IHR-PVS National Bridging Workshop in Cameroon: An interactive and participatory approach to engage stakeholders in the development of a One Health road map.

Introduction: Stakeholders involved in the implementation of the One Health (OH) welcome support for the operationalization of the approach and advice on how to address OH collaboration challenges. The IHR/PVS National Bridging Workshop (NBW) is an operational and outcome-oriented tool approach that allows animal health, human health and other relevant sectors to focus on their coordination. This paper describes how Cameroon leveraged on the NBW success factors to engage stakeholders in strengthening multisectoral collaboration. Methods: Stakeholder's engagement was implemented in two phases. Phase one consisted of engaging the multisectoral national task team for the preparation of the workshop. Phase two consisted of the bridging exercise itself during a three day workshop. The WOAH-WHO standardized IHR/PVS NBW toolkit was used throughout the workshop. Results: A total of 66 participants took part in the exercise. In total, 36% each came from human and animal health sectors with 23% and 5% from the environmental health and other sectors respectively. A total of 55% participants came from the national level and 39% from the regional level. The joint roadmap contained 55 activities and 13 objectives. Priority objectives were the establishment of a OH platform at all levels (62% of the vote) and building stakeholder's capacity on the OH approach (56% of the vote). A total of 67% of the activities required low or moderate cost and 87% would have a high impact on multisectoral collaboration. Conclusion: The NBW allowed consensus on operational activities to fill the gaps in coordination to build health security capacities. It enabled Cameroon to create a joint road map for enhanced multisectoral collaboration for health security. The output will be integrated in the National Action Plan for Health Security operational plan and support operational One Health activities. It would be crucial to develop global capacity assessment frameworks for environmental health, which could be included in the NBW, to incorporate interconnections with environmental sector. This should allow for a stronger multisectoral linkage of sectors all together for a more the robust OH approach in responding to emerging public health threats.

Health Security Planning: Developing the Cameroon National Action Plan for Health Security.

The health security planning process transforms recommendations from various evaluations into priority actions to strengthen countries' capacity for emergency preparedness using the One Health approach. Although the World Health Organization (WHO) has developed many tools to facilitate the planning process of a National Action Plan for Health Security (NAPHS) across the various components, a series of multisectoral workshops is still needed to complete the process. In this article, we report on the process of developing Cameroon's NAPHS and propose an innovative solution to improve the process. The NAPHS development process was conducted from May to December 2018. The WHO NAPHS framework, adapted to the local context, guided the process. The WHO planning matrix was used to plan activities and the WHO NAPHS costing tool was used to facilitate the costing exercise. A total of 84 Joint External Evaluation recommendations were translated into activities included in Cameroon's NAPHS. Among these activities, the majority (56%) were of medium priority. The total cost of a 5-year NAPHS was US$87,668,356, with almost half (49%) of the budget allocated to activities in the "Prevent" category and more than a third (35%) allocated to the "Detect" category. The top 3 cost drivers were immunization (22%), the national laboratory system (21%), and antimicrobial resistance (16%). The NAPHS informed policymakers of planned activities and funding needs to fast-track the development of health security capacities. Running gaps in funding will be addressed during a resource mapping exercise. To improve the overall planning process, a web-based support solution, where stakeholders select from a menu of recommendations from the Joint External Evaluation to develop a NAPHS, should be developed to improve the NAPHS development process.

HFE gene mutations increase the risk of coronary heart disease in women.

The purpose of the present study is to examine HFE gene mutations in relation to newly diagnosed (incident) coronary heart disease (CHD). In a population-based follow-up study of 7,983 individuals aged 55 years and older, we compared the risk of incident CHD between HFE carriers and non-carriers, overall and stratified by sex and smoking status. HFE mutations were significantly associated with an increased risk of incident CHD in women but not in men (hazard ratio [HR] for women = 1.7, 95% confidence interval [CI] 1.2-2.4 versus HR for men = 0.9, 95% CI 0.7-1.2). This increased CHD risk associated with HFE mutations in women was statistically significant in never smokers (HR = 1.8, 95% CI 1.1-2.8) and current smokers (HR = 3.1, 95% CI 1.4-7.1), but not in former smokers (HR = 1.3, 95% CI 0.7-2.4). HFE mutations are associated with increased risk of incident CHD in women.

Association between oxidized LDL, obesity and type 2 diabetes in a population-based cohort, the Health, Aging and Body Composition Study.

BACKGROUND: Accumulating evidence suggests a cross-sectional association between oxidative stress and type 2 diabetes (T2D). Systemic oxidative stress, as measured by oxidized LDL (oxLDL), has been correlated with visceral fat. We examined the relationship between oxLDL, and T2D- and obesity-related traits in a bi-racial sample of 2985 subjects at baseline and after 7 years of follow-up. METHODS: We examined six T2D-related traits (T2D status, HbA(1c), fasting glucose, insulin, adiponectin and HOMA-IR) as well as six obesity-related traits (obesity status, BMI, leptin, % body fat, visceral and subcutaneous fat mass) using logistic and linear regression models. RESULTS: In all subjects at baseline, oxLDL was positively associated with T2D (OR = 1.3, 95% CI:1.1-1.5), fasting glucose (ss = 0.03 +/- 0.006), HbA(1c) (ss = 0.02 +/- 0.004), fasting insulin (ss = 0.12 +/- 0.02), HOMA-IR (ss = 0.13 +/- 0.02) and negatively with adiponectin (ss = -0.16 +/- 0.03), (all p < 0.001). The strength and magnitude of these associations did not differ much between blacks and whites. In both blacks and whites, oxLDL was also associated with obesity (OR = 1.3, 95% CI:1.1-1.4) and three of its related traits (ss = 0.60 +/- 0.14 for BMI, ss = 0.74 +/- 0.17 for % body fat, ss = 0.29 +/- 0.06 for visceral fat; all p < 0.001). Furthermore, of four traits measured after 7 years of follow-up (fasting glucose, HbA1c, BMI and % fat), their relationship with oxLDL was similar to baseline observations. No significant association was found between oxLDL and incident T2D. Interestingly, oxLDL was significantly associated with % change in T2D- and obesity-related traits in whites but not in blacks. CONCLUSION/INTERPRETATION: Our data suggest that systemic oxidative stress may be a novel risk factor for T2D and obesity.

The association between H63D mutations in HFE and amyotrophic lateral sclerosis in a Dutch population.

BACKGROUND: Mutations in HFE, a gene defect that can disrupt iron metabolism, have been implicated in increasing the risk of developing amyotrophic lateral sclerosis (ALS). OBJECTIVE: To further establish the association between ALS and HFE mutations by investigating whether HFE mutations are associated with an increased risk of developing ALS in a population in The Netherlands and by pooling our results with those from previous studies. DESIGN: Retrospective study. SETTING: Tertiary referral center for neuromuscular disorders. PARTICIPANTS: Genotyping for 2 common HFE mutations was performed in 289 patients with ALS and 5886 population-based controls in The Netherlands between January 1, 2000, and December 31, 2004. MAIN OUTCOME MEASURES: Development of ALS and clinical phenotype were compared among the different HFE genotypes, adjusting for known prognostic factors such as age at onset and sex. RESULTS: Homozygosity for H63D was associated with an increased risk of developing ALS (odds ratio [OR], 2.2; 95% confidence interval [CI], 1.1-4.1). After pooling our results with those from previous studies, a positive association between H63D homozygotes (OR, 2.7; 95% CI, 1.7-4.4), heterozygotes (OR, 1.5; 95% CI, 1.0-2.1), and mutation carriers (OR, 1.7; 95% CI, 1.1-2.5) was found. Within the patient group, heterozygosity for the H63D mutation was associated with a higher age at onset. CONCLUSIONS: These findings suggest that H63D mutations in HFE play a role in the pathogenesis of ALS in various populations. This association might involve a later-onset subset of ALS.

An insulin-like growth factor-I promoter polymorphism is associated with increased mortality in subjects with myocardial infarction in an elderly Caucasian population.

We investigated whether an insulin-like growth factor I (IGF-I) promoter polymorphism is associated with excess mortality in elderly subjects with myocardial infarction (MI). This association was assessed in 7,983 subjects of the Rotterdam Study during 14 years of follow-up. Among 345 subjects who developed a MI, the risk of mortality was 1.49 times higher in the variant carriers of the IGF-I promoter polymorphism than in the nonvariant carriers (95% confidence interval 1.10 to 2.10, p = 0.02). The risk of death increased with the number of variant alleles. Our study suggests that genetically determined low IGF-I activity is an important determinant of mortality in subjects with MI.

Mutations in the hemochromatosis gene (HFE) and stroke.

BACKGROUND AND PURPOSE: Increased serum iron is found to be a risk factor for stroke. Carriers of HFE C282Y and H63D mutations have elevated serum iron levels and may have an increased risk for stroke. We studied the association between HFE gene mutations, carotid atherosclerosis, and stroke. METHODS: We compared the frequency of the HFE C282Y and H63D gene mutations in 202 prevalent and incident cases of stroke with that of 2730 controls from a population-based study, the Rotterdam Study. The influence of HFE mutations on the relationship between hypertension, smoking, and stroke was studied by use of a logistic regression model. In the analyses of hypertension, we used noncarriers and nonhypertensives as reference; in the analysis of smoking, we used noncarriers and those who never smoked as the reference group. Furthermore, we studied the mean intima-media thickness of the common carotid artery in relation to hypertension, smoking, and the HFE genotype in subjects without stroke. RESULTS: The percentage of both C282Y and H63D carriers in cases (43.7%, n=87) did not differ significantly (P=0.09) from that of controls (37.6%, n=986). The odds ratio for stroke for HFE carriers who also suffered from hypertension was 3.0 (95% CI, 1.9 to 4.6), and for HFE carriers who were also smokers, the odds ratio for stroke was 2.6 (95% CI, 1.4 to 5.0). The mean+/-SD intima-media thickness of the carotid artery was 0.77+/-0.14 mm for noncarriers without a history of hypertension or smoking compared with 0.81+/-0.17 mm for HFE carriers who smoked (P<0.004) and 0.84+/-0.20 mm for HFE carriers who were hypertensive (P<0.001). CONCLUSIONS: Mutations in the HFE gene were not significantly related to stroke or atherosclerosis in the carotid artery. The HFE gene may modify the relationship between smoking and stroke.

The -514 C->T hepatic lipase promoter region polymorphism and plasma lipids: a meta-analysis.

Investigations of the -514 C-->T single nucleotide polymorphism (SNP) in the hepatic lipase (HL) gene promoter region (LIPC) have yielded contradictory results regarding its association with changes in plasma lipids. The current study is a meta-analysis of 25 publications on this SNP, comprising over 24,000 individuals, and its relationship with total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL), triglycerides, and HL activity. Significant decreases were observed in HL activity for both the CT and TT genotypes compared with the CC genotype [weighted mean difference (WMD), -5.83 mmol/liter.h (95% confidence interval, -8.48, -3.17) and -11.05 mmol/liter.h (95% confidence interval, -14.74, -7.36), respectively]. Moreover, significant increases in HDL were found; the CT to CC comparison showed an increase in WMD of 0.04 mmol/liter (95% confidence interval, 0.02, 0.05) mmol/liter, and the increase in the TT vs. CC difference was WMD of 0.09 mmol/liter (95% confidence interval, 0.07, 0.12). These changes appear to be stepwise, implying an allele dosage effect. All P values for these associations were less than 0.001. This meta-analysis demonstrates the importance of the -514C-->T SNP in determining HL activity and plasma HDL concentration and helps quantify the role that hepatic lipase plays in the metabolism of HDL.

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.

Mutations in the hemochromatosis gene (HFE), Parkinson's disease and parkinsonism.

Iron overload increases oxidative stress and may lead to neurodegenerative disease like Parkinson's disease (PD). We studied the role of mutations in the hemochromatosis gene HFE in PD and other parkinsonism (non-PD PS) in two population-based series. The first series consisted of 137 patients with PD and 47 with non-PD PS, and the second of 60 patients with PD and 25 with non-PD PS. In the first series, PD patients were significantly more often homozygous for the C282Y mutation than controls (P=0.03). Patients with non-PD PS in both series were more often carriers for the C282Y mutation than controls (P=0.009, P=0.006, respectively). Our data are hampered by small numbers, yet suggest that the C282Y mutation increases the risk of PD and non-PD PS. The rarity of this genotype requires a large series of patients to prove our hypothesis.

Reproducibility of peroneal motor nerve conduction measurement in older adults.

OBJECTIVE: While neuropathy is common in the elderly, nerve conduction (NC) reproducibility in older adults is not well-established. We sought to evaluate intraobserver reproducibility of peroneal motor NC measures in a diverse sample of older adults. METHODS: We measured peroneal motor NC amplitude and velocity in a subset of participants (mean age=82.9±2.7, n=62, 50% female, 51.6% black, 35.5% DM) in the Health, Aging, and Body Composition Study. Using coefficients of variation (CVs), intraclass correlation coefficients (ICCs), and Bland Altman Plots, we compared two sets of measurements taken by the same examiner hours apart on the same day. RESULTS: Low CVs (2.15-4.24%) and moderate to high ICCs (0.75-0.99) were observed. No systematic variation was found across measures. Despite small numbers in some subgroups, we found no differences in reproducibility by diabetes, race or study site. CONCLUSION: NC measures have moderate to high intraobsever reproducibility in older adults and are not affected by diabetes, race, or gender. SIGNIFICANCE: These data provide evidence to support use of these measures in aging research.

Identification of heart rate-associated loci and their effects on cardiac conduction and rhythm disorders.

Elevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate-increasing and heart rate-decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets.

Habitual sleep/wake patterns in the Old Order Amish: heritability and association with non-genetic factors.

STUDY OBJECTIVES: We sought to evaluate the contribution of genetic and non-genetic factors on habitual sleep/wake patterns in a community-dwelling agrarian population using a physical activity monitoring device, the Actical. DESIGN: Cross-sectional population-based study of healthy Old Order Amish enrolled in the Heredity and Phenotype Intervention (HAPI) Heart Study. SETTING: Lancaster County, PA, USA. PARTICIPANTS: 723 healthy adults (54% men) with a mean age of 43.3 ± 13.8 years (range: 20-80). 96% of the subjects were connected into one 5-generation pedigree. INTERVENTIONS: N/A. MEASUREMENTS: Participants wore Actical accelerometers 24 hours/day for 7 days to determine physical activity level, as well as habitual wake time, bedtime, and sleep duration. Participants completed the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ), a modified Epworth Sleepiness Scale (ESS), and a lifestyle questionnaire. A sub-study of 164 participants kept sleep diaries. RESULTS: Habitual wake time and bedtime determined by Actical were highly correlated with results from sleep diaries (r = 0.82 for wake time and 0.72 for bedtime, both P < 0.0001). After adjustment for age, sex, occupation, and season, higher activity level was associated with earlier wake time but not with bedtime, and correspondingly with shorter sleep duration. After adjustment for the aforementioned factors and the effects of a shared household, habitual wake time, MEQ score, and ESS score showed significant heritability (wake time h(2) = 0.20, MEQ h(2) = 0.21, and ESS h(2) = 0.17). CONCLUSIONS: Objectively measured wake time, self-reported morningness-eveningness preference, and daytime sleepiness appear heritable and wake time may be associated with physical activity level.

Replication and extension of association between common genetic variants in SIM1 and human adiposity.

Haplo-insufficiency of the bHLH (basic helix-loop-helix) transcription factor single-minded 1 (SIM1) causes severe obesity in mice and humans. We hypothesized that common genetic variations in/near SIM1 could exert more subtle effects on its function and associate with human adiposity. First, SIM1 coding regions were sequenced in severely obese subjects, and two common nonsynonymous single-nucleotide polymorphisms (nsSNPs) in complete linkage disequilibrium (LD) were identified: Pro352Thr (rs3734354) and Ala371Val (rs3734355). We next carried out a SNP association study of five adiposity traits (BMI, % body fat, abdominal visceral and subcutaneous fat, and leptin concentrations) in 1,699 whites and 1,173 blacks. TagSNPs covering SIM1 and nearby conserved regions, and the only common nsSNP in SIM1's binding partner aryl-hydrocarbon receptor nuclear translocator 2 (ARNT2) (Gly679Ser/rs4072568), were investigated. The effects of rs3734355/4 on SIM1 activity were tested using an in vitro reporter assay. We replicated previous observations that homozygosity for the 371Val allele was associated with higher BMI in white males (P = 0.003). Together with previous findings in white males (combined n = 3,479), BMI was increased by 1.10 kg/m(2) in 371Val homozygotes (95% confidence interval (CI): 0.25-1.95 kg/m(2), P = 0.01). In vitro, the 352Thr-371Val haplotype impaired SIM1 transcriptional activity by 22% (P < 0.0001). TagSNP analysis of SIM1 revealed two SNPs in the 3' region (rs9390322 and rs7746743) and another in intron 5 (rs3734353) to be significantly associated with various adiposity measures in ethnicity- and sex-specific manners after multiple testing correction. In white males, rs4072568 in ARNT2 was also associated with BMI (P = 9 × 10(-4)) and % body fat (P = 0.001). Our findings implicate heritable defects of the SIM1-ARNT2 axis in the predisposition to human obesity.

A common variant in the telomerase RNA component is associated with short telomere length.

BACKGROUND: Telomeres shorten as cells divide. This shortening is compensated by the enzyme telomerase. We evaluated the effect of common variants in the telomerase RNA component (TERC) gene on telomere length (TL) in the population-based Health Aging and Body Composition (Health ABC) Study and in two replication samples (the TwinsUK Study and the Amish Family Osteoporosis Study, AFOS). METHODOLOGY: Five variants were identified in the TERC region by sequence analysis and only one SNP was common (rs2293607, G/A). The frequency of the G allele was 0.26 and 0.07 in white and black, respectively. Testing for association between TL and rs2293607 was performed using linear regression models or variance component analysis conditioning on relatedness among subjects. RESULTS: The adjusted mean TL was significantly shorter in 665 white carriers of the G allele compared to 887 non-carriers from the Health ABC Study (4.69±0.05 kbp vs. 4.86±0.04 kbp, measured by quantitative PCR, p = 0.005). This association was replicated in another white sample from the TwinsUK Study (6.90±0.03 kbp in 301 carriers compared to 7.06±0.03 kbp in 395 non-carriers, measured by Southern blots, p = 0.009). A similar pattern of association was observed in whites from the family-based AFOS and blacks from the Health ABC cohort, although not statistically significant, possibly due to the lower allele frequency in these populations. Combined analysis using 2,953 white subjects from 3 studies showed a significant association between TL and rs2293607 (ß = -0.19±0.04 kbp, p = 0.001). CONCLUSION: Our study shows a significant association between a common variant in TERC and TL in humans, suggesting that TERC may play a role in telomere homeostasis.

Association between telomere length, specific causes of death, and years of healthy life in health, aging, and body composition, a population-based cohort study.

Although telomere length (TL) is known to play a critical role in cellular senescence, the relationship of TL to aging and longevity in humans is not well understood. In a large biracial population-based cohort, we tested the hypotheses that elderly persons with shorter TL in peripheral white blood cells have poorer survival, shorter life span, and fewer years of healthy life (YHL). Associations were evaluated using Cox proportional hazard models and linear regression analyses where appropriate. TL (in kilo base pairs) was not associated with overall survival (hazard ratio 1.0; 95% confidence interval 0.9-1.1) or death from any specific underlying cause including infectious diseases, cancer, or cardiac and cerebrovascular diseases. TL, however, was positively associated with more YHL (beta = 0.08 +/- 0.04, p = .03). Findings suggest that TL may not be a strong biomarker of survival in older individuals, but it may be an informative biomarker of healthy aging.

Telomere length is paternally inherited and is associated with parental lifespan.

Telomere length (TL) is emerging as a biomarker for aging and survival. To evaluate factors influencing this trait, we measured TL in a large homogeneous population, estimated the heritability (h(2)), and tested for parental effects on TL variation. Our sample included 356 men and 551 women, aged 18-92 years, from large Amish families. Mean TL in leukocytes was measured by quantitative PCR (mean: 6,198 +/- 1,696 bp). The h(2) of TL was 0.44 +/- 0.06 (P < 0.001), after adjusting for age, sex, and TL assay batch. As expected, TL was negatively correlated with age (r = -0.40; P < 0.001). There was no significant difference in TL between men and women, consistent with our previous findings that Amish men lived as long as Amish women. There was a stronger and positive correlation and association between TL in the offspring and paternal TL (r = 0.46, P < 0.001; beta = 0.22, P = 0.006) than offspring and maternal TL (r = 0.18, P = 0.04; beta = -0.02, P = 0.4). Furthermore, we observed a positive correlation and association between daughter's TL and paternal lifespan (r = 0.20, P < 0.001; beta = 0.21, P = 0.04), but not between daughter's TL and maternal lifespan (r = -0.01, beta = 0.04; both P = not significant). Our data, which are based on one of the largest family studies of human TL, support a link between TL and aging and lifespan and suggest a strong genetic influence, possibly via an imprinting mechanism, on TL regulation.

Is genetic screening for hemochromatosis worthwhile?

Hereditary hemochromatosis is an iron overload disorder and is the most common recessive disease in Caucasians. About 80% of hemochromatosis patients are homozygous for the C282Y mutation in the HFE gene. Since iron accumulation can be prevented by phlebotomy, there is increasing interest in screening populations for hemochromatosis. Hemochromatosis is a disease that meets all the criteria for screening as set by the World Health Organization (WHO) or the US preventive services task force criteria for a screening program. However, there is no consensus on the value of a screening program for hemochromatosis. Moreover, there is no agreement on whether this screening should be based on the phenotype i.e. biochemical levels of serum iron parameters or on the genotype i.e. based on the presence of mutations in the HFE gene. Other important concerns are the lack of important data in evaluating screening as well as the psychosocial impact of a screening program. The present review analyses the current situation from a genetic-epidemiological perspective. We conclude that general population screening may be helpful to identify high-risk groups or individuals in the early stage of the disease so that treatment can be started. We suggest a two-phase screening program based on the first instance on serum iron levels and then a genetic test to only those with elevated serum iron parameters.

Does bilirubin protect against hemochromatosis gene (HFE) related mortality?

Serum bilirubin is an important antioxidant that is found at increased levels in hereditary hemochromatosis patients. We hypothesized that increased levels of serum bilirubin may play a protective role against oxidative stress induced by iron overload in carriers of mutations in the hereditary hemochromatosis gene (HFE). We studied the relation between serum total bilirubin, serum iron levels, the HFE C282Y and H63D mutations, and mortality. The study was conducted in 2,332 randomly selected subjects from the Rotterdam Study, a population-based follow-up study of people aged 55 years or over. Serum bilirubin levels were significantly correlated with serum iron (Pearson's correlation coefficient (r) = 0.4, P < 0.001), transferrin saturation (r = 0.4, P < 0.001), and serum ferritin (r = 0.2, P < 0.05). Carriers of the HFE mutations had higher levels of bilirubin compared to wild-type homozygotes. The relation was the strongest in H63D heterozygotes or homozygotes and C282Y heterozygotes. High levels of serum bilirubin were associated with a 2.8 (95% CI 0.9-8.8) fold reduction in mortality in H63D homozygotes and a 2.2 (1.0-4.7) fold reduction in mortality in C282Y heterozygotes. Taken together, our data suggest that the high levels of the antioxidant bilirubin may counteract the adverse effect of oxidative stress induced by iron overload. This may explain in part the reduced penetrance of the HFE mutations.