Prevalence of hemochromatosis among first-time and repeat blood donors in Norway

Is blood of uncomplicated hemochromatosis patients safe and effective for blood transfusion? A systematic review

Hemochromatosis is a disorder of the iron metabolism, characterized by high body iron content, necessitating frequent phlebotomies to remove excess iron. In some countries, this blood is discarded and not used for blood transfusion because of the non-voluntary character of this donation, and because a potential risk of microbial contamination of the donor blood is assumed. A systematic review was performed in order to collect and critically examine solid evidence with regard to the effectiveness and safety of blood for transfusion when derived from hemochromatosis patients who do not suffer from complications or organ damage. Using three databases (The Cochrane Library, MEDLINE, and Embase) we searched for studies from date of inception until January 2012. Out of 3470 articles, 80 references that were relevant to our question were selected, including many opinion pieces, comments, letters, and narrative reviews. Based on our selection criteria, we finally retained only six observational studies, so evidence on this subject is scarce and furthermore, the strength of the available evidence is low to very low, due to poor study designs. We found no evidence that red blood cell concentrates from hemochromatosis patients without complications of iron overload do not comply with the physiological quality requirements for transfusion, nor that their blood would present a greater risk to recipient safety than blood from non-hemochromatosis donors. However, in vitro findings from two studies suggest that iron-overloaded patients would be more susceptible to bacterial growth, but future in vivo studies are warranted to confirm this. Based on this, we call for harmonization of the blood donor selection policy among countries allowing hemochromatosis patients who do not suffer from complications of iron overload to donate blood, once iron levels are normalized.

Low prevalence of hereditary hemochromatosis in multiethnic populations in Northern Norway

OBJECTIVE

Hereditary hemochromatosis has an autosomal recessive inheritance. The C282Y homozygosity is the most common genetic mutation in persons of Northern European descent. A screen of two multiethnic populations in Northern Norway was performed to investigate whether the prevalence of hereditary hemochromatosis was consistent with previous results in Northern Europe.

MATERIAL AND METHODS

Participants in two population-based studies in Northern Norway were analyzed for serum ferritin (s-ferritin) and transferrin saturation. Participants with s-ferritin or transferrin saturation above the reference limits in two separate blood samples were tested for three different HFE mutations, namely C282Y, H63D and S65.

RESULTS

The estimated prevalence of the C282Y/C282Y mutation in the two municipalities studied was lower than in comparable studies in Norway. The prevalence was the lowest in the Sør-Varanger population (men 0.19% and women 0.22%), which also had the highest proportion of individuals with Sami and Kven affiliation. In Tromsø, the prevalence was consistent with previous results in Norway.

CONCLUSIONS

The prevalence of hereditary hemochromatosis is lower in multiethnic populations in Northern Norway than in previous studies from other parts of Norway.

Was the C282Y mutation an Irish Gaelic mutation that the Vikings helped disseminate? HLA haplotype observations of hemochromatosis from the west coast of Sweden

The HLA-related hemochromatosis mutation C282Y is thought to have originated in Ireland in a person with HLA-A3-B14 and was spread by Vikings. Irish people with two HLA-A3 alleles had a high risk of hemochromatosis. In this study, from west Sweden, we wanted to test these hypotheses.

METHODS

HFE mutations in controls, bone marrow donors with HLA-A3/A3 and patients with hemochromatosis. HLA haplotypes, extended haplotype analysis and pedigree studies.

RESULTS

The allelic C282Y frequency 0.04, (CI 0.01-0.07) was lower (P < 0.001) in Sweden than in Ireland 0.10 (CI 0.08-0.11), and Swedish bone marrow donors with HLA-A3/A3 (n = 77) had a low risk of hemochromatosis. HLA haplotypes available from 239/262 (91.5%) proband patients homozygous for C282Y showed a dominance of A3-B7 and A3-B14 both in linkage disequilibrium with controls (P < 0.001). Pedigree studies extended into the 17th century supported a local founder effect of A3-B14 in the county of Bohuslän. The A3-B14 haplotype may well be the original and A3-B7 the result of centromeric recombinations. The haplotype diversity and recombination events were not different from a Celtic series. These findings do not support the hypothesis of the C282Y mutation being of an Irish Celtic origin.

CONCLUSIONS

The C282Y frequency shows a west to east decline from Ireland through the north of Europe. Vikings may have been involved in the spread of C282Y, but the mutation is probably older and may have been spread in Europe by earlier seafarers.

Frequency of the HFE C282Y and H63D mutations in Danish patients with clinical haemochromatosis initially diagnosed by phenotypic methods

AIM

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.

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.

RESULTS

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.

CONCLUSION

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.

Frequencies of the hereditary hemochromatosis allele in different populations. Comparison of previous phenotypic methods and novel genotypic methods

AIM

The frequencies of the hereditary hemochromatosis allele were compared for different populations assessed by previous phenotypic methods and the present genotypic methods.

METHODS

From a literature survey, the calculated hemochromatosis allele frequencies from 16 studies using phenotypic biochemical markers (threshold levels for transferrin saturation [range, 46%-70%] and serum ferritin [range, 164-700 microg/L]) were compared with allele frequencies of the Cys282Tyr mutation of the hemochromatosis gene reported in 19 genotypic studies.

RESULTS

Calculated phenotypic allele frequencies are high in Scandinavia: Iceland, 6.1% to 7.4%; Norway, 5.8%; central Sweden, 6.3% to 6.9%; Denmark, 6.1%. Frequencies are similarly high in Wales, Canada, Utah, South Africa, and Australia (range, 5.2%-9.8%). Frequencies are low in Finland (1.9%) and northern Italy (4.5%). Genotypic allele frequencies of the Cys282Tyr mutation are likewise high in Scandinavia. Frequencies are high in the United Kingdom and northern France and low in Finland, central Germany, northern Italy, and Greece. The phenotypic-genotypic ratios of the hemochromatosis homozygosity frequencies for the same geographic area were calculated. A ratio of 1.0 indicates that the 2 methods give similar results. In 3 studies, the ratio was above 1.0, the highest ratio of 1.67 being reported from Italy. In most studies the ratio was slightly below 1.0 (0.71-0.97). The lowest ratio was found in Finland (0.33).

CONCLUSION

In most studies there was good agreement between the hemochromatosis allele frequencies determined by phenotypic and genotypic methods. A high ratio (northern Italy) may indicate that phenotypic selection criteria were too loose and/or that causes of iron overload other than the Cys282Tyr mutation are frequent in the region. A low ratio (in Finland) may indicate phenotypic selection criteria that were too stringent and/or a low penetration rate of the mutation.

Screening for hemochromatosis: high prevalence and low morbidity in an unselected population of 65,238 persons

BACKGROUND

Hereditary hemochromatosis (HH) is a common genetic disease leading to accumulation of iron in several organs, most notably the liver. The C282Y/C282Y mutation in the HFE gene is found in most cases. In order to prevent clinical disease and to study the cost and feasibility of screening, a large population was screened.

METHODS

In a Norwegian county, all inhabitants 20 years or older were invited to participate in a population-based health survey programme. Screening for HH was one of several subprojects. Blood samples were obtained from 65,238 persons. Subjects with high serum transferrin saturation in two tests and high serum ferritin were clinically evaluated for HH. All subjects with high serum transferrin saturation in two tests were offered genotyping.

RESULTS

HH was newly diagnosed in 92 women and 177 men. Phlebotomy treatment was performed in 64 women and 152 men. Severe organ damage (liver cirrhosis) was ascertained in only 4 men. We found no correlation between serum ferritin and age. The estimated cost was US$ 1.6 per subject screened and US$ 390 per newly discovered HH subject. The estimated prevalence of phenotypical HH not previously known was 0.34% in women and 0.68% in men. The prevalence of the C282Y/C282Y mutation was at least 0.68%.

CONCLUSION

Large-scale screening for HH can be performed at a relatively low cost if combined with a health survey programme. The yield in terms of newly discovered cases is considerable, but few cases were found seriously ill. Better knowledge of the natural course of HH is necessary if we are to be able to estimate the cost-effectiveness of large-scale screening.

The roles of iron in health and disease

Iron is vital for almost all living organisms by participating in a wide variety of metabolic processes, including oxygen transport, DNA synthesis, and electron transport. However, iron concentrations in body tissues must be tightly regulated because excessive iron leads to tissue damage, as a result of formation of free radicals. Disorders of iron metabolism are among the most common diseases of humans and encompass a broad spectrum of diseases with diverse clinical manifestations, ranging from anemia to iron overload and, possibly, to neurodegenerative diseases. The molecular understanding of iron regulation in the body is critical in identifying the underlying causes for each disease and in providing proper diagnosis and treatments. Recent advances in genetics, molecular biology and biochemistry of iron metabolism have assisted in elucidating the molecular mechanisms of iron homeostasis. The coordinate control of iron uptake and storage is tightly regulated by the feedback system of iron responsive element-containing gene products and iron regulatory proteins that modulate the expression levels of the genes involved in iron metabolism. Recent identification and characterization of the hemochromatosis protein HFE, the iron importer Nramp2, the iron exporter ferroportin1, and the second transferrin-binding and -transport protein transferrin receptor 2, have demonstrated their important roles in maintaining body's iron homeostasis. Functional studies of these gene products have expanded our knowledge at the molecular level about the pathways of iron metabolism and have provided valuable insight into the defects of iron metabolism disorders. In addition, a variety of animal models have implemented the identification of many genetic defects that lead to abnormal iron homeostasis and have provided crucial clinical information about the pathophysiology of iron disorders. In this review, we discuss the latest progress in studies of iron metabolism and our current understanding of the molecular mechanisms of iron absorption, transport, utilization, and storage. Finally, we will discuss the clinical presentations of iron metabolism disorders, including secondary iron disorders that are either associated with or the result of abnormal iron accumulation.

The clinical expression of hemochromatosis in Oslo, Norway. Excessive oral iron intake may lead to secondary hemochromatosis even in HFE C282Y mutation negative subjects

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

High prevalence of the hemochromatosis-associated Cys282Tyr HFE gene mutation in a healthy Norwegian population in the city of Oslo, and its phenotypic expression

BACKGROUND

Previous studies have shown that 5%-10% of white subjects are heterozygous for the HFE gene C282Y mutation, which is associated with hemochromatosis. The aim of our study was to determine the prevalence of heterozygosity and homozygosity for the C282Y HFE gene mutation and its phenotypic expression in a group of healthy Norwegians.

METHODS

Fasting blood samples were obtained from 505 unrelated hospital employees. Serum iron, transferrin, and serum ferritin were measured. Transferrin saturation was calculated. The presence of HFE gene mutation was determined with a polymerase chain reaction-based analysis.

RESULTS

Two of the 505 subjects (0.4%) were homozygous and 75 (14.9%) were heterozygous for the C282Y mutation. Median serum ferritin among the heterozygotes was 59 microg/l, compared with 47 microg/l among individuals without the C282Y mutation (P = 0.12). Median transferrin saturation among the heterozygotes was 31%, compared with 24% among individuals without C282Y mutation (P < 0.001). Twenty-three individuals (4.6%) had a serum ferritin level > 200 microg/l. Eight of these (35%) had the C282Y mutation: two homozygotes and six heterozygotes. Transferrin saturation > 50% was observed in 25 individuals (5.0%). Twelve of these (48%) had the C282Y mutation; two were homozygotes and 10 heterozygotes. Only eight individuals (1.6%) had a transferrin saturation > 60%: one homozygote, five heterozygotes, and two individuals without mutation.

CONCLUSIONS

Fifteen per cent of a healthy Norwegian population is heterozygous for the HFE gene mutation C282Y. This is among the highest reported prevalence values among healthy individuals. Half of the subjects with transferrin saturation greater than 50% were carriers of the C282Y mutation.

HFE mutations in patients with hereditary haemochromatosis in Sweden

OBJECTIVE

To determine the frequency of mutations (C282Y and H63D) in a newly identified gene HFE in patients with hereditary haemochromatosis (HH) in Sweden.

DESIGN

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.

SETTINGS

Patients with HH treated with phlebotomies at Karolinska Hospital and Huddinge Hospital were analyzed.

SUBJECTS

Eighty-seven unrelated patients with HH and 117 healthy controls.

RESULTS

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.

CONCLUSIONS

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.