Heritability of death from coronary heart disease: a 36-year follow-up of 20 966 Swedish twins

Point/Counterpoint: The Role of Carotid Ultrasound

Vascular prevention is most cost-effective in high-risk patients, but secondary prevention misses many opportunities. The high-risk strategy- identifying patients with high levels of risk factors-is problematic because traditional risk factors predict only half of vascular events. In multiple regression, traditional risk factors explained only half of carotid atherosclerosis. New strategies are being explored, such as electron-beam computerized tomographic measurement of coronary calcification, to identify high-risk patients. Carotid plaque is a powerful tool for identifying and managing high-risk vascular patients, as it explains twice as much of unexplained vascular risk as coronary calcium by electron beam computerized tomography, and it has significant advantages compared with intimal-medial thickness. After adjustment for risk factors, patients in the highest quartile of baseline plaque area have 3.5 times the risk of stroke, death, or myocardial infarction compared with those in the lowest quartile. Those with regression or stable plaque have half the risk of those with progression after adjustment for the same panel of risk factors. The therapeutic target is plaque regression or stabilization, not just control of traditional risk factors. Trying to treat arteries without measuring plaque is like trying to treat hypertension without measuring the pressure, or hyperlipidemia without measuring the lipids.

Candidate gene polymorphisms and the 9p21 locus in acute coronary syndromes

It is now widely accepted that the classic environmental risk factors for atherosclerosis only partly explain the incidence of coronary artery disease and the development of acute coronary syndromes. Therefore, genetic factors that vary among human populations seem to be involved in the clinical manifestations of such patients. Substantial data suggest that a significant proportion of genetic polymorphisms involved in endothelial function, inflammation, lipid metabolism, thrombosis and fibrinolysis are often present in patients with acute coronary syndromes. In particular, a common variant on chromosome 9p21 was recently identified to affect the risk of myocardial infarction. Here, we review the progress of candidate gene studies and genome-wide association studies in identifying the genetic bases of complex cardiovascular diseases such as acute coronary syndromes.

[Research progress on the association between genetic variations in lipid metabolism and premature coronary artery disease]

Recent research has demonstrated a strong genetic linkage between premature coronary artery disease (pCAD) and dyslipidemia. Genetic variation in lipid metabolism can lead to impediment of lipid anabolism and catabolism, which promotes vascular arterosclerogenesis. Currently, related studies were focused on: (1) Gene mutations related to low density lipoprotein metabolism, such as low density lipoprotein receptor, apolipoprotein B, apolipoprotein E; (2) Gene mutations related to high density lipoprotein metabolism-related genes, such as ATP binding cassette transporter, apolipoprotein A1, lipoprotein lipase; (3) low density lipoprotein receptor-related genes: Adiponectin. These genes had been proved to be cor-related with pCAD. Mutations of these genes can lead to series of genetic disease characterized by pCAD. This review gives a brief summary of the roles of these genes played in the initiation and development of pCAD, providing valuable information to primer prevention and individualized treatment of CAD.

The genetic response to short-term interventions affecting cardiovascular function: rationale and design of the Heredity and Phenotype Intervention (HAPI) Heart Study

BACKGROUND

The etiology of cardiovascular disease (CVD) is multifactorial. Efforts to identify genes influencing CVD risk have met with limited success to date, likely because of the small effect sizes of common CVD risk alleles and the presence of gene by gene and gene by environment interactions.

METHODS

The HAPI Heart Study was initiated in 2002 to measure the cardiovascular response to 4 short-term interventions affecting cardiovascular risk factors and to identify the genetic and environmental determinants of these responses. The measurements included blood pressure responses to the cold pressor stress test and to a high salt diet, triglyceride excursion in response to a high-fat challenge, and response in platelet aggregation to aspirin therapy.

RESULTS

The interventions were carried out in 868 relatively healthy Amish adults from large families. The heritabilities of selected response traits for each intervention ranged from 8% to 38%, suggesting that some of the variation associated with response to each intervention can be attributed to the additive effects of genes.

CONCLUSIONS

Identifying these response genes may identify new mechanisms influencing CVD and may lead to individualized preventive strategies and improved early detection of high-risk individuals.

Identifying the susceptibility genes for coronary artery disease: from hyperbole through doubt to cautious optimism

The genetic basis of coronary artery disease (CAD) is complex, and the fact that an alarmingly high proportion of reported associations between genetic variants and CAD are not replicated has generated uncertainty as to whether molecular genetics is ever going to deliver on the promises delivered in the late 1990s. However, during 2007, the first generation of large-scale genome-wide association studies using high-density, single nucleotide polymorphism genotyping arrays have revealed genetic variants that are robustly associated with CAD and CAD-related traits such as type 2 diabetes and obesity. In particular, a robust susceptibility locus for CAD has been identified on chromosome 9p21. Also, evidence has been obtained that multiple rare alleles with fairly strong phenotypic effects may contribute to the genetic heritability of CAD, in addition to common variants with a modest impact on risk. Furthermore, new mechanistic connections have been discovered between different common complex diseases including CAD. This review focuses on the challenges and recent advances of molecular genetics in dissecting the molecular pathophysiology of atherothrombosis and defining novel targets for treatment.

Genetic variation and atherosclerosis

A family history of atherosclerosis is independently associated with an increased incidence of cardiovascular events. The genetic factors underlying the importance of inheritance in atherosclerosis are starting to be understood. Genetic variation, such as mutations or common polymorphisms has been shown to be involved in modulation of a range of risk factors, such as plasma lipoprotein levels, inflammation and vascular calcification. This review presents examples of present studies of the role of genetic polymorphism in atherosclerosis.

A kinesin family member 6 variant is associated with coronary heart disease in the Women's Health Study

OBJECTIVES

We asked if carriers of the 719Arg allele of kinesin family member 6 (KIF6) have increased risk of coronary heart disease (CHD) in a cohort of initially healthy Caucasian American women.

BACKGROUND

The 719Arg allele of KIF6 (rs20455) has been reported to be associated with increased risk of CHD in a large population-based prospective study, ARIC (Atherosclerosis Risk in Communities), and in the placebo arms of 2 statin trials, CARE (Cholesterol and Recurrent Events) and WOSCOPS (West of Scotland Coronary Prevention Study). However, this KIF6 variant was not specifically investigated in the female subgroup in the ARIC study, and the CARE and WOSCOPS trials included only a small number of female patients.

METHODS

Genotypes of the rs20455 single nucleotide polymorphism (SNP) were determined among 25,283 initially healthy Caucasian women, age 45 years and older, participating in the WHS (Women's Health Study) who were prospectively followed over a 12-year period for incident cardiovascular events. The risk associated with the 719Arg allele of KIF6 was estimated using Cox proportional hazards models that adjusted for age and traditional risk factors.

RESULTS

During follow-up, 953 women suffered a first-ever CHD event (myocardial infarction, coronary revascularization, or cardiovascular death) or first-ever ischemic stroke. Compared with noncarriers, carriers of the 719Arg allele had an increased risk of CHD (hazard ratio [HR] = 1.24 [95% confidence interval (CI) 1.04 to 1.46, p = 0.013]) and myocardial infarction (HR = 1.34 [95% CI 1.02 to 1.75, p = 0.034]) but not ischemic stroke.

CONCLUSIONS

Confirming and extending previous reports, carriers of the 719Arg allele of KIF6 have 34% higher risk of myocardial infarction and 24% higher risk of CHD compared with noncarriers among 25,283 women from the WHS.

Genetic susceptibility of myocardial infarction

The aim of this study was to determine the influence of genetic factors on the first episode of acute myocardial infarction. Probandwise concordances, tetrachoric correlations and quantitative genetic analyses of liability were applied to data drawn from the Swedish Twin Registry and the Swedish Acute Myocardial Infarction Register. All same-sexed twin pairs born between 1886 and 1958 who were alive in 1987 were included in the analyses. Our results show that concordance rates for acute myocardial infarction in monozygotic (MZ) twins were similar across sexes (among males .26 and females .27). For dizygotic (DZ) twins the concordances were .20 for males and .16 for females, yielding a greater MZ-DZ concordance differential for females than males. Tetrachoric correlations were greater for MZ than DZ twins for both sexes (.49 for male MZ and .34 for male DZ-twins and .56 and .35 for female MZ and DZ twins respectively). Quantitative genetic analyses of liability resulted in equal variance components for males and females (.36) but significantly different thresholds (prevalences). In conclusion, liability to first occurrence of acute myocardial infarction is moderately influenced by genetic variants in both sexes. The familial influence on phenotypic variance is exclusively explained by additive genetic factors.

Five common gene variants identify elevated genetic risk for coronary heart disease

PURPOSE

Because multiple genetic variants influence risk for coronary heart disease, we combined multiple variants that had been associated with coronary heart disease in several studies into a genetic risk score and asked whether a high genetic risk score would be significantly associated with coronary heart disease after accounting for traditional risk factors.

METHODS

We considered five variants that were associated with coronary heart disease in two studies and confirmed in the Atherosclerosis Risk in Communities study: rs20455 (KIF6), rs3900940 (MYH15), rs7439293 (PALLD), rs2298566 (SNX19), and rs1010 (VAMP8). We calculated a genetic risk score for each Atherosclerosis Risk in Communities study participant and estimated the hazard ratio for incident coronary heart disease of a high genetic risk score (compared with not-high) in Cox models that adjusted for traditional risk factors during a median of 13 years of follow-up.

RESULTS

For white participants with a high genetic risk score (4% of the 9129 whites), compared with those without a high genetic risk score, the hazard ratio for incident coronary heart disease was 1.57 (95% confidence interval 1.21-2.04; P = 0.001). Internal validation using bootstrap samples estimated that a hazard ratio of 1.43 could be expected in external populations.

CONCLUSIONS

After adjusting for traditional risk factors, those with a high genetic risk score had a 57% increased risk of incident coronary heart disease in the Atherosclerosis Risk in Communities study.

What will whole genome searches for susceptibility genes for common complex disease offer to clinical practice?

In the developed world the majority of disease results from common, but complex disorders such as diabetes, obesity and cancer. Genetic variation explains a large proportion of an individual's risk of developing these diseases; however, success in identifying the particular gene variants involved has been limited. Recent advances in high-throughput genotyping technology, and a better understanding of the genetic architecture of complex disease has led to the development of genome-wide association studies (GWA), which are providing novel and important insights into disease processes. The results from these studies could be of substantial clinical importance in the relatively near future. In this review, we present some recent, exciting findings from studies that have used the GWA approach, and discuss the clinical application of identifying disease susceptibility genes and variants.

Telomere length predicts survival independent of genetic influences

Telomeres prevent the loss of coding genetic material during chromosomal replication. Previous research suggests that shorter telomere length may be associated with lower survival. Because genetic factors are important for individual differences in both telomere length and mortality, this association could reflect genetic or environmental pleiotropy rather than a direct biological effect of telomeres. We demonstrate through within-pair analyses of Swedish twins that telomere length at advanced age is a biomarker that predicts survival beyond the impact of early familial environment and genetic factors in common with telomere length and mortality. Twins with the shortest telomeres had a three times greater risk of death during the follow-up period than their co-twins with the longest telomere measurements [hazard ratio (RR) = 2.8, 95% confidence interval 1.1-7.3, P = 0.03].

Association of gene variants with incident myocardial infarction in the Cardiovascular Health Study

OBJECTIVE

We asked whether single nucleotide polymorphisms (SNPs) that had been nominally associated with cardiovascular disease in antecedent studies were also associated with cardiovascular disease in a population-based prospective study of 4522 individuals aged 65 or older.

METHODS AND RESULTS

Based on antecedent studies, we prespecified a risk allele and an inheritance model for each of 74 SNPs. We then tested the association of these SNPs with myocardial infarction (MI) in the Cardiovascular Health Study (CHS). The prespecified risk alleles of 8 SNPs were nominally associated (1-sided P<0.05) with increased risk of MI in White CHS participants. The false discovery rate for these 8 was 0.43, suggesting that about 4 of these 8 are likely to be true positives. The 4 of these 8 SNPs that had the strongest evidence for association with cardiovascular disease before testing in CHS (association in 3 antecedent studies) were in KIF6 (CHS HR=1.29; 90%CI 1.1 to 1.52), VAMP8 (HR=1.2; 90%CI 1.02 to 1.41), TAS2R50 (HR=1.13; 90%CI 1 to 1.27), and LPA (HR=1.62; 90%CI 1.09 to 2.42).

CONCLUSIONS

Although most of the SNPs investigated were not associated with MI in CHS, evidence from this investigation combined with previous studies suggests that 4 of these SNPs are likely associated with MI.

The contribution of familial and heritable risks in heart failure

PURPOSE OF REVIEW

The purpose of this review is to summarize the recent literature regarding the familial heritability of heart failure and to discuss the possible mechanisms through which this risk is mediated.

RECENT FINDINGS

Data from the Framingham Heart Study recently showed that the parental occurrence of heart failure increases the risk of heart failure in offspring. Although the mechanisms mediating this increased risk are not elucidated, heritable risks of heart failure may result from genes affecting the cardiac or vascular systems. Alternatively, familial risk may be mediated partly through the inheritance of recognized or as yet unidentified risk factors for heart failure. Heritable components or genetic loci for quantitative traits contribute to the development of hypertension, coronary artery disease, cardiomyopathies, valvular heart disease, and metabolic conditions, which collectively increase the risk of heart failure.

SUMMARY

A careful assessment of the family history of heart failure and associated risk factors may identify treatable targets that can potentially reduce the likelihood of developing heart failure, and can assist in the implementation of preventive strategies for risk populations with stages A and B heart failure.

Heritability of carotid intima-media thickness: a twin study

OBJECTIVE

To estimate the heritability of carotid intima-media thickness (IMT), a surrogate marker for atherosclerosis, independent of traditional coronary risk factors.

METHODS AND RESULTS

We performed a classical twin study of carotid IMT using 98 middle-aged male twin pairs, 58 monozygotic (MZ) and 40 dizygotic (DZ) pairs, from the Vietnam Era Twin Registry. All twins were free of overt cardiovascular disease. Carotid IMT was measured by ultrasound. Bivariate and multivariate analyses were used to determine the association between traditional cardiovascular risk factors and carotid IMT. Intraclass correlation coefficients and genetic modeling techniques were used to determine the relative contributions of genes and environment to the variation in carotid IMT. In our sample, the mean of the maximum carotid IMT was 0.75+/-0.11. Age, systolic blood pressure and HDL were significantly associated with carotid IMT. The intraclass correlation coefficient for carotid IMT was larger in MZ (0.66; 95% confidence interval [CI], 0.62-0.69) than in DZ twins (0.37; 95% CI, 0.29-0.44), and the unadjusted heritability was 0.69 (95% CI, 0.54-0.79). After adjusting for traditional coronary risk factors, the heritability of carotid IMT was slightly reduced but still of considerable magnitude (0.59; 95% CI, 0.39-0.73).

CONCLUSION

Genetic factors have a substantial influence on the variation of carotid IMT. Most of this genetic effect occurs through pathways independent of traditional coronary risk factors.

Apolipoprotein E polymorphism, age and coronary heart disease

Plasma concentrations of lipids, lipoproteins, and apolipoproteins (apo) are established risk factors for coronary heart disease (CHD). The knowledge of lipid profile may predict the potential victims of cardiovascular disease before its initiation and progression and offer the opportunity for primary prevention. The most common apo E polymorphism has been found to influence blood lipid concentrations and its correlation with CHD has been extensively investigated in the last decade. At younger ages, death from CHD is influenced by genetic factors, while the genetic effect decreases at older ages where environmental factors may play a more prominent role. If apo E polymorphism is an important genetic factor in the pathogenesis of atherosclerosis, it could affect the age of CHD onset. This review analyses the influence of apo E polymorphism on blood lipids and CHD in respect to age.

The common Y402H variant in complement factor H gene is not associated with susceptibility to myocardial infarction and its related risk factors

Recently, the genetic variant Y402H in the CFH (complement factor H) gene was associated with an increased risk for MI (myocardial infarction) in a prospective Caucasian cohort. In another nested case-control study, however, the CFH-Y402H variant did not carry susceptibility to MI. The aim of the present study was to test for an association between the CFH-Y402H variant and MI in a large case-control sample with a familial background for CAD (coronary artery disease). A total of 2161 individuals from the German MI family study were studied by questionnaire, physical examination and biochemical analyses. MI patients (n=1188; 51.4±8.6 years at first MI) were recruited from families with at least two members affected by MI and/or severe CAD. Spouses, sisters-in-law and brothers-in-law respectively, without MI/CAD were included as unaffected controls (n=973; 56.9±9.8 years). Genotyping was performed using a TaqMan assay. The common Y402H variant in the CFH gene was not associated with classical cardiovascular risk factors (diabetes, hypercholesterolaemia, hypertension, obesity, smoking and C-reactive protein serum levels). No association was found between the CFH-Y402H variant and susceptibility to MI. Separate analyses in both men and women revealed no gender-specific influence of the gene variant on cardiovascular risk factors or MI. This investigation was unable to replicate the association between the common CFH-Y402H variant and susceptibility to MI in our large Caucasian population which is enriched for genetic factors. We conclude that the CFH-Y402H variant has no relevant risk-modifying effect in our population.

Platelet genomics and the risk of atherothrombosis

Platelets play a pivotal role in atherothrombosis after coronary artery plaque rupture. The extent of response of platelets to such an event varies between individuals. This variation is for a large extent genetically controlled. A comprehensive study of sequence variation that modifies the platelet response to agonists is, however, lacking. We set out to discover the regulatory nodes of platelet function by an integrated systems biology approach. The high density genotyping of 110 genes in a cohort of more than 500 individuals, in whom the platelet response to ADP and collagen-related peptide was determined, allowed the robust definition of the first set of regulatory nodes. Microarray and proteomics studies on platelets from individuals with a so-called 'extreme end' response phenotype provided further insight into key regulators of platelet function. In addition, the completion of the HapMap project allows the comprehensive surveying of the genome for sequence variation by the testing of a limited number of single nucleotide polymorphisms (SNPs). With the advent of high density (i.e. 500,000 SNPs) genotyping arrays large number of case and control samples can be tested at an affordable cost. The recently completed Wellcome Trust Case Control Consortium (WTCCC) study has allowed us to address the question of whether common sequence variation confers risk for seven common diseases, one being myocardial infarction. The results of the WTCCC genome-wide association study and issues of case-control study design, particularly the selection of suitable controls, will be reviewed. In conclusion the integration of the results from the platelet systems biology study with those of the WTCCC project enhances our understanding of the mechanisms underlying common conditions such as atherothrombosis and provides pointers to novel cellular mechanisms and pathways.

Association of a Vcam1 mutation with atherosclerosis susceptibility in diet-induced models of atherosclerosis

We previously identified a G>A single nucleotide polymorphism (SNP) between C57BL/6J (B6) and C3H/HeJ (C3H) mouse strains at position 2077 in the coding region of Vcam1 that leads to substitution of an amino acid from aspartic acid (D) to asparagine (N) in the protein product. In the present study, we investigated the association of this SNP with atherosclerosis susceptibility using a panel of inbred mouse strains, a set of recombinant inbred (RI) strains derived from B6 and C3H mice, and a cohort of F2 mice derived from B6 and C3H apolipoprotein E-deficient (apoE(-/-)) mice. Inbred strain analysis revealed that mouse strains with the B6 Vcam1 genotype developed significantly larger atherosclerotic lesions than strains with the C3H genotype (4622+/-2816 microm(2)/section versus 362+/-697 microm(2)/section; P=0.029). BXH RI strains with the B6 Vcam1 genotype also developed larger atherosclerotic lesions than those with the C3H genotype (8305+/-9031 microm(2)/section versus 2139+/-2931 microm(2)/section) although the difference was not statistically significant (P=0.13). In contrast, no association was detected between Vcam1 and atherosclerotic lesion size in F2 mice. The present data indicate that the G>A mutation of Vcam1 is associated with atherosclerotic lesion formation in the dietary but not apoE(-/-) models of atherosclerosis and this association suggests a role for the Vcam1 gene in influencing atherosclerosis susceptibility.

Lymphotoxin-alpha and galectin-2 SNPs are not associated with myocardial infarction in two different German populations

Recent data provided strong evidence for the association of single nucleotide polymorphisms (SNPs) in the lymphotoxin-alpha (LTA) and galectin-2 (LGALS2) genes with myocardial infarction (MI) in a Japanese population. For populations of other genetic background, the relevance of these polymorphisms in the pathogenesis of MI remains controversial. We aimed to define the role of LTA and LGALS2 SNPs in two German MI populations with markedly different ascertainment strategies. Two different MI populations were studied. In the first population, MI patients were ascertained by a strong family history of MI (n = 1214). Controls were unrelated disease-free participants of the study (n = 1080). The second population included patients suffering from sporadic (nonfamilial) MI from the German KORA register (n = 607). The control group consisted of participants of the WHO MONICA survey in Germany (n = 1492). TaqMan assays were used to determine the genotypes of 4 SNPs in the LTA genomic region and 1 SNP in the LGALS2 gene. Single SNPs in both genomic regions as well as haplotypes in the LTA genomic region were tested for association in various models of inheritance. No association with MI could be found for any of the examined SNPs in the LTA genomic region and LGALS2 gene, or for haplotypes spanning the LTA genomic region. In two MI populations of European descent with markedly different ascertainment strategies, we were not able to identify a significant association of SNPs in the LTA genomic region or the LGALS2 gene with MI. These variants are unlikely to play a significant role in populations of European origin.

Genetic influences on angina pectoris and its impact on coronary heart disease

As functional properties of the coronaries may differ between coronary heart disease (CHD) patients with or without angina pectoris (AP), it is possible that different genetic mechanisms could be involved in the various CHD phenotypes. The primary aim of this study was, therefore, to determine the relative importance of genetic factors for AP as well as the impact of AP on CHD death in general. All same-sexed twins born between 1886 and 1958 included in the Swedish Twin Registry served as a base for this study. Information from the Swedish Cause of Death Register was used for diagnosing CHD death. Standard methods applied in twin research such as survival and quantitative genetic models were used. The impact of AP on CHD death was significant among both sexes, with larger estimates for males (hazard ratio and 95% CI 2.0 (1.8-2.3)) than females (1.6 (1.4-1.8)). Probandwise concordances and intraclass correlations for AP and CHD death were in general greater in monozygotic than dizygotic twins among both sexes. Heritability analyses resulted in moderate heritability estimates for AP in both sexes (0.39 (0.29-0.49) for males and 0.43 (0.08-0.51) for females). The correlation between AP and CHD was exclusively explained by the influence of familial factors in both sexes. In conclusion, our data imply genetic influences for AP and CHD death among both sexes and that AP is important as a risk factor for CHD death in both males and females, due in part to shared genetic pathways.

Understanding diet-gene interactions: lessons from studying nutrigenomics and cardiovascular disease

Socioeconomic development has resulted in an epidemiologic transition which has involved an increase in mortality and morbidity from chronic non-communicable diseases. Cardiovascular disease is one such disease. The rapidity with which this transition has occurred suggests that genetic factors are unlikely to be responsible. However, studies in twins suggest significant heritability for cardiovascular disease and its associated risk factors. We present data showing diet-gene interactions involving polymorphisms at the PPARA and PLIN loci. These data support the hypothesis that chronic diseases such as cardiovascular disease are a consequence of a complex interplay of genetic and environmental factors, of which diet plays an important role. They suggest that the effects of diet on chronic disease may be masked by heterogeneity of effect related to genetic variability between individuals and that consideration of diet-gene interactions may contribute to our understanding of the pathogenesis of cardiovascular disease. The identification of diet-gene interactions offers us an opportunity to develop dietary interventions that will obviate the effects of genetic factors on the risk of disease. In this way, we may be able to develop personalized dietary recommendations that optimize the outcome for the individual concerned. Nevertheless, while existing data points to the value of these studies, significant challenges need to be met to ensure that our conclusions are scientifically valid.

Multiple less common genetic variants explain the association of the cholesteryl ester transfer protein gene with coronary artery disease

OBJECTIVES

The objective of this study was to identify associations of the cholesteryl ester transfer protein (CETP) gene with coronary artery disease (CAD) with tagging (t) single nucleotide polymorphisms (SNPs) chosen to optimally account for intra-genic variation.

BACKGROUND

The CETP gene plays a critical role in lipoprotein metabolism, but the common and well-studied TaqIB variant is inconsistently predictive of CAD.

METHODS

From a deoxyribonucleic acid bank of 10,020 individuals, nondiabetic nonsmoking patients (n = 4,811) with angiographically defined, clinically significant CAD (> or =70% stenosis) or normal coronaries were genotyped for 11 CETP tSNPs. Myocardial infarction (MI) and lipid levels were evaluated as secondary end points.

RESULTS

Analysis of single tSNPs, corrected for multiple comparisons (p < 0.00485), identified allele +1086A to be associated with CAD (p = 0.0034). Suggestive allelic and significant genotypic associations were found for -631AA (odds ratio [OR] = 3.95, p = 0.004 vs. CC) and +2389GA (OR = 1.21, p = 0.003 vs. GG). Haplotype analysis by linkage disequilibrium (LD) group revealed a CAD association for LD group B (p = 0.0025 across T+1086A, C+878T, C+408T) and near significance for LD group A (p = 0.013 across C-631A, MspI, G+2389A). A weak protective trend for TaqIB was eliminated by adjustment for other tSNPs, and haplotype analyses suggested that TaqIB was simply a marker for other tSNPs or haplotypes. No tSNP or haplotype associations with MI were found.

CONCLUSIONS

Multiple, less common SNPs and haplotype variants underlie CETP-related CAD risk, for which the common TaqIB variant is simply a poor marker. The occurrence of risk-related variants on separate haplotypes suggests genetic-risk complexity and allelic heterogeneity. (Database Registry of the Intermountain Heart Collaborative Study; http://clinicaltrials.gov/ct/show/NCT00406185?order=1; NCT00406185).

A common variant on chromosome 9p21 affects the risk of myocardial infarction

The global endemic of cardiovascular diseases calls for improved risk assessment and treatment. Here, we describe an association between myocardial infarction (MI) and a common sequence variant on chromosome 9p21. This study included a total of 4587 cases and 12,767 controls. The identified variant, adjacent to the tumor suppressor genes CDKN2A and CDKN2B, was associated with the disease with high significance. Approximately 21% of individuals in the population are homozygous for this variant, and their estimated risk of suffering myocardial infarction is 1.64 times as great as that of noncarriers. The corresponding risk is 2.02 times as great for early-onset cases. The population attributable risk is 21% for MI in general and 31% for early-onset cases.

Bivariate genetic modeling of cardiovascular stress reactivity: does stress uncover genetic variance?

OBJECTIVE

To test the existence of gene-by-stress interaction by assessing cardiovascular stress reactivity in monozygotic and dizygotic twins.

METHODS

We studied 160 adolescent (mean age 16.7 +/- 2.0 years; range 13-22 years) and 212 middle-aged twin pairs (mean age 44.2 +/- 6.7 years; range 34-63 years). Systolic (SBP) and diastolic (DBP) blood pressure, heart rate (HR), pre-ejection period (PEP), and respiratory sinus arrhythmia (RSA) were measured at rest and during a choice reaction time and a mental arithmetic task. We used a bivariate analysis of the resting and mean stress levels to test for gene-by-stress interaction, which can be caused by the emergence of new genetic variance specific to stress or by stress-induced amplification of the existing genetic variance at rest.

RESULTS

Genetic factors significantly contributed to individual differences in resting SBP, DBP, HR, PEP, and RSA levels in the adolescent (heritability range 0.31-0.70) and middle-aged (heritability range 0.32-0.64) cohorts. The effect of these genetic factors was amplified by stress for all variables in the adolescent cohort, and for SBP in the middle-aged cohort. In addition, stress-specific genetic variation emerged for HR in both cohorts and for PEP and SBP in the adolescent cohort. Heritability of stress levels of SBP, DBP, HR, PEP, and RSA ranged from 0.54 to 0.74 in the adolescents and from 0.44 to 0.64 in the middle-aged cohort.

CONCLUSIONS

Stress uncovers genetic variance in BP, HR, and cardiac sympathovagal balance through the emergence of new stress-specific genetic effects and the amplification of existing genetic effects that also affect the resting values.

Genetics in psychosomatic medicine: research designs and statistical approaches

It has become increasingly clear that genetic factors influence many of the behaviors and disease endpoints of interest to psychosomatic medicine researchers. There has been increasing interest in incorporating genetic variation markers into psychosomatic research. In this Statistical Corner article, we build on the valuable experiences gained during two workshops for "starters in the field" at the American Psychosomatic Society and the Society for Psychophysiological Research to review two common genetically informative research designs for human studies: twin and genetic association studies. We outline statistical techniques for each and, for genetic association studies, address special topics, including the treatment of race and ethnicity, gene x gene and gene x environment interaction, haplotype analysis, and power and sample size. Finally, we discuss the issue of nonreplication and interpretation of results derived from genetic association studies. We hope this overview of twin and genetic association designs will support and stimulate thoughtful applications of genetic approaches within psychosomatic medicine.

Heritability of the ankle-brachial index: the Framingham Offspring study

The ankle-brachial blood pressure index (ABI) is a widely utilized measure for detecting peripheral arterial disease. Genetic contributions to variation in ABI are largely unknown. The authors sought to estimate ABI heritability in a community-based sample. From 1995 to 1998, ABI was measured in 1,097 men and 1,189 women (mean age = 57 years; range, 29-85 years) from 999 families in the Framingham Offspring cohort. Correlation coefficients for sibling pairs were calculated using the family correlations (FCOR) procedure in S.A.G.E. (Case Western Reserve University, Cleveland, Ohio). The heritability of ABI was estimated using variance-components methods in SOLAR (Southwest Foundation for Biomedical Research, San Antonio, Texas). Analyses were performed on normalized crude ABI and on normalized residuals from multiple linear regression analyses in SAS (SAS Institute, Inc., Cary, North Carolina) that adjusted for age, sex, smoking, diabetes, hypertension, ratio of total cholesterol to high density lipoprotein cholesterol, log triglyceride level, and body mass index. The mean ABI was 1.1 (range, 0.4-1.4). The age- and sex-adjusted and multivariable-adjusted sibling-pair correlation coefficients for normalized ABI were 0.15 and 0.11, respectively, resulting in heritability estimates of 0.30 and 0.22. Crude, age- and sex-adjusted, and multivariable-adjusted heritabilities for normalized ABI estimated using variance-components analysis were 0.27 (standard error, 0.06), 0.30 (standard error, 0.06), and 0.21 (standard error, 0.06), respectively (all p values < 0.0001). A modest proportion of the variability in ABI is explained by genetic factors.

The genetics of bronchopulmonary dysplasia

Over the last 15 years, neonatal morbidity and mortality has changed little for very low birth weight babies despite significant technological and therapeutic advances. Bronchopulmonary dysplasia (BPD) continues to be a major problem despite antenatal steroid use, surfactant replacement therapy, gentle noninvasive ventilation techniques, permissive hypercarbia, and judicious use of oxygen. Current evidence supports multiple contributing factors. Prematurity is the cardinal factor; others include pulmonary baro/volutrauma, hyperoxia, and inflammation. BPD is an end product of pulmonary inflammatory response and lung repair with impaired alveolarization and vascularization in response to lung injury. These sequences involve multiple morphoregulatory molecules, which have a range of activities largely determined by genetic variability. A clearer understanding of genetic susceptibility for BPD has recently emerged. Twin studies have shown that the BPD status of one twin, even after correcting for contributing factors, is a highly significant predictor of BPD in the second twin. After controlling for covariates, genetic factors account for 53% (P = 0.004, 95% CI = 16%-89%) of the variance in liability for BPD. Incremental improvements will likely depend on identification of these genetic components for targeting specific therapies.

GATA2 is associated with familial early-onset coronary artery disease

The transcription factor GATA2 plays an essential role in the establishment and maintenance of adult hematopoiesis. It is expressed in hematopoietic stem cells, as well as the cells that make up the aortic vasculature, namely aortic endothelial cells and smooth muscle cells. We have shown that GATA2 expression is predictive of location within the thoracic aorta; location is suggested to be a surrogate for disease susceptibility. The GATA2 gene maps beneath the Chromosome 3q linkage peak from our family-based sample set (GENECARD) study of early-onset coronary artery disease. Given these observations, we investigated the relationship of several known and novel polymorphisms within GATA2 to coronary artery disease. We identified five single nucleotide polymorphisms that were significantly associated with early-onset coronary artery disease in GENECARD. These results were validated by identifying significant association of two of these single nucleotide polymorphisms in an independent case-control sample set that was phenotypically similar to the GENECARD families. These observations identify GATA2 as a novel susceptibility gene for coronary artery disease and suggest that the study of this transcription factor and its downstream targets may uncover a regulatory network important for coronary artery disease inheritance.

Coronary artery disease (CAD) is the most common form of heart disease in the Western world and is one of the leading causes of death in the United States. CAD is inherited and is a complex genetic disease because it results from changes to multiple genes acting in concert with one another and the environment. The authors locate CAD susceptibility genes by convergence of techniques and identify variation within a gene of interest in an early-onset CAD population. If a specific variant is found more often in affected individuals or families than in controls, this can suggest that this gene variant is associated with disease. The authors have identified a gene, GATA2, which is located in a genomic region suspected to contain genes for CAD and displays expression patterns predictive of location of disease within human donor aortas. They have identified several GATA2 variants that segregate with CAD in a family-based early-onset CAD population and have further validated two of these associations in a separate young case-control sample affected with CAD. These data imply that the transcription factor GATA2 may play a role in CAD susceptibility and suggest that the study of GATA2 targets may uncover a set of GATA2-regulated genes important to CAD inheritance.

Joint linkage and association of six single-nucleotide polymorphisms in the factor XIII-A subunit gene point to V34L as the main functional locus

OBJECTIVE

Activated factor XIII (FXIII) crosslinks fibrin to enhance the mechanical strength of a blood clot and increase its resistance to fibrinolysis. The prevalence of a common variant in the FXIII-A gene (V34L) has been reported to be lower in patients with myocardial infarction and ischemic stroke than in controls, suggesting a protective role for this polymorphism in vascular diseases. The current study investigated 6 single-nucleotide polymorphisms (SNPs) within the FXIII A-subunit gene to locate functional polymorphism(s) responsible for variation in FXIII activation.

METHODS AND RESULTS

A total of 201 dizygotic twin pairs were genotyped for 1 promoter and all common nonsynonymous coding polymorphisms in the FXIII A-subunit gene: -246G>A, V34L, Y204F, P564L, V650I, and E651Q. Tests of linkage, association, and combined linkage and association were performed using QTDT software. Significant linkage to the V34L polymorphism (P=5 x 10(-12)) as well as association (P=3 x 10(-49)) was observed. Adjusting for association while performing linkage made the linkage signal disappear for the V34L polymorphism (from chi2=47.55, P=5x10(-12) to chi2=1.30, P=0.25). Only haplotypes containing the 34L allele showed association with FXIII activation.

CONCLUSIONS

Testing multiple SNPs in the FXIII A-subunit gene indicates that V34L is the main functional polymorphism influencing FXIII activation.

Genome-wide mapping of susceptibility to coronary artery disease identifies a novel replicated locus on chromosome 17

Coronary artery disease (CAD) is a leading cause of death world-wide, and most cases have a complex, multifactorial aetiology that includes a substantial heritable component. Identification of new genes involved in CAD may inform pathogenesis and provide new therapeutic targets. The PROCARDIS study recruited 2,658 affected sibling pairs (ASPs) with onset of CAD before age 66 y from four European countries to map susceptibility loci for CAD. ASPs were defined as having CAD phenotype if both had CAD, or myocardial infarction (MI) phenotype if both had a MI. In a first study, involving a genome-wide linkage screen, tentative loci were mapped to Chromosomes 3 and 11 with the CAD phenotype (1,464 ASPs), and to Chromosome 17 with the MI phenotype (739 ASPs). In a second study, these loci were examined with a dense panel of grid-tightening markers in an independent set of families (1,194 CAD and 344 MI ASPs). This replication study showed a significant result on Chromosome 17 (MI phenotype; p = 0.009 after adjustment for three independent replication tests). An exclusion analysis suggests that further genes of effect size lambda(sib) > 1.24 are unlikely to exist in these populations of European ancestry. To our knowledge, this is the first genome-wide linkage analysis to map, and replicate, a CAD locus. The region on Chromosome 17 provides a compelling target within which to identify novel genes underlying CAD. Understanding the genetic aetiology of CAD may lead to novel preventative and/or therapeutic strategies.

Gene variants of VAMP8 and HNRPUL1 are associated with early-onset myocardial infarction

OBJECTIVE

Identify gene variants associated with early-onset myocardial infarction (MI).

METHODS AND RESULTS

We tested 11 647 single-nucleotide polymorphisms (SNPs) for association with early-onset MI in a case-control study (study 1 200 cases, 262 controls). To reduce the number of false positives among the 666 SNPs that were nominally associated with early-onset MI (P<0.05) in study 1, we tested these SNPs in study 2 (434 cases, 504 controls). We found that 8 of the 666 SNPs were associated with early-onset MI in study 2 (P<0.05) and had the same risk alleles as in study 1. These 8 SNPs were then tested for association with early-onset MI in study 3 (187 cases, 434 controls). We found that a VAMP8 variant (P = 0.025; odds ratio [OR], 1.75; CI, 1.17 to 2.62) and an HNRPUL1 variant (P = 0.0043; OR, 1.92; CI, 1.28 to 2.86) were associated with early-onset MI (nominal P<0.05; false discovery rate <10%) and had the same risk alleles in all 3 studies.

CONCLUSIONS

Variants in 2 genes were associated with early-onset MI: VAMP8, which is involved in platelet degranulation, and HNRPUL1, which encodes a ribonuclear protein. The identification of these variants could improve understanding of disease mechanisms and suggest novel drug targets.

Gene by sex interaction in the etiology of coronary heart disease and the preceding metabolic syndrome

BACKGROUND

Despite decades of research, the genetic basis of coronary heart disease and its metabolic risk factors is poorly understood. Few studies consider that sex may modify the effect of gene variants on disease. Investigation of gene by sex interaction may help to elucidate underlying genetic susceptibilities and explain the sexual dimorphism of these complex traits.

AIMS

The aim of this review is to summarize evidence for gene by sex interaction in the etiology of coronary heart disease and the metabolic syndrome.

DATA SYNTHESIS

Published literature was examined in the areas of familial aggregation of coronary heart disease; heritability of body mass, insulin resistance, hypertension and dyslipidemia; genome-wide linkage analysis in humans and rodents; and large-scale genetic association studies. Possible mechanisms of gene by sex interaction are discussed including X-linked inheritance, confounding by risk factors and the effect of sex hormones.

CONCLUSIONS

The strongest evidence for gene by sex interaction in relation to coronary heart disease and the metabolic syndrome is in the etiology of body mass, insulin resistance and possibly dyslipidemia. Genetic studies of these traits would benefit from taking sex differences into account. Alternative mechanisms underlying gene by sex interaction, besides obvious sex hormone differences, should be considered.

The genetics of schizophrenia and bipolar disorder: dissecting psychosis

Much work has been done to identify susceptibility genes in schizophrenia and bipolar disorder. Several well established linkages have emerged in schizophrenia. Strongly supported regions are 6p24-22, 1q21-22, and 13q32-34, while other promising regions include 8p21-22, 6q16-25, 22q11-12, 5q21-q33, 10p15-p11, and 1q42. Genomic regions of interest in bipolar disorder include 6q16-q22, 12q23-q24, and regions of 9p22-p21, 10q21-q22, 14q24-q32, 13q32-q34, 22q11-q22, and chromosome 18. Recently, specific genes or loci have been implicated in both disorders and, crucially, replicated. Current evidence supports NRG1, DTNBP1, DISC1, DAOA(G72), DAO, and RGS4 as schizophrenia susceptibility loci. For bipolar disorder the strongest evidence supports DAOA(G72) and BDNF. Increasing evidence suggests an overlap in genetic susceptibility across the traditional classification systems that dichotomised psychotic disorders into schizophrenia or bipolar disorder, most notably with association findings at DAOA(G72), DISC1, and NRG1. Future identification of psychosis susceptibility genes will have a major impact on our understanding of disease pathophysiology and will lead to changes in classification and the clinical practice of psychiatry.

Genetic susceptibility to coronary artery disease: from promise to progress

Family history is an important independent risk factor for coronary artery disease (CAD), and identification of susceptibility genes for this common, complex disease is a vital goal. Although there has been considerable success in identifying genetic variants that influence well-known risk factors, such as cholesterol levels, progress in unearthing novel CAD genes has been slow. However, advances are now being made through the application of large-scale, systematic, genome-wide approaches. Recent findings particularly highlight the link between CAD and inflammation and immunity, and highlight the biological insights to be gained from a genetic understanding of the world's biggest killer.

Common genetic vulnerability to depressive symptoms and coronary artery disease: a review and development of candidate genes related to inflammation and serotonin

OBJECTIVE

Although it is well established that depressive symptoms are associated with recurrent cardiac events among cardiac patients and novel cardiac events among participants with no known coronary artery disease (CAD), the nature of this association remains unclear. In this regard, little attention has been paid to the possibility that common genetic vulnerability contributes to both depressive symptoms and CAD. In this paper, we review the existing evidence for common genetic contributions to depression and CAD, primarily using evidence from twin and family studies, followed by a review of two major pathophysiological mechanisms thought to underlie covariation between depressive symptoms and CAD: inflammation and serotonin. We conclude with an overview of select candidate genes within these pathways.

METHODS

Literature review.

RESULTS

In twin studies, both depression and CAD appear heritable. In the only twin study to consider depression and CAD jointly, the correlation across heritabilities was 0.42, suggesting that nearly 20% of variability in depressive symptoms and CAD was attributable to common genetic factors. In addition, although it is plausible that genetic variation related to inflammation and serotonin may be associated with both depression and CAD, genetic variation related to inflammation has been primary examined in relation to CAD, whereas genetic variation in the serotonin system has been primarily examined in relation to depression.

CONCLUSIONS

It appears that the covariation of depressive symptoms and CAD may be attributable, in part, to a common genetic vulnerability. Although several pathways may be involved, genes within the inflammation and serotonin pathways may serve as good candidates for the first steps in identifying genetic variation important for depression, CAD or both.

Plasma homocysteine and the genetics of cardiovascular disease

Cardiovascular disease (CVD) is extremely complex. It results from the interaction of many genetic and environmental factors. Several studies have demonstrated its genetic basis, estimating a heritability of approximately 60%. In the last 5 years, at least 19 genome-wide explorations for genes related to CVD have been undertaken, but none has yet unequivocally demonstrated a causal relationship with the disease. One method that can be used to find the causative genes is analyzing intermediate genetic phenotypes or risk factors, such as plasma homocysteine (Hcy). A recent genome-wide quantitative-trait-linkage analysis of Hcy plasma levels has found a previously unsuspected gene as the major genetic determinant of this risk factor. It codes for the enzyme nicotinamide N-methyltransferase, and this gene is now a candidate gene that explains a portion of the genetic basis of CVD. If confirmed, this finding will probably influence future research on the mechanisms underlying atherosclerosis and CVD, as well as other complex diseases related to plasma Hcy levels, such as Alzheimer's disease and osteoporosis.

Genetic influence on thrombotic risk markers in the elderly--a Danish twin study

OBJECTIVE

Several hemostatic variables are identified as cardiovascular risk markers. In young and middle-aged individuals, plasma concentrations of these variables are partly determined by genetic factors. The genetic contribution to cardiovascular disease (CVD) decreases with increasing age, and it is therefore important to determine the heritability of hemostasis also in the elderly.

METHODS

The heritability of plasma levels of factor VII, fibrinogen, tissue factor, tissue factor pathway inhibitor, von Willebrand factor, thrombin activatable fibrinolysis inhibitor (TAFI), and D-dimer was determined in 130 monozygotic and 155 dizygotic same-sex twin pairs, aged 73-94 years, who participated in the Longitudinal Study of Aging of Danish Twins. Furthermore, we determined the influence of promoter polymorphisms in corresponding genes on the plasma level variation.

RESULTS

Genetic factors accounted for 33% (D-dimer) to 71% (TAFI) of the variation in plasma levels. Polymorphisms were associated with concentrations of FVII and TAFI in sib-pair based analyses, but in linkage analyses the polymorphisms did not explain a significant part of the genetic variation for any of the variables.

CONCLUSIONS

Concentrations of hemostatic variables have a substantial genetic variation in the elderly, but in this study the promoter polymorphisms only explained a minimal part of this variation.

Investigating the Genetic Determinants of Cardiovascular Disease Using Candidate Genes and Meta-analysis of Association Studies

Coronary artery disease (CAD) has a polygenic basis, and identification of CAD susceptibility genes has the potential to aid the development of new treatments and enhance prediction of disease risk. Thus far, the strategy has firstly been to choose "candidate" genes coding for important "rate-limiting" proteins in the homeostatic systems involved in maintaining cardiovascular health; secondly to identify common variants in these candidate genes; thirdly to carry out genotyping and statistical analysis using genetic association studies; and finally to test the functional effects of the identified variants in vitro and in vivo. However, lack of reproducibility of genetic association studies has led to uncertainty about the nature and number of genes involved. In part this is because many of the studies conducted have not been adequately powered to detect small risk effects, or to permit adequate exploration of gene-gene or gene-environment interactions in a robust manner. Spurious positive and negative associations due to type I and type II statistical errors are likely to co-exist with real associations in the published literature. By utilising all available data to increase statistical power, meta-analysis of genetic association studies is increasingly being used to identify genotypic risk with a greater degree of precision. Though potentially powerful, this approach may be prone to publication bias. Therefore, very large genetic association studies will also be required to identify risk genes for CAD. This review lays out the framework for the candidate gene approach for CAD and illustrates this with published results from a UK prospective study of 3000 middle-aged men.

Association of apolipoprotein E genotype with early onset of coronary heart disease in Greek men

Apolipoprotein (apo) E polymorphism has been associated with coronary heart disease (CHD) although its relation to the age of CHD onset is still not defined. The age of onset of established CHD was obtained from 502 Greek men and compared to 103 healthy men. The age grouping was based on the age of CHD onset (earlier < or =44 years, n = 73, intermediate 45-64 years, n = 321, and later > or =65 years, n = 108). Apo E genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and the lipid profile was assessed. No differences in genotype and allele frequencies were found within the CHD groups. The apo epsilon3/4 genotype and the apo epsilon4 allele were less frequent in the earlier-onset group than in healthy men (11.0 % vs 22.3%, Pearson Chi-Square p = 0.028 and 6.8% vs 13.6%, Pearson Chi-Square p = 0.023, respectively). The lipid profile was similar in all genotypes of all groups except for high-density lipoprotein cholesterol levels, which were higher in epsilon2 carriers compared to non-epsilon2 carriers (in mg/dL [+/-SD]; 44 [9] vs 39 [10], in mmol/L [+/-SD]; 1.1 [0.2] vs 1.0 [0.3] p = 0.005). There is an association between apo E genotype and early onset of CHD in Greek men. In the earlier CHD onset group, the apo epsilon3/4 genotype was less frequent compared to healthy men. This supports that the apo epsilon3/4 genotype is associated with decreased risk of premature CHD. Because the results of similar studies are not consistent, it may be that the relationship between apo E genotype and CHD is related to ethnicity rather than a universal phenomenon.

Genetic influence on human lifespan and longevity

There is an intense search for longevity genes in both animal models and humans. Human family studies have indicated that a modest amount of the overall variation in adult lifespan (approximately 20-30%) is accounted for by genetic factors. But it is not known if genetic factors become increasingly important for survival at the oldest ages. We study the genetic influence on human lifespan and how it varies with age using the almost extinct cohorts of Danish, Finnish and Swedish twins born between 1870 and 1910 comprising 20,502 individuals followed until 2003-2004. We first estimate mean lifespan of twins by lifespan of co-twin and then turn to the relative recurrence risk of surviving to a given age. Mean lifespan for male monozygotic (MZ) twins increases 0.39 [95% CI (0.28, 0.50)] years for every year his co-twin survives past age 60 years. This rate is significantly greater than the rate of 0.21 (0.11, 0.30) for dizygotic (DZ) males. Females and males have similar rates and these are negligible before age 60 for both MZ and DZ pairs. We moreover find that having a co-twin surviving to old ages substantially and significantly increases the chance of reaching the same old age and this chance is higher for MZ than for DZ twins. The relative recurrence risk of reaching age 92 is 4.8 (2.2, 7.5) for MZ males, which is significantly greater than the 1.8 (0.10, 3.4) for DZ males. The patterns for females and males are very similar, but with a shift of the female pattern with age that corresponds to the better female survival. Similar results arise when considering only those Nordic twins that survived past 75 years of age. The present large population based study shows genetic influence on human lifespan. While the estimated overall strength of genetic influence is compatible with previous studies, we find that genetic influences on lifespan are minimal prior to age 60 but increase thereafter. These findings provide a support for the search for genes affecting longevity in humans, especially at advanced ages.

Atherosclerosis quantitative trait loci are sex- and lineage-dependent in an intercross of C57BL/6 and FVB/N low-density lipoprotein receptor-/- mice

Atherosclerosis is a complex disease that is affected by environmental as well as genetic factors. The aim of the present study was to identify loci of atherosclerosis susceptibility in a cross of atherosclerosis-susceptible C57BL/6 and atherosclerosis-resistant FVB/N mice on the low-density lipoprotein (LDL) receptor (LDLR)-deficient background (LDLR(-/-)) and to test whether these loci are affected by lineage. A total of 459 F(2)s were generated in two ways: In cross "mB6xfFVB," male B6.LDLR(-/-) mice were crossed to female FVB.LDLR(-/-) mice to generate 107 female and 112 male F(2)s. In cross "mFVBxfB6," male FVB.LDLR(-/-) mice were crossed to female B6.LDLR(-/-) mice to generate 120 female and 120 male F(2)s. Animals were phenotyped for cross-sectional atherosclerotic lesion area at the aortic root, and a genome scan was carried out with 192 microsatellite markers. Quantitative trait locus mapping revealed significant loci of atherosclerosis susceptibility on chromosomes 3, 10, and 12. On chromosome 10 maximal logarithm of odds (LOD) scores of 13.1 (D10Mit16, 16 cM) and 5.7 (D10Mit168, 9 cM) were found in female and male mice, respectively. On chromosome 3, a maximal LOD score of 5.1 (D3Mit45, 79 cM) was detected only in females. On proximal chromosome 12 significant LOD scores were lineage-dependent, with maximal LOD scores of 3.9 (D12Mit82, 3 cM) and 4.8 (D12Mit189, 24 cM) present only in female mice of cross mB6xfFVB and male mice of cross mFVBxfB6, respectively. We conclude that, in this intercross, loci of atherosclerosis susceptibility are in part sex- and lineage-dependent. Awareness of these complexities may have major consequences for the identification of atherosclerosis susceptibility genes by quantitative trait locus mapping.

New Paradigms in Cardiovascular Medicine

Considerable progress has been made in understanding the pathophysiology of perioperative stress responses and their impact on the cardiovascular system; however, researchers are just beginning to unravel genetic and molecular determinants that predispose to increased risk for postoperative cardiovascular adverse events. A new field, coined perioperative genomics, aims to apply functional genomic approaches to uncover the biological reasons why similar patients can have dramatically different clinical outcomes after surgery. For the perioperative physician, such findings may soon translate into prospective risk assessment incorporating genomic profiling of markers important in inflammatory, thrombotic, vascular, and neurologic responses to perioperative stress, with implications ranging from individualized additional pre-operative testing and physiological optimization, to perioperative decision-making, choice of monitoring strategies, and critical care resource utilization. We review current knowledge regarding genomic technologies in perioperative cardiovascular disease characterization and outcome prediction, as well as discuss future trends/challenges for translating integrated "omic" information into daily clinical management of the surgical patient.

Common promoter polymorphisms of inflammation and thrombosis genes and longevity in older adults: The cardiovascular health study

Inflammatory response genes may influence life span or quality at advanced ages. Using data from the population-based cardiovascular health study (CHS) cohort, we examined the associations between promoter polymorphisms of several inflammation and thrombosis genes with longevity. We ascertained genotypes for interleukin (IL)-6 -174 G/C, beta-fibrinogen -455 G/A, plasminogen activator inhibitor (PAI)-1 -675 4G/5G, and thrombin-activatable fibrinolysis inhibitor (TAFI) -438 G/A in 2224 men and women > or = 65 years old at baseline. During 10 years of follow-up, men with the TAFI -438 A/A genotype had decreased mortality due to all causes, and lived, on average, 0.9 more years of life, or 1.1 more years of healthy life, than men with the -438 G allele. The effects of TAFI -438 G/A in women were smaller and not statistically significant. PAI-1 4G/4G genotype appeared to be associated with lower non-cardiovascular mortality in men, but with greater cardiovascular mortality in women. In exploratory analyses, we observed a possible interaction among anti-inflammatory drugs, interleukin-6 -174 C/C genotype, and longevity. These findings suggest that modulators of fibrinolytic activity may have a generalized influence on aging, and merit further investigation in studies of genetic determinants of human longevity.

Finding schizophrenia genes

Genetic epidemiological studies suggest that individual variation in susceptibility to schizophrenia is largely genetic, reflecting alleles of moderate to small effect in multiple genes. Molecular genetic studies have identified a number of potential regions of linkage and 2 associated chromosomal abnormalities, and accumulating evidence favors several positional candidate genes. These findings are grounds for optimism that insight into genetic factors associated with schizophrenia will help further our understanding of this disease and contribute to the development of new ways to treat it.