Effects of apolipoprotein E genotype on dietary-induced changes in high-density lipoprotein cholesterol in obese postmenopausal women

Quantile-specific heritability of high-density lipoproteins with implications for precision medicine

BACKGROUND

We have previously shown that the effect of a high-density lipoprotein (HDL) genetic risk score depends on whether the phenotype (HDL cholesterol) is high or low relative to its distribution (quantile-dependent expressivity).

OBJECTIVE

Evidence for quantile-dependent expressivity was sought using a more inclusive genetic measure (quantile-specific heritability, h²) in a larger population (Framingham cohort).

METHODS

Quantile regression was used to test whether the offspring-parent (β_OP) and full-sib (β_FS) regression slopes increased with the percentiles of the offspring's HDL distribution in 10,650 parent-offspring pairs and 2130 sibships. Quantile-specific heritability was estimated by 2β_OP/(1 + r_spouse) and [(8β_FSr_spouse + 1)^0.5-1]/(2r_spouse), where r_spouse is the spouse correlation.

RESULTS

HDL cholesterol heritability estimated from β_OP increased significantly (P = 4.2 × 10^-5) from the 10^th (h² ± SE: 0.44 ± 0.03), 25^th (0.45 ± 0.03), 50^th (0.47 ± 0.03), and 75^th (0.56 ± 0.04) to the 90^th percentiles (0.65 ± 0.06) of the offspring's age- and sex-adjusted HDL cholesterol distribution. Heritability estimated from β_FS also increased significantly with the percentiles of the offspring's HDL cholesterol (P = .002), apo A1 (P = .006), HDL2 cholesterol (P = .003), and HDL3 cholesterol distribution (P = .02). Consistent with quantile-dependent expressivity, published pharmacologic and nutritional interventions that raised (eg, statin, fibrates, estrogen replacement therapy, efavirenz, and dietary fat) or lowered HDL cholesterol concentrations (tamoxifen, dietary carbohydrate) correspondingly increased and decreased genetic effects.

CONCLUSION

HDL cholesterol heritability increased with increasing percentile of the offspring's HDL distribution. Whereas precision medicine is based on the premise that genetic markers identify patients most likely to benefit from drugs and diet, quantile-dependent expressivity postulates that the strong signals from these genetic markers simply trace the heritability increase with increasing plasma HDL concentrations. Thus, quantile-dependent expressivity provides an alternative interpretation to these genotype-specific effects.

Association between APOE polymorphisms and lipid profile in Mexican Amerindian population

BACKGROUND

Apolipoprotein E (ApoE) is a glycoprotein that plays an important role in lipid homeostasis at both cerebral and systemic levels. Moreover, the differential distribution of APOE gene alleles among different populations, means that ApoE isoforms could have different effects on lipids metabolism. The present study aims to evaluate the relationship between APOE gene alleles and the lipid profile in a Mexican Amerindian (MA) population.

METHODS

This study included 1997 MA individuals of different ethnicities distributed throughout different states of Mexico. All individuals underwent anthropometric measurements as well as laboratory tests including fasting glucose (FG), total cholesterol (TC), triglycerides, low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C). TaqMan^® probe genotyping assays were used to genotype APOE. The Kruskal-Wallis test was performed to determine the correlation between APOE gene alleles and genotypes and the biochemical variables measured.

RESULTS

Among the biochemical variables analyzed, only the HDL-C and LDL-C levels showed statistical differences (p-value < .05) between individuals carrying different APOE alleles. For HDL-C, individuals carrying the E2 allele had higher HDL-C levels, followed by individuals carrying the E3 allele and carriers of the E4 allele presented the lowest levels of HDL-C (E2 > E3 > E4). This relationship was inversed for LDL-C levels (E2 < E3 < E4). Nevertheless, the difference of HDL-C levels between APOE-E3 and APOE-E4 carriers remained only in obese individuals.

CONCLUSIONS

Our results suggest that APOE gene genotypes play an important role in the differential modulation of lipid profiles in the MA population with obesity.

Associations Between the Apolipoprotein E ε4 Allele and Reduced Serum Levels of High Density Lipoprotein a Cognitively Normal Aging Han Chinese Population

Background: Previous studies have confirmed that APOE genotype is associated with lipid metabolism, but related studies are inconsistent. Therefore, we conducted this cross-sectional study to explore the associations between apolipoprotein E (APOE) genotypes and serum levels of fasting blood sugar, triglycerides, total cholesterol, high density lipoprotein, and low density lipoprotein in a cognitively normal aging Han Chinese population. Methods: One hundred sixty-nine community elders with normal cognitive function were included in the study. Based on multiplex amplification refractory mutation system polymerase chain reaction (PCR), these subjects were divided into three groups: (1) E2/2 or E2/3 (APOE E2); (2) E3/3 (APOE E3); and (3) E2/4, E3/4, or E4/4 (APOE E4). Correlations of serum levels of fasting blood sugar, triglycerides, total cholesterol, high density lipoprotein, and low density lipoprotein with APOE genotypes were assessed. Results: The results of Mann-Whitney analysis showed that the concentration of high density lipoprotein (HDL) in APOE E2 and E3 groups was higher than that in E4 groups (p < 0.05). Logistic regression analysis also suggested that a lower level of high density lipoprotein was associated with the E4 allele (adjusted odds ratio 0.164, 95% confidence interval 0.031~ 0.876, P = 0.034). Conclusion: APOE E4 is associated with decreased serum high density lipoprotein concentration in healthy elderly. However, the above conclusions need to be further verified.

Effect of APOE polymorphism on obesity and lipid profile in women of differing reproductive status

The aim of this study was to investigate whether the effect of apolipoprotein E polymorphism (APOE) on somatic and lipid risk parameters varies in women of differing reproductive status. We analyzed 447 Slovak women aged between 39 and 90 years. APOE genotypes were determined by PCR-RFLP. Regression analysis confirmed the effect of the APOE genotype on the levels of LDL-cholesterol, apolipoprotein B (apoB), nonHDL-cholesterol and on the three atherogenic indices: apoB-to-apoA1, TC-to-HDLcholesterol, LDL-C-to-HDL-cholesterol. Here, lower mean levels were registered in the E2 carriers than in the E3 and E4 subgroups. However, the impact of menopausal status on lipid parameters was not confirmed. Bonferroni correction showed that systolic blood pressure was significantly lower in the E4 carriers compared to the E3 group (P=0.017). Univariate analysis of covariance revealed a significant interaction between the menopausal group and the APOE group, and their common effect on waist-to-hipratio (WHR). Bonferroni correction in early postmenopausal women showed that the mean WHR values were significantly different between E2 and E4 groups (P=0.008). This study demonstrates that the E*2 allele has a protective effect against higher blood lipid levels. Moreover, the results suggest that E*2 could have a partial negative effect on WHR in early postmenopausal Slovak women.

Nutritional genomics for the characterization of the effect of bioactive molecules in lipid metabolism and related pathways

Cardiovascular disease and cancer are the main causes of morbidity and mortality worldwide. Thus, investigators have focused their efforts on gaining insight into understanding the mechanisms involved in the development and evolution of these diseases. In the past decade, and with the contribution of the -omics technologies, strong evidence has supported an essential role of gene-nutrient interactions in these processes, pointing at natural bioactive molecules as promising complementary agents that are useful in preventing or mitigating these diseases. In addition, alterations in lipid metabolism have recently gained strong interest since they have been described as a common event required for the progression of both diseases. In the present review, we give an overview of lipid metabolism, mainly focusing on lipoprotein metabolism and the mechanisms controlling lipid homeostasis. In addition, we review the modulation of lipid metabolism by bioactive molecules, highlighting their potential use as therapeutic agents in preventing, and treating chronic diseases such as cardiovascular disease and cancer. Finally, we report the usefulness of the -omics technologies in nutritional research, focusing on recent findings, within nutritional genomics, in the interaction of bioactive components from foods with several genes that are involved in the development and progression of these diseases.

Diet, genetics, and disease: a focus on the middle East and north Africa region

The Middle East and North Africa (MENA) region suffers a drastic change from a traditional diet to an industrialized diet. This has led to an unparalleled increase in the prevalence of chronic diseases. This review discusses the role of nutritional genomics, or the dietary signature, in these dietary and disease changes in the MENA. The diet-genetics-disease relation is discussed in detail. Selected disease categories in the MENA are discussed starting with a review of their epidemiology in the different MENA countries, followed by an examination of the known genetic factors that have been reported in the disease discussed, whether inside or outside the MENA. Several diet-genetics-disease relationships in the MENA may be contributing to the increased prevalence of civilization disorders of metabolism and micronutrient deficiencies. Future research in the field of nutritional genomics in the MENA is needed to better define these relationships.

Interactions between hepatic lipase and apolipoprotein E gene polymorphisms affect serum lipid profiles of healthy Canadian adults

The purpose of this study was to assess the individual and interactive effects between hepatic lipase (LIPC; C-514T, G-250A) and apolipoprotein E (APOE) (E2, E3, E4) gene polymorphisms on levels of plasma lipoprotein cholesterol and triglyceride among healthy, young, Canadian adults (n = 440). All subjects with at least one APOE2 allele had significantly lower low-density lipoprotein cholesterol, total cholesterol, and total cholesterol – high-density lipoprotein cholesterol ratio when compared with those with the APOE3 or APOE4 allele. There were significant differences in the LIPC allele and genotype frequencies between Caucasian (n = 207) and Asian (n = 211) individuals, but ethnicity did not contribute to the variations in circulating lipids. In addition, the lowest triglyceride levels (0.87 ± 0.27 mmol·mL–1) were found in all APOE2 individuals carrying LIPC-514-CC and LIPC-250-GG genotypes, whereas the highest triglyceride levels (1.29 ± 0.34 –1.32 ± 0.32 mmol·mL–1) were found in APOE2 individuals carrying the opposite genotypes, LIPC-514TT and LIPC-250AA. These observations, distinct from the anti-atherogenic effects of APOE2 through the lowering of low-density lipoprotein cholesterol and LIPC on high-density lipoprotein cholesterol, suggest that there is an interactive effect between APOE and LIPC genotypes on plasma triglyceride levels. These results provide the basis for further studies on establishing which genotype combinations would be the most protective against hypertriglyceridemia.

A whole genome linkage scan identifies multiple chromosomal regions influencing adiposity-related traits among Samoans

We conducted a genome-wide scan in 46 pedigrees, with 671 phenotyped adults, from the independent nation of Samoa to map quantitative trait loci (QTLs) for adiposity-related phenotypes, including body mass index (BMI), abdominal circumference (ABDCIR), percent body fat (%BFAT), and fasting serum leptin and adiponectin. A set of 378 autosomal and 14 X chromosomal microsatellite markers were genotyped in 572 of the adults. Significant genetic correlations (0.82-0.96) were detected between pairs of BMI, ABDCIR, %BFAT and leptin. Suggestive linkages were found on 13q31 (LOD = 2.30 for leptin, LOD = 2.48 for %BFAT, LOD = 2.04 for ABDCIR, and LOD = 2.09 for BMI) and on 9p22 (LOD = 3.08 for ABDCIR and LOD = 2.53 for %BFAT). Furthermore, bivariate linkage analyses indicated that the genetic regions on 9p22 (bivariate LOD 2.35-3.10, LOD(eq) (1df) 1.88-2.59) and 13q31 (bivariate LOD 1.96-2.64, LOD(eq) 1.52-2.21) might harbor common major genes with pleiotropic effects. Other regions showing suggestive linkage included 4q22 (LOD = 2.95) and 7p14 (LOD = 2.64) for %BFAT, 2q13 for adiponectin (LOD = 2.05) and 19q12 for BMI-adjusted leptin (LOD = 2.03). Further fine mapping of these regions may help identify the genetic variants contributing to the development of obesity in Samoan adults.

Variation in the cholesteryl ester transfer protein (CETP) gene does not influence individual plasma cholesterol response to changes in the nature of dietary fat

BACKGROUND AND AIMS

Some individuals respond to a greater extent than others to changes in dietary fat and cholesterol even when dietary intake is consistent. A prospective study has been undertaken in which two groups of individuals according to cholesteryl ester transfer protein (CETP) genotype were compared in terms of plasma lipid response to altering the nature of dietary fat in a free-living situation.

METHODS AND RESULTS

Following genotyping, 35 individuals with the CETP Taq1 B1B1 genotype were paired with age and sex-matched individuals with one or two CETP B2 alleles, to undertake a single crossover trial with a diet high in saturated fat and a diet high in polyunsaturated fat. There was no washout period between the two 4-week phases. Plasma lipoproteins were measured at the beginning and end of each phase. The difference (95% CI) in plasma LDL-cholesterol concentration at the end of the PUFA and SAFA diets was 0.95 (0.71, 1.19) mmol/l in the CETP B1B1 group and 0.80 (0.57, 1.04) mmol/l in the group with at least one CETP B2 allele. The dietary induced changes in the two genotype groups were not significantly different (p=0.38) from each other. Comparable results were observed for plasma total cholesterol. The high PUFA and SAFA diets did not significantly alter plasma HDL concentration in either of the CETP genotype groups. Response was also similar according to apolipoprotein E genotype (E3E3 vs E4+) and lipoprotein lipase genotype (S447X).

CONCLUSIONS

The results of this study do not support previous studies in which CETP genotype predicted plasma LDL-cholesterol response to diet. CETP genotype does not significantly affect the change in plasma total and LDL-cholesterol concentrations that occur when altering the nature of dietary fat. These data suggest that the influence of genetic factors on total and LDL-cholesterol may be relatively small in comparison with the effect of dietary manipulation.

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.

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.

Nutrigenomics and nutrigenetics

PURPOSE OF REVIEW

Nutritional genomics has tremendous potential to change the future of dietary guidelines and personal recommendations. Nutritional genomics covers nutrigenomics, which explores the effects of nutrients on the genome, proteome and metabolome, and nutrigenetics, the major goal of which is to elucidate the effect of genetic variation on the interaction between diet and disease. Nutrigenetics has been used for decades in certain rare monogenic diseases such as phenylketonuria, and it has the potential to provide a basis for personalized dietary recommendations based on the individual's genetic makeup in order to prevent common multifactorial disorders decades before their clinical manifestation.

RECENT FINDINGS

Preliminary results regarding gene-diet interactions in cardiovascular diseases are for the most part inconclusive because of the limitations of current experimental designs. Success in this area will require the integration of various disciplines, and will require investigators to work on large population studies that are designed to investigate gene-environment interactions.

SUMMARY

Based on the current knowledge, we anticipate that in the future we will be able to harness the information contained in our genomes to achieve successful aging using behavioral changes, with nutrition being the cornerstone of this endeavor.

Sugars, hypertriglyceridemia, and cardiovascular disease

Short-term studies consistently show that raising the carbohydrate content of the diet increases serum triacylglycerol concentrations. As compared with starches, sugars (particularly sucrose and fructose) tend to increase serum triacylglycerol concentrations by approximately 60%. The magnitude of the effect depends on other aspects of the diet, including the total amount of carbohydrate and the types of fat, carbohydrate, and fiber, but definitive studies to describe the dose-response relations are not available. Longer-term studies show that some high-carbohydrate diets are not associated with increased fasting serum triacylgycerol concentrations. However, sedentary subjects with upper-body and visceral obesity who have the metabolic syndrome tend to be at higher risk for hypertriglyceridemia in response to high-sucrose and high-carbohydrate diets; moderate weight loss mitigates the effect. Hyperinsulinemia or insulin resistance may play a role in promoting higher rates of VLDL synthesis and hypertriglyceridemia in obesity, but the mechanisms remain unclear. The effect of fructose in promoting triacylglycerol synthesis is independent of insulinemia, however. In terms of the long-term effects of diets high in sugars on the risk of cardiovascular disease, available epidemiologic evidence indicates no association of sugars or total carbohydrate intake per se, but high dietary glycemic load is associated with higher serum triacylglycerol concentrations and greater risk of coronary heart disease in women. Studies are needed to delineate the independent effects of dietary sugars and glycemic load on serum triacylglycerol concentrations in lean and obese men and women and to determine whether the elevations in fasting and fed concentrations of serum triacylglycerol with high-carbohydrate and high-sugars diets are associated with increased risk of cardiovascular disease.

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 obesity gene map: the 2002 update

This is the ninth update of the human obesity gene map, incorporating published results through October 2002 and continuing the previous format. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) from human genome-wide scans and various animal crossbreeding experiments, and association and linkage studies with candidate genes and other markers is reviewed. For the first time, transgenic and knockout murine models exhibiting obesity as a phenotype are incorporated (N = 38). As of October 2002, 33 Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and the causal genes or strong candidates have been identified for 23 of these syndromes. QTLs reported from animal models currently number 168; there are 68 human QTLs for obesity phenotypes from genome-wide scans. Additionally, significant linkage peaks with candidate genes have been identified in targeted studies. Seven genomic regions harbor QTLs replicated among two to five studies. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 222 studies reporting positive associations with 71 candidate genes. Fifteen such candidate genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. More than 300 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful sites can be found at http://obesitygene.pbrc.edu.

State of nursing science: on the edge

Nurse scientists have had great and important successes contributing to science and to patient care. To review the state of nursing science is an enormous and complex challenge, and yet the pace of discovery constantly quickens. The purpose of this article, which was read at the 2002 State of the Science Congress, was to use the human response model to describe the domains of nursing science and note exemplary, innovative developments in the context of the model's "person" and "environmental" domains. Advances are noted in genetics, aging, development, and gender studies; also noted is work in infection care, disaster care, and identification of health disparities. Asked to predict the future, we chose instead to describe societal challenges and speculate how nursing leaders can contribute importantly by applying nursing's unique perspective. Benchmarks of our success will include reversal of the nursing shortage, patients living to their highest potential, and penetration of evidence based care into clinical practice and health policy. Furthermore, the media and the public will view nurse scientists as key informants related to clinical care. Nurse scientists will be elected to lead major interdisciplinary organizations, our training programs will prepare new scientists with the knowledge and skills to enter a competitive and ever-evolving field, our schools will have adequate infrastructure to support the advancement using cutting-edge technology, centers of excellence will provide research consultation and collaboration beyond university boundaries, and nurse scientists will assume a more visible role in translational research.