Restriction fragment length polymorphisms in the apo B gene in relation to coronary artery disease

Association between Apo B, LDL-R and PCSK9 gene polymorphisms with coronary artery diseases in Egyptians

BACKGROUND

Many studies have focused on the significance of lipid regulatory genes in the pathophysiology of Coronary artery disease (CAD). ApoB XbaI (rs693) and EcoRI (rs1042031) single nucleoid polymorphisms (SNPs) were investigated to detect whether they are risk factors for CAD. Till now, this association remains uncertain. SMARCA4 (rs1122608) SNP has directly related to dyslipidemia. Loss of function mutations (LOF) in PCSK9 result in a reduction in LDL cholesterol and are associated with protection from the development of CAD.

METHODS

This study was conducted on 54 CAD patients who were admitted at Internal Medicine Specialized Hospital (Cardiology Department) and 47 healthy controls. Peripheral blood samples were taken from both groups. DNA was extracted from EDTA-blood samples, then PCR- RFLP for ApoB XbaI (rs693) and EcoRI (rs1042031), SMARCA4 (rs1122608) and PCSK9 (rs505151) SNPs was done.

RESULTS

No statistically significant difference was found between patients and controls as regard EcoRI SNP. XbaI (rs693) X + X + genotype was significantly higher in control group (P = 0.0355). SMARCA4 (TT, GT + TT) genotypes, and T allele (P < 0.001); PCSK9 AG genotype and G allele (P = 0.027 and 0.032 respectively) were more frequent in CAD patients than controls.

CONCLUSION

SMARCA4 (rs1122608) and PCSK9 (rs505151) SNPs are significantly accompanying with the risk of CAD development in the Egyptian population. X + X + genotype appeared to have a protective effect against CAD. However, no observed association between EcoRI (rs1042031) and the risk of CAD development was found.

Macronutrient intake modulates impact of EcoRI polymorphism of ApoB gene on lipid profile and inflammatory markers in patients with type 2 diabetes

We sought to examine whether dietary intakes may affect the relationship between ApoB EcoRI and lipid profile, as well as serum inflammatory markers, in patients with type 2 diabetes (T2DM). This current study consisted of 648 diabetic patients. Dietary intake was calculated by a food frequency questionnaire. Biochemical markers (high-density lipoprotein (HDL), total cholesterol (TC), LDL, TG, CRP, IL-18, PGF2α) were measured based on standard protocols. Genotyping of the Apo-B polymorphisms (rs1042031) was conducted by the PCR–RFLP method. The gene-diet interactions were evaluated using GLMs. In comparison to GG homozygotes, A-allele carriers with above the median -CHO intake (≥ 54 percent of total energy) had considerably greater TC and PGF2a concentrations. Furthermore, as compared to GG homozygotes, A-allele carriers with above the median protein intake (≥ 14 percent of total energy) had higher serum levels of TG (P = 0.001), CRP (P = 0.02), TG/HDL (P = 0.005), and LDL/HDL (P = 0.04) ratios. Moreover, A-allele carriers with above the median total fat intake (≥ 35 percent of total calories) had significantly higher TC level (P = 0.04) and LDL/HDL (P = 0.04) ratios compared to GG homozygotes. Furthermore, when compared to GG homozygotes, A-allele carriers who consumed above the median cholesterol (> 196 mg) had greater TG (P = 0.04), TG/HDL (P = 0.01) ratio, and IL-18 (P = 0.02). Furthermore, diabetic patients with the GA, AA genotype who consume above the median cholesterol had lower ghrelin levels (P = 0.01). In terms of LDL/HDL ratio, ApoB EcoRI and dietary intakes of specific fatty acids (≥ 9 percent for SFA and ≥ 12 percent for MUFA) had significant interaction. LDL/HDL ratio is greater in A-allele carriers with above the median SFA intake (P = 0.04), also when they consumed above the median MUFA this association was inverse (P = 0.04). Our study showed that plasma lipid levels in participants carrying the (AA or AG) genotype were found to be more responsive to increasing the percentage of energy derived from dietary fat, CHO, protein, SFA, and cholesterol consumption. Therefore, patients with a higher genetic susceptibility (AA or AG) seemed to have greater metabolic markers with a higher percentage of macronutrient consumption. Also, ApoB EcoRI correlations with metabolic markers might be attenuated with above the median MUFA consumption.

Associations of the APOB rs693 and rs17240441 polymorphisms with plasma APOB and lipid levels: a meta-analysis

BACKGROUND

The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. This meta-analysis aimed to clarify the associations of the rs693 and rs17240441 polymorphisms with fasting APOB and lipid levels.

METHODS

Sixty-one studies (50,018 subjects) and 23 studies (8425 subjects) were respectively identified for the rs693 and rs17240441 polymorphisms by searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases. The following information was collected for each study: first author, age, gender, ethnicity, health condition, sample size, genotyping, lipid assay method, mean and standard deviation or standard error of APOB and lipid variables by genotypes. A dominant model was used for this meta-analysis.

RESULTS

The carriers of the rs693 variant allele (T) had higher levels of APOB [standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) = 0.16-0.36, P < 0.01], triglycerides (TG) (SMD = 0.12, 95% CI = 0.05-0.20, P < 0.01), total cholesterol (TC) (SMD = 0.24, 95% CI = 0.17-0.30, P < 0.01) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.22, 95% CI = 0.14-0.30, P < 0.01), and lower levels of high-density lipoprotein cholesterol (HDL-C) (SMD = -0.06, 95% CI = -0.11-0.01, P = 0.01) than the non-carriers. The carriers of the rs17240441 deletion allele had higher levels of APOB (SMD = 0.13, 95% CI = 0.06-0.20, P < 0.01), TC (SMD = 0.17, 95% CI = 0.07-0.26, P < 0.01) and LDL-C (SMD = 0.15, 95% CI = 0.07-0.23, P < 0.01) than the non-carriers.

CONCLUSIONS

The rs693 polymorphism is significantly associated with higher levels of APOB, TG, TC and LDL-C, and lower levels of HDL-C. The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and LDL-C. Further studies are needed to elucidate the underlying mechanisms.

Association between apolipoprotein B EcoRI polymorphisms and coronary heart disease : A meta-analysis

OBJECTIVE

The study was carried out to examine the association between apolipoprotein B (ApoB) EcoRI polymorphism (E^- vs. E⁺) (rs1042031) and coronary heart disease (CHD) risk by systematically analyzing multiple independent studies.

METHODS

The Hardy-Weinberg equilibrium (HWE) test was applied to assess genotype frequency distribution in healthy controls. The quality of the studies was assessed using the Newcastle-Ottawa scale (NOS). Power analysis was performed with Power and Precision V4 software. A fixed effect model was used because no deviation from homogeneity was found. Publication bias was quantified and examined with Begg's funnel plot test and Egger's linear regression method. The meta-analysis was performed by Stata 12.0 software.

RESULTS

A total of 21 eligible association studies were merged in this meta-analysis and the pooled sample consisted of 2994 CHD patients and 3258 healthy controls. No significant publication bias and heterogeneity were observed in these studies. The pooled odds ratio (OR) and 95% confidence interval (CI) of E^- vs. E⁺ were 1.18 (1.06-1.32). The pooled OR (95% CI) of E⁺ E^- + E^- E^- vs. E⁺ E⁺ was 1.18 (1.04-1.34).

CONCLUSIONS

This meta-analysis indicated that ApoB EcoRI confers a moderate risk for CHD and the E^- allele at this locus might be a susceptibility allele for the development of CHD.

Association Between Apolipoprotein B XbaI Polymorphism and Coronary Heart Disease in Han Chinese Population: A Meta-Analysis

OBJECTIVE

To examine the association between apolipoprotein B (ApoB) XbaI polymorphisms (rs693) and coronary heart disease (CHD) risk among the Han Chinese population by systematically analyzing multiple independent studies.

METHODS

The Hardy-Weinberg equilibrium test was applied to check genetic equilibrium among genotypes for the selected literatures. The quality of the studies was assessed by using the NewcastleOttawa Scale. Power analysis was performed with Power and Precision V4 software. A fixed or random effect model was used on the basis of heterogeneity. Publication bias was quantified and examined with Begg's funnel plot test and Egger's linear regression test. The meta-analysis was performed by Stata 12.0 software.

RESULTS

A total of 10 eligible association studies were included in this meta-analysis, and the pooled sample consisted of 1195 CHD patients and 1178 health controls. No consistent inference regarding publication bias for the included studies was obtained by using the two above-mentioned methods. The pooled odds ratios (95% confidence intervals [CIs]) for X(-) versus X(+) allele and X(+)X(+) + X(+)X(-) versus X(-)X(-) genotype were 2.25 (1.40-3.62) and 2.21 (1.39-3.50), respectively.

CONCLUSIONS

This meta-analysis indicated that ApoB XbaI allele confers a significant risk towards the development of CHD among the Han Chinese population.

Association between apolipoprotein B gene polymorphisms and the risk of coronary heart disease (CHD): an update meta-analysis

OBJECTIVE

Polymorphisms in the apolipoprotein B (apoB) gene have been reported to be associated with coronary heart disease (CHD). However, the results on this topic are conflicting. The present study aims to derive a more precise estimation of the relationship between CHD and apoB genetic polymorphisms by meta-analysis.

METHODS

We identified a total of 54 studies involving 7236, 10,912, and 14,102 individuals, respectively, for EcoRI, XbaI, and SpIns/Del polymorphisms by searching in PubMed, Web of Science, Google Scholar, the Cochrane Library, Wanfang Data, SinoMed, and CNKI. We utilized RevMan 5.0 software to perform the meta-analyses.

RESULTS

A significant statistical association between apoB EcoRI polymorphism and CHD was observed under an allelic (p = 0.001, odds ratio (OR) = 1.33, 95% confidence interval (CI) = 1.12-1.57), dominant (p = 0.005, OR = 1.22, 95% CI = 1.06-1.40), and recessive (p = 0.04, OR = 1.33, 95% CI = 1.01-1.74) model. We also found similar association of apoB SpIns/Del polymorphism with CHD. However, we did not find association between apoB XbaI polymorphism and CHD.

CONCLUSION

The current meta-analysis found an association of EcoRI polymorphism and SpIns/Del polymorphism with an increased risk of CHD. No significant association between apoB XbaI polymorphism and CHD we observed in the present study.

The roles of genetic polymorphisms and human immunodeficiency virus infection in lipid metabolism

Dyslipidemia has been frequently observed among individuals infected with human immunodeficiency virus type 1 (HIV-1), and factors related to HIV-1, the host, and antiretroviral therapy (ART) are involved in this phenomenon. This study reviews the roles of genetic polymorphisms, HIV-1 infection, and highly active antiretroviral therapy (HAART) in lipid metabolism. Lipid abnormalities can vary according to the HAART regimen, such as those with protease inhibitors (PIs). However, genetic factors may also be involved in dyslipidemia because not all patients receiving the same HAART regimen and with comparable demographic, virological, and immunological characteristics develop variations in the lipid profile. Polymorphisms in a large number of genes are involved in the synthesis of structural proteins, and enzymes related to lipid metabolism account for variations in the lipid profile of each individual. As some genetic polymorphisms may cause dyslipidemia, these allele variants should be investigated in HIV-1-infected patients to identify individuals with an increased risk of developing dyslipidemia during treatment with HAART, particularly during therapy with PIs. This knowledge may guide individualized treatment decisions and lead to the development of new therapeutic targets for the treatment of dyslipidemia in these patients.

Genetic determinants of apolipoprotein B-100 kinetics

PURPOSE OF REVIEW

We review stable isotope tracer studies of apolipoprotein B-100 (apoB) kinetics concerning genetic polymorphisms and mutations that affect human lipoprotein metabolism.

RECENT FINDINGS

In obese men, the allelic combination of the apoB signal peptide, SP24, and cholesteryl ester transfer protein, CETP B1B1, is independently associated with lower VLDL apoB secretion. Microsomal triglyceride transfer protein -493G/T carriers have reduced IDL apoB and LDL apoB production as compared with controls. Mutations in cholesterol transporters (ATP-binding cassette transporter G8 and Niemann-Pick C1 Like 1) are associated with reduced VLDL apoB secretion and increased LDL apoB production and catabolism. The ATP-binding cassette transporter G8 400K variant is a significant, independent predictor of VLDL apoB secretion. Mutations in lipases (lipoprotein lipase and hepatic lipase) and transfer proteins (lecithin-cholesterol acyltransferase and cholesteryl ester transfer protein) alter their functional activity, which impact on VLDL and LDL kinetics.

SUMMARY

Mutations in genes that regulate intrahepatic apoB assembly and lipid substrate availability to the liver impact on VLDL apoB secretion. Lipoprotein tracer studies can provide functional insight into the potential impact of genetic polymorphisms in regulating apoB metabolism in humans.

Influence of apolipoprotein B signal peptide insertion/deletion polymorphism on serum lipids and apolipoproteins in a Chinese population

Insertion/deletion polymorphism of the apo B gene encoding signal peptide and its influence on serum lipids and apolipoproteins was studied in 269 Chinese of both sexes in Singapore. The frequency of the Del allele was found to be 0.20, which is significantly lower than that in Caucasians (France) (0.34). The distribution of genotypes of ins/del polymorphism was at Hardy-Weinberg equilibrium in this population. There was an excess of individuals with the deletion allele in hypercholesterolemic subjects compared to those with normal cholesterol levels (P less than 0.05). All the lipid and apolipoprotein values were regressed for age, sex and BMI by multiple regression analysis. Individuals with one or two del alleles had significantly higher levels of serum total cholesterol (248.8 +/- 13.0 and 255.4 +/- 20.4 mg/dl, respectively) compared to those in individuals with only the Ins allele (218.4 +/- 7.8 mg/dl) (P less than 0.05). Serum LDL cholesterol level was also significantly higher in individuals with del allele (173.4 +/- 11.7 mg/dl) compared to that in those without the del allele (141.1 +/- 7.4 mg/dl) (P = 0.02). The percentages of sample variance of different lipid traits explained by apo B signal peptide polymorphism were estimated by analysis of variance (ANOVA) with sex, age and BMI as covariates. 2.3% of variability of serum total cholesterol (F = 3.27, P = 0.040) and 2.8% of LDL cholesterol (F = 3.87, P = 0.023) could be explained by the ins/del polymorphism of the apo B signal peptide gene.

Genetic variations of the apolipoprotein B gene in Turkish patients with coronary artery disease

BACKGROUND

The results of studies that clarify the association of genetic markers at the apolipoprotein B (apo B) gene (EcoRI and XbaI polymorphisms) with coronary artery disease (CAD) are not consistent and suggest that the effect is context dependent (dependent on ethnicity and sex). The present study represents the first investigation of the apo B gene polymorphisms in Turkish patients with CAD and their influence on lipid levels.

AIM

The study investigated the association of apo B gene EcoRI and XbaI polymorphisms with CAD and with variation in lipid levels (total cholesterol (T-Chol), high-density lipoprotein cholesterol (HDL-Chol), low-density lipoprotein cholesterol (LDL-Chol), and triacylglycerol (TAG)).

SUBJECTS AND METHODS

The study group was composed of 150 individuals with angiographically documented CAD and 100 angiographically proven to be healthy controls. PCR-RFLP was used to determine the DNA polymorphisms of the apo B gene.

RESULTS

The frequencies of apo B genotypes detected with EcoRI (AA, AG, GG) and XbaI (CC, CT, TT) did not differ significantly between case and control subjects. A significant association between EcoRI genotypes and T-Chol (p < or = 0.05), and LDL-Chol (p < or = 0.001) was observed only in CAD patients. Patients with the AA genotype had higher levels of serum T-Chol and LDL-Chol compared with AG. With logistic regression analysis the XbaI TT genotype was found to be associated with CAD prevention. However, no significant differences in lipid variables were determined for the XbaI polymorphisms in the patients with CAD.

CONCLUSIONS

Apo B EcoRI genotypes were not found as risk factors for CAD, whereas XbaI TT genotype was detected to prevent against CAD in our study group.

Apolipoprotein B-gene DNA polymorphisms (Xbal andEcoRI), serum lipids, and apolipoproteins in healthy Chinese

The frequency of restriction fragment length polymorphisms (RFLPs) of the apolipoprotein B (apo B) gene, detected by XbaI and EcoRI, and their influence on serum lipids and apolipoproteins were studied in healthy Chinese of both sexes in Singapore. A total of 221 subjects (150 males, 71 females) were investigated for the XbaI and 159 subjects for the EcoRI polymorphisms, while serum lipids and apolipoprotein levels were available for 196 subjects. The frequency of the X2 allele was found to be significantly lower in the Chinese than that reported in Caucasians from the United Kingdom (0.09 vs. 0.51, P less than 0.001). The haplotype frequencies were also significantly different between the Chinese and Caucasians with a higher frequency of X1R1 in the former compared to the latter (0.85 vs. 0.34, P less than 0.0001). The distribution of RFLP genotypes at both of the restriction sites was at Hardy-Weinberg equilibrium in all groups. The influence of the apo B RFLPs on serum lipids and apolipoprotein levels (apo AI, AII, and B) was studied by both residual and multiple regression analyses considering age, sex, body mass index (BMI), and genotypes as independent variables in all possible combinations. No association was observed between the apo B genotypes and serum lipids or apolipoprotein levels except for high density lipoprotein cholesterol (HDLC), apo AI and AII, with the X2 being associated with significantly lower levels of HDLC as well as apo AI and AII, the effect being stronger in males. These data raise the possibility that the mechanism of reported association between apo B polymorphism and coronary artery disease may be through effects on HDLC.

Exploration of multilocus effects in a highly polymorphic gene, the apolipoprotein (APOB) gene, in relation to plasma apoB levels

A detailed exploration of all the polymorphisms in candidate genes is required to better characterize the relationship between gene variability and complex traits. We propose a novel strategy for investigating the association between a highly polymorphic gene and a phenotype, by combining a multilocus genotype analysis and an haplotype analysis. For the multilocus genotype analysis, a data mining tool--termed DICE (Detection of Informative Combined Effects)--was developed to identify the best subset of polymorphisms that are associated--individually or in combination--with the phenotype. For the haplotype analysis, we used our recently developed method of haplotype-phenotype association to determine the most informative and parsimonious haplotype model fitting the data. We illustrate this strategy by investigating the association between twelve polymorphisms of the APOB gene and plasma apoB levels in 1442 European subjects. After exploring all main effects and interactions between polymorphisms, DICE identified the N4311S polymorphism as the most informative polymorphism in relation to apoB levels. Haplotype analysis led to the same conclusion. Additionally, DICE identified the E4154K (EcoRI) and the T2488T (XbaI) polymorphisms as potentially interesting. This selection was not modified by inclusion of the common APOE polymorphism in the analysis.

The X-X-/E+E+ genotype of the XbaI/EcoRI polymorphisms of the apolipoprotein B gene as a marker of coronary artery disease in a Brazilian sample

Studies that consider polymorphisms within the apolipoprotein B (apo B) gene as risk factors for coronary artery disease (CAD) have reported conflicting results. The aim of the present study was to search for associations between two DNA RFLPs (XbaI and EcoRI) of the apo B gene and CAD diagnosed by angiography. In the present study we compared 116 Brazilian patients (92 men) with CAD (CAD+) to 78 control patients (26 men) without ischemia or arterial damage (CAD-). The allele frequencies at the XbaI (X) and EcoRI (E) sites did not differ between groups. The genotype distributions of CAD+ and CAD- patients were different (chi (1) = 6.27, P = 0.012) when assigned to two classes (X-X-/E+E+ and the remaining XbaI/EcoRI genotypes). Multivariate logistic regression analysis showed that individuals with the X-X-/E+E+ genotype presented a 6.1 higher chance of developing CAD than individuals with the other XbaI/EcoRI genotypes, independently of the other risk factors considered (sex, tobacco consumption, total cholesterol, hypertension, and triglycerides). We conclude that the X-X-/E+E genotype may be in linkage disequilibrium with an unknown variation in the apo B gene or with a variation in another gene that affects the risk of CAD.

The influence of the polymorphism in apolipoprotein B codon 2488 on insulin and lipid levels in a Danish twin population

AIMS

The apolipoprotein B codon 2488 polymorphism has been associated with the metabolism of lipoproteins in subjects with Type 2 diabetes. However, no data are available on the influence of the polymorphism on insulin or glucose metabolism. This study examines the impact of the polymorphism on parameters associated with the insulin resistance syndrome in Danish twins.

METHODS

The effect of the polymorphism on lipid, glucose and insulin measures was studied in 548 same sex twins aged 55-74 years.

RESULTS

The codon 2488 polymorphism influenced fasting triglyceride levels, as well as insulin, as measured at 120 min in an oral glucose tolerance test. Subjects with the genotype T2488T had 14% higher triglyceride levels (P = 0.02) and 31% higher insulin levels (P = 0.004) than subjects with genotype C2488C. In twins discordant for genotype, the T-allele was associated with higher levels of triglyceride (P = 0.04) and insulin (P = 0.02) and lower levels of HDL-cholesterol (P = 0.04).

CONCLUSION

The T-allele of the codon 2488 polymorphism influenced parameters related to the insulin resistance syndrome, i.e. increased levels of insulin, increased levels of triglyceride and decreased levels of HDL. As the polymorphism is silent, these effects must be mediated through linkage to other polymorphisms in apolipoprotein B or other genes on chromosome 2.

Variations of cardiovascular disease associated genes exhibit sex-dependent influence on human longevity

This article investigates the relationship between the polymorphic variations in genes associated with cardiovascular disease and longevity in the Danish population. A new procedure that combines both demographic and the individual genetic information in determining the relative risks of the observed genetic variations is applied. The sex-dependent influences can be found by introducing sex-specific population survival and incorporating the risk of gene-sex interaction. Three genetic polymorphisms, angiotensinogen M/T235, blood coagulation factor VII (FVII) R/Q353 and FVII-323ins10, manifest significant influences on survival in males, with reduced hazards of death for carriers of the angiotensinogen M235 allele, the F VII Q353 allele, and the FVII-323P10 allele. The results show that some of these genotypes associated with lower risk of CVD could also reduce the carrier's death rate and contribute to longevity. However, the presence of sex-dependent effects and the fact that major CVD-associated genes failed to impose detrimental influence on longevity lead us to concur that the aging process is highly complicated.

Apolipoprotein B gene polymorphisms: prevalence and impact on serum lipid concentrations in hypercholesterolemic individuals from Brazil

Genetic polymorphisms at the apolipoprotein B (apo B) have been associated with elevated plasma concentrations of low-density lipoprotein (LDL) cholesterol, atherosclerosis and increased risk for coronary artery disease (CAD). In the present study, four apo B gene polymorphisms (MspI, XbaI, Ins/Del and 3'HVR) have been investigated to determine their frequencies and influence on the lipid profile of 177 hypercholesterolemic white Brazilian subjects (HG) and 100 control individuals (CG). The genotype distribution and allele frequency of MspI, XbaI and Ins/Del polymorphisms of apo B gene were similar between HG and CG groups. The frequency of the alleles smaller than 43 repeats (< or =43) of 3'HVR polymorphism in the HG group was higher when compared to controls (16.4 vs. 8.5%, P<0.05). Moreover, these alleles were associated with higher total cholesterol concentrations in serum of hypercholesterolemic individuals (P<0.05). In addition, an association between Ins/Del and 3'HVR polymorphism was observed. The alleles < or =43 and Del were more frequent in the HG when compared to the CG individuals (P<0.05). We concluded that 3'HVR polymorphism at the apo B gene may be an important genetic marker to evaluate atherosclerotic disease risk.

Seven DNA polymorphisms at the candidate genes of atherosclerosis in Brazilian women with angiographically documented coronary artery disease

The possible association of genetic markers at the apolipoprotein E (HhaI polymorphism), apolipoprotein B (XbaI, EcoRI and Ins/Del polymorphisms), and low-density lipoprotein receptor (LDLR) (AvaII, HincII and PvuII polymorphisms) with coronary artery disease (CAD) was evaluated in 50 Brazilian women with CAD diagnosed by angiography and in 100 healthy women (controls). The frequency of E3/E4 genotype for HhaI polymorphism at the Apo E gene was significantly higher in CAD patients than in controls (40% vs. 14%, respectively, P<0.001). Similarly, the X-X- genotype for XbaI polymorphism was more frequent in CAD individuals than controls (42% vs. 12%, P<0.0001). The A+A+ and P1P1 genotypes for AvaII and PvuII polymorphisms at the LDLR locus were also higher in CAD subjects than controls (44% vs. 16%, P<0.001 and 64% vs. 39%, P<0.05, respectively). The estimated relative risks for CAD in women carrying the E3/E4, X-X-, A+A+ and P1P1 genotypes were 4.1 [95% confidence interval (CI), 3.0-5.6], 5.3 (95% CI, 3.8-7.5), 4.1 (95% CI, 3.0-5.5), and 2.8 (95% CI, 2.2-3.6), respectively. This study demonstrates that Apo E, Apo B and LDLR gene polymorphisms are associated with CAD in Brazilian Caucasian women.

The contribution of candidate genes to the response of plasma lipids and lipoproteins to dietary challenge

The possible role of four candidate genes in lipid and lipoprotein response to diet was examined in 214 members of two large kibbutz settlements in Israel. Four site polymorphisms (signal peptide insertion/deletion, XbaI, EcoRI and MspI) of the apo B gene, the common apo E genotypes, three common mutations (T-93G, S447stop and N291S) of the LPL gene and the CETP I405V RFLP were determined. The average reduction induced by diet in participants with the absence of the EcoRI restriction site (L4154) of the apo B gene compared with those found to be homozygotes for the restriction site (G/G4154) were: 16.2 and 8.0 mg/dl for total cholesterol (TC) (P=0. 01); and 15.6 and 6.2 mg/dl for LDL-C (P=0.007), respectively. TC and LDL-C baseline levels were significantly different among the apo-E genotypes, yet there were no significant effects on lipid and lipoprotein dietary response. Triglyceride baseline values were significantly lower (P=0.007) among subjects with the LPL S447stop mutation and HDL-C was significantly lower (P=0.008) among subjects found to be heterozygous for the LPL N291S mutation. A heterogeneous response for triglyceride was observed for individuals with the S291 allele as compared to those individuals who were found to be homozygous for the N291 allele. No differences in dietary responsiveness were observed among the apo E and CETP genotypes. In conclusion, our results suggest that sequence variation(s) in the coding region of the apo B gene linked to the EcoRI polymorphism are associated with total cholesterol and LDL-C responsiveness to dietary manipulation. In our study population, LPL mutations had a significant effect on TG and HDL-C baseline levels and on their response to diet.

Apolipoprotein B gene polymorphisms and serum lipids: meta-analysis of the role of genetic variation in responsiveness to diet

BACKGROUND

The genetic variance determining plasma lipid and lipoprotein concentrations may modify individual responsiveness to alterations in dietary fat and cholesterol content.

OBJECTIVE

The aim was to examine the role of apolipoprotein (apo) B DNA polymorphisms in responsiveness of plasma lipids and lipoproteins to diet.

DESIGN

A controlled dietary intervention study was conducted in 44 healthy, middle-aged subjects with a 3-mo baseline, a 1-mo fat-controlled, a 1-mo high-fat, and a 1-mo habitual diet period. We also conducted a meta-analysis of all published dietary trials, including our own.

RESULTS

In our own dietary study, the apo B XbaI restriction-site polymorphism affected the responsiveness to diet of the plasma LDL-cholesterol concentration (P < 0.05, repeated-measures analysis of variance). Especially during the high-fat diet, homozygous absence of the XbaI restriction site (X(-)/X(-)) was associated with a greater increase in LDL cholesterol (44 +/- 5%) than was X(+)/X(+) (27 +/- 7%) or X(+)/X(-) (40 +/- 5%). The high-fat diet also induced a larger increase in plasma LDL cholesterol in subjects with the R(-)/R(-) genotype (homozygous absence of the EcoRI restriction site) (59 +/- 10%) than in those with the R(+)/R(-) (39 +/- 6%) or R(+)/R(+) (36 +/- 4%) genotype. The M(+)/M(+) genotype (homozygous presence of the MspI restriction site) was also more responsive (41 +/- 3% increase in LDL cholesterol) than the M(+)/M(-) genotype (27 +/- 10% increase). The meta-analysis supported the finding of the significant role of the EcoRI and MspI polymorphisms, but not that of the XbaI polymorphism.

CONCLUSIONS

The present study indicated that the apo B EcoRI and MspI polymorphisms are associated with responsiveness to diet.

Apolipoprotein E genotype and plasma levels in coronary artery disease. A case-control study in the Italian population

OBJECTIVES

To investigate the role of the apolipoprotein B and apolipoprotein E polymorphisms in coronary artery disease (CAD) susceptibility in the Italian population and their relation to plasma lipid and apolipoprotein levels.

METHODS

APOB (APOB Xbal, EcoRI, Ins/Del), and APOE (APOE Cfol) polymorphisms were analyzed in 150 male CAD patients and 110 matched controls. In the same subjects plasma lipid, apoB, and apoE levels were measured.

RESULTS

No differences in the distribution of the APOB polymorphisms were observed between patients and controls. Among patients the number of e*4-carriers was significantly higher than in controls. e*4-carriers were more frequent among the hypertensive patients and had a higher systolic blood pressure (p = 0.007) than the non-e*4 carriers. The APOB Xbal polymorphism was found to influence the distribution of HDL-cholesterol. Patients showed significantly lower levels of apoE (39.29 mg/L) than controls (54.32 mg/dL) and the lowest concentrations were associated to the E4/E3 and E4/E4 genotypes.

CONCLUSION

Quantitative data are consistent with the hypothesis that apoE has an anti-atherosclerotic role and suggest that the apoE quantitation could be a useful parameter for defining cardiovascular risk. e*4 allele appears to be a risk factor for CAD in the Italian population and could act by its association with low apoE levels.

The genetics of serum lipid responsiveness to dietary interventions

CHD is a multifactorial disease that is associated with non-modifiable risk factors, such as age, gender and genetic background, and with modifiable risk factors, including elevated total cholesterol and LDL-cholesterol levels. Lifestyle modification should be the primary treatment for lowering cholesterol values. The modifications recommended include dietary changes, regular aerobic exercise, and normalization of body weight. The recommended dietary changes include restriction in the amount of total fat, saturated fat and cholesterol together with an increase in the consumption of complex carbohydrate and dietary fibre, especially water-soluble fibre. However, nutrition scientists continue to question the value of these universal concepts and the public health benefits of low-fat diets, and an intense debate has been conducted in the literature on whether to focus on reduction of total fat or to aim efforts primarily towards reducing the consumption of saturated and trans fats. Moreover, it is well known that there is a striking variability between subjects in the response of serum cholesterol to diet. Multiple studies have examined the gene-diet interactions in the response of plasma lipid concentrations to changes in dietary fat and/or cholesterol. These studies have focused on candidate genes known to play key roles in lipoprotein metabolism. Among the gene loci examined, APOE has been the most studied, and the current evidence suggests that this locus might be responsible for some of the inter-individual variability in dietary response. Other loci, including APOA4, APOA1, APOB, APOC3, LPL and CETP have also been found to account for some of the variability in the fasting and fed states.

Response to dietary fat and cholesterol and genetic polymorphisms

1. We examined common polymorphisms in the genes encoding the LDL receptor, lipoprotein lipase, apoAI, apoB, apoAIV and cholesteryl ester transfer protein and related them to changes in LDL and HDL cholesterol after high fat/high cholesterol diets. 2. The only significant association was seen with the apoIV polymorphism, which leads to a structural change in the protein. The response to fat and cholesterol in subjects with at least one apoAIV 2 allele was only 30% of that seen in subjects with the common apoIV 1 allele (P < 0.01), accounting for 6-7% of the variance in response. This confirms the results of two previous studies in which dietary cholesterol intake was changed. 3. No association were seen with polymorphisms of the other five genes examined.

Genetic determinants of atherosclerosis-related dyslipidemias and their clinical implications

New approaches to the study of the genetics of premature coronary heart disease (CHD) have been made possible by the introduction of DNA probes for the apolipoproteins, the receptors and enzymes involved in lipid transport. Initially these were used to identify restriction fragment length polymorphisms for use as genetic markers to locate genes involved in the pathogenesis of atherosclerosis. More recent developments have allowed direct analysis of etiological mutations by such methods as single stranded conformational polymorphism (SSCP) analysis and denaturing gradient gel electrophoresis (DGGE). Loci that have been incriminated by such techniques include the apolipoprotein A-I--C-III--A-IV gene cluster, the apo B gene and the lipoprotein lipase locus. It is to be anticipated that these and other techniques will eventually identify all the major determinants involved in disorders of lipid transport and the development of premature atherosclerosis.

Polymorphisms of the genes encoding apoproteins A-I, B, C-III, and E and LDL receptor, and cholesterol and LDL metabolism during increased cholesterol intake. Common alleles of the apoprotein E gene show the greatest regulatory impact

Genetic and dietary factors regulate serum cholesterol level, but detailed investigations into their interactions have not been established. We assessed the effects of apoprotein (apo) E phenotype and polymorphic alleles of the apo A-I, apo B, apo C-III, and LDL receptor genes, separately and together, on regulation of serum LDL cholesterol level. The study group consisted of 29 middle-aged men, and cholesterol absorption, bile acid, and cholesterol synthesis and LDL apo B kinetics were studied in these men during low- and high-cholesterol diets. The six apo B alleles were identified on the basis of Xba I, EcoRI, and Msp I restriction fragment length polymorphism (RFLP), the apo A-I alleles with the Msp I RFLP, and the apo C-III and LDL receptor alleles corresponded to the Sst I and PvuII RPLPs of these genes, respectively. During low cholesterol intake, LDL cholesterol levels were similar in all of the genetic groups except for men with apo E2 phenotype. They had significantly (P < .05) lower levels of LDL apo B and cholesterol than men without the epsilon 2 allele. The low values were caused by a significantly higher removal of LDL apo B (apo E2, 0.453 +/- 0.03 versus apo E3, 0.312 +/- 0.01 pools per day, P < .05). High cholesterol intake increased LDL cholesterol levels in all genetic categories except in the apo E2 phenotype irrespective of the combinations with other polymorphisms. Carriers of the apo B R+ allele (EcoRI site present) presented with the most prominent LDL cholesterol rise (from 2.71 +/- 0.14 to 3.37 +/- 0.29 mmol/L). In multiple stepwise regression analysis, apo B EcoRI RFLP and apo E phenotypes were the only variables that explained the variability of high cholesterol intake-induced change in LDL cholesterol levels. In summary, in any genetic combination, individuals with the epsilon 2 allele had the lowest LDL cholesterol values and were nonresponders to dietary cholesterol, whereas subjects with the apo B R+ allele had marked LDL elevations, especially in combination with the epsilon 4.

The association between free fatty acid concentrations and triglyceride-rich lipoproteins in the post-prandial state is altered by a common deletion polymorphism of the apo B signal peptide

To investigate whether there were associations between the free fatty acid (FFA) response during a fat tolerance test and changes in concentrations of triglyceride-rich lipoproteins 57 healthy Caucasian men between 57 and 70 years of age underwent a fat tolerance test lasting 8 h. FFA concentrations initially decreased from 0.75 +/- 0.03 to 0.64 +/- 0.03 mmol/l at 2 h and thereafter increased to 1.2 +/- 0.04 mmol/l at 8 h. Maximum FFA concentration was the only significant determinant of 8 h triglyceride-rich lipoprotein (TGRLP) concentrations (pooled chylomicron and VLDL fractions d < 1.006) (TGRLP-TG r = 0.33, P = 0.012; TGRLP apo B r = 0.37, P = 0.004; TGRLP cholesterol r = 0.38, P = 0.004). The strength of the association between FFA and TGRLP was affected by the apo B signal peptide genotype. Only in individuals who were homozygous for the 27 amino acid (SP27 or I) allele of the apo B signal peptide were there significant associations between maximum FFA concentration quartile and 8 h TGRLP concentration (P value for linear trend = 0.025). In this genotype group there were lower HDL cholesterol concentrations (1.16 mmol/l compared to 1.38 mmol/l in subjects either heterozygous or homozygous for the SP24 [D] allele; P = 0.005) and there was a trend toward increased 8 h TGRLP concentrations. We propose that the association between post-prandial FFA concentrations and post-prandial TGRLP concentrations in individuals who are homozygous for the SP27 allele may be linked to the increased prevalence of ischemic heart disease (IHD) in this genotypic group.

Frequencies of five genetic polymorphisms in coronarographed patients and effects on lipid levels in a supposedly healthy population

Allele frequencies of genetic polymorphisms were compared between supposedly healthy subjects and angiographically proven coronary artery disease patients. The polymorphic candidate loci investigated were the apolipoprotein (apo) B signal peptide and XbaI polymorphism, the apo E polymorphism and two polymorphism of lipoprotein lipase (LPL) gene: Hind/III and PvuII. Apo B signal peptide and HindIII/LPL polymorphisms showed significant differences in allele partition between cases and controls; the rare alleles of both polymorphisms were less frequent (p < 0.05) in cases. We looked for associations between the polymorphisms and lipid concentration variability in a supposedly healthy population (145 men and 144 women). Apo B signal peptide, apo E and PvuII/LPL polymorphisms seem to influence some lipid metabolism parameters significantly. Apo AI and LpCIII levels were significantly different among apo B signal peptide genotypes: Del homozygotes had the highest concentrations of both variables. The epsilon 4 allele of apo E polymorphism was associated with increased concentrations of total cholesterol, LDL cholesterol and apo B. Increased LpAI:AII levels observed in E3 homozygotes (p < 0.01) have not previously been reported. LpAI:AII concentration was also influenced by PvuII/LPL polymorphisms.

Polymorphism of the apolipoprotein B gene and blood lipid concentrations in Japanese and Caucasian population samples

To examine whether a racial difference in apolipoprotein B (Apo B) gene polymorphism between Japanese and American Caucasians corresponds with the lower blood cholesterol concentrations in Japanese than in Americans, we examined the EcoRI polymorphism of the Apo B gene for 271 nonsmoking men and women aged 47-69 years in two population-based samples: rural Japanese living in Akita and Caucasians living in Minneapolis-St. Paul, Minnesota, USA. Mean values of serum cholesterol concentrations were significantly lower in Japanese than in Caucasians for both men and women (difference = 25-26 mg/dl). An allele-specific polymerase chain reaction was conducted to examine the Eco RI cutting site at the 12669 cDNA position of the Apo B gene. The allele R2 (absence of the cutting site) has been associated with lower cholesterol concentrations in two previous studies. The frequency of the R2 allele was 6% for Japanese and 17% for Caucasians (P < 0.001), and this race difference in allele frequency was identical for men and women. After controlling for age, body mass index, alcohol intake, and for women, menopausal status and hormone replacement therapy, the adjusted mean (SE) cholesterol level among Japanese was 204 (3) mg/dl for genotype R1R1 and 185 (7) mg/dl for genotype R1R2 or R2R2 combined (P = 0.01). The respective mean values among Caucasians were 224(5) mg/dl and 232(7) mg/dl (P = 0.36). The polymorphism had a similar effect on total cholesterol concentrations for both men and women. The observed lower prevalence of the R2 allele in Japanese than in Caucasians indicates that this variation in the Apo B gene does not explain the racial difference in blood cholesterol concentrations.

Genetic contributions to LDL-C, Apo-B and LDL-C/Apo-B ratio in a sample of Israeli offspring with a parental history of myocardial infarction

One hundred and forty sibships consisting of 280 brothers and 256 sisters with a family history of myocardial infarction were investigated for the possible involvement of a major gene in the determination of LDL-C, Apo-B and LDL-C/ Apo-B ratio (as a surrogate for LDL subclasses). The mean ages were 29.5 years (range 15-48) and 29.2 years (range 15-47), for brothers and sisters, respectively, and values were initially adjusted for age effects through multiple regression analysis. Results from commingling analysis indicated that for LDL-C a single normal distribution fitted the data as well as a mixture of two distributions. For Apo-B, a mixture of two normal distributions fitted the data significantly better than a single distribution (chi 2 = 7.8, df = 2, p = 0.02). For LDL-C/ Apo-B ratio a mixture of three normal distributions fitted the data significantly better than two distributions (chi 2 = 9.2, df = 2, p = 0.01). A regression analysis applied to the logarithm of the sex- and age-adjusted mean and variance within sibship, showed no indication of a major gene involvement for LDL-C. For Apo-B and LDL-C/Apo-B ratio, there existed, however, significant linear relationships between the logarithmically transformed means and within sibship variances which support the involvement of major genes. In addition, the Bartlett test applied to the data of within-sibship variances also rejected the null hypothesis of multifactorial transmission for Apo-B and LDL-C/Apo-B ratio (p < 0.0001). Lastly, the results from sib-pair linkage analyses provided significantly positive evidence for linkage between ApoB levels and the Apo-B XbaI restriction site.

Association of polymorphisms of the apolipoprotein B gene with coronary heart disease in Han Chinese

Four polymorphic sites of the apolipoprotein B (apo B) gene were investigated by using polymerase chain reaction (PCR) in 103 patients with coronary heart disease (CHD) and 100 age-matched healthy individuals selected from a population of Han Chinese in the Beijing area. The rare X+ allele of the XbaI restriction site was more frequently seen in CHD patients than in controls (0.088 vs. 0.025, P < 0.01). The relative frequency of rare E- allele of the EcoRI restriction site was significantly higher in CHD patients compared with controls (0.11 vs. 0.04, P < 0.01). Similarly, 3'VNTR-L allele (number of repeat units > 39) at the VNTR region was also present at an apparently high frequency in CHD patients in comparison to that in controls (0.602 vs. 0.290, P < 0.001). However, the difference in relative frequency of rare Del allele of the Ins/Del polymorphism at the signal peptide was not significant between the two groups (0.282 vs. 0.235. P > 0.05). In comparison with Caucasians, the relative frequencies of rare alleles (Del, X+ and E-) were found to be statistically lower in Han Chinese. Furthermore, the Del and X+ alleles, in linkage disequilibrium, were associated with significantly lower plasma level of HDL-C in CHD patients. Therefore it is suggested that genetic variation with the apo B gene may exert some impact on lipid metabolism and contribute to the susceptibility to development of CHD in Han Chinese.

Evidence for nonesterified fatty acids as modulators of neutral lipid transfers in normolipidemic human plasma

The relations between the level of plasma nonesterified fatty acid (NEFA) and both the mass concentration and activity of the cholesteryl ester transfer protein (CETP) were studied in fasted normolipidemic subjects. Plasma NEFA correlated positively with both CETP mass concentration (r = .50; P < .01) and the transfer of cholesteryl ester from HDL toward plasma VLDL+LDL (CETHDL-->VLDL+LDL activity) (r = .46; P < .05) but not with the transfer of cholesteryl ester from LDL toward plasma HDL (CETLDL-->HDL activity) (r = .05; NS). The high binding capacity of albumin for NEFA was used to investigate whether lipoprotein-bound NEFAs were implicated in the modulation of the cholesteryl ester transfer reaction. As compared with nonsupplemented controls, the addition of an excess of fatty acid-free albumin (8 g/L) to total normolipidemic plasmas reduced CETHDL-->VLDL+LDL activity (18.3 +/- 5.5% versus 9.8 +/- 3.1%; P < .0001) but not CETLDL-->HDL activity (22.3 +/- 4.5% versus 23.3 +/- 5.1%; NS). Moreover, CETHDL-->VLD+LDL and CETLDL-->HDL activities correlated negatively when measured in native plasma (r = -.45; P < .05) but positively when measured in albumin-supplemented plasma (r = .40; P < .05). In long-term incubation experiments, lipoprotein-bound NEFA increased the net mass transfer of cholesteryl esters from HDL toward VLDL+LDL but reduced the net mass transfer of triglycerides in the opposite direction, from VLDL+LDL toward HDL. Taken together, data of the present study brought strong and concordant arguments in favor of a dual effect of plasma NEFA in modulating both the mass and the activity of CETP in vivo.

Apolipoprotein E and B alleles in Parkinson's patients

Parkinson's patients were genotyped for the apolipoprotein E alleles as well as polymorphisms at the apolipoprotein B loci to determine whether they were at risk for late onset Alzheimer's disease or coronary disease. The Parkinson's patients were at no greater risk for either disease than were the control spouses. The frequency for the APOE4 allele was 11% compared with the spouses, 10%. Interestingly, 20% of the patients had the 2/3 genotype which may have a protective effect from late onset Alzheimer's disease.

Common variation in the gene for apolipoprotein B modulates postprandial lipoprotein metabolism: a hypothesis generating study

We have carried out a pilot study to examine the influence on postprandial lipid and lipoprotein metabolism of common genetic variation in the gene coding for apolipoprotein (apo) B, in a previously described group of 30 individuals who had survived a myocardial infarction (MI) before the age of 45 (normo (NTG)- and hypertriglyceridaemic (HTG) patients) and 11 age-matched healthy individuals. Postprandial lipid or lipoprotein levels were examined by genotypes in the three groups separately and after adjustment for fasting triglycerides (TG) in the whole group combined. For the signal peptide polymorphism in the apo B gene, individuals with one or more SP-24 alleles had a 38% smaller mean area under curve (AUC) (P = 0.06) for postprandial large chylomicron remnants and a 29% smaller mean AUC (P = 0.01) for large very low density lipoproteins (VLDLs) compared to individuals homozygous for the wild type SP-27 allele. Previously in this patient group, small chylomicron remnants (apo B-48 levels in the Sf 20-60 range) were found to relate significantly and positively to progression of coronary atherosclerosis suggesting that these lipoproteins are implicated in progression of atherosclerosis. For the apo B Val591-Ala polymorphism (Ag a1/d), individuals homozygous for the V591 allele had a 33% greater AUC for Sf 20-60 postprandial triglycerides (P = 0.006), with higher postprandial levels of both apo B-48- and apo B-100-containing lipoproteins in this fraction. This pilot study gives insight into the mechanisms of the previously reported associations between polymorphisms in the apo B gene and fasting plasma lipids and lipoproteins.

Apolipoprotein E alleles but neither apolipoprotein B nor apolipoprotein AI/CIII alleles are associated with late onset, familial Alzheimer's disease

The possibility of a genetic association between late onset, familial Alzheimer's disease and alleles at the apolipoprotein B and AI/CIII loci have been examined. In contrast to the genetic association with the apolipoprotein E locus, no evidence for genetic associations to these loci was found.

Sibling correlations of coronary heart disease risk factors in a sample of Israeli offspring with parental history of myocardial infarction

Sibling correlations for coronary heart disease risk factors were analyzed in 731 pairs of siblings whose parents experienced a first myocardial infarction. Sibling correlations for lipids, lipoproteins and apolipoproteins ranged from 0.29 to 0.48, with limited changes on adjustment for sex, age, education and body mass index. For most lipid variables brother-brother correlation coefficients were highest and sister-brother correlation coefficients were lowest. Sib-sib correlation coefficients for lipids, lipoproteins, blood pressure and body mass index were similar to those estimated from a random sample of Jewish families. The sibling correlations were relatively low for waist to hip ratio, triceps and suprailiac skinfolds, moderate for subscapular skinfolds and body circumference measurements and high for number of cigarettes smoked by the siblings. The sibling correlations for lipid variables showed a moderate dependency on the apolipoprotein B XbaI genotypes. Siblings living in the same household tended to have higher correlation coefficients for HDL-C, apolipoprotein B and apolipoprotein AI than those living apart. The correlation coefficients for number of cigarettes and anthropometric variables tended to be heterogeneous due to the higher correlations among siblings living apart. A clear trend of decline in sib-sib correlations for apolipoprotein AI, glucose, cigarette smoking, body mass index and circumference measurements with increased spacing between sibling's ages was indicated. This temporal trend in sibling correlations for coronary heart disease risk factors suggests that genetic and/or environmental factors may have different influences at different ages.

Cholesterol absorption and metabolism and LDL kinetics in healthy men with different apoprotein E phenotypes and apoprotein B Xba I and LDL receptor Pvu II genotypes

Apoprotein (apo) E, apoB Xba I, and LDL receptor gene Pvu II polymorphisms are associated with LDL cholesterol level, but little is known about cholesterol and LDL metabolism in subjects with the latter two genetic polymorphisms alone or in combination with different apoE phenotypes. We studied cholesterol absorption efficiency, cholesterol and bile acid synthesis, and LDL apoB kinetics in 52 healthy men and related the metabolic results to the apoB Xba I and LDL receptor Pvu II restriction fragment length polymorphism (RFLP) and apoE phenotypes. New findings were as follows. ApoB Xba I polymorphism was not associated with the metabolic variables of cholesterol, but LDL receptor Pvu II RFLP was associated with fractional catabolic rate for LDL apoB, cholesterol absorption, and cholesterol and bile acid synthesis. ApoE polymorphism exerted the most powerful effect on the LDL cholesterol concentration, so that the apoE2 subjects had the lowest LDL cholesterol and apoB levels and cholesterol absorption, and the highest fractional catabolic rate and bile acid and cholesterol synthesis compared with the apoE3 or especially apoE4 phenotypes in different genetic combinations. In multiple stepwise regression analysis with LDL cholesterol as the dependent and the genetic and metabolic parameters as the independent variables, 47.0% (n = 35, P < .001) of the variability of LDL cholesterol was explained by the apoE polymorphism, 7.1% (P < .05) by the LDL receptor Pvu II RFLP, and 11.3% (P < .01) by bile acid synthesis, while the contribution of the apoB Xba I RFLP was nonsignificant.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging and genetic variation of plasma apolipoproteins. Relative loss of the apolipoprotein E4 phenotype in centenarians

We determined the common polymorphism of apolipoprotein E (E2, E3, and E4), apolipoprotein B Xba I polymorphism, and apolipoprotein C-III Sst I polymorphism in almost all Finnish centenarians alive in 1991 (n = 179/185). Plasma lipid and lipoprotein levels in different apolipoprotein genotypes were also measured. In comparison with younger Finnish populations studied previously, the frequency of the apolipoprotein E epsilon 2 allele was almost twice as high (7.0% versus 4.1%; P < .05) and that of the epsilon 4 allele only approximately one third as high (8.4% versus 22.7%; P < .001) in the centenarians. Plasma cholesterol and high-density lipoprotein cholesterol levels tended to be lowest in the group with the epsilon 2 allele (4.33 mmol/L and 1.41 mmol/L, respectively), intermediate in those with the epsilon 3 allele (4.57 mmol/L and 1.48 mmol/L, respectively), and highest in those with the epsilon 4 allele (4.82 mmol/L and 1.60 mmol/L, respectively). The frequencies of the apolipoprotein B X1 and X2 alleles (Xba I restriction site absent or present, respectively) among the centenarians and among the young Finns were not significantly different, whereas the apolipoprotein C-III S2 allele (Sst I restriction site present) occurred more often in the centenarians (frequency, 12.9%) than in the youngest reference population (frequency, 8.8%; P < .05). Centenarians with the apolipoprotein B X2X2 genotype and apolipoprotein E4 phenotype had a higher mean plasma cholesterol level than those with the X1X1 genotype and E2 phenotype (5.24 versus 3.43 mmol/L; P < .05).(ABSTRACT TRUNCATED AT 250 WORDS)

ApoB-100 gene EcoRI polymorphism. Relations to plasma lipoprotein changes associated with abdominal visceral obesity

The aim of this study was to investigate whether the EcoRI restriction fragment length polymorphism (RFLP) of the apolipoprotein (apo) B-100 gene influences the associations described among obesity, regional adipose tissue distribution, and plasma lipoprotein levels. For this purpose, blood samples were collected from 56 healthy men for whom we had extensive measurements of regional adipose tissue distribution (both anthropometric and computed tomography-derived measurements) and data on the plasma lipoprotein-lipid profile. DNA was extracted from white blood cells, and RFLP analysis was performed. Subjects were classified into two groups on the basis of their apoB-100 EcoRI genotype: subjects homozygous for the major 11-kb allele, the 11/11 group (n = 40), and subjects carrying the minor 13-kb allele, the 13/11 group (n = 16). Subjects carrying the 13-kb allele had lower percent body fat and abdominal adipose tissue accumulation than subjects homozygous for the 11-kb allele (P < .05). Although leaner, the 13/11 group did not show a more favorable plasma lipoprotein-lipid profile than the group homozygous for the 11-kb allele. In fact, after statistical control for the difference in percent body fat between the two genotype groups, the 13/11 group showed significantly higher plasma cholesterol levels (P < .05) and nearly significantly higher apoB levels than the 11/11 group (P = .06). The association patterns between indices of regional adiposity and plasma cholesterol and apoB levels were also different between the two EcoRI genotype groups. Only in the 13/11 group was the abdominal visceral adipose tissue area significantly associated with these plasma variables.(ABSTRACT TRUNCATED AT 250 WORDS)

Apolipoprotein polymorphisms fail to define risk of coronary artery disease. Results of a prospective, angiographically controlled study

BACKGROUND

Because genetic factors are believed to contribute to the etiology of coronary artery disease (CAD), it has been suggested that DNA polymorphisms at candidate loci might identify individuals at high risk for developing disease. In this regard, apolipoprotein genes represent extremely promising loci because levels of apolipoproteins and their associated lipoproteins represent a major risk factor for CAD, and rare dysfunctional mutations in these genes result in a significant risk for CAD. To date, although some reports indicate that DNA polymorphisms at these loci are associated with increased risk of CAD, other reports have failed to find such associations.

METHODS AND RESULTS

To resolve the question of whether genetic polymorphisms at apolipoprotein loci can be used to identify individuals at increased risk for CAD, we evaluated the distribution of apolipoprotein genetic polymorphisms in a large series of subjects (n = 848) undergoing coronary angiography. Blinded assessment of angiograms was used to discriminate between patients with CAD (> or = 60% stenosis of any major branch, n = 444) and control subjects without disease (< or = 10% stenosis, n = 404). A total of 12 polymorphisms were evaluated at the following loci: apolipoprotein (apo) A-I/C-III/A-IV (five restriction site polymorphisms--Msp I, Pst I, Sst I, Pvu IIa, Pvu IIb), apo B (three restriction site polymorphisms--Xba I, EcoRI, Msp I, plus an insertion/deletion polymorphism), apo A-II (Msp I polymorphism), apo C-II (Taq I polymorphism), and apo E (protein isoforms revealed by DNA analysis). All subjects were of Northern European (primarily Angloscandinavian) descent, and, within each sex, patients and control subjects were of comparable age. All 12 loci were in Hardy-Weinberg equilibrium, with no indication of population heterogeneity. As expected, patients were distinguished from control subjects by their lipid profiles and a higher frequency of known risk factors for CAD. However, analysis by log-linear models indicated that there were no significant associations between apolipoprotein polymorphisms and the risk of CAD (P = .10 to .90). The lack of association was maintained irrespective of whether the analysis was carried out for the entire sample or the contrast was made more stringent by comparing patients most likely to have a genetic component to their disease (ie, young patients with early-onset CAD) with the control subjects least likely to have genetic susceptibility (ie, older control subjects who had ample time to develop CAD).

CONCLUSIONS

Despite the fundamental role of apolipoprotein genes in lipid metabolism, we find no evidence that common genetic polymorphisms of the major apolipoprotein loci have a significant influence on the risk of developing angiographically defined CAD in this representative population. Therefore, at this time we find no support for the hypothesis that mass screening for genetic polymorphisms at candidate loci can reduce the burden of CAD by identifying a substantial proportion of high-risk individuals. Instead, it appears more appropriate to direct attention toward modifying high-risk behaviors to alleviate the consequences of traditional environmental risk factors.

Apolipoprotein B gene polymorphisms in ischemic heart disease and hypercholesterolemia: effects of age and sex

The association of polymorphic alleles of the apolipoprotein B gene (Insertion/Deletion-, XbaI-, MspI-, EcoRI-, and 3'-VNTR polymorphisms) with variation in lipid concentrations (total cholesterol (T-C), HDL cholesterol (HDL-C), and log-triglycerides (TG)) in plasma was studied in 259 men and 59 women with moderate hypercholesterolemia (T-C 5.5-8.0 mmol/l and TG < 2.5 mmol/l) and ischemic heart disease, especially in relation to the effect of sex and age. The XbaI and the Ins/Del polymorphic alleles were associated with variation in T-C, but only in patients below the 75th percentile for age. The XbaI and Ins/Del polymorphic alleles were synergistically associated with variation in T-C: the X+ and the Del alleles were associated with higher cholesterol concentrations. Younger male patients had the highest frequency of haplotypes including both the X+ and the Del alleles, but the most striking difference was a significantly higher frequency of haplotypes including both the X- and the Ins alleles in female and in older male patients. The heterogeneity of association of polymorphic alleles in the apolipoprotein B gene to complex traits like hypercholesterolemia and ischemic heart disease in this study could explain why in most studies the X+ allele has been associated with higher cholesterol levels, whereas the X- allele has been associated with symptomatic atherosclerosis. The results of our study emphasize the importance of age and sex in measured genotype association studies.

Influence of polymorphisms for apolipoprotein B (ins/del, XbaI, EcoRI) and apolipoprotein E on serum lipids and apolipoproteins in a Javanese population

A total of 231 healthy subjects from a central Javanese population were investigated for the distribution of three apolipoprotein B (apo B) polymorphisms (ins/del, XbaI, and EcoRI), as well as apolipoprotein E (apo E) polymorphism in relation to serum lipid and apolipoprotein concentrations. The frequencies of the rarer alleles (del, 0.09; X+, 0.1; and R-, 0.06) were lower than have been found for some Asian and European populations. Distribution of genotypes was in Hardy-Weinburg equilibrium for all the polymorphisms. A linkage disequilibrium was observed only between the ins/del and XbaI site polymorphisms of apo B (chi 2(4)) = 25.3; P < 0.001) consistent with that observed in some other population studies. No polymorphism of the apo B gene had an association with serum lipid or apolipoprotein concentrations in this population except for XbaI, which appeared to be associated with serum TG (as the log transform: R2 = 8.3; F = 4.8; P < 0.01). The apo E4 allele was found to be associated with significantly higher serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC). Apo E polymorphism explained 5.9% of the sample variance of serum LDLC (F = 5.4; P < 0.01).

Apolipoprotein E and B polymorphisms--longevity factors assessed in nonagenarians

To test if the prevalence of genetic risk factors for coronary heart disease (CHD) is low in individuals who have reached an extremely old age, the allele frequencies of apolipoprotein E (apo E) and B (apo B) polymorphisms and plasma lipoprotein(a) levels were investigated in nonagenarians and in younger control groups. The frequency of the epsilon 4 allele of apo E was significantly lower in the nonagenarians than in the middle-aged and young adults (P < 0.05). Also, the frequency of EcoRI allele R- of apo B was low in the nonagenarians, whereas the allele frequency for the XbaI polymorphism of apo B and plasma lipoprotein(a) concentrations did not differ between the nonagenarians and the younger groups. These findings strongly suggest that the presence of these potential genetic risk factors for CHD, namely the epsilon 4 allele of apo E and the R- allele of apo B, decreases the probability of an individual reaching an extremely old age.