Haemochromatosis mutations in North-East Scotland

The evolutionary adaptation of the C282Y mutation to culture and climate during the European Neolithic

OBJECTIVES

The C282Y allele is the major cause of hemochromatosis as a result of excessive iron absorption. The mutation arose in continental Europe no earlier than 6,000 years ago, coinciding with the arrival of the Neolithic agricultural revolution. Here we hypothesize that this new Neolithic diet, which originated in the sunny warm and dry climates of the Middle East, was carried by migrating farmers into the chilly and damp environments of Europe where iron is a critical micronutrient for effective thermoregulation. We argue that the C282Y allele was an adaptation to this novel environment.

MATERIALS AND METHODS

To address our hypothesis, we compiled C282Y allele frequencies, known Neolithic sites in Europe and climatic data on temperature and rainfall for statistical analysis.

RESULTS

Our findings indicate that the geographic cline for C282Y frequency in Europe increases as average temperatures decrease below 16°C, a critical threshold for thermoregulation, with rainy days intensifying the trend.

DISCUSSION

The results indicate that the deleterious C282Y allele, responsible for most cases of hemochromatosis, may have evolved as a selective advantage to culture and climate during the European Neolithic.

Dupuytren's Contracture in Alabama HFE Hemochromatosis Probands

BACKGROUND

Dupuytren's contracture (DC) and HFE hemochromatosis occur in some of the same at-risk populations and present with similar comorbid conditions.

METHODS

We estimated DC prevalence in two cohorts of white Alabama hemochromatosis probands (294 C282Y homozygotes, 67 C282Y/H63D compound heterozygotes) in a retrospective study. We performed logistic regressions on DC using the following independent variables: age, body mass index, heavy ethanol consumption, serum ferritin, elevated serum AST/ALT, non-alcoholic fatty liver disease, viral hepatitis, cirrhosis, and diabetes.

RESULTS

One man and two women with C282Y homozygosity had DC (prevalence 1.02%; 95% CI 0.35%-2.96%). A man with C282Y/H63D had DC (prevalence 1.49%; 95% CI 0.26%-7.98%). DC occurred as an autosomal dominant trait in his kinship. In regression analyses, no single variable predicted DC. We observed no new DC cases after the diagnosis of hemochromatosis (mean follow-up 12.9 ± 7.5 years (1 SD), and 9.0 ± 5.1 years, respectively).

CONCLUSIONS

Our prevalence estimates of DC in white Alabama hemochromatosis probands are similar to those found in the white US population cohorts. DC risk was unrelated to the variables we studied.

Prevalence of 845G>A HFE mutation in Slavic populations: an east-west linear gradient in South Slavs

AIM

To compare A allele frequencies of the 845G>A mutation of 10 Slavic populations in central, eastern, and southern Europe between each other and with other European populations.

METHODS

The 845G>A mutation from the DNA of 400 Polish neonates collected in 2005-2006 was analyzed by polymerase chain reaction-restriction fragment length polymorphism. The data were compared with reports from other countries.

RESULTS

We identified 381 GG homozygotes, 18 GA heterozygotes, and 1 AA homozygote. The 845A allele frequency was 2.5%, which makes the summary figure for Poland from this and previous studies 3.5%. The average prevalence for Poland and other West Slavic countries was 3.6%, similar to Russia (inhabited by the East Slavs, 3.5%). The average prevalence in South Slavic countries was 2.2%, gradually decreasing from 3.6% in Slovenia to 0% in Bulgaria, with a longitudinal linear gradient (adjusted R(2)=0.976, P<0.001).

CONCLUSIONS

The West and East Slavs, together with Finland, Estonia, Germany, Austria, Hungary, Slovenia, and Croatia, form a group with 845A allele frequencies between 3% and 4%. In the South Slavs, there is a gradual decline in the prevalence of 845A allele from northwest to southeast, with a surprisingly exact east-west linear gradient.

Analysis of the HFE gene (C282Y, H63D and S65C) mutations in a general Chinese Han population

Hereditary hemochromatosis (HH) is one of the most common autosomal recessive genetic disorders of iron metabolism in white populations, which leads to inappropriately high iron absorption. C282Y, H63D, and S65C are three major missense mutations of the hemochromatosis gene (HFE). In the present study, C282Y, H63D, and S65C mutations in 395 normal Chinese Han populations from Zhejiang province were investigated. No C282Y, S65C mutations, and H63D homozygote was observed, while the genotype frequency of H63D heterozygote was 4.6% and the allelic frequency 2.3% in this population. This was the first report to analyze the prevalence of C282Y, H63D, and S65C mutations in the HFE gene in a Chinese Han population. Low incidence of the HFE gene mutations could be a reason for the rarity of HH in the Chinese Han population studied.

Human leukocyte antigen haplotypes and HFE mutations in Spanish hereditary hemochromatosis and sporadic porphyria cutanea tarda

BACKGROUND AND AIMS

It has been postulated that the HFE C282Y mutation (linked to human leukocyte antigen [HLA]-A3-B7 haplotype) is not only responsible for hereditary hemochromatosis; HLA class I alleles would also contribute to the disease pathogenesis. In addition, H63D mutation linked to HLA-A29-B44 would also be pathogenetic, particularly in the Mediterranean Basin and throughout the world. However, sporadic porphyria cutanea tarda (s-PCT) has also been linked to these HFE mutations. In the present work, we have studied HFE mutations and HLA genes to test these hypotheses.

METHODS

C282Y and H63D mutations together with HLA genetic typing have been performed in Spanish hereditary hemochromatosis (n = 98) and PCT (n = 63) patients. The etiologic fraction (delta) has been used to determine the absolute strongest gene linkage to both diseases.

RESULTS

The Spanish frequent HLA-A29-B44 haplotype is not significantly associated to the H63D mutations in hereditary hemochromatosis patients (although it is found more frequently in patients than in controls). Sporadic porphyria cutanea tarda patients do not show a significant association to H63D mutations, although it is also more frequent than in controls; however, compound H63D/C282Y subjects seem to bear a significant risk to s-PCT. Allelic C282Y (and not H63D) frequencies show a significant association with s-PCT.

CONCLUSIONS

The postulated additional risk of hereditary hemochromatosis given by class I HLA antigens may be secondary to the HFE gene linkage disequilibrium with certain class I alleles or to the existence of other neighboring genetic pathogenetic factors in our Spanish sample.

Haemochromatosis gene mutations and risk of coronary heart disease: a west of Scotland coronary prevention study (WOSCOPS) substudy

OBJECTIVES

To measure the frequency of genotypes of the HFE (haemochromatosis) gene in patients recruited to the west of Scotland coronary prevention study (WOSCOPS), and relate them to the subsequent occurrence of coronary clinical events.

DESIGN

Nested case-control study, drawing samples of DNA from the biological bank of a cohort study.

PATIENTS

Men aged 45-64 years in 1989, with moderate hypercholesterolaemia and no evidence of coronary heart disease at baseline.

INTERVENTIONS

Follow up for a mean period of 4.9 years. Typing for C282Y and H63D mutations of the HFE gene in 482 subjects with a subsequent coronary event and 1104 without an event.

RESULTS

The C282Y mutation was present in 81 of 482 cases (16.8%) and 182 of 1104 controls (16.5%). Comparing the prevalence of gene mutations in the cases and controls, there were no significant differences. The hazard ratio for C282Y heterozygotes was 1.03 (95% confidence interval (CI) 0.77 to 1.36) and for C282Y/H63D compound heterozygotes 1.04 (95% CI 0.50 to 2.14). Prespecified subgroup analyses of the pravastatin, placebo, smoking, and non-smoking groups showed no significant differences between cases and controls. Repeating the analyses after adjusting for possible confounding factors produced no change in the results.

CONCLUSIONS

In a population of moderately hypercholesterolaemic middle aged Scottish men who did not have any evidence of coronary heart disease at baseline, the presence of a C282Y mutation in the HFE gene did not predict the occurrence of coronary events over a mean follow up of 4.9 years.

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

BACKGROUND/AIMS

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The prevalence of haemochromatosis gene mutations in the West of Scotland and their relation to ischaemic heart disease

OBJECTIVES

Excess iron stores have been postulated to enhance the risk of ischaemic heart disease. This study aims to determine whether the two major mutations of the haemochromatosis (HFE) gene (C282Y and H63D) are associated with ischaemic heart disease (IHD) or myocardial infarction (MI).

DESIGN

Cross sectional case-control study.

SETTING

The geographical area studied by the MONICA (monitoring trends and determinants in cardiovascular disease) heart attack register for North Glasgow in Scotland, UK.

PATIENTS

1009 control subjects chosen at random from general practitioner registers were studied. Additionally, 924 subjects who had survived a first MI sustained between 1985 and 1992 were identified from the MONICA register.

MAIN OUTCOME MEASURES

C282Y and H63D mutations, previous MI, and presence or absence of IHD.

RESULTS

Mutant gene prevalences in the whole control population were as follows: C282Y: homozygote 0.9%, heterozygote 17.7%; H63D: homozygote 2.1%, heterozygote 25.5%; and compound heterozygote: 2.4%. Analysis by chi(2) test and logistic regression analysis did not identify any significant difference in genotype prevalence between normal control, IHD control, and MI survivor groups.

CONCLUSIONS

The C282Y homozygote and heterozygote prevalences are among the highest reported worldwide. No association between IHD or MI and HFE genotype was identified. However, these results need to be interpreted in the light of the cross sectional case-control nature of the study.

Evidence that the Cys282Tyr mutation of the HFE gene originated from a population in Southern Scandinavia and spread with the Vikings

Hereditary hemochromatosis has been recognized as a clinical disorder for more than 100 years. The common form of the disorder is caused by the Cys282Tyr mutation (C282Y) of the HFE gene. Hereditary hemochromatosis affects predominantly people of Northern European origin. The C282Y mutation probably occurred on a single chromosome carrying the ancestral hemochromatosis haplotype, which subsequently was spread by emigration and the founder effect. It has been estimated that the C282Y mutation appeared 60-70 generations ago. It was initially suggested that the ancestral C282Y mutation occurred within the Celtic group of peoples. However, we hypothesize that the distribution of the C282Y mutation in Europe is more consistent with an origin among the Germanic Iron Age population in Southern Scandinavia. From this area, the mutation could later be spread by the migratory activities of the Vikings. The aim of the present study was to evaluate the validity of these two hypotheses. Several arguments are in favor of the 'Viking hypothesis': first, the highest frequencies (5.1-9.7%) of the C282Y mutation are observed in populations in the Northern part of Europe, i.e. Denmark, Norway, Sweden, Faeroe Islands, Iceland, Eastern part of England (Danelaw) and the Dublin area, all Viking homelands and settlements. Second, the highest allele frequencies are reported among populations living along the coastlines. Third, the frequencies of the C282Y mutation decline from Northern to Southern Europe. Intermediate allele frequencies (3.1-4.8%) are seen in the populations in Central Europe, which is the original Celtic homeland. Low allele frequencies (0-3.1%) are recognized in populations in Southern Europe and the Mediterranean.

Non-alcoholic steatohepatitis: a common cause of progressive chronic liver injury?

AIM

To investigate the natural history of patients with non-alcoholic steatohepatitis by means of a prospective histological study.

METHODS

One thousand five hundred and seventy one patients underwent liver biopsy at the Western Infirmary in Glasgow during the 10 year period 1985 to 1994. All biopsies were reported by a single pathologist: 62 were confirmed as having non-alcoholic steatohepatitis and prospective follow up was conducted in 1999. Repeat liver biopsy was carried out where appropriate to assess disease progression.

RESULTS

Initial biopsy scores for the 62 patients (20 men; mean age at biopsy, 52 years) showed a mean of 1.85, 1.39, and 0.5 for necroinflammation, fibrosis, and iron stores, respectively. Forty six were traceable and invited for review, and 26 attended (six men; mean age at initial biopsy, 49.9 years) at a mean of 8.7 years after the initial liver biopsy. No patients had symptoms or signs of chronic liver disease. Four patients had normal liver function tests, one had cirrhosis; the remaining 21 were invited to have a repeat biopsy. Seven patients agreed, a mean 8.2 years after the initial biopsy, and repeat biopsy scores showed no significant difference over this time period, with mean scores of 1.71 (initial score, 2.14), 1.43 (initial score, 0.71), and 0.14 (initial score, 0) for necroinflammation, fibrosis, and iron stores, respectively.

CONCLUSION

In this series of patients with non-alcoholic steatohepatitis, with a mean clinical follow up of 8.7 years, and a histological follow up of 8.2 years, there was no evidence of progressive chronic liver injury.

Low penetrant hemochromatosis phenotype in eight families: no evidence of modifiers in the MHC region

The gene responsible for hemochromatosis (HFE) has been identified on the short arm of chromosome 6, 4.5 Mb telomeric to HLA-A. A major mutation C282Y is closely correlated with the disease, as it accounts for 68 to 100\% of the cases of hemochromatosis. Nevertheless, some C282Y homozygotes subjects have no clinical or biological expression of the disease. Moreover, in Northern European populations a large discrepancy is observed between the number of C282Y homozygotes and the number of diagnosed hemochromatosis patients, suggesting incomplete penetrance of the mutation. To localize and identify the modifying genes, we investigated eight families including C282Y homozygous relatives showing no clinical signs of the disease, in addition to the hemochromatosis patients. Genomic DNA from 20 C282Y homozygotes (10 patients and 10 siblings presenting no or minor biological abnormalities) were studied. Five polymorphisms from the HFE gene were determined by PCR restriction. Extended haplotypes of the 6p21.3 region were constructed with 10 microsatellite markers. All the C282Y homozygotes shared the same HFE polymorphism. The haplotypes presented no significant difference between the probands and their unaffected relatives. These studies suggest that neither HFE polymorphism nor genes surrounding HFE are able to modulate HFE expression.

Frequency analysis and allele map in favor of the celtic origin of the C282Y mutation of hemochromatosis

After the main hereditary hemochromatosis mutation C282Y in the HFE gene was described, we report here the C282Y frequencies for various European populations. The aim of this meta-analysis is to compile the Y allele frequencies of the C282Y mutation for 53 European populations, representing a total of 9265 unrelated people representing control samples. The most elevated values are observed in residual Celtic populations in Ireland, in the United Kingdom, and in France, in accordance with the initial hypothesis of Simon et al. (Prog. Med. Genet. 4, 135-168, 1980) concerning a Celtic origin of the hereditary hemochromatosis mutation.

Geography of HFE C282Y and H63D mutations

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.

Transferrin saturation phenotype and HFE genotype screening for hemochromatosis and primary iron overload: predictions from a model based on national, racial, and ethnic group composition in central Alabama

There is interest in general population screening for hemochromatosis and other primary iron overload disorders, although not all persons are at equal risk. We developed a model to estimate the numbers of persons in national, racial, or ethnic population subgroups in Jefferson County, Alabama, who would be detected using transferrin saturation (phenotype) or HFE mutation analysis (genotype) screening. Approximately 62% are Caucasians, 37% are African Americans, and the remainder are Hispanics, Asians, or Native Americans. The predicted phenotype frequencies are greatest in a Caucasian subgroup, ethnicity unspecified, which consists predominantly of persons of Scotch and Irish descent (0.0065 men, 0.0046 women), and in African Americans (0.0089 men, 0.0085 women). Frequencies of the HFE genotype C282Y/C282Y > or = 0.0001 are predicted to occur only among Caucasians; the greatest frequency (0.0080) was predicted to occur in the ethnicity-unspecified Caucasian population. C282Y/C282Y frequency estimates were lower in Italian, Greek, and Jewish subgroups. There is excellent agreement in the numbers of the ethnicity-unspecified Caucasians who would be detected using phenotype and genotype criteria. Our model also indicates that phenotyping would identify more persons with primary iron overload than would genotyping in our Italian Caucasian, Hispanic, and African American subgroups. This is consistent with previous observations that indicate that primary iron overload disorders in persons of southern Italian descent and African Americans are largely attributable to non-HFE alleles. Because the proportions of population subgroups and their genetic constitution may differ significantly in other geographic regions, we suggest that models similar to the present one be constructed to predict optimal screening strategies for primary iron overload disorders.