Role of genetic polymorphisms in myocardial infarction at young age

Identification of Important Genes Associated with the Development of Atherosclerosis

Atherosclerosis is one of the most important medical problems due to its prevalence and significant contribution to the structure of temporary and permanent disability and mortality. Atherosclerosis is a complex chain of events occurring in the vascular wall over many years. Disorders of lipid metabolism, inflammation, and impaired hemodynamics are important mechanisms of atherogenesis. A growing body of evidence strengthens the understanding of the role of genetic and epigenetic factors in individual predisposition and development of atherosclerosis and its clinical outcomes. In addition, hemodynamic changes, lipid metabolism abnormalities, and inflammation are closely related and have many overlapping links in regulation. A better study of these mechanisms may improve the quality of diagnosis and management of such patients.

SARS CoV2 infection _The longevity study perspectives

Like other infectious diseases, COVID-19 shows a clinical outcome enormously variable, ranging from asymptomatic to lethal. In Italy, like in other countries, old male individuals, with one or more comorbidity, are the most susceptible group, and show, consequently, the highest mortality, and morbidity, including lethal respiratory distress syndrome, as the most common complication. In addition, another extraordinary peculiarity, that is a surprising resistance to COVID-19, characterizes some Italian nonagenarians/centenarians. Despite having the typical COVID-19 signs and/or symptoms, such exceptional individuals show a surprising tendency to recover from illness and complications. On the other hand, long-lived people have an optimal performance of immune system related to an overexpression of anti-inflammatory variants in immune/inflammatory genes, as demonstrated by our and other groups. Consequently, we suggest long-lived people as an optimal model for detecting genetic profiles associated with the susceptibility and/or protection to COVID-19, to utilize as potential pharmacological targets for preventing or reducing viral infection in more vulnerable individuals.

Plasma Viscosity and NLR in Young Subjects with Myocardial Infarction: Evaluation at the Initial Stage and at 3 and 12 Months

In the "Sicilian study on juvenile myocardial infarction," we had evaluated plasma viscosity (PV) and neutrophil/lymphocyte ratio (NLR) in patients with acute myocardial infarction (AMI) at the age of ⩽45 years. Now, we examined the relationship between these 2 parameters in 120 subjects (109 men and 11 women) aged ⩽45 years with recent AMI. The patients were classified according to the number of cardiovascular risk factors, the electrocardiographic criteria (ST-segment elevation myocardial infarction [STEMI] or non-ST-segment elevation myocardial infarction [NSTEMI]), and the extent of coronary stenosis, evaluated with coronary angiography. On fasting venous blood, we measured PV at the shear rate of 450 s^-1 and NLR. The control group included 50 healthy subjects (mean age = 35.1 ± 7.8 years). At the initial stage, PV and NLR were significantly increased in comparison with controls. Subdividing AMI patients according to the median value of NLR, in the group with high NLR PV was significantly higher, whereas subdividing the patients according to the PV median value, NLR was not different between the 2 groups; 3 and 12 months after AMI, we observed only a significant decrease in NLR. Only PV was discriminant regarding the cardiovascular complications registered during an 18-month follow-up. The evaluation of PV may be of prognostic value in juvenile AMI.

Analysis of the Blood Viscosity Behavior in the Sicilian Study on Juvenile Myocardial Infarction

Considering the role of hemorheology in coronary circulation, we studied blood viscosity in patients with juvenile myocardial infarction. We examined whole blood viscosity at high shear rate using the cone-on-plate viscosimeter Wells-Brookfield ½ LVT and at low shear rate employing a viscometer Contraves LS30 in 120 patients (aged <46 years) with myocardial infarction, at the initial stage and subsequently 3 and 12 months after. At the initial stage, patients had an increased whole blood viscosity in comparison to normal controls. This hemorheological profile was not influenced by the cardiovascular risk factors, nor by the extent of coronary lesions, even if some differences were evident between patients with ST-segment elevation myocardial infarction (STEMI) and non-STEMI (NSTEMI). The blood viscosity pattern at the initial stage did not influence recurring ischemic events or the onset of heart failure during an 18 months’ follow-up. The neutrophil to lymphocyte ratio did not affect the blood viscosity pattern. We reevaluated 83 patients 3 months after and 70 patients 12 months after the acute coronary syndrome, and we found that the hemorheological parameters were still altered in comparison to normal controls at both times. We observed an impairment of the hemorheological pattern in young patients with myocardial infarction, partially influenced by the infarction type (STEMI and NSTEMI) and persisting in the long term.

Toll-like receptor-4 signaling pathway in aorta aging and diseases: "its double nature"

Recent advances in the field of innate immunity have revealed a complex role of innate immune signaling pathways in both tissue homeostasis and disease. Among them, the Toll-like receptor 4 (TLR-4) pathways has been linked to various pathophysiological conditions, such as cardiovascular diseases (CVDs). This has been interrogated by developing multiple laboratory tools that have shown in animal models and clinical conditions, the involvement of the TLR-4 signaling pathway in the pathophysiology of different CVDs, such as atherosclerosis, ischemic heart disease, heart failure, ischemia-reperfusion injury and aorta aneurysm. Among these, aorta aneurysm, a very complex pathological condition with uncertain etiology and fatal complications (i.e. dissection and rupture), has been associated with the occurrence of high risk cardiovascular conditions, including thrombosis and embolism. In this review, we discuss the possible role of TLR-4 signaling pathway in the development of aorta aneurysm, considering the emerging evidence from ongoing investigations. Our message is that emphasizing the role of TLR-4 signaling pathway in aorta aneurysm may serve as a starting point for future studies, leading to a better understanding of the pathophysiological basis and perhaps the effective treatment of this difficult human disease.

Plasma Metabolic Profile Determination in Young ST-segment Elevation Myocardial Infarction Patients with Ischemia and Reperfusion: Ultra-performance Liquid Chromatography and Mass Spectrometry for Pathway Analysis

Background:

This study was to establish a disease differentiation model for ST-segment elevation myocardial infarction (STEMI) youth patients experiencing ischemia and reperfusion via ultra-performance liquid chromatography and mass spectrometry (UPLC/MS) platform, which searches for closely related characteristic metabolites and metabolic pathways to evaluate their predictive value in the prognosis after discharge.

Methods:

Forty-seven consecutive STEMI patients (23 patients under 45 years of age, referred to here as “youth,” and 24 “elderly” patients) and 48 healthy control group members (24 youth, 24 elderly) were registered prospectively. The youth patients were required to provide a second blood draw during a follow-up visit one year after morbidity (n = 22, one lost). Characteristic metabolites and relative metabolic pathways were screened via UPLC/MS platform base on the Kyoto encyclopedia of genes and genomes (KEGG) and Human Metabolome Database. Receiver operating characteristic (ROC) curves were drawn to evaluate the predictive value of characteristic metabolites in the prognosis after discharge.

Results:

We successfully established an orthogonal partial least squares discriminated analysis model (R₂X = 71.2%, R₂Y = 79.6%, and Q₂ = 55.9%) and screened out 24 ions; the sphingolipid metabolism pathway showed the most drastic change. The ROC curve analysis showed that ceramide [Cer(d18:0/16:0), Cer(t18:0/12:0)] and sphinganine in the sphingolipid pathway have high sensitivity and specificity on the prognosis related to major adverse cardiovascular events after youth patients were discharged. The area under curve (AUC) was 0.671, 0.750, and 0.711, respectively. A follow-up validation one year after morbidity showed corresponding AUC of 0.778, 0.833, and 0.806.

Conclusions:

By analyzing the plasma metabolism of myocardial infarction patients, we successfully established a model that can distinguish two different factors simultaneously: pathological conditions and age. Sphingolipid metabolism is the top most altered pathway in young STEMI patients and as such may represent a valuable prognostic factor and potential therapeutic target.

Genetic association of Toll-like receptor 4 gene and coronary artery disease in a Chinese Han population

PURPOSE

Toll-like receptor 4 (TLR4) is known to be involved in innate immunity and inflammatory responses that play important roles in the pathogenesis of coronary artery disease (CAD). But the relationship between TLR4 gene and CAD has yet to be investigated. The present study aimed to evaluate the association of TLR4 gene polymorphisms with CAD susceptibility in a Chinese Han population.

METHODS

A total of 1094 subjects (577 unrelated patients with CAD and 517 controls) were recruited between 2008 and 2012. Three tag SNPs (rs1927907, rs1927911 and rs11536889) present in the TLR4 gene were genotyped using Sequenom Mass-ARRAY system.

RESULTS

The genotypic distributions of the three SNPs were not deviate from Hardy-Weinberg equilibrium. There was no significant difference in distributions of allelic frequencies of each SNPs between healthy controls and CAD patients (P > 0.05). Genotype frequencies of TLR4 gene did not show any statistically significant difference between the two groups in co-dominant, dominant or recessive genetic models (P > 0.05). The frequency of haplotypes in the case group was similar to that in the control group (P > 0.05).

CONCLUSION

TLR4 gene do not relate to genetic susceptibility of CAD in the Chinese Han population.

TLR4 Asp299Gly (rs4986790) polymorphism and coronary artery disease: a meta-analysis

Background. Previous studies have shown conflicting results on the association between toll-like receptor 4 (TLR4) Asp299Gly (rs4986790) polymorphism and coronary artery disease (CAD). The aim of this study was to evaluate the influence of TLR4 Asp299Gly polymorphism on CAD risk, CRP level and the number of stenotic coronary arteries, as well as to investigate whether G allele carriers would benefit more from statin treatment. Methods. PubMed, EMBASE, and CNKI databases were searched until May 2015. All the statistical tests were performed using R version 3.1.2. Odds ratio (OR) and 95% confidence interval (CI) were used to assess the association between TLR4 Asp299Gly polymorphism and CAD risk, the number of stenotic vessels, and the incidence of cardiovascular events according to statin-treated patients. Weighted mean difference (WMD) was calculated for the association between Asp299Gly and CRP level. Results. Overall, 12 case-control studies with 10,258 cases and 5,891 controls were included, and no association of TLR4Asp299Gly polymorphism with CAD was found (G allele vs. A allele: OR = 0.97, 95% CI [0.81-1.17], P = 0.75; AA vs. GG + AG: OR = 0.97, 95% CI [0.80-1.18], P = 0.76; GG vs. AG + AA: OR = 1.08, 95% CI [0.57-2.02], P = 0.82; AG vs. AA + GG: OR = 1.03, 95% CI [0.85-1.25], P = 0.74). Also, no association was noted between Asp299Gly and CRP level (WMD = -0.10, 95% CI [-0.62, 0.41], P = 0.69). Furthermore, no synergistic effect of statin and 299Gly was reported (Statin_AA vs. Statin_

AG/GG

OR = 1.12, 95% CI [0.41-3.09], P = 0.82). Discussion. This meta-analysis suggests no association of TLR4 Asp299Gly polymorphism with CAD and CRP level. It is further indicated that the G allele carriers may not benefit more from statin treatment. Further studies should include large sample size and high-quality literature to understand this issue in depth.

Polymorphisms in IL-10 and INF-γ genes are associated with early atherosclerosis in coronary but not in carotid arteries: A study of 122 autopsy cases of young adults

Atherosclerosis is a complex disease, involving both genetic and environmental factors. However, the influence of genetic variations on its early development remains unclear. This study examined the association of 12 different polymorphisms with atherosclerosis severity in anterior descending coronary (DA, n = 103) and carotid arteries (CA, n = 66) of autopsied young adults (< 30 years old). Histological sections (H-E) were classified according to the American Heart Association. Polymorphisms in ACE, TNF-α (− 308G/A and − 238 G/A), IFN-γ (+ 874 A/T), MMP-9 (− 1562 C/T), IL-10 (− 1082 A/G and − 819 C/T), NOS3 (894 G/T), ApoA1 (rs964184), ApoE (E2E3E4 isoforms), and TGF-β (codons 25 and 10) genes were genotyped by gel electrophoresis or automatic DNA sequencing. Firearm projectile or car accident was the main cause of death, and no information about classical risk factors was available. Histological analysis showed high prevalence of type III atherosclerotic lesions in both DA (69%) and CA (39%) arteries, while severe type IV and V lesions were observed in 14% (DA) and 33% (CA). Allele frequencies and genotype distributions were determined. Among the polymorphisms studied, IFN-γ and IL-10 (− 1082 A/G) were related to atherosclerosis severity in DA artery. No association between genotypes and lesion severity was found in CA. In conclusion, we observed that the high prevalence of early atherosclerosis in young adults is associated with IFN-γ (p < 0.001) and IL-10 (p = 0.013) genotypes. This association is blood vessel dependent. Our findings suggest that the vascular system presents site specialization, and specific genetic variations may provide future biomarkers for early disease identification.

•

Twelve SNPs were associated with atherosclerosis severity in autopsied young adults.

•

We found high prevalence of type III lesions in coronary and carotid arteries.

•

Even severe lesions (types IV and V) were found in DA (14%) and CA (33%) arteries.

•

Lesion severity was associated with IL-10 and IFN-γ genotype.

•

The association was observed only in coronary, but not in carotid artery.

Association of Connexin37 C1019T with myocardial infarction and coronary artery disease: a meta-analysis

BACKGROUND

Several studies have reported that Connexin37 (Cx37) gene C1019T polymorphism is associated with myocardial infarction (MI) and coronary artery disease (CAD). However, the results remain contradictory.

METHODS AND RESULTS

Pubmed, Embase, and Cochrane library databases were systemically searched. Data were extracted by two independent reviewers and pooled odds ratio (OR) with 95% confidence interval (CI) was calculated. A total of 3498 MI cases and 3986 controls, as well as 1808 CAD cases and 1197 controls were enrolled in this meta-analysis. For MI, the overall ORs and 95% CIs of 1019T were 1.04, 0.95-1.15; and 1.02, 0.85-1.22 in dominant and recessive models, respectively. For CAD, the overall ORs and 95% CIs of 1019T were 0.61, 0.51-0.72; and 0.52, 0.43-0.62 in dominant and recessive models, respectively. No publication bias was found in this meta-analysis.

CONCLUSIONS

This meta-analysis showed that Cx37 C1019T was a risk factor for MI and a protective factor for CAD.

Association of TLR and TREM-1 gene polymorphisms with risk of coronary artery disease in a Russian population

Atherosclerosis, manifesting itself as acute coronary syndrome, stroke, and peripheral arterial diseases, is a chronic progressive inflammatory disease which is driven by responses of both innate and adaptive immunity. Toll-like receptors (TLRs) and Triggering Receptor Expressed on Myeloid Cells-1 (TREM-1) are important effectors of the innate immune system, and polymorphisms within genes encoding them may increase risk of occurrence of various pathologies including cardiovascular disorders. Thus, we carried out a genetic association study on the sample of 702 consecutive Caucasian (Russian) patients with coronary artery disease (CAD) and 300 age-, sex-, and ethnicity-matched healthy controls. We revealed that the C/C genotype of the TLR1 rs5743551 polymorphism was significantly associated with a reduced risk of CAD according to the recessive model (OR=0.41, 95% CI=0.20-0.84, P=0.017, adjusted by age and gender). Concerning TREM-1 gene polymorphisms, we found that A/A genotype of the rs2234237 polymorphism, the G/G genotype of the rs6910730 polymorphism, the C/C genotype of the rs9471535 polymorphism, and the T/T genotype of the rs4711668 polymorphism were significantly associated with elevated CAD risk according to the recessive model (OR=5.52, 95% CI=1.17-25.98, P=0.011; OR=4.28, 95% CI=1.09-16.81, P=0.021; OR=5.55, 95% CI=1.18-26.09, P=0.011, and OR=1.66, 95% CI=1.10-2.52, P=0.014, respectively, adjusted by age and gender). Conversely, the G allele of the rs1817537 polymorphism, the T allele of the rs2234246 polymorphism, and the T allele of the rs3804277 polymorphism significantly correlated with similarly decreased risk of CAD according to the dominant model (OR=0.57, 95% CI=0.40-0.81, P=0.0013; OR=0.59, 95% CI=0.42-0.84, P=0.003, and OR=0.58, 95% CI=0.41-0.81, P=0.0014, respectively, adjusted by age and gender). We conclude that certain TLR and TREM-1 gene polymorphisms may be associated with CAD in Russian population; however, their significance as predictive and pathogenic markers of CAD should be interpreted with caution in other populations.

Cx37 C1019T polymorphism may contribute to the pathogenesis of coronary heart disease

OBJECTIVE

We conducted a meta-analysis of case-control studies to evaluate whether Cx37 C1019T (rs1764391 C>T) polymorphism may be implicated in the pathogenesis of coronary heart disease (CHD).

METHODS

The MEDLINE (1966-2013), the Cochrane Library Database (Issue 12, 2013), EMBASE (1980-2013), CINAHL (1982-2013), Web of Science (1945-2013), and the Chinese Biomedical Database (CBM) (1982-2013) were searched without language restrictions. Meta-analysis was performed with the use of the STATA statistical software. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were calculated.

RESULTS

Nine case-control studies with a total of 1426 CHD patients and 929 healthy controls met the inclusion criteria. Our results revealed that Cx37 C1019T polymorphism might be significantly correlated with the risk of CHD (T allele vs. C allele: OR=1.63, 95% CI=1.20-2.21, p=0.002; CT+TT vs. CC: OR=1.86, 95% CI=1.28-2.69, p=0.001; TT vs. CC+CT: OR=1.81, 95% CI=1.24-2.64, p=0.002; TT vs. CC: OR=2.50, 95% CI=1.46-4.27, p=0.001; TT vs. CT: OR=1.53, 95% CI=1.12-2.09, p=0.008; respectively). Further subgroup analysis by country indicated that Cx37 C1019T polymorphism might be closely linked to an increased risk of CHD among Chinese populations, while no positive associations were observed among non-Chinese populations (all p>0.05).

CONCLUSION

Our findings provide empirical evidence that Cx37 C1019T polymorphism may contribute to the pathogenesis of CHD, especially among Chinese populations.

Periodontal disease immunology: 'double indemnity' in protecting the host

During the last two to three decades our understanding of the immunobiology of periodontal disease has increased exponentially, both with respect to the microbial agents triggering the disease process and the molecular mechanisms of the host engagement maintaining homeostasis or leading to collateral tissue damage. These foundational scientific findings have laid the groundwork for translating cell phenotype, receptor engagement, intracellular signaling pathways and effector functions into a 'picture' of the periodontium as the host responds to the 'danger signals' of the microbial ecology to maintain homeostasis or succumb to a disease process. These findings implicate the chronicity of the local response in attempting to manage the microbial challenge, creating a 'Double Indemnity' in some patients that does not 'insure' health for the periodontium. As importantly, in reflecting the title of this volume of Periodontology 2000, this review attempts to inform the community of how the science of periodontal immunology gestated, how continual probing of the biology of the disease has led to an evolution in our knowledge base and how more recent studies in the postgenomic era are revolutionizing our understanding of disease initiation, progression and resolution. Thus, there has been substantial progress in our understanding of the molecular mechanisms of host-bacteria interactions that result in the clinical presentation and outcomes of destructive periodontitis. The science has embarked from observations of variations in responses related to disease expression with a focus for utilization of the responses in diagnosis and therapeutic outcomes, to current investigations using cutting-edge fundamental biological processes to attempt to model the initiation and progression of soft- and hard-tissue destruction of the periodontium. As importantly, the next era in the immunobiology of periodontal disease will need to engage more sophisticated experimental designs for clinical studies to enable robust translation of basic biologic processes that are in action early in the transition from health to disease, those which stimulate microenvironmental changes that select for a more pathogenic microbial ecology and those that represent a rebalancing of the complex host responses and a resolution of inflammatory tissue destruction.

Gap junctions and connexin hemichannels underpin hemostasis and thrombosis

BACKGROUND

Connexins are a widespread family of membrane proteins that assemble into hexameric hemichannels, also known as connexons. Connexons regulate membrane permeability in individual cells or couple between adjacent cells to form gap junctions and thereby provide a pathway for regulated intercellular communication. We have examined the role of connexins in platelets, blood cells that circulate in isolation but on tissue injury adhere to each other and the vessel wall to prevent blood loss and to facilitate wound repair.

METHODS AND RESULTS

We report the presence of connexins in platelets, notably connexin37, and that the formation of gap junctions within platelet thrombi is required for the control of clot retraction. Inhibition of connexin function modulated a range of platelet functional responses before platelet-platelet contact and reduced laser-induced thrombosis in vivo in mice. Deletion of the Cx37 gene (Gja4) in transgenic mice reduced platelet aggregation, fibrinogen binding, granule secretion, and clot retraction, indicating an important role for connexin37 hemichannels and gap junctions in platelet thrombus function.

CONCLUSIONS

Together, these data demonstrate that platelet gap junctions and hemichannels underpin the control of hemostasis and thrombosis and represent potential therapeutic targets.

Genetics of longevity. data from the studies on Sicilian centenarians

The demographic and social changes of the past decades have determined improvements in public health and longevity. So, the number of centenarians is increasing as a worldwide phenomenon. Scientists have focused their attention on centenarians as optimal model to address the biological mechanisms of "successful and unsuccessful ageing". They are equipped to reach the extreme limits of human life span and, most importantly, to show relatively good health, being able to perform their routine daily life and to escape fatal age-related diseases, such as cardiovascular diseases and cancer. Thus, particular attention has been centered on their genetic background and immune system. In this review, we report our data gathered for over 10 years in Sicilian centenarians. Based on results obtained, we suggest longevity as the result of an optimal performance of immune system and an over-expression of anti-inflammatory sequence variants of immune/inflammatory genes. However, as well known, genetic, epigenetic, stochastic and environmental factors seem to have a crucial role in ageing and longevity. Epigenetics is associated with ageing, as demonstrated in many studies. In particular, ageing is associated with a global loss of methylation state. Thus, the aim of future studies will be to analyze the weight of epigenetic changes in ageing and longevity.

NAMPT (visfatin) and AKT1 genetic variants associate with myocardial infarction

BACKGROUND

High plasma levels of the adipokine NAMPT (or visfatin) have been associated with cardiovascular disease. However experimental data suggest that NAMPT, via Akt signaling, protects the myocardium against hypoxic insults. We studied whether the NAMPT rs1319501, AKT1 rs3730358, p53 rs1042522, Mdm2 rs2279744 or eNOS rs1799983 SNP:s linked to NAMPT and Akt signaling associate with risk of myocardial infarction (MI).

METHODS

Cases were 828 men and 346 women aged 45-70 who had suffered a first MI. Control individuals, 1062 men and 513 women, were randomly chosen from the study base. We employed unconditional logistic regression analysis.

RESULTS

The rs1319501 minor allele associated with MI among women aged 45-60; odds ratio (OR) under a recessive model of inheritance: 2.96 (95% confidence interval [CI] 1.06-8.29). Replication analysis in an independent material yielded OR point estimates in the same direction. The rs3730358 minor allele associated with low MI risk in men aged 45-60 (OR dominant model: 0.72, 95% CI 0.53-0.97), an association completely attenuated by adjusting for inflammatory markers.

CONCLUSIONS

The NAMPT rs1319501 minor allele associates with increased MI risk in young women. In young men a protective effect of the AKT1 rs3730358 minor allele was suggested, possibly related to an attenuated inflammation.

Prevalence of at-risk genotypes for genotoxic effects decreases with age in a randomly selected population in Flanders: a cross sectional study

BACKGROUND

We hypothesized that in Flanders (Belgium), the prevalence of at-risk genotypes for genotoxic effects decreases with age due to morbidity and mortality resulting from chronic diseases. Rather than polymorphisms in single genes, the interaction of multiple genetic polymorphisms in low penetrance genes involved in genotoxic effects might be of relevance.

METHODS

Genotyping was performed on 399 randomly selected adults (aged 50-65) and on 442 randomly selected adolescents. Based on their involvement in processes relevant to genotoxicity, 28 low penetrance polymorphisms affecting the phenotype in 19 genes were selected (xenobiotic metabolism, oxidative stress defense and DNA repair, respectively 13, 6 and 9 polymorphisms). Polymorphisms which, based on available literature, could not clearly be categorized a priori as leading to an 'increased risk' or a 'protective effect' were excluded.

RESULTS

The mean number of risk alleles for all investigated polymorphisms was found to be lower in the 'elderly' (17.0 ± 2.9) than the 'adolescent' (17.6 ± 3.1) subpopulation (P = 0.002). These results were not affected by gender nor smoking. The prevalence of a high (> 17 = median) number of risk alleles was less frequent in the 'elderly' (40.6%) than the 'adolescent' (51.4%) subpopulation (P = 0.002). In particular for phase II enzymes, the mean number of risk alleles was lower in the 'elderly' (4.3 ± 1.6 ) than the 'adolescent' age group (4.8 ± 1.9) P < 0.001 and the prevalence of a high (> 4 = median) number of risk alleles was less frequent in the 'elderly' (41.3%) than the adolescent subpopulation (56.3%, P < 0.001). The prevalence of a high (> 8 = median) number of risk alleles for DNA repair enzyme-coding genes was lower in the 'elderly' (37,3%) than the 'adolescent' subpopulation (45.6%, P = 0.017).

CONCLUSIONS

These observations are consistent with the hypothesis that, in Flanders, the prevalence of at-risk alleles in genes involved in genotoxic effects decreases with age, suggesting that persons carrying a higher number of at risk alleles (especially in phase II xenobiotic-metabolizing or DNA repair genes) are at a higher risk of morbidity and mortality from chronic diseases. Our findings also suggest that, regarding risk of disease associated with low penetrance polymorphisms, multiple polymorphisms should be taken into account, rather than single ones.