replete men and women) was 0% in men, 1.92% in women < or =50 yr of age and 0% in women >50 yr of age.
Haemoglobin concentrations in Greenlanders were significantly lower than in Danes both in men (p<0.0001) and in women (p<0.0001). Delta(mean haemoglobin) in men was 8.0 g/L (0.5 mmol/L) and in women 6.2 g/L (0.4 mmol/L). Variations in haemoglobin levels may be due to genetic differences.
The frequency of HLA-A3 and HLA-B14 antigens was significantly higher in a series of 51 patients with idiopathic haemochromatosis than in a control group, being respectively 78-4 versus 27-0% and 25-5 versus 3-4%. This finding strongly supports the suggestion that idiopathic haemochromatosis is a genetic disease and suggests that the gene(s) responsible for the disease may be linked to the histocompatibility genes.
The aim of this cross-sectional study was to estimate the prevalence of iron deficiency and overload in the adult population in Iceland, a developed Scandinavian country. The study population consisted of 4240 individuals aged 25-74 years randomly selected from the national roster. Basic hematological, S-iron, S-total iron binding capacity (TIBC), and S-ferritin measurements were obtained on 2588 individuals (61.0%). The results indicated unusually large iron stores in the adult Icelandic population and significantly larger iron stores in the rural compared to the urban population. Iron deficiency was rare except in urban premenopausal women, where 1 in 4 showed evidence of iron deficiency and 3.2% had iron deficiency anemia. Seven patients with hereditary hemochromatosis were identified from a subgroup of 1887 subjects, resulting in a prevalence of 0.37%. Two of the hereditary hemochromatosis patients had been gastrectomized. Measures to improve the iron balance in urban premenopausal women cannot therefore include increased iron fortification of food but must be more directed towards the target group.
Hereditary haemochromatosis is an autosomal recessive disease that is genetically expressed by excessive accumulation of iron in the tissues, resulting in cirrhosis, diabetes mellitus, cardiomyopathy and hypogonadism. As the disease may be diagnosed before the appearance of symptoms, and prevented by repeated phlebotomies, there are strong implications for adoption of a screening procedure. Determinations of transferrin saturation (TS) and serum ferritin concentration (SF) were used to screen 4302 blood donors, who were selected for follow-up studies if they fulfilled any of the following three criteria: (i) TS greater than or equal to 0.7; (ii) TS greater than or equal to 0.5 together with SF greater than or equal to 150 micrograms l-1; (iii) SF greater than or equal to 300 micrograms l-1. A total of 58 subjects who fulfilled at least one of these criteria were reinvestigated, after which 18 individuals still fulfilled at least one criterion. Fifteen subjects having SF greater than or equal to 300 micrograms l-1 were offered liver biopsy and thirteen of these accepted. In one individual, no stainable iron was detected, and two subjects did not fulfil the previously established diagnostic criteria for the diagnosis of hereditary haemochromatosis. Ten subjects who had a high TS and liver iron grade 2-4 according to Bassett were classified accordingly as homozygotes. On the basis of these results, the prevalence of haemochromatosis in Denmark was estimated to be 0.0037-0.0046.
During the period 1950-1985, a total of 179 cases of clinically overt hereditary haemochromatosis (HH) were registered in Denmark, 140 males and 39 females. Median age at diagnosis was 55 years (range 29-81). Diagnostic approaches, symptoms and physical signs at discovery are described. All patients had grade 3-4 liver haemosiderin iron, and cirrhosis was present in 84%. Serum (S-) transaminase was elevated in 92%, S-alkaline phosphatase in 47% and S-bilirubin in 23%, while plasma prothrombin time was below normal in 34%. Females had higher alkaline phosphatase than males (p less than 0.05). Bone marrow haemosiderin iron (n = 81) showed no relation to iron status indicators and was unsuitable as a diagnostic tool. Skin biopsy (n = 56) was positive for haemosiderin iron in 67% and for melanin in 57%, but was of limited value in the assessment of HH. Arthropathy was registered in 44%; arthralgias and clinical joint abnormalities occurred more frequently in females than in males (p less than 0.05). Latent diabetes mellitus was found in 34% and overt diabetes in 55%, being more frequent in males than in females (p less than 0.05). Other endocrine abnormalities were seen in 66%. Cardiac failure was observed in 9% and abnormal ECG in 35%. Males had higher haemoglobin (p less than 0.0001) and S-iron (p less than 0.01) than females, while S-transferrin, transferrin saturation, S-ferritin and mobilizable iron stores showed no significant sex differences. Median transferrin saturation was 87% (range 52-100); values greater than 62% were observed in 96% of the patients. Median S-ferritin was 3,400 micrograms/l (800-12,700) and median iron stores 14.8 g (4.5-36.4).
Iron status markers, serum iron, serum transferrin, transferrin saturation and serum ferritin were analysed in 162 homozygous patients with clinical haemochromatosis, in 12 homozygous relatives with preclinical haemochromatosis, in 84 heterozygous, and in 9 normal subjects. In the distinction between homozygous patients with clinical haemochromatosis and heterozygotes, transferrin saturation and serum ferritin showed the highest diagnostic efficiencies. A diagnostic efficiency of 0.97 was obtained with a transferrin saturation value of 60%. A discriminatory transferrin saturation value of greater than 50% correctly classified 173 out of the 174 individuals with preclinical + clinical haemochromatosis, whereas a discriminatory value of greater than 60% identified 158 out of the 162 patients with clinical haemochromatosis. All patients with clinical haemochromatosis had transferrin saturation values greater than 50%. 10 heterozygotes had transferrin saturation values greater than 50%, and 3 values greater than 60%. Normal subjects had transferrin saturation values less than 47%. A diagnostic efficiency of 0.99 was obtained using a discriminatory serum ferritin value of 800 micrograms/l. Patients with clinical haemochromatosis had higher ferritin (p less than 0.001) than subjects with preclinical haemochromatosis, who in turn had higher values than heterozygotes (p less than 0.001). Iron status markers in heterozygotes and normal subjects displayed no significant differences.
This study investigated the long-term survival rates of 85 patients with hereditary hemochromatosis. Eighty-five patients with documented hereditary hemochromatosis diagnosed between 1958 and 1989 and followed up at the University Hospital (University of Western Ontario) medical center were retrospectively reviewed for this analysis. The current status of the patient was assessed by interview or written questionnaire completed by the patient or the family physician. Estimates of differences in survival rates were obtained using Kaplan-Meier life-table and Cox regression analysis. Liver histology, clinical features of the disease, and number of venesections were analyzed to determine their relationship to survival. In the course of a mean follow-up interval of 8.1 +/- 6.8 years (range, 0-31 years), there were 17 deaths among the 85 hemochromatosis patients. Patients with cirrhosis at the time of diagnosis were 5.5 times more likely to die than noncirrhotic patients. Patients who were noncirrhotic at the time of diagnosis had an estimated survival that was not significantly different from age- and sex-matched members of the normal population. Diabetes did not increase the risk of death after data were controlled for the presence of cirrhosis. Early diagnosis and treatment of hemochromatosis in the precirrhotic stage can lead to long-term survival similar to that in the general population. The presence of cirrhosis significantly increases mortality and is the major clinical factor affecting survival.
HLA-A, -B, -C and -DR antigens were determined in 70 unrelated Danish patients with idiopathic haemochromatosis. The frequencies of HLA-A and -B antigens compared to 1967 normal control subjects and the relative risk values (RR) were: A3, 80.0% vs. 26.9% (P less than 0.0001), RR = 10.9; B7, 60.0% vs. 26.8% (P less than 0.0001), RR = 4.1; B14, 10.0% vs. 4.5% (P = 0.03), RR = 2.4; B47, 4.3% vs. 0.5% (P less than 0.0001), RR = 9.7; A3, B7, 51.4% vs. 12.2% (P less than 0.0001), RR = 7.6; A3, B14, 10.0% vs. 1.4% (P less than 0.0001), RR = 7.7; A3, B47, 4.3% vs. 0.5% (P less than 0.0001), RR = 9.7. Six patients (8.6%) possessed none of these four typical antigens. There was no association between disease and the frequencies of HLA-C and HLA-DR antigens. The pattern of HLA-antigens associated with haemochromatosis in Denmark shows similarities to those reported both in Germany, being HLA-A3, B7 dominated, and in Brittany, Great Britain and Central Sweden, being HLA-A3, B14 dominated.
A genetic analysis of 96 pedigrees has confirmed our previously published report and demonstrated an autosomal recessive mode of inheritance for idiopathic haemochromatosis.
Three generations have been analyzed in each family: the sibship of the patient; the parents of the patient; the offspring of the patient. All the data are consistent with a recessive autosomal transmission: (1) An increased rate of consanguineous matings was found among the parents of the patients. (2) Not a single patient having the disease (latent or manifat) was found among either the parents or the children of the probands. (3) Three distinct levels of iron stores - normal, slightly increased and heavily overloaded - have been statistically separated in the haemochroma-totic families. (4) The result of a segregation analysis has shown a percentage of parsom with heavy iron overloads per sibship corresponding to that expected for a recessive autosomal transmission, taking into account a penetrance of 0.20 in the female (the estimate used in this study).
The present study was undertaken to confirm or reject recent findings indicating a high prevalence of iron deficiency in Swedish male adolescents; a second aim was to study the prevalence of genetic iron overload.
The diagnostic criteria were: anaemia: Hb < 130 g L-1 (a): iron deficiency: serum ferritin (SF) < 12 micrograms L-1 + transferrin saturation (TS) < 16% (b): iron deficiency anaemia a + b. Iron overload: SF (90th percentile) + TS (90th percentile) in repeat tests.
Central Sweden.
A total 3975 men aged 18 years studied on enrollment into military service.
Serum ferritin averaged 36.8 micrograms L-1. Anaemia was present in 0.5%, iron deficiency anaemia in 0.17% and iron deficiency in 0.4%. If iron deficiency is defined as SF < 16 micrograms L-1, as was recently suggested, the prevalence would be 2.8%. Such a cut-off value would include 73% normal people (false positives). Iron overload had the same prevalence as iron deficiency, 0.4%.
Iron stores, as measured by serum ferritin, are small in young men studied at the end of their growth spurt. However, iron deficiency is rare. Therefore, the present study has not been able to confirm the high prevalence of iron deficiency recently reported. A prevalence of genetic haemochromatosis of 0.4%, confirms earlier findings and would mean that 12.6% of the population are heterozygotic carriers of the iron-loading genes. These findings give no support for a proposed, more effective iron-enrichment of food. It is not needed and can be harmful.
The course of hereditary hemochromatosis may depend on the degree of iron overload and the time of therapeutic intervention. This analysis evaluates the impact of early diagnosis and iron removal on survival and complications in hereditary hemochromatosis.
A Cohort of 251 patients with hemochromatosis was followed up for 14.1 +/- 6.8 years.
Survival was reduced in the total group of patients when compared with a matched normal population. Survival in noncirrhotic and nondiabetic patients and in patients diagnosed between 1982 and 1991 was identical with rates expected. Survival was reduced in patients with severe iron overload vs. those with less severe overload. The percentage of early diagnoses increased threefold between 1947 and 1969 to that between 1970 and 1981; there was only a further 20%-25% increase in the last decade. Deaths caused by liver cancer, cardiomyopathy, liver cirrhosis, and diabetes mellitus were increased as compared with expected rates. Liver cancers were associated with cirrhosis and amount of mobilizable iron but not with hepatitis B or C markers.
Prognosis of hemochromatosis and most of its complications, including liver cancer, depend on the amount and duration of iron excess. Early diagnosis and therapy largely prevent the adverse consequences of iron overload.
A candidate gene for hemochromatosis has recently been localized on the short arm of chromosome 6, about 4 megabases telomeric to the major histocompatibility complex. It encodes a protein that exhibits significant similarity to the HLA class I molecules and can be provisionally designated HLA-hc. Genotype analysis of 94 hemochromatosis patients living in France and a similar number of controls confirms that the disease is strongly associated with homozygosity at nucleotide 845 (72% of the patients and none of the controls carry two copies of the 845A variant). The data are consistent with hemochromatosis being a heterogeneous disease: about 79% of the cases in this sample would be caused by a defect in HLA-hc and 21% by an unrelated mechanism. A second variant (187 G) enriched on patient chromosomes that do not carry the 845A mutation might influence the affinity of a ligand for HLA-hc; the exact nature of this ligand remains to be discovered. The 845A variant is the best genetic marker for the disease identified to date, and the detection of 845A homozygosity should now permit diagnosis of a readily curable disease and the prevention of sometimes deadly complications in at least 72% of the patients.
The observed prevalence of hemochromatosis has ranged considerably from 0.05 to 0.37% in studies requiring liver biopsy. We aimed to study the prevalence of genetic hemochromatosis among Norwegian blood donors.
We studied 10,552 healthy blood donors (5312 women and 5240 men) using serum ferritin as a screening parameter. If serum ferritin concentration was > or = 100 micrograms/l in women and > or = 200 micrograms/l in men, serum iron and transferrin (measured as total iron binding capacity = TIBC) were measured. Blood donors who repeatedly had a transferrin saturation above 40% and a ferritin concentration above these limits were referred to a hepatologist (H.B.).
Serum ferritin was > or = 100 micrograms/l in 94/5312 (1.8%) women and > or = 200 microliters in 79/5240 (1.5%) men. Of these, 37 persons had a serum ferritin concentration above 100 micrograms/l (females) or above 200 micrograms/l (males) and a transferrin saturation above 40%. Nineteen of them (13 men and 6 women, median age 36 years, range 28-68) were identified as having hemochromatosis on the basis of increased hepatic iron index. Serum ferritin ranged from 111 to 1980 micrograms/l (median 357 micrograms/l and transferrin saturation from 50 to 100% (median 92%), hepatic iron from 48 to 471 mumol/g dry weight (median 118 mumol/g) and hepatic iron index from 1.5 to 12.1 (median 3.0). One person had cirrhosis and none had diabetes. The prevalence of hemochromatosis was significantly higher among first-time blood donors (12 out of 3500 [3.4/1000]) compared with repeat donors (7 out of 7052 [1/1000]), p < 0.005.
The observed prevalence of hemochromatosis in Norwegian first-time blood donors of 0.34% is comparable to recently observed prevalences in other studies. However, the use of serum ferritin as a first-step screening tool may have failed to detect hemochromatosis in the early stage where iron overload has not yet occurred.
Hemochromatosis (HH) is an inborn error of iron metabolism, frequent among Caucasians, characterized by progressive iron loading that, if untreated, causes high morbidity and death. HLA-H, a putative HH gene, has recently been isolated. The large majority of patients so far studied are homozygous for a single mutation, which results in a cysteine-to-tyrosine substitution at amino acid 282 of the protein. A second, less frequent, variant, His63Asp, has an undefined role in the pathogenesis of the disease. Here we report that the Cys282Tyr change accounts for 69% of HH chromosomes in a series of 75 unrelated Italian patients who fulfilled well-defined criteria for HH diagnosis. Sixty-four percent of patients were Cys282Tyr homozygous, 10% were heterozygous, and 21% carried the normal allele. The same mutation was rare in normal controls. The His63Asp variant was less frequent but had a similar frequency among affected and normal chromosomes. Subjects without two copies of the Cys282Tyr change were both isolated patients and individuals from families with a 6p-linked disease. Mutation analysis of the HLA-H gene, carried out by RNA-SSCP in the latter patients, did not reveal any significant nucleotide abnormality in coding sequences and intron-exon boundaries. The absence of mutations in HLA-H gene was confirmed in three cases by direct sequencing. Major deletions or rearrangements of the gene were excluded by Southern blotting. The existence of patients with clinical and histological features of HH, but without mutations in HLA-H gene, suggests that in Italy the disease is more heterogeneous than reported in northern Europe.
Genetic haemochromatosis is the most common autosomal recessive disorder in Northern European populations. A major histocompatibility complex class I-like gene, HLA-H, has been proposed to be responsible for genetic haemochromatosis. The prevalence of HLA-H gene mutations 282(TGC; Cys/TAC; Tyr) and 63(CAT; His/GAT; Asp) was determined in patients of Austrian origin.
DNA extracted from the blood of 40 Austrian patients and 271 controls was used to amplify HLA-H gene fragments by the polymerase chain reaction method. The base changes responsible for mutations Cys282Tyr and His63Asp alter recognition sites for restriction enzymes SnaB I and Bcl I, respectively. Digestion products were separated by agarose gel electrophoresis and visualised by ethidium bromide staining.
Thirty-one (77.5%) genetic haemochromatosis patients were homozygous for mutation Cys282Tyr and three compound heterozygous for mutations Cys282Tyr and His63Asp. One patient was homozygous for mutation His63Asp but normal for mutation Cys282Tyr. Four patients were normal at both genetic loci and one patient was heterozygous for mutation His63Asp. One control subject homozygous for mutation Cys282Tyr was found on investigation to fulfill diagnostic criteria for haemochromatosis. Eight control subjects homozygous for mutation His63Asp showed no biochemical or clinical evidence of haemochromatosis indicating that this variant is not directly responsible for haemochromatosis. Absence of the Cys282Tyr mutation in six genetic haemochromatosis patients with distinct haplotypes indicates mutations within the HLA-H gene or at alternative genetic loci are the cause of genetic haemochromatosis in these patients.
The HLA-H Cys282Tyr defect is likely to play a key role in the pathogenesis of haemochromatosis in most patients. Predominance of a single HLA-H gene mutation in haemochromatosis allows presymptomatic screening by genotypic analysis.
The identification of a candidate gene for hereditary hemochromatosis in 69%-100% of patients with hemochromatosis has resulted in a diagnostic genotypic test (C282Y). The aim of this study was to reassess the phenotypic diagnostic criteria for hemochromatosis in patients homozygous for the C282Y mutation of the HFE gene.
Transferrin saturation, ferritin, hepatic iron index, and iron removed by venesection were studied in C282Y++ homozygotes and C282Y-- putative homozygotes.
Patients were homozygous for the C282Y mutation in 122 of 128 cases (95%). In C282Y homozygotes, the results were as follows: hepatic iron index, >1.9 in 91.3%; transferrin saturation, >55% in 90%; serum ferritin, >300 microg/L in 96% of men and >200 microg/L in 97% of women; and iron removed, >5 g in 70% of men and 73% of women. There were four homozygotes for C282Y with no biochemical evidence of iron overload.
The sensitivity of the phenotypic tests in decreasing order was as follows: serum ferritin, hepatic iron index, transferrin saturation, and iron removed by venesection. Although the genetic test is useful in the diagnostic algorithm, this study has shown both iron-loaded patients without the mutation and homozygous patients without iron overload.
Patients with hemochromatosis show variable phenotype expression. We evaluated the frequency of hemochromatosis gene (HFE) mutations and the contribution of HFE genotype, ancestral haplotype, ethnic background, and additional factors (alcohol intake, hepatitis viruses, and beta-thalassemia trait) to the severity of iron overload in a large series of Italian patients with a hemochromatosis phenotype.
HFE genotype was studied in 188 patients. Phenotype evaluation was available in 153 men and 20 women and was based mainly on iron removed. HFE genotype was determined by a polymerase chain reaction restriction assay and ancestral haplotype through D6S265 and D6S105 microsatellite analysis.
The frequency of C282Y homozygotes was 64%, with a decreasing gradient from north to south. C282Y homozygotes showed more severe iron overload than the other HFE genotypes. In the same group, ancestral haplotype was associated with a more severe phenotype. Additional factors may favor the development of a relatively mild hemochromatosis phenotype in patients nonhomozygous for the C282Y mutation.
Hemochromatosis in Italy is a nonhomogenous disorder in which genetic and acquired factors are involved. In patients with a single or no HFE mutation, further studies will enable a differentiation between true genetic disorders and interactions between genetic and acquired factors.
To determine the frequency of mutations (C282Y and H63D) in a newly identified gene HFE in patients with hereditary haemochromatosis (HH) in Sweden.
Molecular genetic analyses of the HFE gene (polymerase chain reaction (PCR) followed by enzyme restriction) were performed in genomic DNA from unrelated patients with a clinical diagnosis of HH and in healthy subjects.
Patients with HH treated with phlebotomies at Karolinska Hospital and Huddinge Hospital were analyzed.
Eighty-seven unrelated patients with HH and 117 healthy controls.
It was found that the HFE C282Y mutation occurs in 94.2% of chromosomes from patients with HH. Eighty patients (92.0%) were homozygous for the C282Y mutation and one was heterozygous. Three patients were heterozygous for both C282Y and H63D mutations. One patient was homozygous and one was heterozygous for the H63D mutation. One patient carried normal alleles. In healthy controls, the C282Y mutation occurred in nine subjects (7.7%), all of which were heterozygous. The H63D mutation was found in 28 control subjects, one of which was homozygous.
We found that the majority of patients with HH have the C282Y mutation in the HFE gene. The frequency of the H63D mutation was higher in controls than in patients with HH, although in chromosomes at risk the frequency of the H63D mutation was higher in patients.
Genetic haemochromatosis (GH) is the most common, autosomal recessive disorder in Northern Europe. The studies which led to the identification of the HFE gene are described. In the UK over 90% of patients with GH are homozygous for the C282Y mutation of this gene. This mutation is confined to populations of European origin. The significance of another mutation, H63D, in causing iron overload is less certain. Preliminary studies on the localization of the protein and the effects of the mutations are described. Genetic testing and the measurement of iron status now provide the means to allow for widespread testing for the prevention of iron overload and its consequences. However, questions remain about the clinical penetrance of GH.
Mutation analysis was performed for two HFE mutations (C282Y, H63D) in unrelated patients with hereditary haemochromatosis (n = 92), family members of patients (n = 34), and unrelated controls (n = 157) from Northern Germany, 87/92 patients (94.6%) revealed the C282Y mutation in homozygous form, five were heterozygous. No H63D mutation was found in 174 chromosomes of patients homozygous for C282Y, whereas four of the heterozygote patients also carried the H63D mutation. Among the control group, 9.6% were heterozygotes for C282Y. 2/157 subjects were homozygous, 37/157 were heterozygous for the H63D mutation, but showed no signs of iron overload.
Hereditary hemochromatosis (HH) is a common autosomal recessive genetic disorder of iron metabolism. The HFE candidate gene encoding an HLA class I-like protein involved in HH was identified in 1996. Two missense mutations have been described: C282Y, accounting for 80% to 90% of HH chromosomes, and H63D, which is associated with a milder form of the disease representing 40% to 70% of non-C282Y HH chromosomes. We report here on the analysis of C282Y, H63D, and the 193A-->T substitution leading to the S65C missense substitution in a large series of probands and controls. The results confirm that the C282Y substitution was the main mutation involved in hemochromatosis, accounting for 85% of carrier chromosomes, whereas the H63D substitution represented 39% of the HH chromosomes that did not carry the C282Y mutation. In addition, our screening showed that the S65C substitution was significantly enriched in probands with at least one chromosome without an assigned mutation. This substitution accounted for 7.8% of HH chromosomes that were neither C282Y nor H63D. This enrichment of S65C among HH chromosomes suggests that the S65C substitution is associated with the mild form of hemochromatosis.
Haemochromatosis is a common recessive disorder characterized by progressive iron overload, which may lead to severe clinical complications. Most patients are homozygous for the C282Y mutation in HFE on 6p (refs 1-5). A locus for juvenile haemochromatosis (HFE2) maps to 1q (ref. 7). Here we report a new locus (HFE3) on 7q22 and show that a homozygous nonsense mutation in the gene encoding transferrin receptor-2 (TFR2) is found in people with haemochromatosis that maps to HFE3.
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.
Although genotyping studies suggest that hereditary haemochromatosis is one of the most common genetic disorders in white people, it is still thought of as an uncommon disease. Our aim was to test the hypothesis that hereditary haemochromatosis is a disease often overlooked in patients with late-onset type 1 diabetes mellitus, a late manifestation of untreated iron overload.
We did a retrospective study in which we genotyped for the C282Y and H63D mutations in the haemochromatosis gene in 716 unselected Danish patients who developed type 1 diabetes mellitus after age 30 years and 9174 controls from the general Danish population. We also screened for hereditary haemochromatosis by assessment of transferrin saturation.
More patients with diabetes (n=9, relative frequency 1.26%, 95% CI 0.58-2.37) than controls (23, 0.25%, 0.16-0.38) were homozygous for C282Y (odds ratio 4.6, 2.0-10.1, p=0.0001). These patients had unrecognised signs of haemochromatosis. Transferrin saturation and ferritin concentrations ranged from 57% to 102% and 17 microg/L to 8125 microg/L, respectively. Frequency of compound heterozygosity (C282Y/H63D) did not differ between patients with diabetes (eight) and controls (131) (odds ratio 0.8, 95% CI 0.4-1.7). Positive and negative predictive values of transferrin saturation greater than 50%, in identification of C282Y homozygosity, were 0.26 and 1.00, respectively. A saturation of less than 50% therefore excluded C282Y homozygosity, whereas a saturation of more than 50% suggested C282Y homozygosity.
Measurement of transferrin saturation followed by genetic testing could prevent liver and heart problems and improve life expectancy in patients with diabetes. Population screening before the onset of diabetes might improve the outlook of patients even further, but will be less cost effective.
We describe an uncommon case of adenosquamous carcinoma arising in a Barrett esophagus in a 72-year-old white man who occasionally used alcohol, and was a nonsmoker for 34 years. Polymerase chain reaction-based microsatellite analysis was performed on the adenocarcinoma component (AC) and squamous cell carcinoma component (SC) of the tumor. The metaplastic Barrett epithelium (BE), the AC and the SC all showed loss of the same allele at 4 markers on chromosome 9p. Furthermore, the AC and the SC both showed loss of the same allele at all informative markers tested on chromosomal arms 3p, 5q, 10q, 14q, and 18q. In addition, both the SC and AC component contained the same missense mutation in the p53 tumor-suppressor gene. The only observed difference was a shift at a marker on chromosome 16q in the AC, whereas no shift was found in the BE and the SC. These findings suggest that this biphasic tumor has a monoclonal origin. The divergence presumably occurred late in the tumorigenesis of this carcinoma.
Two major mutations are defined within the hemochromatosis gene, HFE. Although the effects of the C282Y mutation have been well characterized, the effects of the H63D mutation remain unclear. We accessed a well-defined population in Busselton, Australia, and determined the frequency of the H63D mutation and its influence on total body iron stores.
Serum transferrin saturation and ferritin levels were correlated with the H63D mutation in 2531 unrelated white subjects who did not possess the C282Y mutation.
Sixty-two subjects (2.1%) were homozygous for the H63D mutation, 711 (23.6%) were heterozygous, and 1758 (58.4%) were wild-type for the H63D mutation. Serum transferrin saturation was significantly increased in male and female H63D homozygotes and heterozygotes compared with wild-types. Serum ferritin levels within each gender were not influenced by H63D genotypes. Elevated transferrin saturation > or = 45% was observed in a greater proportion of male H63D carriers than male wild-types. Male H63D homozygotes (9%) and heterozygotes (3%) were more likely to have both elevated transferrin saturation and elevated ferritin > or = 300 ng/mL than male wild-types (0.7%). Homozygosity for H63D was not associated with the development of clinically significant iron overload.
Presence of the H63D mutation results in a significant increase in serum transferrin saturation but does not result in significant iron overload. In the absence of the C282Y mutation, the H63D mutation is not clinically significant.
Iron is a vitally important element in mammalian metabolism because of its unsurpassed versatility as a biologic catalyst. However, when not appropriately shielded or when present in excess, iron plays a key role in the formation of extremely toxic oxygen radicals, which ultimately cause peroxidative damage to vital cell structures. Organisms are equipped with specific proteins designed for iron acquisition, export, transport, and storage as well as with sophisticated mechanisms that maintain the intracellular labile iron pool at an appropriate level. These systems normally tightly control iron homeostasis but their failure can lead to iron deficiency or iron overload and their clinical consequences. This review describes several rare iron loading conditions caused by genetic defects in some of the proteins involved in iron metabolism. A dramatic decrease in the synthesis of the plasma iron transport protein, transferrin, leads to a massive accumulation of iron in nonhematopoietic tissues but virtually no iron is available for erythropoiesis. Humans and mice with hypotransferrinemia have a remarkably similar phenotype. Homozygous defects in a recently identified gene encoding transferrin receptor 2 lead to iron overload (hemochromatosis type 3) with symptoms similar to those seen in patients with HFE-associated hereditary hemochromatosis (hemochromatosis type 1). Transferrin receptor 2 is primarily expressed in the liver but it is unclear how mutant forms cause iron overload. Mutations in the gene encoding the iron exporter, ferroportin 1, cause iron overload characterized by iron accumulation in macrophages yet normal plasma iron levels. Plasma iron, together with dominant inheritance, discriminates iron overload due to ferroportin mutations (hemochromatosis type 4) from hemochromatosis type 1. Heme oxygenase 1 is essential for the catabolism of heme and in the recycling of hemoglobin iron in macrophages. Homozygous heme oxygenase 1 deletion in mice leads to a paradoxical accumulation of nonheme iron in macrophages, hepatocytes, and many other cells and is associated with low plasma iron levels, anemia, endothelial cell damage, and decreased resistance to oxidative stress. A similar phenotype occurred in a child with severe heme oxygenase 1 deficiency. Recently, a mutation in the L-subunit of ferritin has been described that causes the formation of aberrant L-ferritin with an altered C-terminus. Individuals with this mutation in one allele of L-ferritin have abnormal aggregates of ferritin and iron in the brain, primarily in the globus pallidus. Patients with this dominantly inherited late-onset disease present with symptoms of extrapyramidal dysfunction. Mice with a targeted disruption of a gene for iron regulatory protein 2 (IRP2), a translational repressor of ferritin, misregulate iron metabolism in the intestinal mucosa and the central nervous system. Significant amounts of ferritin and iron accumulate in white matter tracts and nuclei, and adult IRP2-deficient mice develop a movement disorder consisting of ataxia, bradykinesia, and tremor. Mutations in the frataxin gene are responsible for Friedreich ataxia, the most common of the inherited ataxias. Frataxin appears to regulate mitochondrial iron (or iron-sulfur cluster) export and the neurologic and cardiac manifestations of Friedreich ataxia are due to iron-mediated mitochondrial toxicity. Finally, patients with Hallervorden-Spatz syndrome, an autosomal recessive, progressive neurodegenerative disorder, have mutations in a novel pantothenate kinase gene (PANK2). The cardinal feature of this extrapyramidal disease is pathologic iron accumulation in the globus pallidus. The defect in PANK2 is predicted to cause the accumulation of cysteine, which binds iron and causes oxidative stress in the iron-rich globus pallidus.
Juvenile hemochromatosis or type 2 hemochromatosis is a rare inherited recessive disease, which leads to severe iron overload earlier in life than HFE-related hemochromatosis. Increased transferrin saturation and serum ferritin as well as parenchymal iron deposition and liver fibrosis may be observed in childhood. Clinical symptoms of hypogonadism and cardiac disease develop before the age of 30. The disease is usually progressive and if untreated may become fatal because of heart failure. The type 2 hemochromatosis locus maps to chromosome 1q21, but the gene has not yet been isolated. The severity and the early expression of juvenile hemochromatosis suggest that the gene product has a crucial role in the regulation of iron homeostasis.
Iron overload may predominantly involve parenchymal or reticuloendothelial cells, the prototype of parenchymal iron overload being HFE-related genetic haemochromatosis. We studied a family with autosomal dominant hyperferritinaemia in whom the proband showed selective iron accumulation in the Kupffer cells on liver biopsy. Analysis of L and H ferritin genes excluded mutations responsible for hereditary hyperferritinaemia/cataract syndrome or similar translational disorders. Sequence analysis of the ferroportin gene (SLC11A3) in four individuals with hyperferritinaemia singled out a three base pair deletion in a region that contains four TTG repeats. This mutation removes a TTG unit from 780 to 791, and predicts the loss of one of three sequential valine residues 160-162. Denaturing high performance liquid chromatography can be used for its detection. SLC11A3 polymorphism analysis indicates that this probably represents a recurrent mutation due to slippage mispairing. Affected individuals may show marginally low serum iron and transferrin saturation, and young women may have marginally low haemoglobin concentration levels. Serum ferritin levels are directly related to age, but are 10-20 times higher than normal. Heterozygosity for the ferroportin Val 162 deletion represents the prototype of selective reticuloendothelial iron overload, and should be taken into account in the differential diagnosis of hereditary or congenital hyperferritinaemias.