Analysis of Genes Involved in Oxidative Stress and Iron Metabolism in Heart Failure: A Step Forward in Risk Stratification

INTRODUCTION

Heart failure (HF) is a clinical syndrome characterized by cardinal symptoms that may be accompanied by signs. It results from structural and/or functional abnormalities of the heart leading to elevated intracardiac pressures and/or inadequate cardiac output at rest and/or during exercise. The prevalence of iron deficiency and anemia justifies the current guidelines recommendation of screening. Genes HP, ACE, MTHFR, HFE, and CYBA are involved in oxidative mechanisms, iron metabolism, and hematologic homeostasis. This study investigates the contribution of variants Hp1/2 (HP), I/D (ACE), C677T (MTHFR), C282Y and H63D (HFE), and C242T (CYBA) to the development of HF, either independently or in epistasis.

METHODS

We used a database of 389 individuals, 143 HF patients, and 246 healthy controls. Genotypes were characterized through PAGE electrophoresis, PCR, PCR-RFLP, and multiplex-ARMS. Data analysis was performed with the SPSS® 26.0 software (IBM Corp., Armonk, NY).

RESULTS

We observed a significant association between the MTHFR gene and HF predisposition. The presence of allele T and genotype CT constituted risk, while genotype CC granted protection. Epistatic interactions revealed risk between genotype II of the ACE gene and genotypes CC (C282Y) or HH (H63D) of the HFE gene. Risk was also observed for interactions between genotype CC (CYBA)and genotypes 2-2 (HP), CT (MTHFR), or HH (HFE-H63D).

CONCLUSION

We concluded that genes HP, ACE, MTHFR, HFE, and CYBA contribute to the susceptibility for HF, individually or in epistasis. This study contributes to the clarification of the role that genes involved in oxidative mechanisms and iron metabolism play in the physiopathology of HF. It is, therefore, a step forward in risk stratification and personalized medicine.

A prospective cohort examination of haematological parameters in relation to cancer death and incidence: the Busselton Health Study

BACKGROUND

Cancer risk is associated with serum iron levels. The aim of this study was to evaluate whether haematological parameters reflect serum iron levels and may also be associated with cancer risk.

METHODS

We studied 1564 men and 1769 women who were enrolled in the Busselton Health Study, Western Australia. Haematological parameters evaluated included haemoglobin (Hb), mean cell volume (MCV), mean cell haemoglobin (MCH) and mean cell haemoglobin concentration (MCHC) and red cell distribution width (RCDW). Statistical analyses included t-tests for quantitative variables, chi-square tests for categorical variables and Cox proportional hazards regression modelling for cancer incidence and death.

RESULTS

There was marginal evidence of an association between MCV (as a continuous variable) and non-skin cancer incidence in women (HR 1.15, 95% CI 1.013, 1.302; p = 0.030) but the hazard ratio was attenuated to non-significance after adjustment for serum ferritin (SF), iron and transferrin saturation (TS) (HR 1.11, 95% CI 0.972, 1.264; p = 0.126). There was strong evidence of an association between MCHC and prostate cancer incidence in men; the estimated hazard ratio for an increase of one SD (0.5) in MCHC was 1.27 (95% CI 1.064, 1.507; p = 0.008). These results remained significant after further adjustment for SF and iron; the estimated hazard ratio for an increase of one SD (0.5) in MCHC was 1.25 (p = 0.014, 95% CI 1.05 to 1.48).

CONCLUSIONS

The MCHC and MCV were associated with cancer incidence in a Western Australian population, although only MCHC remained associated with prostate cancer after adjusting with serum iron and TS (circulating iron) and SF (storage iron). Haematological parameters are thus of limited utility in population profiling for future cancer risk.

Genome-wide compound heterozygosity analysis highlighted 4 novel susceptibility loci for congenital heart disease in Chinese population

Genome-wide association studies (GWASs) have achieved great success in deciphering the genetic cause of congenital heart disease (CHD). However, the heritability of CHD remains to be clarified, and numerous genetic factors responsible for occurrence of CHD are yet unclear. In this study, we performed a genome-wide search for relaxed forms of compound heterozygosity (CH) in association with CHD using our existing GWAS data including 2265 individuals (957 CHD cases and 1308 controls). CollapsABEL was used to iteratively test the association between the CH genotype and the CHD phenotype in a sliding window manner. We highlighted 17 genetic loci showing suggestive CH-like associations with CHD (P < 5 × 10^-8 ), among which 4 genetic loci had expression quantitative trait loci (eQTL) effects in blood (P_eQTL  < 0.01). After conditional association analysis, each loci had only 1 independently effective signal reaching the significance threshold (rs2071477/rs3129299 at 6p21.32, P = 2.47 × 10^-10 ; rs10773097/rs2880921 at 12q24.31, P = 3.30 × 10^-8 ; rs73032040/rs7259476 at 19q13.11, P = 1.14 × 10^-8 ; rs10416386/rs4239517 at 19q13.31, P = 1.15 × 10^-9 ), together explained 7.83% of the CHD variance. Among these 4 associated loci, outstanding candidates for CHD-associated genes included UBC, CFM2, ZNF302, LYPD3 and CADM4. Although replication studies with larger sample size are warranted, the first CH GWAS of CHD may extend our current knowledge of the genetic contributions to CHD in the Han Chinese population.

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.

Primary neuroendocrine tumor (carcinoid tumor) of the testis: a case report with review of literature

BACKGROUND

The term carcinoid (Karzinoide) was coined by German pathologist Oberndorfer in 1907. Primary testicular carcinoid tumors (TCT) are rare, constituting 0.23% of all testicular tumors. In this report we describe a case of primary TCT of the testis and present the results of an extensive literature review to cover all the aspects of carcinoid tumor, including the definition, classification, origin, presentation, diagnostic evaluation, management, prognosis, and follow-up.

CASE REPORT

A 34-year-old male presented with chronic right scrotal swelling with recent onset of pain. Radical orchiectomy revealed a solid intratesticular tumor confined to the testis and epididymis, without lymphovascular invasion. Histology was consistent with neuroendocrine carcinoma. The tumor was staged as pT1 N0 M0 S2. Immunohistochemistry was positive for neuroendocrine markers. An extratesticular carcinoid tumor was ruled out. Urinary excretion of 5-hydroxyindoleacetic acid and Chromogranin A were within normal range.

CONCLUSIONS

It is important to follow serotonin levels since the elevated levels of serotonin can cause carcinoid heart disease. If metastatic lesions are not accessible for resection, a trial of octreotide therapy can be given. This case also adds to the rare reports in the literature of primary carcinoid tumors of the testis having low malignant potential. The literature review highlights new diagnostic and therapeutic interventions and stresses the importance of long-term follow-up due to evidence of delayed metastasis or recurrences and also due to emergence of new complications as a result of improved prognosis and prolonged survival.

Natural history of HFE simple heterozygosity for C282Y and H63D: a prospective 12-year study

BACKGROUND AND AIM

The risk of hemochromatosis-related morbidity for HFE simple heterozygosity for either the C282Y or H63D substitutions in the HFE protein was assessed using a prospective community-based cohort study.

METHODS

HFE genotypes were measured for 31,192 persons of northern European descent, aged between 40 and 69 years when recruited to the Melbourne Collaborative Cohort Study, and subjects were followed for an average of 12 years. For a random sample of 1438 participants stratified according to HFE genotype, two sets of biochemical iron indices performed 12 years apart and, at follow-up only, the presence/absence of six disease features associated with hereditary hemochromatosis were obtained. Summary data for 257 (139 female) C282Y simple heterozygotes and 123 (74 female) H63D simple heterozygotes were compared with 330 (181 female) controls with neither HFE mutation.

RESULTS

At baseline, mean transferrin saturation (TS) (95% confidence interval) and prevalence of TS > 55% were 35.14% (33.25, 37.04) and 3/112 (3%), 33.03% (29.9, 36.15) and 0/39 (0%), and 29.67% (27.93, 31.4) and 3/135 (2%) for C282Y, H63D and wild-type male participants, respectively. At follow-up, mean TS levels remained similar to baseline levels for both men and women irrespective of simple heterozygosity for either mutation. No HFE C282Y or H63D simple heterozygotes had documented iron overload (based on hepatic iron measures or serum ferritin greater than 1000 mg/L at baseline with documented therapeutic venesection).

CONCLUSION

No documented iron overload was observed for HFE simple heterozygotes for either C282Y or H63D, and morbidity for both HFE simple heterozygote groups was similar to that of HFE wild-type participants.

Screening for hereditary haemochromatosis

Hereditary haemochromatosis (HH) is a common autosomal recessive disorder of iron overload in Caucasian populations. Clinical manifestations usually occur in individuals homozygous for the C282Y mutation in the HFE gene product and who have developed significant iron loading. Current screening methods can detect affected individuals either prior to or early during disease evolution, enabling early introduction of phlebotomy treatment that can normalise life expectancy. Evaluation of possible iron overload, via measurement of serum transferrin saturation and ferritin level, is the most appropriate initial test for those subjects presenting clinically for evaluation. HFE genotyping, when combined with serum biochemical measurements, defines the presence of likely iron overload and the underlying genetic disorder and is the preferred initial screening modality for families of an affected individual. Definitive proof of iron overload requires measurement of hepatic iron concentration or total iron burden via therapeutic phlebotomy; elevated serum ferritin level alone is not adequate. We now recognise that the natural history of HH is not as discrete as previously believed, because genetic and environmental modifiers of disease penetrance are increasingly identified as influencing the clinical expression of HH. In fact, a minority of C282Y homozygotes develop classical 'iron overload disease', although it has recently emerged that the disorder may predispose to breast and colorectal cancer. Uncertainties as to the true clinical impact of the condition at a population level lead to current recommendations of cascade screening of families of affected patients, case-finding in high-risk groups, such as patients with clinical manifestations consistent with the diagnosis, and a high level of clinical awareness in the community to facilitate early diagnosis. Generalised population screening is not presently recommended.

Four variants in transferrin and HFE genes as potential markers of iron deficiency anaemia risk: an association study in menstruating women

BACKGROUND

Iron deficiency anaemia is a worldwide health problem in which environmental, physiologic and genetic factors play important roles. The associations between iron status biomarkers and single nucleotide polymorphisms (SNPs) known to be related to iron metabolism were studied in menstruating women.

METHODS

A group of 270 Caucasian menstruating women, a population group at risk of iron deficiency anaemia, participated in the study. Haematological and biochemical parameters were analysed and 10 selected SNPs were genotyped by minisequencing assay. The associations between genetic and biochemical data were analysed by Bayesian Model Averaging (BMA) test and decision trees. Dietary intake of a representative subgroup of these volunteers (n = 141) was assessed, and the relationship between nutrients and iron biomarkers was also determined by linear regression.

RESULTS

Four variants, two in the transferrin gene (rs3811647, rs1799852) and two in the HFE gene (C282Y, H63D), explain 35% of the genetic variation or heritability of serum transferrin in menstruating women. The minor allele of rs3811647 was associated with higher serum transferrin levels and lower transferrin saturation, while the minor alleles of rs1799852 and the C282Y and H63D mutations of HFE were associated with lower serum transferrin levels. No association between nutrient intake and iron biomarkers was found.

CONCLUSIONS

In contrast to dietary intake, these four SNPs are strongly associated with serum transferrin. Carriers of the minor allele of rs3811647 present a reduction in iron transport to tissues, which might indicate higher iron deficiency anaemia risk, although the simultaneous presence of the minor allele of rs1799852 and HFE mutations appear to have compensatory effects. Therefore, it is suggested that these genetic variants might potentially be used as markers of iron deficiency anaemia risk.

Xeroderma pigmentosum variant: complementary molecular approaches to detect a 13 base pair deletion in the DNA polymerase eta gene

Deficiencies of DNA polymerase eta-an enzyme mediating replication past UV-induced DNA damage-predispose individuals to xeroderma pigmentosum variant (XPV) and result in a high incidence of skin cancers. We designed, developed and assessed several complementary molecular approaches to detect a genetically inherited deletion within DNA polymerase eta. RNA was reverse transcribed from XPV fibroblasts and from normal human cells, and standard polymerase chain reaction (PCR) was conducted on the cDNA targeting a region with a 13 base pair deletion within the polymerase eta gene. PCR products were subjected to restriction fragment length polymorphism (RFLP) analysis and cycle DNA sequencing. The deletion was found to eliminate a BsrGI restriction site and affected the number of resultant fragments visualized after gel electrophoresis. Cycle sequencing of polymerase eta-specific amplicons from XPV and normal cells provided a second approach for detecting the mutation. Additionally, the use of a fluorescent nucleic acid dye-EvaGreen-in real-time PCR and melt curve analysis distinguished normal and XPV patient-derived amplicons as well as heteroduplexes that represent heterozygotic carriers without the need for high resolution melt analysis-compatible software. Our approaches are easily adaptable by diagnostic laboratories that screen for or verify genetically inherited disorders and identify carriers of a defective gene.

EASL clinical practice guidelines for HFE hemochromatosis

Iron overload in humans is associated with a variety of genetic and acquired conditions. Of these, HFE hemochromatosis (HFE-HC) is by far the most frequent and most well-defined inherited cause when considering epidemiological aspects and risks for iron-related morbidity and mortality. The majority of patients with HFE-HC are homozygotes for the C282Y polymorphism [1]. Without therapeutic intervention, there is a risk that iron overload will occur, with the potential for tissue damage and disease. While a specific genetic test now allows for the diagnosis of HFE-HC, the uncertainty in defining cases and disease burden, as well as the low phenotypic penetrance of C282Y homozygosity poses a number of clinical problems in the management of patients with HC. This Clinical Practice Guideline will therefore, focus on HFE-HC, while rarer forms of genetic iron overload recently attributed to pathogenic mutations of transferrin receptor 2, (TFR2), hepcidin (HAMP), hemojuvelin (HJV), or to a sub-type of ferroportin (FPN) mutations, on which limited and sparse clinical and epidemiologic data are available, will not be discussed. We have developed recommendations for the screening, diagnosis, and management of HFE-HC.

Phenotypic expression of hereditary hemochromatosis: what have we learned from the population studies?

Profound advances in our knowledge of hereditary hemochromatosis (HH) during the past 150 years have resulted in two distinct "iron ages": the pre-HFE gene era and the post-HFE gene era. During these periods, family studies, HLA association studies, and ultimately HFE gene studies in various populations informed us of the genotypic prevalence as well as the clinical and biochemical penetrance of HH. We learned that HH has a highly variable clinical penetrance in susceptible individuals of Northern European ancestry. Further, we now recognize that the natural history of HH is not as discrete as previously believed, because genetic and environmental modifiers of disease penetrance are increasingly identified as influencing the clinical expression of HH.

HFE C282Y/H63D compound heterozygotes are at low risk of hemochromatosis-related morbidity

The risk of hemochromatosis-related morbidity is unknown among HFE compound heterozygotes (C282Y/H63D). We used a prospective population-based cohort study to estimate the prevalence of elevated iron indices and hemochromatosis-related morbidity for compound heterozygotes. In all, 31,192 subjects of northern European descent were genotyped for HFE C282Y and H63D. An HFE-genotype stratified random sample of 1,438 subjects, followed for an average of 12 years to a mean age of 65 years, completed questionnaires and gave blood. Clinical examinations were blinded to HFE genotype. A total of 180 (84 males) clinically examined C282Y/H63D participants were compared with 330 (149 males) controls with neither HFE mutation; 132 (65 males) and 270 (122 males), respectively, had serum iron measures at both timepoints. Mean serum ferritin (SF) and transferrin saturation (TS) were significantly greater for male and female compound heterozygotes than for wild-types at baseline and follow-up (all P < 0.02) except for females who were premenopausal at baseline, where SF was similar in both genotype groups. For subjects with serum measures from both baseline and follow-up, mean SF and TS levels did not change significantly for men or for postmenopausal women, but for premenopausal women SF levels increased from 43 to 109 microg/L for compound heterozygotes and from 35 to 64 microg/L for wild-types (both P < 0.001). Male and female compound heterozygotes had a similar prevalence of hemochromatosis-related morbidity to wild-types. One of 82 males and zero of 95 females had documented iron overload-related disease.

CONCLUSION

For male compound heterozygotes, mean iron indices do not change during middle age but for female compound heterozygotes menopause results in increased mean SF. Although compound heterozygotes might maintain elevated iron indices during middle age, documented iron overload-related disease is rare.

Review article: the modern diagnosis and management of haemochromatosis

Haemochromatosis is the most common genetic disease in populations of European ancestry. Despite estimates based on genetic testing in Caucasian populations of 1 in 227, many physicians consider haemochromatosis to be a rare disease. The diagnosis can be elusive because of the non-specific nature of the symptoms. Of all the symptoms, liver disease has the most consistent relationship to haemochromatosis and the prognosis of haemochromatosis is most closely linked to the degree of iron overload. With the discovery of the HFE gene in 1996, comes new insights into the pathogenesis of the disease and new diagnostic strategies. However, a growing number of new iron-related genes have been discovered and linked to other iron overload syndromes.

Hemochromatosis Gene Mutations, Body Iron Stores, Dietary Iron, and Risk of Colorectal Adenoma in Women

BACKGROUND

Some experimental evidence suggests that iron may play a role in colorectal carcinogenesis, but human data for this role have been conflicting, possibly because of problems related to study design or measurement of iron exposure. We assessed dietary iron intake and genetic and biochemical markers of iron status in a prospective, nested case-control study of women enrolled in the Nurses' Health Study.

METHODS

Among 32 826 women who provided a blood specimen, we identified 527 women with colorectal adenoma and 527 matched control subjects who underwent endoscopy but were not diagnosed with adenoma after blood collection. We assessed iron intake, mutations in the HFE gene that are associated with hereditary hemochromatosis (i.e., H63D and C282Y), and plasma biochemical measures of total body iron, including transferrin saturation and the ratio of the concentrations of transferrin receptors to ferritin. Logistic regression models were used to estimate relative risks (RR) and 95% confidence intervals (CI). All statistical tests were two-sided.

RESULTS

Women with any HFE gene mutation had higher total body iron stores, as reflected by higher transferrin saturations (P < .001) and lower levels of the ratio of transferrin receptors to ferritin (P = .02), than women with no HFE gene mutation. However, HFE gene mutations were not associated with risk of adenoma (multivariable RR = 1.08, 95% CI = 0.83 to 1.39; P = .58). Moreover, comparison of extreme categories showed no associations between adenoma and the extent of transferrin saturation (multivariable RR = 0.96, 95% CI = 0.63 to 1.47; Ptrend = .66), the ratio of transferrin receptors to ferritin (multivariable RR = 0.98, 95% CI, 0.60 to 1.60; Ptrend = .99), or dietary iron intake (multivariable RR = 1.04, 95% CI = 0.68 to 1.57; Ptrend = .94).

CONCLUSIONS

Although our study used several distinct measures of iron status (i.e., genetic mutations, biochemical markers, and dietary intake) and a nested case-control design, we did not observe a role for iron in the pathogenesis of colorectal neoplasia in women.

Inherited iron loading: genetic testing in diagnosis and management

Elucidation of the molecular pathways of iron transport through cells and its control is leading to an understanding of genetic iron loading conditions. The general phenotype of haemochromatosis is iron accumulation in liver parenchymal cells, a raised serum transferrin saturation and ferritin concentration. Four types have been identified: type 1 is the common form and is an autosomal recessive disorder of low penetrance strongly associated with mutations in the HFE gene on chromosome 6(p21.3); type 2 (juvenile haemochromatosis) is autosomal recessive, of high penetrance with causative mutations identified in the HFE2 gene on chromosome 1 (q21) and the HAMP gene on chromosome 19 (q13); type 3 is also autosomal recessive with mutations in the TfR2 gene on chromosome 3 (7q22); type 4 is an autosomal dominant condition with heterozygous mutations in the ferroportin 1 gene. In type 4, iron accumulates in both parenchymal and reticuloendothelial cells and the transferrin saturation may be normal. There are also inherited neurodegenerative conditions associated with iron accumulation. The current research challenges include understanding the central role of the HAMP gene (hepcidin) in controlling iron absorption and the reasons for the variable penetrance in HFE type 1.

The evaluation of hyperferritinemia: an updated strategy based on advances in detecting genetic abnormalities

The number of new genes implicated in iron metabolism has dramatically increased during the last few years. Alterations of these genes may cause hyperferritinemia associated or not with iron overload. Correct assignment of the specific disorder of iron metabolism requires the identification of the causative gene mutation. Here, we propose a rational strategy that allows targeting the gene(s) to be screened for a diagnostic purpose. This strategy relies on the age of onset of the disease, the type of clinical symptoms, the biochemical profile (elevated or normal serum transferrin saturation (TfSat)), the presence or not of visceral iron excess, and the mode of inheritance (autosomal recessive or dominant). Then, two main entities can be differentiated: genetic (adult or juvenile) hemochromatosis characterized by elevated TfSat, and hereditary hyperferritinemias where TfSat is normal (or only slightly modified). Adult genetic hemochromatosis (GH) is related mainly to mutations of the HFE gene, and exceptionally to mutations of the TFR2 gene. Juvenile GH is a rare condition related principally to mutations of the HJV gene coding for hemojuvelin, and rarely to mutations of the HAMP gene coding for hepcidin. Hereditary hyperferritinemias are linked to mutations of three genes: the L-ferritin gene responsible for the hereditary hyperferritinemia cataract syndrome (without iron overload), the ferroportin gene leading to a dominant form of iron overload, and the ceruloplasmin (CP) gene corresponding to an iron overload syndrome with neurological symptoms. The proposed strategic approach may change with the identification of other genes involved in iron metabolism.

Analysis of hemochromatosis gene mutations in 52 consecutive patients with polycythemia vera

A literature review reports increased erythrocyte indices [hemoglobin concentration, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin (MCH), MCH concentration] in subjects with hereditary hemochromatosis (HH). We, therefore, screened 52 consecutive patients with polycythemia vera for 12 HH gene mutations, comparing iron status and red cell parameters between patients positive or negative for HH gene mutations. Our results support the evidence that there is no association between these two conditions.

Analysis of HFE and TFR2 gene mutations in patients with acute leukemia

There are increasing evidences regarding the association between iron overload and extra-hepatic malignancies. We studied the prevalence of 12 hereditary hemochromatosis (HH) gene mutations (C282Y, V53M, V59M, H63D, H63H, S56C, Q127H, E168Q, E168X, W169X and Q283P in the HFE gene and Y250X in the TFR2 gene) and its correlation with the iron status in 82 adult patients with acute leukemia (AL); 48 patients (58.5%) were affected by acute myeloid leukemia (AML) and 34 patients (41.5%) by acute lymphoblastic leukemia (ALL); 27 patients (32.9%) had at least one HH gene mutation (6 heterozygous for C282Y, 6 homozygous for H63D, 13 heterozygous for H63D and 2 heterozygous for S56C). Mean serum ferritin levels at diagnosis were increased (822.5+/-811.4 microg/L). However, there was no difference between patients positive or negative for the HH gene mutations. Similarly, we did not observe any statistically significant difference as far as iron status between AML and ALL patients. Our study does not support the evidence of an association between hemochromatosis gene mutations and iron overload in AL patients.

Iron deficiency and erythropoiesis: new diagnostic approaches

Iron deficiency anemia is one of the most common diseases worldwide. In the majority of cases, the presence of hypochromic microcytic anemia and biochemical evidence for depletion of body iron stores makes the diagnosis relatively straightforward. However, in several clinical conditions, classic biochemical indices such as serum iron, transferrin saturation, and ferritin may not be informative or may not change rapidly enough to reflect transient iron-deficient states (functional iron deficiency), such as the ones that develop during recombinant human erythropoietin (r-HuEPO) therapy. The identification and treatment of iron deficiency in settings such as r-HuEPO therapy, anemia of chronic disease, and iron deficiency of early childhood may be improved by the use of red cell and reticulocyte cellular indices, which reflect in almost real time the development of iron deficiency and the response to iron therapy. In the anemia of chronic disease, measurements of plasma cytokines and iron metabolism regulators such as hepcidin (when available) may be helpful in the characterization of the pathophysiologic basis of this condition. The ratio of serum transferrin receptor (sTfR) to serum ferritin (R/F ratio) has been shown to have excellent performance in estimating body iron stores, but it cannot be used widely because of the lack of standardization for sTfR assays. The combination of hematologic markers such as reticulocyte hemoglobin content, which decreases with iron deficiency, and R/F ratio may allow for a more precise classification of anemias.

HFE genotype and transferrin saturation in the United States

PURPOSE

Examine the penetrance (defined by high transferrin saturation [TS]) of C282Y and H63D in the U.S. population.

METHODS

5171 participants from the Third National Health and Nutrition Examination Survey, 1992 to 1994.

RESULTS

77.1% (95% confidence interval [CI], 2.3, 95.1) of men and 51.9% (95% CI, 0, 84.2) of women with C282Y homozygosity had high TS. The associations of H63D homozygosity with high TS were stronger in people aged 50 years or older than in younger persons. Among Mexican-Americans, simple H63D heterozygosity was associated with high TS.

CONCLUSIONS

The associations between HFE genotype and high TS may vary by sex, age, and ethnic group.

Haematological effects of the C282Y HFE mutation in homozygous and heterozygous states among subjects of northern and southern European ancestry

High frequencies of the C282Y and H63D mutations of the HFE gene occur in European populations, even though homozygous and compound heterozygous states are associated with hereditary haemochromatosis, which is a disease that decreases fitness. This suggests that heterozygotes may possess a selective advantage. HFE mutations increase iron absorption in patients with haemochromatosis, and the mean transferrin saturations and ferritin levels are mildly increased in heterozygotes, suggesting that HFE mutations may protect against iron depletion and iron deficiency anaemia. In this study of 23,681 Caucasian adults, mean transferrin saturation, serum ferritin and haemoglobin levels were significantly higher in subjects carrying HFE mutations compared with wild types. Analysed by ethnicity, mean haemoglobin and mean erythrocyte volume (MCV) were significantly lower in those with a southern versus northern European ancestry. C282Y mutation carriers had an increased mean haemoglobin level in both ethnic groups. Prevalence of non-anaemic iron deficiency was significantly lower among female carriers of the C282Y mutation compared with HFE wild types. However, prevalence of frank iron deficiency anaemia did not differ significantly among genotypes. Quantile:quantile plots showed a small but significant upward shift in the mid-range of the haemoglobin distribution among C282Y mutation carriers that was consistent with an increased mean haemoglobin level without significant changes in the anaemic range.

A population-based study of the effect of the HFE C282Y and H63D mutations on iron metabolism

The C282Y and H63D mutations in the HFE gene are important causes of hemochromatosis. In the elderly, these mutations might be associated with increased morbidity because of the lifelong accumulation of iron. In a population-based sample of the elderly, we determined the value of genotyping for HFE mutations to screen for subclinical hemochromatosis. HFE genotype frequencies were determined in a random group of 2095 subjects (55 years and over). In this random group, we selected within the six genotype groups a total of 342 individuals and measured their serum transferrin saturation, iron and ferritin levels. We also estimated the heritability and parameters needed to evaluate screening, including the sensitivity, specificity, positive and negative predictive values (PPV, NPV) of HFE genotypes. Iron parameters were significantly increased in subjects homozygous, heterozygous or compound heterozygous. The effect of the mutations was more pronounced in men than in women. For the H63D mutation, an allele dose effect was observed. The HFE gene explained about 5% of the variability in serum iron indices. The PPV for hemochromatosis for the C282Y homozygous was 100% in men and 67% in women. The NPV of the wild-type allele was 97% for both men and women. The sensitivity of both mutations was 70% for men and 52% for women and the specificity was 62% for men and 64% for women. Our study shows that the HFE C282Y and H63D are determinants of iron parameters in the elderly and will be effective in detecting individuals at high risk of hemochromatosis. However, when screening based on these two mutations, some individuals with subclinical hemochromatosis will be missed.

Dietary factors associated with the risk of high iron stores in the elderly Framingham Heart Study cohort

BACKGROUND

High body iron stores may increase the risk of several chronic diseases. Whether dietary factors contribute to the risk of high iron stores is unknown.

OBJECTIVE

We assessed the relation between dietary factors and the risk of high iron stores in the elderly Framingham Heart Study cohort.

DESIGN

We examined the relation between the usual intake of dietary factors (food-frequency questionnaire) and the risk of high iron stores (serum ferritin >300 and 200 micro g/L in men and women, respectively) in 614 subjects aged 68-93 y.

RESULTS

The risk of high iron stores was significantly higher 1) in subjects who took > or =30 mg supplemental Fe/d than in nonusers [odds ratio (OR): 4.32; 95% CI: 1.63, 11.47], 2) in subjects who consumed >21 servings of fruit/wk than in those who consumed < or =14 servings/wk (OR: 2.88; 95% CI: 1.26, 6.61), and 3) in subjects who consumed >4 but <7 or > or=7 servings of red meat/wk than in those who consumed < or =4 servings/wk (ORs: 2.94 and 3.61, respectively; 95% CIs: 1.33, 6.47 and 1.57, 8.27, respectively). Whole-grain intake (>7 servings/wk) was inversely associated (OR: 0.23; 95% CI: 0.07, 0.75).

CONCLUSIONS

Among elders, intakes of highly bioavailable forms of iron (supplemental iron and red meat) and of fruit, a dietary source of an enhancer of nonheme-iron absorption (vitamin C), promote high iron stores, whereas foods containing phytate (whole grains) decrease these stores. Individual dietary patterns may be important modulators of high iron stores.

Liver pathology in compound heterozygous patients for hemochromatosis mutations

BACKGROUND

While hepatic pathology of homozygous carriers of the C282Y mutation of the HFE haemochromatosis gene is well defined, the impact of the C282Y/H63D compound heterozygous carrier state is unknown.

AIMS

To evaluate the range of hepatic pathology in C282Y/H63D compound heterozygous patients.

PATIENTS

25 C282Y/H63D compound heterozygous patients with and without known underlying liver disease underwent liver biopsies for evaluation or abnormal liver tests. Eleven cadaveric liver donors with HFE wild type served as controls.

METHODS

Mutations in the HFE gene were detected by polyacrylamide gel electrophoresis (PAGE) separation of digested polymerase chain reaction (PCR)-amplificates. The extent of light microscopic changes of liver architecture were studied on haematoxylin, eosin (H. E.) stains. In addition, the extent and the distribution of iron deposition was graded on Prussian blue-stained sections and hepatic iron was quantified by atom absorption spectroscopy. Serum ferritin concentration and the transferrin saturation index were measured using routine laboratory methods.

RESULTS

Patients without underlying liver disease (n = 15): Hepatic inflammation was seen in only 8% but fibrosis was found in 36% of compound heterozygous patients. Eighty six percent of those patients had stainable iron predominantly found in Rappaport's zone 1 and 2, but all had a liver iron-index < 1.9. Transferrin saturation was found elevated in 36% of compound heterozygous patients. Patients with liver fibrosis showed significantly higher ferritin levels than patients without liver fibrosis (1110 ng/mL versus 307 ng/mL, p < 0.05). Patients with underlying disease (n = 10): In compound heterozygous patients, 77% had hepatic inflammation and 88% fibrosis. Stainable iron (44%) was less frequently found than in patients without underlying liver disease. Hepatic iron-index in patients with underlying liver disease was always below 1.17; transferrin saturation was elevated in only 22% of the compound heterozygous patients. Histologic hepatic iron-index was significantly lower in patients with underlying disease (median 0.047) as compared to patients without underlying liver disease (median 0.274, P < 0.05).

CONCLUSIONS

The underlying liver disease determines the extent of hepatic pathology seen in livers of compound heterozygous patients. However, considerable histologic fibrosis can also be found in compound heterozygous patients without underlying liver disease.

A primer for predicting risk of disease in HFE-linked hemochromatosis

Since the discovery of the hemochromatosis gene (HFE) in 1996, there has been increasing interest in diagnostic testing for the C282Y and H63D mutations. The high frequency of these two alleles and their incomplete penetrance in homozygotes and compound heterozygotes make genetic counseling for hemochromatosis different from some other autosomal recessive conditions in that parents and children may also be at risk for iron overload, while homozygotes may remain asymptomatic. We provide a guideline for genetic counseling in HFE-linked hemochromatosis based on the genetic probability of inheriting HFE mutations and known information about expression of iron overload in various HFE genotypes. Genetic probabilities were based on allele frequencies derived from large population studies and Hardy-Weinberg equilibrium estimates. Expression of iron overload in those of various genotypes was based on available estimates of serum ferritin from population screening studies. Estimates for the likelihood of clinical iron overload requiring follow-up screening or treatment are provided by gender and genotype. The probability of inheriting HFE mutations and developing iron overload can be estimated in family members of a proband with HFE mutations. Many C282Y homozygotes will not have clinical iron overload. The risk is highest in men and their C282Y homozygous brothers and significantly lower in homozygous women. Iron overload is uncommon in compound heterozygotes and H63D homozygotes.

Relationship between transferrin saturation and iron stores in the African American and US Caucasian populations: analysis of data from the third National Health and Nutrition Examination Survey

In previous analyses of transferrin saturation data in African Americans and Caucasians from the second National Health and Nutrition Examination Survey (NHANES II), subpopulations were found consistent with population genetics for common loci that influence iron metabolism. The goal of this new study was to determine if these transferrin saturation subpopulations have different levels of iron stores. Statistical mixture modeling was applied to transferrin saturation data for African Americans and Caucasians from the third National Health and Nutrition Examination Survey (NHANES III), and then the mean serum ferritin concentrations were determined for the transferrin saturation subpopulations that were identified. After adjustment for diurnal variation, 3 subpopulations of transferrin saturation were identified in each racial group. Satisfying Hardy-Weinberg conditions for major locus effects, in both racial groups the sum of the square roots of the proportion with the lowest mean transferrin saturation and the proportion with the highest mean transferrin saturation was approximately 1. When weighted to reflect the US adult population as a whole, these subpopulations of increasing transferrin saturations had progressively increasing mean age-adjusted serum ferritin concentration values in each ethnic grouping as stratified by sex (trend test, P <.002 for all). These results are consistent with the concept that population transferrin saturation subpopulations reflect different levels of storage iron.

Reference Centiles for Serum Ferritin and Percentage of Transferrin Saturation, with Application to Mutations of the HFE Gene

Background: The gene that causes most cases of hereditary hemochromatosis is designated HFE. Individuals with mutations in the HFE gene may have increased serum iron, transferrin saturation, and ferritin concentrations relative to individuals with the wild-type genotype.

Methods: We generated reference centiles for percentage of transferrin saturation and serum ferritin concentrations in normal (wild-type), healthy Caucasian adults. We then examined transferrin and ferritin concentrations relative to these centiles in 81 individuals homozygous for the major hemochromatosis mutation C282Y and 438 individuals with the compound heterozygous HFE genotype C282Y/H63D.

Results: Serum ferritin concentrations, but not percentage of transferrin saturation, in normal, healthy women tended to increase sharply as they progressed through menopause. Transferrin and serum ferritin centiles for normal, healthy females were lower than the corresponding centiles in normal, healthy males. C282Y homozygotes had abnormally high transferrin saturation and serum ferritin values relative to the wild types. Compound heterozygotes appeared to be a mixture of individuals with unexceptional transferrin and ferritin values and those with abnormally large values similar to the homozygotes, with equal proportions of each.

Conclusions: There are age- and sex-related differences in reference centiles for the percentage of transferrin saturation and serum ferritin concentrations in normal, healthy adults. Individuals homozygous for the C282Y mutation in the HFE gene have abnormal transferrin saturation and serum ferritin values relative to the reference population; penetrance with the compound heterozygotes, as reflected by abnormal transferrin and ferritin values, is less than with the homozygotes.

Hemochromatosis at the intersection of classical medicine and molecular biology

Hemochromatosis is a genetic disease of iron overload due to intestinal hyperabsorption of iron. It is one of the most prevalent autosomal recessive diseases in Caucasian populations. Hemochromatosis causes severe visceral and metabolic complications at adulthood, which include cirrhosis, diabetes, arthropathy and cardiac failure. A major breakthrough has been the discovery, in 1996, of the HFE gene which is strongly associated with the phenotypic expression of the disease. This discovery has, very quickly, provided a powerful genetic blood test which permits, in most cases, to establish the diagnosis in a non invasive way (i.e. without a liver biopsy). Hemochromatosis can be cured by repeated venesections provided the diagnosis has been detected sufficiently early. Moreover, an efficient preventive strategy can be applied to family members and should now be proposed to the general population. Finally, the identification of the HFE gene has paved the way for the identification of new iron overload entities.

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.

Pleiotropic and epistatic effects in sickle cell anemia

Sickle cell anemia is the first monogenic disease ever described, and it became the paradigm for a disease traceable to a single mutation in a single gene. Pauling's concept of "molecular disease," based on this discovery, opened a new chapter in the history of medicine. Nevertheless, at the phenotypic level, sickle cell anemia is not a monogenic disease; it is a multigenic disease. The latter is the product of pleiotropic genes (involved in secondary pathophysiologic events) and epistatic genes (same gene but with significant pathophysiologic consequences among individual=polymorphism). These secondary events are an important part of the phenotype and explain the intense interindividual differences in the severity of the disease, in spite of all the patients having the same sickle globin gene in the homozygote form. In the last decade a number of epistatic genes and pleiotropic genes have been defined, and many others are potential candidates. CHIP technology and high-throughput sequencing promise to accelerate our full multigenic understanding of this disease, contributing to a more individualized concept of disease in conjunction as we enter the new millennium.

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.

Iron deficiency and iron overload: effects of diet and genes

Like most essential nutrients, Fe needs to be maintained in the body at a defined level for optimal health, with appropriate adaptation to varying Fe needs and supply. The primary mechanism for controlling Fe level is the regulation of Fe absorption. Several different proteins have been identified as contributors to the process. Despite a complex regulatory system, Fe disorders (both Fe deficiency and Fe overload) occur. Fe deficiency is a common problem worldwide, resulting from inadequate dietary Fe and blood loss. Complications include pre-term labour, developmental delay, and impaired work efficiency. No specific genetic syndromes causing isolated Fe deficiency have been described, but animal studies and clinical observations suggest that such a relationship may be a possibility. Conversely, the known causes of Fe overload are genetic. Fe overload is less common than Fe deficiency, but can result in serious medical complications, including cirrhosis, primary liver cancer, diabetes, cardiomyopathy and arthritis. The most common and best characterized syndrome of Fe overload is hereditary haemochromatosis (HHC), an autosomal recessive disorder. Mutations in the HFE protein cause HHC, but the clinical presentation is variable. Of particular interest is the factor that some FIFE genotypes appear to be associated with protection from Fe deficiency. Other genetic variants in the regulatory pathway may influence the likelihood of Fe deficiency and Fe overload. Studies of genetic variants in HFE and other regulatory proteins provide important tools for studying the biological processes in Fe regulation. This work is likely to lead to new insights into Fe disorders and potentially to new therapeutic approaches. It will not be complete, however, until coordinated study of both genetic and nutritional factors is undertaken.

Effect of Hemochromatosis Genotype and Lifestyle Factors on Iron and Red Cell Indices in a Community Population

Background: Heterozygotes for the C282Y mutation of the HFE gene may have altered hematology indices and higher iron stores than wild-type subjects.

Methods: We performed a cross-sectional analysis of 1488 females and 1522 males 20–79 years of age drawn from the Busselton (Australia) population study to assess the effects of HFE genotype, age, gender, and lifestyle on serum iron and hematology indices.

Results: Male C282Y heterozygotes had increased transferrin saturation compared with the wild-type genotype. Neither male nor female heterozygotes had significantly increased ferritin values compared with the wild-type genotype. Younger (20–29 years) wild-type males, but not heterozygous males, had significantly lower ferritin values than wild-type males in the older age groups. Compound heterozygous subjects had increased means for serum iron, transferrin saturation, corpuscular volume, and corpuscular hemoglobin compared with the wild-type genotype, and the males also had increased ferritin values (medians 323 vs 177 μg/L; P = 0.003). In both male and female wild-type subjects, an increased body mass index was associated with decreased serum iron and transferrin saturation and increased ferritin values. There was a significant increase in ferritin concentrations in both genders with increasing frequency of red meat consumption above a baseline of 1–2 times per week and alcohol intakes &gt;10 g/day.

Conclusions: Male C282Y heterozygotes had significantly increased transferrin saturation values. Compound heterozygous (C282Y/H63D) subjects formed a separate category of C282Y heterozygotes in whom both iron and red cell indices were significantly increased compared with the wild-type genotype.

Genotyping of two mutations in the HFE gene using single-base extension and high-performance liquid chromatography

Currently, a major focus of human genetics is the utilization of single-nucleotide polymorphisms for clinical diagnostics, whole-genome linkage disequilibrium screens to identify common disease genes such as Alzheimer disease, determination of the recent evolutionary history of a species, and the process of speciation. We have examined single-nucleotide extension coupled with high-performance liquid chromatography as a method to simultaneously genotype two SNPs occurring in the coding region of the HFE gene that produce clinical effects. This assay allows concurrent genotyping of the C282Y and H63D mutations in 11 min and is 100% concordant with current testing methods for both of these mutations.

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.

Serum ferritin and C282Y mutation of the hemochromatosis gene as predictors of asymptomatic carotid atherosclerosis in a community population

BACKGROUND AND PURPOSE

Serum ferritin and heterozygosity for the C282Y mutation of the hemochromatosis gene have both been associated with an increased risk of cardiovascular events. The purpose of the study was to test whether either is a risk predictor for asymptomatic carotid atherosclerosis.

METHODS

We assessed carotid intima-media wall thickness (IMT) and focal plaque formation by high-resolution B-mode ultrasound, conventional risk factors, serum ferritin levels, and the C282Y mutation of the hemochromatosis gene in a randomly selected community population of 1098 subjects (545 women and 553 men) aged 27 to 77 years.

RESULTS

After adjustment for conventional risk factors, serum ferritin was not associated with carotid mean IMT. Women with ferritin values over the first quartile (>34 microg/L) had an adjusted odds ratio of 2.1 (95% CI, 1. 3 to 3.4; P:=0.0016) for carotid plaque compared with the first quartile. Ferritin was not associated with carotid plaque in men. Subjects who were heterozygous for the C282Y mutation constituted 11. 4% of the population, and there was no independent association of this genotype with either carotid IMT or focal plaque formation.

CONCLUSIONS

We conclude that in our community population, C282Y genotype status was not a risk predictor for either carotid mean IMT or plaque formation. Serum ferritin values in women were independently associated with carotid plaque.

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.