Comparative study of the two more frequent HFE mutations (C282Y and H63D): significant different allelic frequencies between the North and South of Portugal

An earlier study of reference values of iron parameters in Portugal showed significant differences between populations from northern and southern villages. This study addresses the question of the geographical distribution in Portugal of the two main mutations (C282Y and H63D) of the hereditary hemochromatosis gene, HFE. For that purpose, a stratified sample of 640 anonymous dried blood spot samples was randomly selected from the major regions of Portugal: North, Center, Lisbon and the Tagus Valley, Alentejo and Algarve. Differences in the geographical distribution of these two mutations were observed thus confirming the presumed differences between the age of the two mutations which is compatible with the postulated Celtic/Nordic origin of the C282Y mutation. The finding of a significantly higher allelic frequency of the C282Y mutation in the North (0.058) than in the South (0.009) could also point to an effect of differential selective forces acting in the different geographical areas of the country. Data on archaeological, ethnographic and linguistic records and on the North/South distribution of Portuguese cattle breeds of European or African origin have also been reported. In addition to their interest for population genetics, the results represent a reminder of the need to take into account regional differences in the design of strategies for population screening of hereditary hemochromatosis.

Aspirin intake and the use of serum ferritin as a measure of iron status

BACKGROUND

Atherosclerosis, a primary cause of myocardial infarction (MI), is an inflammatory disease. Aspirin use lowers risk of MI, probably through antithrombotic and antiinflammatory effects. Because serum ferritin (SF) can be elevated spuriously by inflammation, reported associations between elevated SF, used as an indicator of iron stores, and heart disease could be confounded by occult inflammation and aspirin use if they affect SF independently of iron status.

OBJECTIVE

We tested the hypothesis that aspirin use is associated with reduced SF.

DESIGN

We used analysis of covariance to investigate the relation between SF and categories of aspirin use in 913 elderly participants aged 67-96 y in the Framingham Heart Study.

RESULTS

After adjustment for sex, age, body mass index, smoking, alcohol use, concentrations of C-reactive protein and liver enzymes, white blood cell count, and use of nonaspirin nonsteroidal antiinflammatory drugs and other medications, subjects who took >7 aspirins/wk had a significantly lower (by 25%) geometric mean SF than did nonusers, who took <1 aspirin/wk (71 compared with 95 microg/L, respectively; P for trend = 0.004). This effect of aspirin on SF was more marked in diseased subjects than in healthy subjects (mean SF was 50% lower compared with 21% lower, respectively).

CONCLUSIONS

Aspirin use is associated with lower SF. We suggest this effect results from possible increased occult blood loss and a cytokine-mediated effect on SF in subjects with inflammation, infection, or liver disease. The relations between aspirin, inflammation, and SF may confound epidemiologic associations between elevated SF, as an indicator of iron stores, and heart disease risk.

HFE mutations, iron deficiency and overload in 10,500 blood donors

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.

Iron status and HFE genotype in erythrocyte pyruvate kinase deficiency: study of Italian cases

We evaluated the iron status and searched for mutations C282Y and H63D in the hereditary hemochromatosis gene (HFE) in 34 pyruvate kinase (PK)-deficient patients from 29 unrelated families. Nine had received multiple transfusions. Thirteen of the 25 nontransfused patients displayed increased serum ferritin concentration, in the absence of conditions known to raise this parameter. HFE genotype was abnormal in 9 of 34 patients. The allele frequency was 1.8% for mutation 845G--> (C282Y) and 16.1% for mutation 187C-->G (H63D). Nontransfused subjects with abnormal genotype had serum ferritin and transferrin saturation values significantly higher than those with wild-type genotype. Of the 12 adult nontransfused patients with increased iron status parameters, 1 was C282Y homozygous, 1 compound heterozygous for C282Y and H63D, 3 H63D heterozygous, and 7 had a normal HFE genotype. Serum ferritin and transferrin saturation were not related to hemoglobin, reticulocytes, and bilirubin concentration. At multivariate analysis serum ferritin was independently associated with age and gender, but not with splenectomy and HFE genotypes. The retrospective evaluation of the iron status profile of 10 patients (3 with abnormal and 7 with wild-type HFE genotype) with at least 10 years follow-up showed that overt iron accumulation requiring iron chelation had occurred only in the 3 patients (2 of whom were splenectomized) with the mutated HFE gene.

Frequency and biochemical expression of C282Y/H63D hemochromatosis (HFE) gene mutations in the healthy adult population in Italy

BACKGROUND/AIMS

The actual prevalence of the main hemochromatosis (HFE) mutations in the Italian adult population and their phenotypic expression have not yet been established. This information is key to advocate a mass-screening program.

METHODS

Two thousand one hundred adults were tested for the C282Y/H63D HFE gene mutations by an automated genotyping assay as well as transferrin saturation (TS) and serum ferritin levels.

RESULTS

No homozygotes for the C282Y mutation were found. Heterozygosity for the C282Y mutation was 3.1%, while heterozygosity and homozygosity for the H63D mutation were 21.5% and 2.5%, respectively. TS was significantly higher in C282Y heterozygotes and H63D homozygotes as compared to wild-type individuals (P < 0.01). Interestingly, of the HFE wild-type subjects 5.9% had a TS value above the 45% threshold.

CONCLUSIONS

This study shows that (i) the predicted prevalence for C282Y homozygosity in Italy is 1:3900; (ii) the C282Y/H63D wild-type population has an increased baseline of iron parameters possibly due to genetic factors not linked to the C282Y/H63D mutations; (iii) since in the latter population the actual tissue iron burden cannot be assessed, phenotypic (TS) screening in Italy is not recommended until the true prevalence of all mutations in the HFE gene and in other hemochromatosis genes will be established.

Iron status of the free-living, elderly Framingham Heart Study cohort: an iron-replete population with a high prevalence of elevated iron stores

BACKGROUND

Although iron deficiency occurs commonly in vulnerable groups of women of reproductive age, infants, and children, less is known about the iron nutriture of the elderly.

OBJECTIVE

Our objective was to evaluate the iron status of a noninstitutionalized, elderly US population, with a particular focus on 2 concerns unique to the elderly: 1) potential confounding effects of chronic disease on iron measures and 2) increased occurrence of elevated iron stores.

DESIGN

Multiple iron measures, including serum ferritin (SF), transferrin saturation, mean cell volume, and hemoglobin, were used to evaluate the prevalence of iron deficiency (ID), iron deficiency anemia (IDA), and other measures of iron nutriture in 1016 elderly white Americans aged 67-96 y from the Framingham Heart Study. "Diseased" subjects were defined as those with possible pathologically altered iron measures due to inflammation, infection, elevated liver enzymes, hereditary hemochromatosis, or cancer. The effect of altered iron status on various prevalence estimates was assessed.

RESULTS

The elderly subjects had a low prevalence of ID (2.7%), IDA (1.2%), and depleted iron stores (3%; SF < 12 microg/L). In contrast, 12.9% had elevated iron stores (SF > 300 microg/L in men and SF > 200 microg/L in women), of which only 1% was attributable to chronic disease. The prevalence of ID, IDA, and depleted iron stores was unaffected by the presence of chronic disease.

CONCLUSIONS

The Framingham Heart Study cohort is an iron-replete elderly population with a high prevalence of elevated iron stores in contrast with a low prevalence of iron deficiency, with insignificant effects of chronic disease on these iron status estimates. The likely liability in iron nutriture in free-living, elderly white Americans eating a Western diet is high iron stores, not iron deficiency.

Celtic origin of the C282Y mutation of hemochromatosis

The main hereditary hemochromatosis mutation C282Y in the HFE gene was recently described, and the C282Y frequencies were reported for various European populations. The aim of this synthesis is to compile the Y allele frequencies of the C282Y mutation for 40 European populations. The most elevated values are observed in residual Celtic populations in Ireland, the United Kingdom, and France, in accordance with the hypothesis of Simon et al. (1980) concerning a Celtic origin of the hereditary hemochromatosis mutation.

Population screening in hereditary hemochromatosis

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.

Early detection of genetic hemochromatosis: should all young adults be offered the genetic test?

Genetic hemochromatosis (GH) is a late-onset, autosomal recessive disorder. The majority of those at risk from iron overload and its clinical consequences may be detected by a simple genetic test. Furthermore, treatment by phlebotomy, if instituted early, removes excess iron and prevents the complications of iron overload which include arthralgia, diabetes, and cirrhosis of the liver. GH seems to be an obvious candidate for inclusion in national screening programs. However, important questions remain concerning the proportion of individuals with the high-risk genotype who eventually show clinical manifestations of iron overload and the significance of heterozygosity for haemochromatosis in terms of morbidity. Until these questions are resolved, the introduction of widespread genetic screening cannot be justified.

Genotype Screening for Hereditary Hemochromatosis among Voluntary Blood Donors in Hungary

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.

Biochemical expression of heterozygous hereditary hemochromatosis

Background: Hereditary hemochromatosis (HH) is a common autosomal recessive disease caused by an iron overload. Two mutations (C282Y and H63D) on the responsible HFE gene have been described. HH heterozygotes may have a slight iron overload that does not cause clinical disease. Compound heterozygosity may be associated with higher iron stores than C282Y heterozygosity. We studied biochemical iron parameters in HH C282Y and compound heterozygotes without a clinically significant iron overload. Methods: Data on hemoglobin, hematocrit, mean corpuscular volume, serum ferritin, serum iron, transferrin, and transferrin saturation were obtained from 40 C282 wild type controls (irrespective of H63D genotype), 61 C282Y heterozygotes, and 18 compound (C282Y/H63D) heterozygotes without clinical iron overload disease. Results: Serum ferritin levels were significantly higher in female HH heterozygotes, particularly in compound heterozygotes, than in normal women. In male heterozygotes, no difference in serum ferritin was found. We found higher mean serum iron and transferrin saturation levels in male and female HH heterozygotes than in normal controls, the highest in the group of compound heterozygotes. Conclusions: Mean serum ferritin (only in women), serum iron, and transferrin saturation are highest in compound heterozygotes and lowest in controls. C282Y heterozygotes seem to be an intermediate group between compound heterozygotes and the normal population.

Co-inheritance of mutations in the uroporphyrinogen decarboxylase and hemochromatosis genes accelerates the onset of porphyria cutanea tarda

Porphyria cutanea tarda is a skin disease caused by photosensitization by porphyrins whose accumulation is caused by deficiency of hepatic uroporphyrin- ogen decarboxylase activity. Mutations in the uroporphyrinogen decarboxylase gene are present in the low-penetrant, autosomal dominant familial form but not in the commoner sporadic form of porphyria cutanea tarda. We have investigated the relationship between age of onset of skin lesions and mutations (C282Y, H63D) in the hemochromatosis gene in familial (19 patients) and sporadic porphyria cutanea tarda (65 patients). Familial porphyria cutanea tarda was identified by mutational analysis of the uroporphyrinogen decarboxylase gene. Five previously described and eight novel mutations (A80S, R144P, L216Q, E218K, L282R, G303S, 402-403delGT, IVS2 + 2 delTAA) were identified. Homozygosity for the C282Y hemochromatosis mutation was associated with an earlier onset of skin lesions in both familial and sporadic porphyria cutanea tarda, the effect being more marked in familial porphyria cutanea tarda where anticipation was demonstrated in family studies. Analysis of the frequencies of hemochromatosis genotypes in each type of porphyria cutanea tarda indicated that C282Y homozygosity is an important susceptibility factor in both types but suggested that heterozygosity for this mutation has much less effect on the development of the disease.

Prevalence of the C282Y mutation for haemochromatosis on the Island of Majorca

The C282Y mutation of the HFE gene has been reported to be present in most of the patients with hereditary haemochromatosis (HH) of Northern European ancestry. HH affects approximately 1/300 individuals, but it is not evenly distributed in the different European countries. In the present study, polymerase chain reaction (PCR) and restriction-enzyme digestion were used to analyse the frequency of the most important mutation in haemochromatosis (C282Y) in subjects from Majorca (Balearic Islands, Spain) and patients with haemochromatosis. The results were compared with other studies from Spain and Europe. A total of 420 Majorcan chromosomes were analysed and the C282Y mutation was observed at a frequency of 2.62%+/-0.8 (11 heterozygotes: eight men and three women). In the group of hereditary haemochromatosis probands, 13 out of 14 were homozygous for the C282Y mutation. In the distribution of the C282Y mutation, a north-west to south-east cline was detected, supporting the Celtic origin of this mutation.

Are hereditary hemochromatosis mutations involved in Alzheimer disease?

Mutations in the class I-like major histocompatibility complex gene called HFE are associated with hereditary hemochromatosis (HHC), a disorder of excessive iron uptake. We screened DNA samples from patients with familial Alzheimer disease (FAD) (n = 26), adults with Down syndrome (DS) (n = 50), and older (n = 41) and younger (n = 52) healthy normal individuals, for two HHC point mutations-C282Y and H63D. Because the apolipoprotein E (ApoE) E4 allele is a risk factor for AD and possibly also for dementia of the AD type in DS, DNA samples were also ApoE genotyped. Chi-squared analyses were interpreted at the 0.05 level of significance without Bonferroni corrections. In the pooled healthy normal individuals, C282Y was negatively associated with ApoE E4, an effect also apparent in individuals with DS but not with FAD. Relative to older normals, ApoE E4 was overrepresented in both males and females with FAD, consistent with ApoE E4 being a risk factor for AD; HFE mutations were overrepresented in males and underrepresented in females with FAD. Strong gender effects on the distribution of HFE mutations were apparent in comparisons among ApoE E4 negative individuals in the FAD and healthy normal groups (P < 0.002). Our findings are consistent with the proposition that among ApoE E4 negative individuals HFE mutations are predisposing to FAD in males but are somewhat protective in females. Further, ApoE E4 effects in our FAD group are strongest in females lacking HFE mutations. Relative to younger normals there was a tendency for ApoE E4 and H63D to be overrepresented in males and underrepresented in females with DS. The possibility that HFE mutations are important new genetic risk factors for AD should be pursued further.

Effects of HFE C282Y and H63D polymorphisms and polygenic background on iron stores in a large community sample of twins

The aim of this study was to assess and to compare the role of HFE polymorphisms and other genetic factors in variation in iron stores. Blood samples were obtained from 3,375 adult male and female twins (age range 29-82 years) recruited from the Australian Twin Registry. There were 1,233 complete pairs (562 monozygotic and 571 dizygotic twins). Serum iron, transferrin, transferrin saturation with iron, and ferritin were measured, and the HFE C282Y and H63D genotypes were determined. The frequency of the C282Y allele was.072, and that of the H63D allele was.141. Significant sources of variation in the indices of iron status included age, sex, age-sex interaction, body-mass index, and both the C282Y and H63D genotypes. The iron, transferrin, and saturation values of CC and CY subjects differed significantly, but the ferritin values did not. After correction for age and body-mass index, 23% and 31% of the variance in iron, 66% and 49% of the variance in transferrin, 33% and 47% of the variance in transferrin saturation, and 47% and 47% of the variance in ferritin could be explained by additive genetic factors, for men and women, respectively. HFE C282Y and H63D variation accounted for <5% of the corrected phenotypic variance, except for saturation (12% in women and 5% in men). We conclude that HFE CY and HD heterozygotes differ in iron status from the CC and HH homozygotes and that serum transferrin saturation is more affected than is serum ferritin. There are highly significant effects of other as-yet-unidentified genes on iron stores, in addition to HFE genotype.

Compound Heterozygous Hemochromatosis Genotype Predicts Increased Iron and Erythrocyte Indices in Women

Background: Women who inherit heterozygosity for the C282Y mutation of the HFE gene may have increased serum iron indices and hemoglobin and are less likely to develop iron deficiency compared with women with the wild-type genotype.

Methods: We performed a cross-sectional analysis of 497 women 20–44 years of age and 830 women &gt;51 years of age drawn from the Busselton (Australia) population study to assess the effects of the HFE genotype on serum iron and hematology indices.

Results: Heterozygosity for the C282Y mutation occurred in 13.8% of the study population, comprising 11.8% C282Y wild-type heterozygotes and 2.0% C282Y/H63D compound heterozygotes. In the younger age group, C282Y wild-type women did not have significantly increased serum iron, transferrin saturation, or hemoglobin values, and were not protected from developing iron deficiency, compared with women of the same age with the wild-type genotype. Young compound heterozygous women had higher means for serum iron (25.0 vs 16.9 μmol/L; P &lt;0.001), transferrin saturation (42.0% vs 25.6%; P &lt;0.05), hemoglobin (139.4 vs 132.3 g/L; P &lt;0.05), and corpuscular volume (91.1 vs 87.7 fL; P &lt;0.05), and a higher median ferritin (53 vs 44 μg/L; P &lt;0.05) compared with the wild-type genotype. Similar results were observed for compound heterozygotes in the &gt;51 years age group.

Conclusions: Women with the compound heterozygous HFE genotype C282Y/H63D, but not the C282Y wild-type genotype, had increased values for serum iron and transferrin saturation, and the younger age group also had increased hemoglobin values. We conclude that the compound heterozygous genotype may have a beneficial effect in protecting women from iron deficiency.

A study of the iron and HFE status of blood donors, including a group who failed the initial screen for anaemia

A complete data set (age, weight, diet and recent donation history; venous blood cell count, serum ferritin and soluble transferrin receptor concentrations and transferrin saturation; HFE genotype) was obtained from 113 male and 122 female blood donors. Progressive iron depletion and deficiency - most apparent from serum concentrations of soluble transferrin receptor divided by the logarithm of ferritin concentrations (the TfR-F index) - developed in men donating up to six times in 2 years, although the serum ferritin alone was also informative; however, no prediction could be made for those iron-depleted individuals who will develop iron deficiency after donation. Iron stores in the groups of donors with 'low-normal' haemoglobin (Hb) concentrations were indistinguishable from those in donors with higher Hb values, whereas donors failing the anaemia screen had reduced stores. This supports the UK policy of accepting donations from people whose Hb concentration is up to 0. 5 g/dl below the recommended European threshold. Women eating red meat once a week sustained higher ferritin concentrations, and the iron status of first-time women donors resembled that of men donating twice each year. Homozygosity for either HFE variant allowed greater iron retention in the face of regular donation, but among heterozygotes the findings were inconclusive.