Environmental factors modulate the effect of the APOE genetic polymorphism on plasma lipid concentrations: ecogenetic studies in a Mediterranean Spanish population

An approach to identify gene-environment interactions and reveal new biological insight in complex traits

There is a long-standing debate about the magnitude of the contribution of gene-environment interactions to phenotypic variations of complex traits owing to the low statistical power and few reported interactions to date. To address this issue, the Gene-Lifestyle Interactions Working Group within the Cohorts for Heart and Aging Research in Genetic Epidemiology Consortium has been spearheading efforts to investigate G × E in large and diverse samples through meta-analysis. Here, we present a powerful new approach to screen for interactions across the genome, an approach that shares substantial similarity to the Mendelian randomization framework. We identify and confirm 5 loci (6 independent signals) interacted with either cigarette smoking or alcohol consumption for serum lipids, and empirically demonstrate that interaction and mediation are the major contributors to genetic effect size heterogeneity across populations. The estimated lower bound of the interaction and environmentally mediated heritability is significant (P < 0.02) for low-density lipoprotein cholesterol and triglycerides in Cross-Population data. Our study improves the understanding of the genetic architecture and environmental contributions to complex traits.

Single and Combined Associations of Plasma and Urine Essential Trace Elements (Zn, Cu, Se, and Mn) with Cardiovascular Risk Factors in a Mediterranean Population

Trace elements are micronutrients that are required in very small quantities through diet but are crucial for the prevention of acute and chronic diseases. Despite the fact that initial studies demonstrated inverse associations between some of the most important essential trace elements (Zn, Cu, Se, and Mn) and cardiovascular disease, several recent studies have reported a direct association with cardiovascular risk factors due to the fact that these elements can act as both antioxidants and pro-oxidants, depending on several factors. This study aims to investigate the association between plasma and urine concentrations of trace elements and cardiovascular risk factors in a general population from the Mediterranean region, including 484 men and women aged 18−80 years and considering trace elements individually and as joint exposure. Zn, Cu, Se, and Mn were determined in plasma and urine using an inductively coupled plasma mass spectrometer (ICP-MS). Single and combined analysis of trace elements with plasma lipid, blood pressure, diabetes, and anthropometric variables was undertaken. Principal component analysis, quantile-based g-computation, and calculation of trace element risk scores (TERS) were used for the combined analyses. Models were adjusted for covariates. In single trace element models, we found statistically significant associations between plasma Se and increased total cholesterol and systolic blood pressure; plasma Cu and increased triglycerides and body mass index; and urine Zn and increased glucose. Moreover, in the joint exposure analysis using quantile g-computation and TERS, the combined plasma levels of Zn, Cu, Se (directly), and Mn (inversely) were strongly associated with hypercholesterolemia (OR: 2.03; 95%CI: 1.37−2.99; p < 0.001 per quartile increase in the g-computation approach). The analysis of urine mixtures revealed a significant relationship with both fasting glucose and diabetes (OR: 1.91; 95%CI: 1.01−3.04; p = 0.046). In conclusion, in this Mediterranean population, the combined effect of higher plasma trace element levels (primarily Se, Cu, and Zn) was directly associated with elevated plasma lipids, whereas the mixture effect in urine was primarily associated with plasma glucose. Both parameters are relevant cardiovascular risk factors, and increased trace element exposures should be considered with caution.

Apolipoprotein E Genotype Moderation of the Association Between Physical Activity and Brain Health. A Systematic Review and Meta-Analysis

Introduction

Possession of one or two e4 alleles of the apolipoprotein E (APOE) gene is associated with cognitive decline and dementia risk. Some evidence suggests that physical activity may benefit carriers of the e4 allele differently.

Method

We conducted a systematic review and meta-analysis of studies which assessed APOE differences in the association between physical activity and: lipid profile, Alzheimer's disease pathology, brain structure and brain function in healthy adults. Searches were carried out in PubMed, SCOPUS, Web of Science and PsycInfo.

Results

Thirty studies were included from 4,896 papers screened. Carriers of the e4 allele gained the same benefit from physical activity as non-carriers on most outcomes. For brain activation, e4 carriers appeared to gain a greater benefit from physical activity on task-related and resting-state activation and resting-state functional connectivity compared to non-carriers. Post-hoc analysis identified possible compensatory mechanisms allowing e4 carriers to maintain cognitive function.

Discussion

Though there is evidence suggesting physical activity may benefit e4 carriers differently compared to non-carriers, this may vary by the specific brain health outcome, perhaps limited to brain activation. Further research is required to confirm these findings and elucidate the mechanisms.

Improved metabolomic data-based prediction of depressive symptoms using nonlinear machine learning with feature selection

To solve major limitations in algorithms for the metabolite-based prediction of psychiatric phenotypes, a novel prediction model for depressive symptoms based on nonlinear feature selection machine learning, the Hilbert-Schmidt independence criterion least absolute shrinkage and selection operator (HSIC Lasso) algorithm, was developed and applied to a metabolomic dataset with the largest sample size to date. In total, 897 population-based subjects were recruited from the communities affected by the Great East Japan Earthquake; 306 metabolite features (37 metabolites identified by nuclear magnetic resonance measurements and 269 characterized metabolites based on the intensities from mass spectrometry) were utilized to build prediction models for depressive symptoms as evaluated by the Center for Epidemiologic Studies-Depression Scale (CES-D). The nested fivefold cross-validation was used for developing and evaluating the prediction models. The HSIC Lasso-based prediction model showed better predictive power than the other prediction models, including Lasso, support vector machine, partial least squares, random forest, and neural network. L-leucine, 3-hydroxyisobutyrate, and gamma-linolenyl carnitine frequently contributed to the prediction. We have demonstrated that the HSIC Lasso-based prediction model integrating nonlinear feature selection showed improved predictive power for depressive symptoms based on metabolome data as well as on risk metabolites based on nonlinear statistics in the Japanese population. Further studies should use HSIC Lasso-based prediction models with different ethnicities to investigate the generality of each risk metabolite for predicting depressive symptoms.

Whole-Genome Approach Discovers Novel Genetic and Nongenetic Variance Components Modulated by Lifestyle for Cardiovascular Health

Background

Both genetic and nongenetic factors can predispose individuals to cardiovascular risk. Finding ways to alter these predispositions is important for cardiovascular disease prevention.

Methods and Results

We used a novel whole‐genome approach to estimate the genetic and nongenetic effects on—and hence their predispositions to—cardiovascular risk and determined whether they vary with respect to lifestyle factors such as physical activity, smoking, alcohol consumption, and dietary intake. We performed analyses on the ARIC (Atherosclerosis Risk in Communities) Study (N=6896–7180) and validated findings using the UKBB (UK Biobank, N=14 076–34 538). Lifestyle modulation was evident for many cardiovascular traits such as body mass index and resting heart rate. For example, alcohol consumption modulated both genetic and nongenetic effects on body mass index, whereas smoking modulated nongenetic effects on heart rate, pulse pressure, and white blood cell count. We also stratified individuals according to estimated genetic and nongenetic effects that are modulated by lifestyle factors and showed distinct phenotype–lifestyle relationships across the stratified groups. Finally, we showed that neglecting lifestyle modulations of cardiovascular traits would on average reduce single nucleotide polymorphism heritability estimates of these traits by a small yet significant amount, primarily owing to the overestimation of residual variance.

Conclusions

Lifestyle changes are relevant to cardiovascular disease prevention. Individual differences in the genetic and nongenetic effects that are modulated by lifestyle factors, as shown by the stratified group analyses, implies a need for personalized lifestyle interventions. In addition, single nucleotide polymorphism–based heritability of cardiovascular traits without accounting for lifestyle modulations could be underestimated.

Interactive effects of C-reactive protein levels on the association between APOE variants and triglyceride levels in a Taiwanese population

Background

Apolipoprotein E (APOE) plays a major role in lipid metabolism and inflammation. However, the association between APOE gene polymorphisms and serum triglyceride levels remains controversial. We tested the effects of APOE variants on triglyceride levels and their interactions with the inflammatory marker C-reactive protein (CRP) in a Taiwanese population.

Methods

Two APOE single nucleotide polymorphisms (SNPs) rs429358 and rs7412 were genotyped by TaqMan Assay using real time PCR in 595 healthy subjects attending the clinic for routine visits.

Results

After adjustment for clinical covariates, subjects carrying the rs429358-TT genotype and non-ε4 alleles were found to have higher CRP levels, whereas those with rs7412-CC genotype and non-ε2 alleles had significantly higher total and low-density lipoprotein cholesterol levels (all P < 0.01). Using subgroup and interaction analyses, we observed significantly lower triglyceride levels in subjects carrying the rs429358-TT genotype and non-ε4 alleles in the low CRP group (P = 2.71× 10⁻⁴ and P = 4.32 × 10⁻⁴, respectively), but not in those in the high CRP group (interaction P = 0.013 and 0.045, respectively). In addition, multivariate stepwise linear regression analysis showed that subjects carrying the rs429358-TT genotype and non-ε4 alleles with low CRP levels had significantly lower triglyceride levels (P < 0.001 and P < 0.001, respectively). In addition, when combined with the risk alleles of GCKR, APOA5 and LPL gene variants, we observed that triglyceride levels increased significantly with the number of risk alleles (P = 2.9 × 10⁻¹²).

Conclusions

The combination of SNPs and ε alleles at the APOE locus is involved in managing lipid and CRP levels in the Taiwanese population. APOE polymorphisms interact with CRP to regulate triglyceride levels, thus triglyceride concentration is influenced by both the genetic background of the APOE locus and the inflammatory status of a subject.

Electronic supplementary material

The online version of this article (doi:10.1186/s12944-016-0262-z) contains supplementary material, which is available to authorized users.

Nutrigenomics, the Microbiome, and Gene-Environment Interactions: New Directions in Cardiovascular Disease Research, Prevention, and Treatment: A Scientific Statement From the American Heart Association

Cardiometabolic diseases are the leading cause of death worldwide and are strongly linked to both genetic and nutritional factors. The field of nutrigenomics encompasses multiple approaches aimed at understanding the effects of diet on health or disease development, including nutrigenetic studies investigating the relationship between genetic variants and diet in modulating cardiometabolic risk, as well as the effects of dietary components on multiple "omic" measures, including transcriptomics, metabolomics, proteomics, lipidomics, epigenetic modifications, and the microbiome. Here, we describe the current state of the field of nutrigenomics with respect to cardiometabolic disease research and outline a direction for the integration of multiple omics techniques in future nutrigenomic studies aimed at understanding mechanisms and developing new therapeutic options for cardiometabolic disease treatment and prevention.

Epigenetic considerations of the APOE gene. [corrected]

The apolipoprotein E (APOE) gene is robustly linked with numerous physiological conditions, including healthy aging, altered cardiovascular fitness, and cognitive function. These connections have been established primarily by phenotype-genotype association studies using APOE's three common genetic variants (ε2, ε3, and ε4). These variants encode for the three apoE protein isoforms (E2, E3, and E4), which have slightly different structures and, consequently, distinct functions in lipid metabolism. However, the differential lipid binding and transferring properties of these isoforms cannot fully explain the association of APOE with such a wide range of physiological phenotypes. One potential explanation for APOE's pleiotropic roles may lie in its unique epigenetic properties. In this article, we present a brief review of the APOE gene and protein, its disease associations, and epigenetic components, with a focus on DNA methylation. We close with a discussion of the prospective epigenetic implications of APOE in disease.

Aging and cardiovascular diseases: the role of gene-diet interactions

In the study of longevity, increasing importance is being placed on the concept of healthy aging rather than considering the total number of years lived. Although the concept of healthy lifespan needs to be defined better, we know that cardiovascular diseases (CVDs) are the main age-related diseases. Thus, controlling risk factors will contribute to reducing their incidence, leading to healthy lifespan. CVDs are complex diseases influenced by numerous genetic and environmental factors. Numerous gene variants that are associated with a greater or lesser risk of the different types of CVD and of intermediate phenotypes (i.e., hypercholesterolemia, hypertension, diabetes) have been successfully identified. However, despite the close link between aging and CVD, studies analyzing the genes related to human longevity have not obtained consistent results and there has been little coincidence in the genes identified in both fields. The APOE gene stands out as an exception, given that it has been identified as being relevant in CVD and longevity. This review analyzes the genomic and epigenomic factors that may contribute to this, ranging from identifying longevity genes in model organisms to the importance of gene-diet interactions (outstanding among which is the case of the TCF7L2 gene).

Aerobic fitness modulates the association between APOE genotypes and serum lipemia in adolescents

The purpose of this study was to analyze the association between APOE alleles and serum lipemia in adolescents with low and adequate aerobic fitness. The sample was comprised of 105 boys and 151 girls (49% and 46% from rural area) of European ancestry, aged 11 to 17 years, and classified according to: 1) APOE genotype: group ε2 (ε2/3+ε2/2), ε3 (ε3/3), and ε4 (ε3/4+ε4/4); 2) aerobic fitness: adequate or low; 3) serum lipemia: elevated total cholesterol (TC), low-density lipoprotein (LDL) and triglycerides, and low high-density lipoprotein (HDL). The results showed that aerobic fitness modulates the association between APOE alleles and serum lipemia in adolescents, suggesting that adequate aerobic fitness levels exert a greater effect of reducing TC and LDL in ε2 carriers, as well as of increasing HDL and reducing triglycerides in ε3 and ε4 carriers.

The potential applications of Apolipoprotein E in personalized medicine

Personalized medicine uses various individual characteristics to guide medical decisions. Apolipoprotein (ApoE), the most studied polymorphism in humans, has been associated with several diseases. The purpose of this review is to elucidate the potential role of ApoE polymorphisms in personalized medicine, with a specific focus on neurodegenerative diseases, by giving an overview of its influence on disease risk assessment, diagnosis, prognosis, and therapy. This review is not a systematic inventory of the literature, but rather a summary and discussion of novel, influential and promising works in the field of ApoE research that could be valuable for personalized medicine. Empirical evidence suggests that ApoE genotype informs pre-symptomatic risk for a wide variety of diseases, is valuable for the diagnosis of type III dysbetalipoproteinemia, increases risk of dementia in neurodegenerative diseases, and is associated with a poor prognosis following acute brain damage. ApoE status appears to influence the efficacy of certain drugs, outcome of clinical trials, and might also give insight into disease prevention. Assessing ApoE genotype might therefore help to guide medical decisions in clinical practice.

Nutrigenetics and personalized nutrition: are we ready for DNA-based dietary advice?

Common genetic variation affects individual nutrient requirements and the use of DNA-based dietary advice, derived from nutrigenetics, has been growing. The growth is about to accelerate as the cost of genotyping continues to fall and research results from major nutrigenetics projects are published. There is still some skepticism; some barriers remain including some commercial tests, which make exaggerated, incorrect claims. There is a need for more public resources dedicated to unbiased, objective review and dissemination of nutrigenetics information; however, nutrigenetics evidence should be assessed in the context of standard nutritional evidence and should not require higher standards. This article argues that we are ready for some DNA-based dietary advice in general nutrition and it can be beneficial. Examples of the scientific validity and health utility of gene-diet interactions will be given and the development of guidelines for assessment and validation of benefits will be discussed.

Education modulates the association of the FTO rs9939609 polymorphism with body mass index and obesity risk in the Mediterranean population

OBJECTIVE

To define whether the rs9939609 FTO (fat mass and obesity associated) single nucleotide polymorphism (SNP) is associated with anthropometric measurements and its modulation by educational level in a Mediterranean population.

METHODS

We studied 3 independent adult samples: a random sample (n = 1580) from the general population (GP), obese hospital patients (OHP) (n = 203) and elderly subjects (n = 1027) with high cardiovascular risk (HCR). Weight and height were directly measured. Education and physical activity (PA) were measured using questionnaires.

RESULTS

The rs9939609 presented heterogeneous associations with BMI. In the GP, the minor A-allele was significantly associated with greater BMI, following a co-dominant pattern (P = 0.009), whereas in the OHP this association was recessive (P = 0.004). Conversely, we did not find a significant association with BMI in the HCR group (P < 0.596). In the GP we found a significant interaction between the FTO SNP and education (P = 0.048). In the stratified analysis, no association of the FTO SNP with greater BMI in university subjects was detected (P = 0.786), whereas the association was observed in non-university subjects (P = 0.001). The FTO × education interaction (P = 0.020) was also observed in determining obesity risk in the GP. A-allele carriers had a greater risk of being obese only if they had no university education (OR: 1.56; 95%CI: 1.09-2.23 for TA and OR: 2.01; 95%CI: 1.27-3.26 for AA subjects). The interaction of the FTO with education remained significant even after adjustment for PA.

CONCLUSIONS

The association of the FTO SNP with greater BMI and obesity risk in the GP was strongly modulated by education.

Serum vitamins A and E as modifiers of lipid trait genetics in the National Health and Nutrition Examination Surveys as part of the Population Architecture using Genomics and Epidemiology (PAGE) study

Both environmental and genetic factors impact lipid traits. Environmental modifiers of known genotype-phenotype associations may account for some of the "missing heritability" of these traits. To identify such modifiers, we genotyped 23 lipid-associated variants identified previously through genome-wide association studies (GWAS) in 2,435 non-Hispanic white, 1,407 non-Hispanic black, and 1,734 Mexican-American samples collected for the National Health and Nutrition Examination Surveys (NHANES). Along with lipid levels, NHANES collected environmental variables, including fat-soluble macronutrient serum levels of vitamin A and E levels. As part of the Population Architecture using Genomics and Epidemiology (PAGE) study, we modeled gene-environment interactions between vitamin A or vitamin E and 23 variants previously associated with high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and triglyceride (TG) levels. We identified three SNP × vitamin A and six SNP × vitamin E interactions at a significance threshold of p < 2.2 × 10(-3). The most significant interaction was APOB rs693 × vitamin E (p = 8.9 × 10(-7)) for LDL-C levels among Mexican-Americans. The nine significant interaction models individually explained 0.35-1.61% of the variation in any one of the lipid traits. Our results suggest that vitamins A and E may modify known genotype-phenotype associations; however, these interactions account for only a fraction of the overall variability observed for HDL-C, LDL-C, and TG levels in the general population.

Segregating variation for temperature-dependent sex determination in a lizard

Temperature-dependent sex determination (TSD) was first reported in 1966 in an African lizard. It has since been shown that TSD occurs in some fish, several lizards, tuataras, numerous turtles and all crocodilians. Extreme temperatures can also cause sex reversal in several amphibians and lizards with genotypic sex determination. Research in TSD species indicates that estrogen signaling is important for ovary development and that orthologs of mammalian genes have a function in gonad differentiation. Nevertheless, the mechanism that actually transduces temperature into a biological signal for ovary versus testis development is not known in any species. Classical genetics could be used to identify the loci underlying TSD, but only if there is segregating variation for TSD. Here, we use the 'animal model' to analyze inheritance of sexual phenotype in a 13-generation pedigree of captive leopard geckos, Eublepharis macularius, a TSD reptile. We directly show genetic variance and genotype-by-temperature interactions for sex determination. Additive genetic variation was significant at a temperature that produces a female-biased sex ratio (30°C), but not at a temperature that produces a male-biased sex ratio (32.5°C). Conversely, dominance variance was significant at the male-biased temperature (32.5°C), but not at the female-biased temperature (30°C). Non-genetic maternal effects on sex determination were negligible in comparison with additive genetic variance, dominance variance and the primary effect of temperature. These data show for the first time that there is segregating variation for TSD in a reptile and consequently that a quantitative trait locus analysis would be practicable for identifying the genes underlying TSD.

Estudo de associação entre nível de atividade física, risco cardiovascular e o polimorfismo do gene da apolipoproteína e em idosos

INTRODUÇÃO: com o envelhecimento, ocorre perda gradual do volume da massa muscular, responsável por quase toda a perda da força nos idosos. Estudos têm mostrado que a atividade física pode diminuir a morbidade por doenças cardiovasculares, acidente vascular cerebral e aumentar a autonomia e independência. OBJETIVO: analisar a associação entre nível de atividade física, risco cardiovascular e o polimorfismo do gene da Apolipoproteína E em idosos. MÉTODOS: estudo retrospectivo, observacional a partir de um banco de dados de base populacional onde foram selecionados idosos sedentários e com histórico de atividade física regular que eram portadores e não portadores do alelo e4 do gene da apolipoproteína E. Foram aplicados os seguintes questionários: (a) International Physical Activity Questionnaire (IPAC); (b) recordatório 24 horas e miniquestionário de frequência alimentar; (c) análises bioquímicas do perfil lipídico e glicêmico. RESULTADOS: 255 idosos foram investigados; destes, 51 (20%) eram homens e 204, mulheres (80%). A idade média da amostra foi de 67,8±5.9 anos de idade (mínimo 60 máximo 86 anos). A frequência dos alelos foi de: alelo e3 =0.78, e4=0.16 e e2=0.06; 45 idosos (17.6%) possuíam pelo menos um alelo e4 e eram sedentários, 31 (12.2%) possuíam pelo menos um alelo e4 e apresentava atividade física regular (ativa), 50 (19.6%) foram classificados como tendo os demais alelos da apoE (e2/e3) e ativos enquanto 129 (60.6%) eram e2/e3 e sedentários. CONCLUSÃO: a atividade física poderia ser um fator importante na atenuação dos efeitos genéticos negativos associados ao alelo e4 do polimorfismo da apoE.

Saturated fat intake and alcohol consumption modulate the association between the APOE polymorphism and risk of future coronary heart disease: a nested case-control study in the Spanish EPIC cohort

The association is still not clear between the common APOE polymorphism and coronary heart disease (CHD) risk, nor its modulation by diet. Thus, our aim was to study the association between the APOE genotypes and incident CHD and how dietary fat and alcohol consumption modify these effects. We performed a nested case-control study in the Spanish European Prospective Investigation into Cancer and Nutrition cohort. Healthy men and women (41,440, 30-69 years) were followed up over a 10-year period, with the incident CHD cases being identified. We analyzed 534 incident CHD cases and 1123 controls. APOE, dietary intake and plasma lipids were determined at baseline. The APOE polymorphism was significantly associated with low-density lipoprotein cholesterol (LDL-C), and gene-alcohol interactions in determining LDL-C were detected. In the whole population, the E2 allele was significantly associated with a lower CHD risk than E3/E3 subjects [odds ratio (OR), 0.58; 95% confidence interval (CI), 0.38-0.89]. The E4 allele did not reach statistical significance vs. E3/E3 (OR, 1.17; 95% CI, 0.88-1.58). However, saturated fat intake modified the effect of the APOE polymorphism in determining CHD risk. When saturated fat intake was low (<10% of energy), no statistically significant association between the APOE polymorphism and CHD risk was observed (P=.682). However, with higher intake (≥10%), the polymorphism was significant (P=.005), and the differences between E2 and E4 carriers were magnified (OR for E4 vs. E2, 3.33; 95% CI, 1.61-6.90). Alcohol consumption also modified the effect of the APOE on CHD risk. In conclusion, in this Mediterranean population, the E2 allele is associated with lower CHD risk, and this association is modulated by saturated fat and alcohol consumption.

Additive effects of LPL, APOA5 and APOE variant combinations on triglyceride levels and hypertriglyceridemia: results of the ICARIA genetic sub-study

Background

Hypertriglyceridemia (HTG) is a well-established independent risk factor for cardiovascular disease and the influence of several genetic variants in genes related with triglyceride (TG) metabolism has been described, including LPL, APOA5 and APOE. The combined analysis of these polymorphisms could produce clinically meaningful complementary information.

Methods

A subgroup of the ICARIA study comprising 1825 Spanish subjects (80% men, mean age 36 years) was genotyped for the LPL-HindIII (rs320), S447X (rs328), D9N (rs1801177) and N291S (rs268) polymorphisms, the APOA5-S19W (rs3135506) and -1131T/C (rs662799) variants, and the APOE polymorphism (rs429358; rs7412) using PCR and restriction analysis and TaqMan assays. We used regression analyses to examine their combined effects on TG levels (with the log-transformed variable) and the association of variant combinations with TG levels and hypertriglyceridemia (TG ≥ 1.69 mmol/L), including the covariates: gender, age, waist circumference, blood glucose, blood pressure, smoking and alcohol consumption.

Results

We found a significant lowering effect of the LPL-HindIII and S447X polymorphisms (p < 0.0001). In addition, the D9N, N291S, S19W and -1131T/C variants and the APOE-ε4 allele were significantly associated with an independent additive TG-raising effect (p < 0.05, p < 0.01, p < 0.001, p < 0.0001 and p < 0.001, respectively). Grouping individuals according to the presence of TG-lowering or TG-raising polymorphisms showed significant differences in TG levels (p < 0.0001), with the lowest levels exhibited by carriers of two lowering variants (10.2% reduction in TG geometric mean with respect to individuals who were homozygous for the frequent alleles of all the variants), and the highest levels in carriers of raising combinations (25.1% mean TG increase). Thus, carrying two lowering variants was protective against HTG (OR = 0.62; 95% CI, 0.39-0.98; p = 0.042) and having one single raising polymorphism (OR = 1.20; 95% CI, 1.39-2.87; p < 0.001) or more (2 or 3 raising variants; OR = 2.90; 95% CI, 1.56-5.41; p < 0.001) were associated with HTG.

Conclusion

Our results showed a significant independent additive effect on TG levels of the LPL polymorphisms HindIII, S447X, D9N and N291S; the S19W and -1131T/C variants of APOA5, and the ε4 allele of APOE in our study population. Moreover, some of the variant combinations studied were significantly associated with the absence or the presence of hypertriglyceridemia.

The human gene map for performance and health-related fitness phenotypes: the 2006-2007 update

This update of the human gene map for physical performance and health-related fitness phenotypes covers the research advances reported in 2006 and 2007. The genes and markers with evidence of association or linkage with a performance or a fitness phenotype in sedentary or active people, in responses to acute exercise, or for training-induced adaptations are positioned on the map of all autosomes and sex chromosomes. Negative studies are reviewed, but a gene or a locus must be supported by at least one positive study before being inserted on the map. A brief discussion on the nature of the evidence and on what to look for in assessing human genetic studies of relevance to fitness and performance is offered in the introduction, followed by a review of all studies published in 2006 and 2007. The findings from these new studies are added to the appropriate tables that are designed to serve as the cumulative summary of all publications with positive genetic associations available to date for a given phenotype and study design. The fitness and performance map now includes 214 autosomal gene entries and quantitative trait loci plus seven others on the X chromosome. Moreover, there are 18 mitochondrial genes that have been shown to influence fitness and performance phenotypes. Thus,the map is growing in complexity. Although the map is exhaustive for currently published accounts of genes and exercise associations and linkages, there are undoubtedly many more gene-exercise interaction effects that have not even been considered thus far. Finally, it should be appreciated that most studies reported to date are based on small sample sizes and cannot therefore provide definitive evidence that DNA sequence variants in a given gene are reliably associated with human variation in fitness and performance traits.

Nutrigenetics and personalised nutrition: how far have we progressed and are we likely to get there?: Conference on ‘Multidisciplinary approaches to nutritional problems’

Nutrigenetics and personalised nutrition are components of the concept that in the future genotyping will be used as a means of defining dietary recommendations to suit the individual. Over the last two decades there has been an explosion of research in this area, with often conflicting findings reported in the literature. Reviews of the literature in the area of apoE genotype and cardiovascular health, apoA5 genotype and postprandial lipaemia and perilipin and adiposity are used to demonstrate the complexities of genotype–phenotype associations and the aetiology of apparent between-study inconsistencies in the significance and size of effects. Furthermore, genetic research currently often takes a very reductionist approach, examining the interactions between individual genotypes and individual disease biomarkers and how they are modified by isolated dietary components or foods. Each individual possesses potentially hundreds of ‘at-risk’ gene variants and consumes a highly-complex diet. In order for nutrigenetics to become a useful public health tool, there is a great need to use mathematical and bioinformatic tools to develop strategies to examine the combined impact of multiple gene variants on a range of health outcomes and establish how these associations can be modified using combined dietary strategies.

Genotype-phenotype associations: modulation by diet and obesity

Changes in diet are likely to reduce chronic disorders, but after decades of active research and heated discussion, the question still remains: what is the optimal diet to achieve this elusive goal? Is it a low-fat diet, as traditionally recommended by multiple medical societies? Or a high monounsaturated fat (MUFA) diet as predicated by the Mediterranean diet? Perhaps a high polyunsaturated fat (PUFA) diet based on the cholesterol-lowering effects? The right answer may be all of the above but not for everybody. A well-known phenomenon in nutrition research and practice is the dramatic variability in interindividual response to any type of dietary intervention. There are many other factors influencing response, and they include, among many others, age, sex, physical activity, alcohol, and smoking as well as genetic factors that will help to identify vulnerable populations/individuals that will benefit from a variety of more personalized and mechanistic-based dietary recommendations. This potential could and needs to be developed within the context of nutritional genomics that in conjunction with systems biology may provide the tools to achieve the holy grail of dietary prevention and therapy of chronic diseases and cancer. This approach will break with the traditional public health approach of "one size fits all." The current evidence based on nutrigenetics has begun to identify subgroups of individuals who benefit more from a low-fat diet, whereas others appear to benefit more from high MUFA or PUFA diets. The continuous progress in nutrigenomics will allow some time in the future to provide targeted gene-based dietary advice.

Common missense variant in the glucokinase regulatory protein gene is associated with increased plasma triglyceride and C-reactive protein but lower fasting glucose concentrations

OBJECTIVE

Using the genome-wide association approach, we recently identified the glucokinase regulatory protein gene (GCKR, rs780094) region as a novel quantitative trait locus for plasma triglyceride concentration in Europeans. Here, we sought to study the association of GCKR variants with metabolic phenotypes, including measures of glucose homeostasis, to evaluate the GCKR locus in samples of non-European ancestry and to fine- map across the associated genomic interval.

RESEARCH DESIGN AND METHODS

We performed association studies in 12 independent cohorts comprising >45,000 individuals representing several ancestral groups (whites from Northern and Southern Europe, whites from the U.S., African Americans from the U.S., Hispanics of Caribbean origin, and Chinese, Malays, and Asian Indians from Singapore). We conducted genetic fine-mapping across the approximately 417-kb region of linkage disequilibrium spanning GCKR and 16 other genes on chromosome 2p23 by imputing untyped HapMap single nucleotide polymorphisms (SNPs) and genotyping 104 SNPs across the associated genomic interval.

RESULTS

We provide comprehensive evidence that GCKR rs780094 is associated with opposite effects on fasting plasma triglyceride (P(meta) = 3 x 10(-56)) and glucose (P(meta) = 1 x 10(-13)) concentrations. In addition, we confirmed recent reports that the same SNP is associated with C-reactive protein (CRP) level (P = 5 x 10(-5)). Both fine-mapping approaches revealed a common missense GCKR variant (rs1260326, Pro446Leu, 34% frequency, r(2) = 0.93 with rs780094) as the strongest association signal in the region.

CONCLUSIONS

These findings point to a molecular mechanism in humans by which higher triglycerides and CRP can be coupled with lower plasma glucose concentrations and position GCKR in central pathways regulating both hepatic triglyceride and glucose metabolism.

[Lack of association between the APOE genotype and the response to statin treatment in patients with acute ischemic episodes]

BACKGROUND AND OBJECTIVE

APOE genotype has been shown to have an influence on lipid concentrations. However, its relation with response to lipid-lowering treatment is not well established. The aim of our work was to analyze whether this genotype is associated with changes in the lipid profile in response to statins treatment.

PATIENTS AND METHOD

A total of 222 consecutive patients with acute ischemic episodes and subjected to treatment with statins were included in a retrospective study. The patients' lipid profile was determined at the first visit to the Lipids Unit and after one year on a statin regime. APOE genotypes were determined by PCR-RFLP, and separated in three groups: E2 (E2 carriers), E4 (E4 carriers) and E3 (E3/E3). E2/E4 patients were not included in the study.

RESULTS

Relative frequencies of alleles epsilon2, epsilon3 and epsilon4 were 10.5%, 70.9% and 18.6% respectively. Significant differences among groups (p = 0.039) were observed for c-LDL concentrations. E2 group had lower c-LDL than E3 group (p = 0.017) and E4 group (p = 0.01). No significant differences in c-LDL, c-HDL and c-HDL/CT were observed among the three groups with regard to variation after statin treatment.

CONCLUSION

APOE genotype does not significantly affect the lipid response in patients with acute ischemic episodes after statin treatment.

Impact of apoE genotype on oxidative stress, inflammation and disease risk

Although in developing countries an apolipoprotein E4 (apoE4) genotype may offer an evolutionary advantage, as it has been shown to offer protection against certain infectious disease, in Westernised societies it is associated with increased morbidity and mortality, and represents a significant risk factor for cardiovascular disease, late-onset Alzheimer's disease and other chronic disorders. ApoE is an important modulator of many stages of lipoprotein metabolism and traditionally the increased risk was attributed to higher lipid levels in E4 carriers. However, more recent evidence demonstrates the multifunctional nature of the apoE protein and the fact that the impact of genotype on disease risk may be in large part due to an impact on oxidative status or the immunomodulatory/anti-inflammatory properties of apoE. An increasing number of studies in cell lines, targeted replacement rodents and human volunteers indicate higher oxidative stress and a more pro-inflammatory state associated with the epsilon4 allele. The impact of genotype on the antioxidant and immunomodulatory/anti-inflammatory properties of apoE is the focus of the current review. Furthermore, current information on the impact of environment (diet, exercise, smoking status, alcohol) on apoE genotype-phenotype associations are discussed with a view to identifying particular lifestyle strategies that could be adapted to counteract the 'at-risk' E4 genotype.

Gender, a significant factor in the cross talk between genes, environment, and health

BACKGROUND

Although men and women share most genetic information, they have significantly different disease susceptibilities that go well beyond the expected gender-specific diseases. Sex influences the risk of nearly all common diseases that affect both men and women, including atherosclerosis and diabetes and their preceding risk factors (eg, hyperlipidemia, insulin resistance, and obesity).

OBJECTIVE

The goal of this article was to examine the interplay between genes, gender, and disease susceptibility, and assess it in the context of the added complexity of environmental factors (ie, dietary habits, smoking, alcohol consumption) in the modulation of the balance between health and disease.

METHODS

Original and review articles published by the author were reexamined for evidence of gene-gender interactions.

RESULTS

Evidence from some key factors in lipid metabolism (apolipoprotein E [APOE])and obesity (perilipin [PLIN]) indicates that the interplay between genes, gender, and environmental factors modulates disease susceptibility. In the Framingham Heart Study, complex interactions have been shown between a promoter polymorphism at the apolipoprotein A1 gene, gender, and dietary poly-unsaturated fatty acid intake that modulate plasma concentrations of high-density lipoprotein cholesterol. Likewise, highly and clinically relevant interactions have been observed between the APOE gene common alleles APOE2 , APOE3, and APOE4 , gender, and smoking that determine cardiovascular disease risk. Most interesting is the gender-dependent association between common polymorphisms at the PLIN locus and obesity risk that has been replicated in several populations around the world.

CONCLUSIONS

These data support the idea that gender-specific differences in morbidity and mortality may be mediated in part by genetic factors and by their differential response to the environment. The new knowledge generated by a more careful and complete elucidation of the complex interactions predisposing to common diseases will result in an increased ability to provide successful personalized behavioral recommendations to prevent chronic disorders.

ApoE genotype, cardiovascular risk and responsiveness to dietary fat manipulation

Cardiovascular risk is determined by the complex interactions between genetic and environmental factors. The apoE genotype represents the most-widely-studied single nucleotide polymorphism in relation to CVD risk, with >3600 publications cited in PubMed. Although originally described as a mediator of lipoprotein metabolism, the lipoprotein-independent functions of apoE are being increasingly recognised, with limited data available on the potential impact of genotype on these metabolic processes. Furthermore, although meta-analyses suggest that apoE4 carriers may have a 40-50% increased CVD risk, the associations reported in individual studies are highly heterogeneous and it is recognised that environmental factors such as smoking status and dietary fat composition influence genotype-phenotype associations. However, information is often derived from observational studies or small intervention trials in which retrospective genotyping of the cohort results in small group sizes in the rarer E2 and E4 subgroups. Either larger well-standardised intervention trials or smaller trials with prospective recruitment according to apoE genotype are needed to fully establish the impact of diet on genotype-CVD associations and to establish the potential of dietary strategies such as reduced total fat, saturated fat, or increased antioxidant intakes to counteract the increased CVD burden in apoE4 carriers.

Gene-lifestyle interaction on risk of type 2 diabetes

The descriptive epidemiology of type 2 diabetes suggests that gene-lifestyle interactions are critical to the development of the condition. However, unravelling the molecular detail of these interactions is a complex task. The existing literature is based on small intervention studies or cross-sectional observational quantitative trait studies. Our systematic review of the literature identified some evidence of interactions, most notably for a common variant in the PPAR-gamma gene which appears to interact with the nature of dietary fat intake. Other interactions have been reported for adrenoceptors, uncoupling proteins, fatty acid binding proteins, apolipoproteins and lipoprotein lipase. There are, to date, no reports based on the ideal study design which is a case-control study nested within a cohort. To limit the likelihood of false discovery, such studies would need to be large and the search for interaction should be restricted to a priori biologically driven hypotheses. Additional study designs that examine differential response to lifestyle change or test interaction in the context of quantitative trait studies would complement the nested case-control approach, but the emphasis here should be on precision of measurement of both phenotype and lifestyle behaviour.

The human gene map for performance and health-related fitness phenotypes: the 2005 update

The current review presents the 2005 update of the human gene map for physical performance and health-related fitness phenotypes. It is based on peer-reviewed papers published by the end of 2005. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed, but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, in the early version of the gene map, 29 loci were depicted. In contrast, the 2005 human gene map for physical performance and health-related phenotypes includes 165 autosomal gene entries and QTL, plus five others on the X chromosome. Moreover, there are 17 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes. Thus, the map is growing in complexity. Unfortunately, progress is slow in the field of genetics of fitness and performance, primarily because the number of laboratories and scientists focused on the role of genes and sequence variations in exercise-related traits continues to be quite limited.

Influencia de los factores genéticos y ambientales en el metabolismo lipídico y riesgo cardiovascular asociado al gen apoE

The apolipoprotein E (ApoE) plays an important role in lipid metabolism. This apoprotein presents three major isoforms (apoE2, apoE3 and apoE4) that modulate lipid levels. Carriers of the apoE4 allele have higher total and LDL-cholesterol plasma concentration and a greater coronary risk, particularly for myocardial infarction. Nevertheless, not all the people with this allele develop the disease, which suggests that other genetic or environmental factors are necessary for its total expression. In this review, we will analyze the importance of several polymorphisms in the apoE gene promoter region, as well as various environmental factors, including diet, in the association of this gene with lipid metabolism and cardiovascular risk.

SINGLE NUCLEOTIDE POLYMORPHISMS THAT INFLUENCE LIPID METABOLISM: Interaction with Dietary Factors

Cardiovascular disease (CVD) risk is the result of complex interactions between genetic and environmental factors. During the past few decades, much attention has focused on plasma lipoproteins as CVD risk factors. The current evidence supports the concept that gene-environment interactions modulate plasma lipid concentrations and potentially CVD risk. The findings from studies examining gene-diet interactions and lipid metabolism have been highly promising. Several loci (i.e., APOA1, APOA4, APOE, and LIPC) are providing proof-of-concept for the potential application of genetics in the context of personalized nutritional recommendations for CVD prevention. However, the incorporation of these findings to the clinical environment is not ready for prime time. There is a compelling need for replication using a higher level of scientific evidence. Moreover, we need to evolve from the simple scenarios examined nowadays (i.e., one single dietary component, single nucleotide polymorphism, and risk factor) to more realistic situations involving interactions between multiple genes, dietary components, and risk factors. In summary, there is need for both large population studies and well-standardized intervention studies.

Baseline levels of low-density lipoprotein cholesterol and lipoprotein (a) and the AvaII polymorphism of the low-density lipoprotein receptor gene influence the response of low-density lipoprotein cholesterol to pravastatin treatment

To investigate some individual and genetic factors that may influence the response of low-density lipoprotein cholesterol (LDL-C) to pravastatin treatment, we recruited 440 subjects with hypercholesterolemia (mean age, 57 years; 43% men) from 21 primary health care centers-outpatient clinics into a prospective, multicentered intervention trial. Pravastatin (20 mg/d) was prescribed for 16 weeks. The main outcome was the percentage variation in LDL-C concentration relative to baseline. Blood analyses and genotyping were performed centrally. The results indicated that LDL-C decreased by 20.5% (range, +21% to -66%) after pravastatin treatment. Baseline concentration of LDL-C (the higher the concentration, the greater the decrease), lipoprotein (a) levels (the lower the concentration, the greater the response), and Ava II polymorphism of the LDL-receptor gene significantly influenced the hypolipemic effect ( P < .001, P = .014, and P = .004, respectively). These 3 factors combined explained 10.6% of the variation in LDL-C response. Age, sex, smoking habit, alcohol consumption, body mass index, and apolipoprotein E genotype had no significant effect on response. We conclude that baseline levels of LDL-C and lipoprotein (a) together with the Ava II polymorphism of the LDL-receptor gene have a significant influence on the LDL-C response to pravastatin treatment in patients monitored in a standard primary health care outpatient clinic setting.

The effect of apolipoprotein E polymorphism on lipid levels in Korean adults

The aim of this study was to determine the effects of polymorphisms in the apolipoprotein E gene (APOE) on lipid levels in Korean adults and to investigate the interactions between these polymorphisms and environmental factors in determining lipid levels. We performed a cross-sectional study of 1,900 subjects (668 men and 1,232 women; 45-74 yr old) in Namwon, Korea, in 2004. APOE polymorphisms were determined by polymerase chain reaction and restriction enzyme analysis. Carriers of the APOE*E2 (E2) allele had significantly lower total cholesterol and low-density lipoprotein cholesterol (LDL-C) concentrations than did carriers of the APOE*E3 (E3) or APOE*E4 (E4) alleles, regardless of gender. The APOE allele type had significant effect on high-density lipoprotein cholesterol (HDL-C) and triglyceride levels in women, but not in men. The effect of APOE allele type on HDL-C levels was modified by age in women. In addition, in men, the effect of APOE allele type on triglyceride levels was modified by smoking. These findings highlight the important effect of gene-environment interactions on lipid levels.

Distribution of apolipoprotein E alleles in the Omani population

OBJECTIVE

To estimate the apolipoprotein E (apo E) allele distribution in the Omani population and to compare them with those of other populations.

SUBJECTS AND METHODS

One hundred and sixty-two healthy Omanis of Arab Bedouin origin were genotyped by polymerase chain reaction followed by restriction fragment length polymorphism.

RESULTS

The apo E allele frequencies were: epsilon2, 0.052; epsilon3, 0.886; epsilon4, 0.062. This pattern of distribution, characterized by the lowest epsilon4 and among the highest epsilon3 allele frequencies in the world, was very similar to that of Arabs, Southern Europeans of the Mediterranean basin, Indians, and Japanese populations.

CONCLUSION

The results indicate that the allelic distribution of apo E in healthy Omanis is characterized by low Apo epsilon4 and high epsilon3 allele frequencies similar to those of other Arab, Southern European, Japanese and Indian populations. The homogeneous distribution of apo E alleles in this group of populations might have been influenced by diet and/or genetic admixture.

Genetic variation at the perilipin (PLIN) locus is associated with obesity-related phenotypes in White women

Perilipin coats intracellular lipid droplets and modulates adipocyte lipolysis. We have evaluated the association between several polymorphisms at the perilipin (PLIN) locus (PLIN1 : 6209T > C, PLIN4 : 11482G > A, PLIN5 : 13041A > G, and PLIN6 : 14995A > T) with obesity-related phenotypes in 1589 White subjects randomly selected from a general Spanish population. In women (n = 801), the less common alleles of PLIN1 and PLIN4, in strong linkage disequilibrium (D' : 0.96), were significantly associated with lower body mass index. Carriers of the allele 2 (6209C) at the PLIN1 locus weighed significantly less (-2.2 kg; p = 0.007) than women homozygotes for the wild-type genotype. The same was true for 11482A carriers at PLIN4 (p = 0.01). Moreover, the PLIN4 variant was associated with significantly lower waist-to-hip ratio, plasma glucose, and triacylglycerol concentrations. No significant associations with these obesity-related phenotypes were found in men. In agreement with these results, statistically significant gene-gender interactions were obtained when the risk of obesity was estimated (281 subjects were obese and 1308 non-obese). Only in women, PLIN1 and PLIN4 variant alleles (6209C and 11482A) were associated with a lower obesity risk [Odds ratio (OR) = 0.58, 95% confidence interval (CI): 0.38-0.93 and OR = 0.56, 95% CI: 0.36-0.89, respectively]. In summary, our data suggest that common alleles at the PLIN locus modulate body weight and metabolic variables in humans.

The human gene map for performance and health-related fitness phenotypes: the 2003 update

This review presents the 2003 update of the human gene map for physical performance and health-related fitness phenotypes. It is based on peer-reviewed papers published by the end of 2003 and includes association studies with candidate genes, genome-wide scans with polymorphic markers, and single-gene defects causing exercise intolerance to variable degrees. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, 29 loci were depicted on the first edition of the map. In contrast, the 2003 human gene map for physical performance and health-related phenotypes includes 109 autosomal gene entries and QTL, plus two on the X chromosome. Moreover, there are 15 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes.

Apolipoprotein E polymorphism modifies the alcohol-HDL association observed in the National Heart, Lung, and Blood Institute Family Heart Study

BACKGROUND

The apolipoprotein E gene (APOE) allele epsilon4 is associated with an increased risk of cardiovascular disease. The presence of the epsilon4 allele has been associated with lower concentrations of HDL cholesterol, but it is not known whether the epsilon4 allele modifies the association between alcohol consumption and HDL-cholesterol concentrations.

OBJECTIVE

The objective of the study was to assess whether the epsilon4 allele modifies the association between alcohol consumption and HDL-cholesterol concentrations.

DESIGN

In a cross-sectional design, we studied 670 men and women aged 26-78 y who participated in the National Heart, Lung, and Blood Institute Family Heart Study to assess whether the epsilon4 allele of the gene APOE modifies the association between alcohol consumption and HDL-cholesterol concentrations. Alcohol data were self-reported, and we used multivariate, generalized estimating equations to assess interactions.

RESULTS

In a model with adjustment for age, sex, body mass index, smoking, exercise, waist-hip ratio, TV viewing, and study site, there was a significant effect of the interaction between the epsilon4 allele and alcohol consumption on HDL cholesterol (P=0.0001). In the absence of the epsilon4 allele, multivariate adjusted means of HDL were 1.24, 1.36, and 1.54 mmol/L among subjects who never drank and those who currently drink 0.1-12 and >12 g alcohol/d, respectively; in the presence of the epsilon4 allele, the corresponding values were 1.19, 1.27, and 1.25 mmol/L.

CONCLUSION

Our data show a significant effect of the interaction between the epsilon4 allele and alcohol consumption on HDL. The increase in HDL associated with alcohol appears to be stronger in subjects without the epsilon4 allele than in those with the epsilon4 allele.

Apolipoprotein E and cholesteryl ester transfer protein polymorphisms in normal and preeclamptic pregnancies

OBJECTIVES

To evaluate the association of apolipoprotein (apo) E polymorphism and a cholesteryl ester transfer protein (CETP) polymorphism (CETP/TaqIB) with preeclampsia and with lipid/lipoprotein profile in pregnancy.

MATERIALS AND METHODS

A group of 144 normal pregnant women (67 in the third trimester) were compared with 51 cases of preeclampsia in the third trimester of gestation. Apo E and CETP genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Serum lipids, lipoproteins and apolipoproteins were evaluated using commercially available kits. LDL size was assessed by gradient gel electrophoresis.

RESULTS

No differences were found in the distribution of subjects with respect to genotypes, in the apo E and CETP polymorphisms, between control and pathologic groups. In the third trimester of gestation (both control and case groups considered), apo E polymorphism, but not CETP polymorphism, was associated with different lipid and lipoprotein levels. Patients carrying the E2 allele (E2+) presented with significantly lower values of LDL cholesterol (LDLc) compared with carriers of E4 (E4+) and E3/3 individuals. E2+ also presented with the highest triglyceride (TG) level, although this was not statistically significant. On the other hand, HDL cholesterol (HDLc) and apo A-I levels were significantly reduced in E4+, compared with E3/3. Furthermore, E4+ presented with the highest total cholesterol and LDL and therefore LDLc/HDLc and apo B/apo A-I ratios were significantly higher in this group compared with the other two.

CONCLUSIONS

Neither of our candidate genes showed association with preeclampsia. However, apo E genotype was associated with changes in lipid and lipoprotein profiles in pregnant women.

APOE polymorphism and lipid profile in three ethnic groups in the Singapore population

BACKGROUND

Serum lipid concentrations are modulated by environmental factors such as exercise, alcohol intake, smoking, obesity and dietary intake and genetic factors. Polymorphisms at the Apolipoprotein E (APOE) locus have consistently shown a significant association with total and LDL-cholesterol (LDL-C). However, their impact on HDL-cholesterol (HDL-C) may be population dependent. Having three major ethnic groups within a similar social environment allows us to study the role of genetics and their interactions with lifestyle factors on the serum lipid profile and coronary risk in Asians.

METHODS

This study included 1740 males (1146 Chinese, 327 Malays and 267 Asian Indians) and 1950 females (1329 Chinese, 360 Malays and 261 Asian Indians) with complete data on anthropometric indices, fasting lipids, smoking status, alcohol consumption, exercise frequency and genotype at the APOE locus.

RESULTS

Malays and Asian Indians were more obese compared with the Chinese. Smoking was uncommon in all females but Malay males had significantly higher prevalence of smokers. Malays had the highest LDL-C whilst Indians had the lowest HDL-C, The epsilon 3 allele was the most frequent allele in all three ethnic groups. Malays had the highest frequency of epsilon 4 (0.180 and 0.152) compared with Chinese (0.085 and 0.087) and Indians (0.108 and 0.075) in males and females, respectively. The epsilon 2 allele was the least common in Asian Indians. Total cholesterol (TC) and LDL-C was highest in epsilon 4 carriers and lowest in epsilon 2 carriers. The reverse was seen in HDL-C with the highest levels seen in epsilon 2 subjects. The association between ethnic group and HDL-C differed according to APOE genotype and gender. Asian Indians had the lowest HDL-C for each APOE genotype except in Asian Indian males with epsilon 2, where HDL-C concentrations were intermediate between Chinese and Malays.

CONCLUSION

Ethnic differences in lipid profile could be explained in part by the higher prevalence of epsilon 4 in the Malays. Ethnicity may influence the association between APOE genotypes and HDL-C. APOE genotype showed no correlation with HDL-C in Malay males whereas the association in Asian Indians was particularly marked. Further studies of interactions between genes and environmental factors will contribute to the understanding of differences of coronary risk amongst ethnic groups.

The human gene map for performance and health-related fitness phenotypes: the 2002 update

This review presents the 2002 update of the human gene map for physical performance and health-related phenotypes. It is based on peer-reviewed papers published by the end of 2002 and includes association studies with candidate genes, genome-wide scans with polymorphic markers, and single gene defects causing exercise intolerance to variable degrees. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed, but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, 29 loci were depicted on the map. The 2001 map includes 71 loci on the autosomes and two on the X chromosome. In contrast, the 2002 human gene map for physical performance and health-related phenotypes includes 90 gene entries and QTL, plus two on the X chromosome. To all these loci, one must add 14 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes.

Apolipoprotein and apolipoprotein receptor genes, blood lipids and disease

PURPOSE OF REVIEW

Apolipoproteins and their receptors are the main controllers of lipid metabolism and, as such, have a major impact not only on the risk of cardiovascular disease but also on the development and degeneration of the central nervous system. Variations in the genes coding for these apolipoproteins and their receptors and the interaction with the environment determine individual susceptibility to metabolic disturbances, the response to dietary or pharmacological intervention and, finally, to disease.

RECENT FINDINGS

This review will focus on recent findings, such as the latest concepts regarding apolipoprotein E in neurodevelopment, the newly identified apolipoprotein A-V and its influence in triglyceride metabolism, and the improved understanding of apolipoprotein A-I and HDL metabolism in the light of the discovery of the ABC family of transporters. Other key aspects of lipoprotein metabolism and cardiovascular disease risk such as apolipoprotein B-100, the LDL receptor, apolipoprotein C-III or apolipoprotein (a) will be updated.

SUMMARY

Variations in these genes will be analysed in relation to plasma lipid levels, their interactions with diet, treatment or other environmental stimuli, and their influence on the risk of cardiovascular disease and neurological disorders.

Cardiovascular disease genetics: a long and winding road

PURPOSE OF REVIEW

This review has two major goals. The first goal is to raise some of the methodological problems associated with studying the genetics of complex disorders, specifically cardiovascular diseases. The second is to update the reader with the most recent findings in the area of genotype-phenotype associations as well as the interaction between genetic factors and cardiovascular disease risk markers, with emphasis on those related to lipid metabolism.

RECENT FINDINGS

In terms of new information, three topics are presented: (1) new findings related to classical candidate genes, such as apolipoprotein E, cholesteryl ester transfer protein and hepatic lipase; (2) recent reports related to new loci that have joined the growing list of cardiovascular disease candidate genes (i.e. ATP-binding cassette transporters A1 and C6, peroxisome proliferator activated receptor alpha, interleukin-6); and (3) studies showing that multiple genes appear to be at the intersection of several age-related disorders such as cardiovascular disease, neurological disorders and osteoporosis (i.e. apolipoprotein E, vitamin D receptor, matrix Gla protein, peroxisome proliferator activated receptor gamma, angiotensin-converting enzyme, estrogen receptor, androgen receptor, methylenetetrahydrofolate reductase).

SUMMARY

The dramatic increase in our ability to carry out genotyping is creating a tremendous wealth of information in terms of associations between genetic markers and biochemical or clinical phenotypes. Increased attention, however, should be placed on study design and replication of findings. This should also be facilitated by the inclusion of multiple markers per loci in order to provide a more precise definition of the alleles associated with the phenotypes of interest. Moreover, given the fact that most of the phenotypes are equally affected by genetic and environmental factors, studies should emphasize the analyses of their interaction.

Genetics, the environment, and lipid abnormalities

Plasma lipid levels have been identified as major risk factors for cardiovascular disease. Multiple behavioral and environmental factors are known to modulate their concentrations in the general population; however, there is dramatic individual variability in the association between risk factors and disease, as well as in the individual response to therapeutic intervention. These differences may be due to the interaction between genetic and nongenetic factors that are ultimately responsible for the individual disease risk and response to intervention. Great strides have been made to characterize the genes involved in the homeostasis of plasma lipoprotein levels and to identify polymorphisms that could contribute to an earlier and more precise individual risk assessment. Especially relevant has been the recent interest and progress on examining the interaction between a number of candidate genes and nongenetic factors, namely smoking, alcohol drinking, physical activity, and sex. The APOE locus continues to be the most thoroughly studied gene in this regard; however, other genes (ie, LPL, APOC3, ADH3) are showing promising results.