APOC3/A5 haplotypes, lipid levels, and risk of myocardial infarction in the Central Valley of Costa Rica

Genetic variation in the APOC3 and APOA5 genes has been associated with plasma triglyceride concentrations and may affect the risk of myocardial infarction (MI). To assess whether APOC3/A5 haplotypes are associated with risk of MI, we examined three single-nucleotide polymorphisms (SNPs) in APOC3 (3238C>G, -455T>C, and -482C>T) and six SNPs in the APOA5 gene (-1131T>C, c.-3A>G, c.56C>G, IVS3+476G>A, c.553G>T, and c.1259T>C) in incident cases (n = 1,703) of a first nonfatal MI matched for gender, age, and area of residence with population-based controls (n = 1,703). Conditional logistic regression models, adjusted for potential environmental confounders, were used for analysis. The common APOC3*222 haplotype was more frequent in cases than in controls (17.4% and 13.7%, respectively, P < 0.001) and was associated with increased risk of MI [odds ratio (OR) = 1.27; 95% confidence interval (95% CI), 1.09, 1.48] compared with APOC3*111 wild-type haplotype. This association was independent of the APOA5 SNPs. Although the APOC3 3238G, APOA5 -1131C, APOA5 c.-3G, and APOA5 c.1259C alleles were associated with higher triglyceride plasma concentrations, these effects could not explain the associations with MI in this population. In summary, this study supports the hypothesis that haplotypes in the APOC3 gene but not in the APOA5 gene increase susceptibility to MI.     

Variants at the APOA5 locus, association with carotid atherosclerosis, and modification by obesity: the Framingham Study

Genetic variation at the apolipoprotein A5 gene (APOA5) is associated with increased triglyceride concentrations, a risk factor for atherosclerosis. Carotid intimal medial thickness (IMT) is a surrogate measure of atherosclerosis burden. We sought to determine the association of common APOA5 genetic variants with carotid IMT and stenosis. A total of 2,273 Framingham Offspring Study participants underwent carotid ultrasound and had data on at least one of the five APOA5 variants (-1131T>C, -3A>G, 56C>G, IVS3+476G >A, and 1259T>C). Although none of the individual variants was significantly associated with carotid measures, the haplotype defined by the presence of the rare allele of the 56C>G variant was associated with a higher common carotid artery (CCA) IMT compared with the wild-type haplotype (0.75 vs. 0.73 mm; P < 0.05). The rare allele of each of the -1131T >C, -3A>G, IVS3+476G>A, and 1259T>C variants and the haplotype defined by the presence of the rare alleles in these four variants were each significantly associated with CCA IMT in obese participants. These associations remained significant even after adjustment for triglycerides. APOA5 variants were associated with CCA IMT, particularly in obese participants. The mechanism of these associations and the effect modification by obesity are independent of fasting triglyceride levels.     

The effect of APOA5 and APOC3 variants on lipid parameters in European Whites, Indian Asians and Afro-Caribbeans with type 2 diabetes

Common variants in APOA5 and APOC3 have been associated with differences in plasma triglyceride (TG) levels in healthy individuals. The aim of this study was to examine the association of APOA5 (-1131T>C, S19W) and APOC3 (-482C>T, 1100C>T) polymorphisms in patients with type 2 diabetes (T2D) of European White (EW) (n=931), Indian Asian (IA) (n=610) and Afro-Caribbean (AC) (n=167) origin, with lipid and T2D parameters. Rare allele frequencies and linkage disequilibrium differed significantly amongst ethnic groups. Compared to APOA5 -1131T and 19S homozygotes, -1131C and 19W carriers had higher TGs in all groups, but this effect was only statistically significant for the -1131C in the EWs (P=0.04) and 19W in the IAs (P<0.001). APOC3 SNPs showed no significant association with lipid levels in any ethnic group. While haplotypes carrying -1131C allele showed significant TG-raising in the EWs only, the 19W defined haplotype showed significant TG-raising in both IAs and EWs. Comparing all four SNPs in EW T2D subjects with healthy EWs (n=2579), the APOC3 1100C>T frequency was significantly higher in T2D [0.26 (0.24, 0.28)] vs. healthy EWs [0.22 (0.20, 0.23)], P=0.001. While the variable size effects of the two APOA5 SNPs on TG levels may result from ethnically different gene-gene or gene-environment interactions, APOA5 and APOC3 variants did not affect parameters of T2D. However, comparison between EWs with T2D and healthy EWs suggest APOC3 1100C>T is associated with increased risk of diabetes probably through mechanisms other than direct effects on TG.     

Apolipoprotein A-V: a potential modulator of plasma triglyceride levels in Turks

The apolipoprotein A-V gene (APOA5) plays an important role in determining plasma triglyceride levels. We studied the effects of APOA5 polymorphisms on plasma triglyceride levels in Turks, a population with low levels of HDL cholesterol and a high prevalence of coronary artery disease. We found 15 polymorphisms, three of which were novel. Seven haplotype-tagging single nucleotide polymorphisms (SNPs) were chosen and genotyped in approximately 3,000 subjects. The rare alleles of the -1464T>C, -1131T>C, S19W, and 1259T>C SNPs were significantly associated with increased triglyceride levels (19-86 mg/dl; P < 0.05) and had clear gene-dose effects. Haplotype analysis of the nine common APOA5 haplotypes revealed significant effects on triglyceride levels (P < 0.001). Detailed analysis of haplotypes clearly showed that the -1464T>C polymorphism had no effect by itself but was a marker for the -1131T>C, S19W, and 1259T>C polymorphisms. The -1131T>C and 1259T>C polymorphisms were in a strong but incomplete linkage disequilibrium and appeared to have independent effects. Thus, the APOA5 -1131T>C, S19W, and 1259T>C rare alleles were associated with significant increases in plasma triglyceride levels. At least one of these alleles was present in approximately 40% of the Turks. Similar associations were observed for -1131T>C and S19W in white Americans living in San Francisco, California.     

APOA5 variants and metabolic syndrome in Caucasians

Apolipoprotein A5 (APOA5) gene variants were reported to be associated with two components of metabolic syndrome (MetS): higher TG levels and lower HDL levels. Moreover, a recent Japanese case-control study found variant -1131T>C associated with MetS itself. Thus, our study systematically analyzed the APOA5 gene for association with lipid parameters, any other features of MetS, including waist circumference, glucose-related parameters, blood pressure, uric acid, and MetS itself in Caucasians. Ten polymorphisms were analyzed in a large fasting sample of the population-based Cooperative Health Research in the Region of Augsburg (KORA) survey S4 (n = 1,354; southern Germany) and in a second fasting sample, the Salzburg Atherosclerosis Prevention Program in Subjects at High Individual Risk (SAPHIR) study (n = 1,770; Austria). Minor alleles of variants -1131T>C, -3A>G, c.56C>G, 476G>A, and 1259T>C were significantly associated with higher TG levels in single polymorphism (P < 0.001) and haplotype (P G was associated with higher risk for MetS [odds ratio (95% confidence interval) = 1.43 (1.04, 1.99), P = 0.03 for KORA and 1.48 (1.10, 1.99), P = 0.009 for SAPHIR). Our study confirms the association of the APOA5 locus with TG and HDL levels in humans. Furthermore, the data suggest a different mechanism of APOA5 impact on MetS in Caucasians, as variant c.56C>G (not analyzed in the Japanese study) and not -1131T>C, as in the Japanese subjects, was associated with MetS.     

湖北汉族人群载脂蛋白A5遗传多态性分析

采用聚合酶链反应-限制性片断长度多态性(polymerase chain reaction restriction-fragment length polymorphism, PCR-RFLP)对257例湖北健康汉族人群APOA5 -1131T>C及56C>G基因多态性进行鉴定。结果发现: 湖北汉族人群中ApoA5 -1131T>C存在TT、TC、CC基因型, 3种基因型的频率分别为50.9%、32.9%及16.2%; 56C>G位点存在CC、CG基因型, 257名研究对象中, G等位基因分布频率小于5%; 各基因型频率和等位基因频率在不同种族和地域间分布存在显著性差异。结论: 湖北汉族人群中ApoA5基因-1131T>C位点存在单核苷酸多态性(single nucleotide polymorphism, SNP), 56C>G在该人群中应视为一个突变位点而不是多态性位点     

Contribution of APOA5 gene variants to plasma triglyceride determination and to the response to both fat and glucose tolerance challenges

The aim of this study was to investigate the influence of APOA5 variants on fasting lipids and to the response to both an oral fat tolerance test (OFTT) and an oral glucose tolerance test (OGTT). The association of two APOA5 SNPs [S19W (SNP5), -1131T>C (SNP3)] and an APOA4/A5 intergenic SNP [-12238T>C (SNP4)] were examined in healthy young men (n=774) who had undergone both an OFTT and an OGTT. Both -1131T>C and S19W rare alleles were associated with triglyceride (TG)-raising effects (11%, P=0.008; 21% (in cases), P<0.026, respectively) and showed additive effects on TG. None of the variants influenced the responsiveness to the OFTT after correcting for baseline TG. Homozygosity for the -12238T>C rare allele was associated with higher waist to hip ratio (P<0.0006), systolic blood pressure (P=0.012) and AUC and peak of insulin after OGTT (P=0.003 and P=0.027, respectively), traits that define the metabolic syndrome. Our results strongly support the role of APOA5 in determining plasma TG levels in an age-independent manner and highlight the importance of the APOC3/A4/A5 gene cluster in both TG and metabolic homeostasis.     

?1131T>C and SW19 polymorphisms in APOA5 gene and lipid levels in type 2 diabetic patients

Type 2 diabetes mellitus is a metabolic, vascular, and neuropathic disease with a high risk of atherosclerotic events due to dyslipidemic states. Polymorphisms in Apolipoprotein A5 gene (APOA5) have been associated with increased triglyceride levels in many different populations. This study aimed to identify the frequencies of the APOA5 -1131T>C and SW19 polymorphisms and evaluate their effects on lipid levels in patients with type 2 diabetes. Genotyping of APOA5 -1131T>C and SW19 polymorphisms was performed by PCR-RFLP in 146 diabetic patients and in controls (n = 173), from 30 to 80 years of age. Diabetic patients were divided into two groups: patients not treated with lipid lowering drugs (group G1; n = 62) and those treated with lipid lowering drugs (group G2, n = 84). Lipids and lipoproteins were determined enzymatically. Among participants not treated with lipid-lowering drugs (diabetics G1 and controls; n = 235), the -1131C was associated with lower LDLc levels (p = 0.015). In the diabetic patients, the 19W allele was associated with higher triglyceride levels (p = 0.004). In G1 diabetic patients, the combined analysis of APOA5 -1131T>C and SW19 polymorphisms showed that [TC or CC] + SS carriers presented lower total cholesterol levels than did other genotype combinations (p = 0.049). It could therefore be concluded that APOA5 -1131T>C and SW19 polymorphisms influence lipid levels in type 2 diabetic patients.     

Rapid genotyping of APOA5 -1131T>C polymorphism using high resolution melting analysis with unlabeled probes

The APOA5 -1131 T/C polymorphism (rs662799) exhibits a very strong association with elevated TG levels in different racial groups. High resolution melting (HRM) analysis with the use of unlabeled probes has shown to be a convenient and reliable tool to genotyping, but not yet been used for detecting rs662799 polymorphism. We applied the unlabeled probe HRM analysis and direct DNA sequencing to assay the -1131T>C SNP in 130 cases DNA samples blindly. This HRM analysis can be completed in <3 min for each sample. The two melting peaks were displayed at 66.1±0.4°C for CC homozygote and 68.7±0.2°C for TT homozygote; TC heterozygote showed the both melting peaks. The genotyping results by HRM method were completely concordant with direct DNA sequencing. The distribution of CC, TC, and TT genotypes for the -1131T>C SNP was 9.2, 49.2, and 41.5%, respectively. This assay was sensitive enough to detect C allele down to 20% and 10% for T allele. The limit of detection for C and T allele was 6.2 and 2.5 ng/μL DNA, respectively. The developed unlabeled probe HRM method provides an alternative mean to detect ApoA5 -1131T>C SNP rapidly and accurately.     

Influence of apoA-V gene variants on postprandial triglyceride metabolism: impact of gender

Although apolipoprotein A-V (apoA-V) polymorphisms have been consistently associated with fasting triglyceride (TG) levels, their impact on postprandial lipemia remains relatively unknown. In this study, we investigate the impact of two common apoA-V polymorphisms (-1131 T>C and S19W) and apoA-V haplotypes on fasting and postprandial lipid metabolism in adults in the United Kingdom (n = 259). Compared with the wild-type TT, apoA-V -1131 TC heterozygotes had 15% (P = 0.057) and 21% (P = 0.002) higher fasting TG and postprandial TG area under the curve (AUC), respectively. Significant (P = 0.038) and nearly significant (P = 0.057) gender x genotype interactions were observed for fasting TG and TG AUC, with a greater impact of genotype in males. Lower HDL-cholesterol was associated with the rare TC genotype (P = 0.047). Significant linkage disequilibrium was found between the apoA-V -1131 T>C and the apoC-III 3238 C>G variants, with univariate analysis indicating an impact of this apoC-III single nucleotide polymorphism (SNP) on TG AUC (P = 0.015). However, in linear regression analysis, a significant independent association with TG AUC (P = 0.007) was only evident for the apoA-V -1131 T>C SNP, indicating a greater relative importance of the apoA-V genotype.     

Haplotype analyses of the APOA5 gene in patients with familial combined hyperlipidemia

BACKGROUND: Familial combined hyperlipidemia (FCH) is the most common genetic lipid disorder with an undefined genetic etiology. Apolipoprotein A5 gene (APOA5) variants were previously shown to contribute to FCH. The aim of the present study was to evaluate the association of APOA5 variants with FCH and its related phenotypes in Dutch FCH patients. Furthermore, the effects of variants in the APOA5 gene on carotid intima-media thickness (IMT) and cardiovascular disease (CVD) were examined. MATERIALS AND METHODS: The study population consisted of 36 Dutch families, including 157 FCH patients. Two polymorphisms in the APOA5 gene (-1131T>C and S19W) were genotyped. RESULTS: Haplotype analysis of APOA5 showed an association with FCH (p=0.029), total cholesterol (p=0.031), triglycerides (p<0.001), apolipoprotein B (p=0.011), HDL-cholesterol (p=0.013), small dense LDL (p=0.010) and remnant-like particle cholesterol (p=0.001). Compared to S19 homozygotes, 19W carriers had an increased risk of FCH (OR=1.6 [1.0-2.6]; p=0.026) and a more atherogenic lipid profile, reflected by higher triglyceride (+22%) and apolipoprotein B levels (+5%), decreased HDL-cholesterol levels (-7%) and an increased prevalence of small dense LDL (16% vs. 26%). In carriers of the -1131C allele, small dense LDL was more prevalent than in -1131T homozygotes (29% vs. 16%). No association of the APOA5 gene with IMT and CVD was evident. CONCLUSION: In Dutch FCH families, variants in the APOA5 gene are associated with FCH and an atherogenic lipid profile.     

Apolipoprotein A5-1131T>C polymorphism, but not APOE genotypes, increases susceptibility for dyslipidemia in children and adolescents

Apolipoprotein A5 (APOA5) and apolipoprotein E (APOE) play important roles in the metabolism of cholesterol and triglycerides. The aim of this study was to determine the allelic and genotypic distributions of the APOA5-1131T>C (rs 662799) and the APOE HhaI polymorphisms and to identify the association of both individual and combined APOA5-APOE genetic variants and the risk for dyslipidemia in children and adolescents. We genotyped 53 dyslipidemic and 77 normolipidemic individuals. The total cholesterol, triglycerides and HDL cholesterol were determined enzymatically. For APOA5 polymorphism, the presence of the allele C confers an individual risk for dyslipidemia (OR = 2.38, 95% CI = 1.15-4.89; P = 0.018). No significant differences were observed for lipid parameters among the APOA5 groups, except for a higher value of HDLc (P = 0.024) in C-carriers. The allelic and genotypic frequencies of APOE polymorphism were similar between groups and did not increase the susceptibility for dyslipidemia. None of the combined APOA5-APOE polymorphisms increased risk for dyslipidemia. We demonstrated an association between APOA5-1131T>C polymorphism and dyslipidemia in children and adolescents. This finding may be useful to guide new studies with genetic markers down a path toward a better characterization of the genetic risk factors for dyslipidemia and atherosclerotic diseases.     

Apolipoprotein A-V, triglycerides and risk of coronary artery disease: the prospective Epic-Norfolk Population Study

In mouse models, apolipoprotein A-V (apoA-V) exhibits triglyceride (TG)-lowering effects. We investigated the apoA-V/TG relationship and the association of apoA-V with coronary artery disease (CAD) risk by determining serum apoA-V levels and genotypes in a nested case-control (n = 1,034/2,031) study. Both univariate and multivariate apoA-V levels showed no association with future CAD (P = 0.4 and 0.5, respectively). Unexpectedly, there was a significant positive correlation between serum apoA-V and TG in men and women (r = 0.36 and 0.28, respectively, P < 0.001 each) but a negative correlation between apoA-V and LPL mass (r = -0.14 and -0.12 for men and women respectively, P < 0.001 each). The frequency of the c.56C>G polymorphism did not differ between cases and controls despite significant positive association of c.56G with both apoA-V and TG levels. For -1131T>C, the minor allele was significantly associated with lower apoA-V yet higher TG levels and was overrepresented in cases (P = 0.047). The association of -1131T>C with CAD risk, however, was independent of apoA-V levels and likely acts through linkage disequilibrium with APOC3 variants. The positive correlation of apoA-V levels with TG levels, negative correlation with LPL levels, and lack of association with CAD risk highlight the need for further human studies to clarify the role of apoA-V.     

Insertion/deletion polymorphism in clusterin gene influences serum lipid levels and carotid intima-media thickness in hypertensive Japanese females

Clusterin has been implicated in lipid metabolism and atherogenesis, however, the influence of genetic variation has not been examined in Japanese. In this study, we identified 11 single nucleotide polymorphisms (SNPs) of clusterin gene by direct sequencing. Among them, one promoter SNP (-4453T>G), one missense SNP (4183G>A), and 2 common SNPs (5608T>C and 6316delT) were genotyped in 525 asymptomatic hypertensives not treated with lipid lowering agents. -4453T>G, 4183G>A, and 5608T>C showed no correlation with the clinical characteristics, however, in the 6316delT, an insertion (I)/deletion (D) polymorphism, D/D subjects had significantly higher levels of total cholesterol and low-density lipoprotein (LDL)-cholesterol than I/I subjects in females but not in males. Female subjects with the D allele (D/D+I/D) had greater intima-media thickness of the carotid artery than I/I subjects. In a multiple logistic regression analysis, the D allele of 6316delT was detected as an independent predictor for the plaque prevalence. In conclusion, the clusterin gene polymorphism may contribute to the serum lipid levels and the progression of carotid atherosclerosis in hypertensive Japanese females.     

The promoter region of the adiponectin gene is a determinant in modulating insulin sensitivity in childhood obesity

We investigated the association of the -11,391G>A, -11,377G>C, +45T>G, and +276G>T adiponectin single-nucleotide polymorphisms (SNPs) and expected haplotypes with the insulin resistance (IR) state in overweight/obese children; by using the haplotype background analysis, we also assessed the effect of each SNP independently. GG genotype at the -11,391 locus was associated with higher fasting insulin levels and homeostasis model assessment-IR index and lower adiponectin levels compared with GA + AA genotypes (p = 0.01, 0.002, and 0.03, respectively). Those heterozygous and homozygous for G allele at the -11,377 locus showed higher fasting glucose (p = 0.001 for both), fasting insulin (p = 0.001 for both), homeostasis model assessment-IR index (p < 0.001 for both), and triglyceride levels (p = 0.02 and 0.03, respectively) and lower adiponectin levels (p = 0.002 and 0.02, respectively) compared with C homozygotes. The +45G carriers showed higher fasting and 2-hour glucose levels (p = 0.01 for both) and lower adiponectin levels (p = 0.02) compared with non-carriers. Haplotype analysis suggested that, considering the same haplotypic background, each of the three polymorphisms exerted an independent effect on investigated parameters. The -11,391G>A, -11,377C>G, and +45T>G SNPs are associated with IR syndrome in overweight/obese children; they independently influence the investigated variables. The effect of +45T>G SNP seems to be marginal compared with the promoter SNPs. The GGT haplotype is associated with the highest degree of IR.     

Identification of single nucleotide polymorphisms in the bovine CCL2, IL8, CCR2 and IL8RA genes and their association with health and production in Canadian Holsteins

The aim of this study was to identify the presence of SNPs in the chemokine genes CCL2 and IL8 and the chemokine receptor genes IL8RA and CCR2, and assess their potential contribution to variation in estimated breeding values (EBVs) for somatic cell score (SCS) and four other traits in Canadian Holstein bulls. Pools of DNA for bulls with high (H) and low (L) EBVs for SCS were used for identification of 11 SNPs. Two unreported SNPs were found in the CCL2 gene and one SNP was found in the CCR2 gene. Previously reported SNPs (three in the IL8 gene and five in the IL8RA chemokine receptor) were also identified. Two SNPs in CCL2, three in IL8, one in IL8RA and one in CCR2 were genotyped in Canadian Holstein bulls (n = 338) using tetra primer ARMS-PCR. We investigated associations of these seven polymorphisms with three production traits (milk yield, fat yield and protein yield) and one conformation trait related to mastitis (udder depth). The allele substitution effect for the CCL2 rs41255713:T>C SNP was significant at an experimental-wise level for milk yield (247.5 +/- 79.9 kg) and protein yield (7.4 +/- 2.3 kg) EBVs (P T SNP on SCS was significant at the comparison-wise level (-0.04 +/- 0.02, P = 0.05), which might indicate a possible association in support of other published studies. Lastly, we assigned CCR2 to BTA22q24, where a previously QTL for SCS was identified.     

APOA5 gene variants, lipoprotein particle distribution, and progression of coronary heart disease: results from the LOCAT study

Animal and human studies support a role for apolipoprotein A-V (apoA-V) in triglyceride (TG) metabolism. We examined the relationship of APOA5 -1131T>C and S19W with lipid subfractions and progression of atherosclerosis in the Lopid Coronary Angiography Trial. Compared with -1131TT men (n = 242), carriers of the -1131C allele (n = 54) had significantly higher total TG (P = 0.03), reflected in significantly increased VLDL mass [higher VLDL-TG, VLDL-cholesterol, VLDL-protein, and surface lipids (all P < 0.05)]. Because apoB levels were unaffected by genotype, this suggests an increase in VLDL size and not number. Compared with 19SS men (n = 268), 19W carriers (n = 44) had higher intermediate density lipoprotein (IDL)-TG, IDL-cholesterol (P = 0.04), and IDL-surface components [free cholesterol (P = 0.005) and phospholipids (P = 0.017)] but not protein content, suggesting an increase in IDL lipid enrichment resulting in an increase in IDL size. 19W carriers also showed a trend toward increased progression of atherogenesis, as measured by change in average diameter of segments (-0.46 +/- 0.011 mm compared with -0.016 +/- 0.006 mm) in 19SS men (P = 0.08). There was no effect of genotype on the response of these parameters to gemfibrozil treatment. These results shed new light on the role of APOA5 variants in TG metabolism and coronary heart disease risk.     

Haplotypes in the promoter region of the ADIPOQ gene are associated with increased diabetes risk in a German Caucasian population.

Adiponectin, which is encoded by the ADIPOQ gene, has been shown to modulate insulin sensitivity and glucose homeostasis. Plasma adiponectin levels are decreased in type 2 diabetes and obesity. Genetic variations within the ADIPOQ gene are associated with decreased adiponectin hormone levels. To analyze specific single-nucleotide polymorphisms (SNPs) and their association with T2D, 365 German subjects with T2D and 323 control subjects were screened. Three common SNPs - +45T>G in exon 2, and 2 promoter variants SNPs -11391G>A and -11377C>G - were analyzed. We found that the variant allele of SNP -11391G>A was significantly more frequent in the diabetic patient group than in the control group (p=0.003). Carrying the haplotype of SNP -11391A and SNP -11377C was associated with a 1.50-fold (p=0.03) increase in diabetes risk. The combination of the A-C haplotype and the G-C haplotype was associated with significantly elevated diabetes risk (OR=2.82 (95% CI: 1.35-5.91), p=0.006) after correction for BMI and age. Our observations suggest that diploid combinations of haplotype in the adiponectin gene promoter region contribute to the genetic risk of T2D in individuals from a German Caucasian population.