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

Role of APOC3 3238C/G, APOB 12669G/A and SCARB1 1050C/T polymorphisms, their expression in patients of HIV-associated lipodystrophy

Apolipoproteins and Scavenger Receptor Class B1 (SCARB1) proteins are involved in the etiology of HIV-associated lipodystrophy (HIVLD). APOC3 3238C/G, APOB 12669G/A and SCARB1 1050C/T polymorphisms were linked with increased level of APOB, TG, HDL-C and risk of cardiovascular diseases (CVDs). Hence, we evaluated the genetic variations of APOC3 3238C/G, APOB 12669G/A and SCARB1 1050C/T in 187 patients of HIV (64 with HIVLD, 123 without HIVLD) and 139 healthy controls using PCR-RFLP and expression by qPCR. The genotypes of SCARB1 1050 TT and APOB 12669AA showed a risk to severe HIVLD (P = 0.23, OR = 4.95; P = 0.16, OR = 2.02). The APOC3 3238 GG genotype was associated with a lesser risk of severe HIVLD (P = 0.07, OR = 0.22). The APOB 12669 GA genotype was associated with a greater risk of HIVLD severity in patients with impaired LDL, triglyceride (TG), and cholesterol levels (P = 0.34, OR = 4.13; P = 0.25, OR = 3.64; P = 0.26, OR = 5.47). Similarly, APOB 12669AA genotypes in the presence of impaired triglyceride levels displayed the susceptibility to severity of HIVLD (P = 0.77, OR = 2.91). APOB 12669 GA genotype along with impaired HDL and cholesterol levels indicated an increased risk for HIVLD acquisition among patients without HIVLD (P = 0.42, OR = 2.42; P = 0.26, OR = 2.27). In patients with and without HIVLD, APOC3 3238CG genotypes having impaired cholesterol and glucose levels had higher risk for severity and development of HIVLD (P = 0.13, OR = 2.84, P = 0.34, OR = 1.58; P = 0.71, OR = 1.86; P = 0.14, OR = 2.30). An increased expression of APOB and SCARB1 genes were observed in patients with HIVLD (+0.51 vs. -0.93; +4.78 vs. +3.29), and decreased expression of APOC3 gene was observed in patients with HIVLD (-0.35 vs. -1.65). In conclusion, the polymorphisms mentioned above were not associated with the modulation of HIVLD. However, in the presence of impaired triglyceride, HDL, cholesterol and glucose levels, APOB 12669AA and 12669 GA, APOC3 3238CG genotypes indicated a risk for the development and severity of HIVLD.

Role of APOC3 3238C/G polymorphism in HIV-associated neurocognitive disorder

Apolipoprotein not only have a role in cholesterol metabolism but also play a role in normal brain function. Apolipoprotein gene polymorphisms are known risk factors for a number of mental and neurological disorders. The expression of brain apolipoproteins is significantly altered in several brain disorders. Therefore, we assed ApoC33238C/G polymorphism in a total of 248 patient infected with HIV (45 with HAND, 89 without HAND, 114 without ART) and 134 healthy controls using PCR-RFLP. ApoC3 3238CG, 3238GG genotypes and 3238G allele showed a non-significant increased risk for severity of HAND (P = 0.16, OR = 1.83; P = 0.32, OR = 2.78; P = 0.10, OR = 1.65) while comparing individuals with and without HAND. ApoC3 3238GG genotype and 3238G allele revealed an increased risk for disease progression when compared between HIV patients with and without ART (P = 0.55, OR = 1.76; P = 0.65, OR = 1.12) though risk could not reach statistical significance. ApoC3 3238GG genotype and 3238G allele were associated with the reduced risk of acquiring HIV infection when comparing HIV patients who are not on ART with healthy controls (P = 0.05, OR = 0.29; P = 0.04, OR = 0.66). In HIV patients on ART,ApoC3 3238GG genotype showed an increased susceptibility to development of HAND (P = 0.48, OR = 2.24) when comparing alcohol drinkers and non-drinkers however risk could not reach statistical significance. In conclusion, the genotype ApoC33238GG displayed an inclination of risk for the severity of HAND and HIV disease progression. The polymorphism of APOC3 3238C/G may have a role to reduce the risk for acquisition of HIV infection. ApoC33238GG genotype in presence of alcohol may increase susceptibility to development of HAND.

Frequencies of variants in genes associated with dyslipidemias identified in Costa Rican genomes

Dyslipidemias are risk factors in diseases of significant importance to public health, such as atherosclerosis, a condition that contributes to the development of cardiovascular disease. Unhealthy lifestyles, the pre-existence of diseases, and the accumulation of genetic variants in some loci contribute to the development of dyslipidemia. The genetic causality behind these diseases has been studied primarily on populations with extensive European ancestry. Only some studies have explored this topic in Costa Rica, and none have focused on identifying variants that can alter blood lipid levels and quantifying their frequency. To fill this gap, this study focused on identifying variants in 69 genes involved in lipid metabolism using genomes from two studies in Costa Rica. We contrasted the allelic frequencies with those of groups reported in the 1000 Genomes Project and gnomAD and identified potential variants that could influence the development of dyslipidemias. In total, we detected 2,600 variants in the evaluated regions. However, after various filtering steps, we obtained 18 variants that have the potential to alter the function of 16 genes, nine variants have pharmacogenomic or protective implications, eight have high risk in Variant Effect Predictor, and eight were found in other Latin American genetic studies of lipid alterations and the development of dyslipidemia. Some of these variants have been linked to changes in blood lipid levels in other global studies and databases. In future studies, we propose to confirm at least 40 variants of interest from 23 genes in a larger cohort from Costa Rica and Latin American populations to determine their relevance regarding the genetic burden for dyslipidemia. Additionally, more complex studies should arise that include diverse clinical, environmental, and genetic data from patients and controls and functional validation of the variants.

Association of c.56C > G (rs3135506) Apolipoprotein A5 Gene Polymorphism with Coronary Artery Disease in Moroccan Subjects: A Case-Control Study and an Updated Meta-Analysis

PURPOSE

Coronary artery diseases (CAD) are clinical cardiovascular events associated with dyslipidemia in common. The interaction between environmental and genetic factors can be responsible for CAD. The present paper aimed to examine the association between c.56C > G (rs3135506) APOA5 gene polymorphism and CAD in Moroccan individuals and to perform an association update meta-analysis.

MATERIALS AND METHODS

The c.56C > G variant was genotyped in 122 patients with CAD and 134 unrelated controls. Genetic association analysis and comparison of biochemical parameters were performed using R statistical language. In addition, a comprehensive meta-analysis including eleven published studies in addition to our case-control study results was conducted using Review Manager 5.3. Publication bias was examined by Egger's test and funnel plot.

RESULTS

The case-control study data showed that the c.56C > G polymorphism was associated with CAD susceptibility under codominant (P-value = 0.001), recessive (P-value <0.001) and log-additive (P-value = 0.008) inheritance models. In addition, this polymorphism was significantly associated with increased levels of systolic and diastolic blood pressures, triglycerides, glycemia, and total cholesterol. Furthermore, meta-analysis showed a significant association between the c.56C > G gene polymorphism and increased risk of CAD under recessive (OR = 3.39[1.77-6.50], P value <0.001) and homozygote codominant (OR = 3.96[2.44-6.45], P value <0.001) models.

CONCLUSION

Our case-control study revealed a significant association between c.56C > G polymorphism and CAD in the Moroccan population. In addition, meta-analysis data supported the implication of this polymorphism in CAD susceptibility.

Proteomics analysis of potential serum biomarkers for insulin resistance in patients with polycystic ovary syndrome

The aim of the present study was to identify potential serum biomarkers for insulin resistance (IR) in patients with polycystic ovary syndrome (PCOS) by comparing the differences in serum protein expression levels between PCOS patients with and without IR. PCOS patients aged from 18 to 35 years were recruited at Guangdong Women and Children’s Hospital from January, 2013 to February, 2014. A total of 218 PCOS patients were enrolled and divided into the insulin resistance (PCOS-IR) and non-insulin resistance (PCOS-NIR) groups according to their homeostasis model assessment of insulin resistance. Two-dimensional difference gel electrophoresis (2D-DIGE) and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS/MS) techniques were used to identify differences in protein expression levels between the PCOS-IR and PCOS-NIR groups. The present study demonstrated that the total cholesterol (TCH), triglycerides (TG), low-density lipoprotein (LDL), fasting plasma glucose (FPG), 3-h blood glucose (3hBG) and uric acid (UA) levels in the PCOS-IR group were higher than those in the PCOS-NIR group (P<0.05). Between the PCOS-IR and PCOS-NIR groups, a total of 20 differentially expressed protein spots were detected by 2D-DIGE. Among these, 4 proteins, namely afamin, serotransferrin, complement C3 and apolipoprotein C3 (APOC3), were also identified by MALDI-TOF-MS/MS. The alteration of APOC3 was further confirmed by western blot analysis and enzyme-linked immunosorbent assay (ELISA). The present study also confirmed that the expression level of APOC3 was positively associated with the homeostasis model assessment of insulin resistance (HOMA-IR). On the whole, the data indicate that APOC3 may be a potential diagnostic marker for PCOS-IR patients.

Acyl-CoA: cholesterol acyltransferases-2 gene polymorphism is associated with increased susceptibility to coronary artery disease in Uygur population in Xinjiang, China

BACKGROUND

Acyl-CoA: cholesterol acyltransferases (ACAT) is the only enzyme that catalyzes the synthesis of cholesterol esters (CE) from free cholesterol and long-chain fatty acyl-CoA and plays a critical role in cellular cholesterol homeostasis. In the present study, our primary objective was to explore whether the single-nucleotide polymorphisms (SNPs) in ACAT-2 gene were associated with coronary artery disease (CAD) in Uygur subjects, in Xinjiang, China.

METHODS

We designed a case-control study including 516 CAD patients and 318 age- and sex-matched control subjects. Using the improved multiplex ligation detection reaction (iMLDR) method, we genotyped two SNPs (rs28765985 and rs7308390) of ACAT-2 gene in all subjects.

RESULTS

We found that the genotypes, the dominant model (CC + CT vs TT) and over-dominant model (CT vs CC + TT) of rs28765985 were significantly different between CAD patients and the controls (P=0.027, P=0.012 and P=0.035, respectively). The rs28765985 C allele was associated with a significantly elevated CAD risk [CC/CT vs TT: odds ratio (OR) = 1.48, 95% confidence interval (CI) = 1.02-2.16, P=0.04] after adjustment for confounders. The TC and LDL-C levels were significantly higher in rs28765985 CC/CT genotypes than that in TT genotypes (P<0.05).

CONCLUSIONS

Rs28765985 of ACAT-2 gene are associated with CAD in Uygur subjects. Subjects with CC/CT genotype or C allele of rs28765985 were associated with an increased risk of CAD.

Association of genetic variations in the Wnt signaling pathway genes with myocardial infarction susceptibility in Chinese Han population

Numerous studies have implicated the Wnt pathway in the development and progression of myocardial infarction (MI); however, there are very few investigations addressing the effects of polymorphisms in the Wnt pathway genes on MI susceptibility. We investigated the possible correlation between genetic variations in Wnt pathway genes and MI risk. Three polymorphisms (rs7832767 C > T in SFRP1 gene, rs2293303 C > T in CTNNB1 gene, rs16893344 C > T in WISP1 gene) were finally selected and genotyped in 465 MI patients and 485 healthy controls, using the PCR-RFLP method. We found that the SFRP1 rs7832767 variant allele (T) was associated with a significantly increased risk of MI [TT vs. CC: adjusted odds ratio (AOR) = 3.13, 95% CI = 1.78-5.51; CT/TT vs. CC: AOR = 1.53, 95% CI = 1.12-2.08; TT vs. CC/CT: AOR = 2.87, 95% CI = 1.66-4.97)]. The significant association with MI risk was also found for the CTNNB1 rs2293303 (CT vs. CC: AOR = 3.48, 95% CI = 2.28-5.33; TT vs. CC: AOR = 7.37, 95% CI = 2.08-26.16; CT/TT vs. CC: AOR = 3.72, 95% CI = 2.46-5.62; TT vs. CC/CT: AOR = 5.52, 95% CI = 1.58-19.28), and WISP1 rs16893344 polymorphisms (CT vs. CC: AOR = 2.43, 95% CI = 1.70-3.47; TT vs. CC: AOR = 5.17, 95% CI = 1.85-14.41; CT/TT vs. CC: AOR = 2.58, 95% CI = 1.83-3.66; TT vs. CC/CT: AOR = 3.88, 95% CI = 1.41-10.64). The associations remain significant in stratified analysis by demographic and clinical characteristics of participants, with few exceptions. Our study provided the first evidence of the association between polymorphisms in the Wnt pathway genes and MI susceptibility in Chinese Han population. Epidemiological studies with larger samples and functional analyses are warranted to further verify our results.

Genome-wide association study identifies a missense variant at APOA5 for coronary artery disease in Multi-Ethnic Cohorts from Southeast Asia

Recent genome-wide association studies (GWAS) have identified multiple loci associated with coronary artery disease (CAD) among predominantly Europeans. However, their relevance to multi-ethnic populations from Southeast Asia is largely unknown. We performed a meta-analysis of four GWAS comprising three Chinese studies and one Malay study (Total N = 2,169 CAD cases and 7,376 controls). Top hits (P < 5 × 10-8) were further evaluated in 291 CAD cases and 1,848 controls of Asian Indians. Using all datasets, we validated recently identified loci associated with CAD. The involvement of known canonical pathways in CAD was tested by Ingenuity Pathway Analysis. We identified a missense SNP (rs2075291, G > T, G185C) in APOA5 for CAD that reached robust genome-wide significance (Meta P = 7.09 × 10-10, OR = 1.636). Conditional probability analysis indicated that the association at rs2075291 was independent of previously reported index SNP rs964184 in APOA5. We further replicated 10 loci previously identified among predominantly Europeans (P: 1.33 × 10-7-0.047). Seven pathways (P: 1.10 × 10-5-0.019) were identified. We identified a missense SNP, rs2075291, in APOA5 associated with CAD at a genome-wide significance level and provided new insights into pathways contributing to the susceptibility to CAD in the multi-ethnic populations from Southeast Asia.

ACAT-1 gene polymorphism is associated with increased susceptibility to coronary artery disease in Chinese Han population: a case-control study

Several studies suggest an important role of Acyl-CoA: cholesterol acyltransferase-1(ACAT-1) in the development of atherosclerosis. The aim of present study was to investigate whether there exists a possible correlation between genetic variations in ACAT-1 genes and coronary artery disease (CAD) risk. Four polymorphisms (rs1044925, rs11545566, rs12121758 and rs10913733) were finally selected and genotyped in 750 CAD patients and 580 health controls, using the improved multiplex ligation detection reaction (iMLDR) method. We found that the rs11545566 G allele was associated with a significantly elevated CAD risk [GG vs. AA: adjusted odds ratio (AOR) = 1.62, 95% confidence interval (CI) = 1.13-2.32, P = 0.008; GA/GG vs. AA: AOR = 1.67, 95% CI = 1.22-2.29, P = 0.001]. The rs10913733 G allele was also associated with a significantly elevated CAD risk (GG vs. TT: AOR = 1.57, 95% CI = 1.08-2.28, P = 0.018; GT/GG vs. TT: AOR = 1.39, 95% CI = 1.07-1.79, P = 0.013). Multivariate linear regression analysis showed that the rs11545566 polymorphism was independently associated with the Gensini scores (P = 0.005). The Gensini score of subjects in the variant GG genotype group and the GG/GA genotype group were higher than the score of subjects in the AA genotype group (32.49 ± 26.60 and 31.26 ± 26.96 vs. 23.45 ± 21.64; P = 0.001 and 0.002, respectively). Our results demonstrate that ACAT-1 rs1154556 and rs10913733 polymorphism are novel genetic factors in the development of CAD. Rs11545566 was also associated with the severity of CAD.

Positive Association between APOA5 rs662799 Polymorphism and Coronary Heart Disease: A Case-Control Study and Meta-Analysis

Objective

Apolipoprotein A5 (APOA5) is associated with plasma triglyceride (TG) levels, a risk factor for coronary heart disease (CHD). This study explored the association between CHD and the APOA5 rs662799 polymorphism.

Methods

We collected 1,521 samples (783 CHD patients and 738 controls) for this case-control study. Meta-analysis was performed using Review Manager Software and Stata Software.

Results

Significant differences were observed between CHD cases and controls at the level of both genotype (χ² = 8.964, df = 2, P = 0.011) and allele (χ² = 9.180, df = 1, P = 0.002, OR = 1.275, 95% CI = 1.089–1.492). A breakdown analysis by gender showed a significant association of APOA5 rs662799 with CHD in males (χ² = 7.770, df = 1, P = 0.005; OR = 1.331, 95% CI = 1.088–1.628). An additional meta-analysis using 21378 cases and 28428 controls established that rs662799 is significantly associated with CHD (P < 0.00001).

Conclusion

Both our case-control study and meta-analysis confirm a significant association between APOA5 rs662799 and CHD. In addition, our results suggest a male-specific association between the APOA5 rs662799 polymorphism and CHD.

Association of two common polymorphisms of apolipoprotein A5 gene with metabolic syndrome indicators in a North Iranian population, a cross-sectional study

Background

Metabolic syndrome is an obesity dependent disorder with a worldwide high prevalence. Regarding the high prevalence of Metabolic syndrome in Iran we analyzed the influence of -1131T>C (rs662799) and c.56C>G (S19W, rs3135506) polymorphisms of the novel apolipoprotein gene, ApoA5, on some Metabolic Syndrome indicators in population from north of Iran.

Methods

199 volunteers from Babol city-Iran were divided in two groups of low (N = 99, TG ≤ 103 mg/dl) and high (N = 100, TG ≥ 150 mg/dl) serum levels of Triglycerides (TG). We amplified the gene fragments containing -1131T>C and c.56C>G polymorphisms by PCR method and revealed the polymorphisms by RFLP analysis.

Results

We found a significant association (p = 0.016, Independent t-test) between high levels of TG and -1131T>C polymorphism but not between this polymorphism and serum HDL-C concentrations. Carriers of the C allele had a 1.97 times higher odds ratio to be in the high-TG group than those of the TT genotype (95%, CI = 1.05-3.68). We observed no association between -1131T>C polymorphism with either Waist-to-Hip Ratio (WHR) or Body-Mass-Index (BMI). In the case of c.56C>G polymorphism, although it showed a significant relationship with WHR (p = 0/040, Independent t-test), but failed to correlate with either levels of TG (p = 0.594) or HDL-C (p = 0.640) in serum.

Conclusion

Our study confirms that ApoA5 gene polymorphisms, -1131T>C and c.56C>G are associated with the two criteria of Metabolic Syndrome, TG and WHR, respectively.

Association of APOA5 rs662799 and rs3135506 polymorphisms with arterial hypertension in Moroccan patients

BACKGROUND

The goal of the study is to investigate the association between the APOA5 polymorphisms and haplotypes with Arterial Hypertension (AHT) in Moroccan patients.

METHODS

The study was performed in 283 subjects, 149 patients with AHT and 134 controls. All subjects were genotyped for the APOA5 -1131 T > C (rs662799), 56C > G (rs3135506) and c.553G > T (rs2075291) polymorphisms.

RESULTS

There was a strong association between -1131 T > C and 56C > G polymorphisms with AHT. The -1131 T > C and 56C > G polymorphisms were significantly associated with increased systolic blood pressure (SBP) and triglycerides (TG) levels. There were 4 haplotypes with a frequency higher than 5%, constructed from APOA5 polymorphisms, with the following order: -1131 T > C, 56C > G and c.553G > T. Haplotype H1 (TCG) was associated with decreased risk of AHT, whereas the haplotypes H2 (CCG) and H4 (CGG) were significantly associated with an increased risk of AHT. Carriers of H1 haplotype had a lower SBP and DBP and TG. In contrast, significant elevated SBP, DBP and TG were found in H4 haplotypes carriers.

CONCLUSIONS

Our data demonstrate for the first time that several common SNPs in the APOA5 gene and their haplotypes are closely associated with modifications of blood pressure and serum lipid parameters in the AHT patient.

Monogenic causes of elevated HDL cholesterol and implications for development of new therapeutics

Identification of the CETP, LIPG (encoding endothelial lipase) and APOC3 genes, and ana lysis of rare genetic variants in them, have allowed researchers to increase understanding of HDL metabolism significantly. However, development of cardiovascular risk-reducing therapeutics targeting the proteins encoded by these genes has been less straightforward. The failure of two CETP inhibitors is complex but illustrates a possible over-reliance on HDL cholesterol as a marker of therapeutic efficacy. The case of endothelial lipase exemplifies the importance of utilizing population-wide genetic studies of rare variants in potential therapeutic targets to gain information on cardiovascular disease end points. Similar population-wide studies of cardiovascular end points make apoC-III a potentially attractive target for lipid-related drug discovery. These three cases illustrate the positives and negatives of single-gene studies relating to HDL-related cardiovascular drug discovery; such studies should focus not only on HDL cholesterol and other components of the lipid profile, but also on the effect genetic variants have on cardiovascular end points.

Apolipoprotein A5 gene variants and the risk of coronary heart disease: a case‑control study and meta‑analysis

Previous studies have shown that apolipoprotein A5 (APOA5) gene variants are genetic determinants of the concentration of triglycerides, which are a known risk factor for coronary heart disease (CHD). Using the standardized coronary angiography method, 290 CHD patients and 198 non‑CHD controls were recruited from Ningbo Lihuili Hospital. In addition, 331 unrelated healthy volunteers were recruited as healthy controls from Ningbo Ximen Community residents. Three variants of the APOA5 gene, S19W, ‑1131T>C and 553G>T, were analyzed for their association with CHD. Under a dominant inheritance model, ‑1131CT>C was shown to be a CHD risk factor (P=0.030; OR, 1.422; 95% CI, 1.036‑1.952). The single nucleotide polymorphism, 553G>T, was found to correlate with the severity of CHD in males (P=0.032). Meta‑analysis showed that ‑1131T>C was significantly associated with CHD (P<0.0001). By contrast, negative correlations with CHD were observed for S19W and 553G>T. In the present case‑control study, APOA5 gene variants were not found to correlate with the risk of CHD in the populations studied; however, ‑1131CT>C was shown to be a CHD risk factor under a dominant inheritance model. Meta‑analysis showed a significant contribution of ‑1131T>C to the risk of CHD, implying an ethnic difference in APOA5 gene variants.

Associations of polymorphisms in the apolipoprotein APOA1-C3-A5 gene cluster with acute coronary syndrome

Background. Acute coronary syndromes (ACSs) are clinically cardiovascular events associated with dyslipidemia in common. Single nucleotide polymorphisms (SNPs) and haplotypes in the APOA1/C3/A5 gene cluster are associated with diabetes and familial combined hyperlipidaemia (FCH). Little is known about whether the polymorphisms in these genes affect lipid homeostasis in patients with ACSs. The present paper aimed to examine these associations with 4 SNPs in the APOA1 −75G > A, the APOC3 −455T > C, and APOA5 −1131T > C, c.553G > T variant to ACSs in Chinese Han. Methods. Chinese Han of 229 patients with ACSs and 254 unrelated controls were analyzed. Four SNPs in APOA1/C3/A5 cluster were genotyped and lipid was determined. Results. Our data show that minor allelic frequencies of APOC3 −455T > C, APOA5 −1131T > C, and c.553G > T polymorphisms in patients with ACSs were significantly higher than control group (P < 0.05). Furthermore, the 3 polymorphic sites were strongly of linkage disequilibrium, and minor alleles of 3 SNP sites had higher TG level than wild alleles (P < 0.05), APOC3 −455C and APOA5 c.553T allele carriers also had lower level of HDL-C. Conclusions. The minor alleles of APOC3 −455T > C, APOA5 −1131T > C, and c.553G > T polymorphisms are closely associated with ACSs.

The influence of the S19W SNP of the APOA5 gene on triglyceride levels in southern Brazil: interactions with the APOE gene, sex and menopause status

BACKGROUND AND AIMS

Hypertriglyceridemia is an important independent risk factor for coronary artery diseases and is determined by a wide range of factors, both genetic and exogenous. The A5 apolipoprotein, which is associated with the synthesis and removal of triglycerides (TG), is encoded by the APOA5 gene. One of the polymorphisms of this gene that has been the focus of a large number of studies, and which appears to be associated with increased TG, is S19W (rs 3135506). In this study, we examined the influence of this single nucleotide polymorphism (SNP) on TG levels of a sample of southern Brazilians.

METHODS AND RESULTS

Samples obtained from 567 people of European descent were genotyped; interactions between this variant and anthropometric variables were analyzed, and the effects of lifestyle, sex, menopause, and variations of the APOE gene were evaluated. We found that the 19W allele is associated with increased TG (p = 0.025) and that this influence was modulated by sex (p = 0.003), menopause (p = 0.022) and the presence of the E*4 allele (p = 0.027).

CONCLUSION

Our data showed, for the first time, the importance and magnitude of the influence of the S19W variant in a southern Brazilian population.

Interaction between MMP-9 gene polymorphisms and smoking in relation to myocardial infarction in a Uighur population

OBJECTIVES

Matrix metalloproteinase 9 (MMP-9) plays a pivotal role in early atherosclerosis, vascular remodeling, and development of arterial plaque rupture. The potentially functional MMP-9 gene polymorphism may contribute to the susceptibility of myocardial infarction (MI). We aimed to investigate the association between the interaction of 2 single-nucleotide polymorphisms ([SNPs] -1562C>T and R279Q) of the MMP-9 gene and smoking with MI in a Uighur population of China.

METHODS

A case-control study composed of 384 coronary angiography proven patients with MI and 451 sex-matched and ethnically matched control participants were enrolled in the study. The genotypes of the 2 selected SNPs were determined by the method of polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP).

RESULTS

Analysis of 2 SNPs, the frequency of -1562 CT and TT genotypes in MI group was significantly higher than in control group (25.52% vs 17.29%; P = .004). And the -1562 T allele showed significant association with MI (MI vs controls: 14.19% vs 9.31%; P = .002). R279Q locus did not show significant differences between patients and controls ( P > .05). Multiple logistic regression analysis showed that -1562 T allele (CT or TT genotype; odds ratio [OR] 1.31, 95% confidence interval [CI] 1.22-1.40; P = .004), the interaction between -1562 T allele and smoking (OR 4.42, 95% CI 2.74-7.13; P < .001), and the interaction between 279 Q allele and smoking (OR 2.07, 95% CI: 1.04-4.13; P = .021) were independent risk factors for MI.

CONCLUSIONS

There findings suggest that MMP-9 -1562C>T polymorphism could be associated with the susceptibility to MI. Another SNP (R279Q) polymorphism was not significantly associated with MI. The -1562C>T or R279Q polymorphism of MMP-9 gene and smoking have a synergistic effect and are significantly associated with the risk of MI in Chinese Uighur population, respectively.

Interaction between COX-2 G-765C and smoking in relation to coronary artery disease in a Chinese Uighur population

BACKGROUND

Coronary artery disease (CAD) is a complex multifactorial and polygenic disorder where multiple environmental and genetic factors are involved simultaneously. The purpose of this study was to explore the relationship between the interaction of cyclooxygenase-2 (COX-2) gene polymorphism and smoking and CAD in a Uighur population.

METHODS

Using a case-control study of Chinese Uighur CAD patients (n=430) and healthy controls (n=470), we investigated the roles of G-765C polymorphism in the COX-2 gene (PTGS2) by the use of polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

The PTGS2 GG genotype was significantly more prevalent in CAD patients (84.6% vs. 78.3%; p=0.014). Multiple logistic regression analysis showed two independent risk factors: smoking (OR 1.89, 95% CI 1.01-5.24; p=0.008) and hypertension (OR 2.73, 95% CI 1.59-7.21; p=0.001). Moreover, there was a synergistic effect between smoking and the PTGS2 polymorphism and the occurrence of CAD (interaction p=0.009). The odds ratio (OR) estimated by the combined analysis of the PTGS2 GG genotype and smoking history (OR 4.09, 95% CI 2.7-9.3) was markedly higher than that estimated separately from the PTGS2 GG genotype (OR 1.28, 95% CI 0.8-1.9) or smoking (OR 2.51, 95% CI 1.5-5.7) alone. Plasma 6-keto-PGF1α, a stable metabolite of PGI(2), was lower in individuals with the PTGS2 GG genotype (p<0.05). Smoking could further lower plasma 6-keto-PGF1α concentrations in GG genotype carriers than non-smokers, especially in patients with CAD.

CONCLUSIONS

The PTGS2 polymorphism and smoking were synergistically and significantly associated in Chinese Uighur patients with CAD.

Influence of genetic variants in the apolipoprotein A5 and C3 gene on lipids, lipoproteins, and its association with coronary artery disease in Indians

Indians worldwide demonstrate a triad of elevated triglyceride (TG) with high low-density lipoprotein cholesterol and low high-density lipoprotein cholesterol levels. In the present study, we aim to investigate the effect of -1131T > C, -3A > G, c.56 C > G, and c.553 G > T SNPs in the apolipoprotein A5 (APOA5) gene and 1100C > T and 3238C > G in the apolipoprotein C3 (APOC3) on plasma lipid and lipoprotein levels and risk of coronary artery disease (CAD) in Indians. Genotyping and lipid assays were carried out using standard protocols in a study population that included 150 controls and 90 cases with CAD. Significant associations between minor alleles and higher TG levels were seen for -1131T > C (P < 0.001), -3A > G (P < 0.001), c.56C > G (P = 0.026), and c.553G > T (P = 0.003) SNPs in the APOA5 gene and 1100C > T (P = 0.001) and 3238C > G (P = 0.009) in the APOC3 gene. The haplotypes 11211, 22111, 11112, and 22112 were significantly associated with TG levels (P = 0.025, P = 0.017, P = 0.027, and P < 0.001, respectively) and very-low-density lipoprotein cholesterol levels (P = 0.025, P = 0.017, P < 0.001, and P = 0.002) in males. The 22111, 11112, and 22112 were associated with elevated TG (P = 0.030, P = 0.036, and P = 0.024) but not VLDL-C levels in females. No association with other lipid parameters was seen. In the logistic regression model, the rare S2 allele was a significant risk factor (P = 0.030, 95% CI 1.186-31.432) along with smoking (P < 0.0001, 95% CI 2.018-10.397) for CAD. The APOA5 and APOC3 locus is a strong determinant of plasma TG levels in Indians. The APOC3 3238G is a risk factor for CAD and a higher frequency was also seen with type 2 diabetes mellitus.

Three periods of one and a half decade of ischemic stroke susceptibility gene research: lessons we have learned

Candidate gene association studies, linkage studies and genome-wide association studies have highlighted the role of genetic factors in the development of ischemic stroke. This research started over a decade ago, and can be separated into three major periods of research. In the first wave classic susceptibility markers associated with other diseases (such as the Leiden mutation in Factor V and mutations in the prothrombin and 5,10-methylenetetrahydrofolate reductase (MTHFR) genes) were tested for their role in stroke. These first studies used just a couple of hundred samples or even less. The second and still ongoing period bridges the two other periods of research and has led to a rapid increase in the spectrum of functional variants of genes or genomic regions, discovered primarily in relation to other diseases, tested on larger stroke samples of clinically better stratified patients. Large numbers of these alleles were originally discovered by array-based genome-wide association studies. The third period of research involves the direct array screening of large samples; this approach represents significant progress for research in the field. Research into susceptibility genes for stroke has taught us that careful stratification of patients is critical, that susceptibility alleles are often shared between diseases, and that not all susceptibility factors that associate with clinical traits that are themselves risk factors for stroke (such as increase of triglycerides) necessarily represent susceptibility for stroke. Research so far has been mainly focused on large- and small-vessel associated stroke, and knowledge on other types of stroke, which represent much smaller population samples, is still very scarce. Although some susceptibility allele tests are on the palette of some direct-to-consumer companies, the clinical utility and clinical validity of these test results still do not support their use in clinical practice.

Haplotype analysis of the apolipoprotein A5 gene in patients with the metabolic syndrome

BACKGROUND AND AIMS

In recent studies, the T-1131C variant of apolipoprotein A5 (APOA5) gene was found to confer a risk for metabolic syndrome (MS). Here we determined four haplotype-tagging polymorphisms (T-1131C, IVS3+G476A, T1259C, and C56G), and studied the distribution of the naturally occurring major haplotype profiles in MS.

METHODS AND RESULTS

A total of 343 MS patients and 284 controls were genotyped using PCR-RFLP methods. Both in MS and control groups, we confirmed the already known association of -1131C, IVS3+473A and 1259C minor alleles with elevated triglyceride levels. The prevalence of the APOA5*2 haplotype (the combination of T-1131C, IVS3+G476A and T1259C SNPs) was 13.1% in MS patients, and 4.9% in controls (p<0.001); multiple logistic regression analysis revealed that this haplotype confers risk for the development of MS (OR=2.880; 95% CI: 1.567-5.292; p=0.001). We also observed a gender effect: in males a more prominent degree of susceptibility was found. Contrary to the APOA5*2 haplotype, the prevalence rate of APOA5*4 (determined by the T-1131C SNP alone) did not differ between MS patients and controls. We identified a novel haplotype, designated here as APOA5*5 (1259C allele alone); which appears to be protective against MS.

CONCLUSION

Our results refined the role of SNP T-1131C in the development of MS. The susceptibility nature of this SNP is limited to the APOA5*2 haplotype, while in APOA5*4 haplotype it did not confer a risk for the disease. In addition, as our current data suggest, the novel APOA5*5 haplotype can confer protection against MS.

Interactions of the apolipoprotein C-III 3238C>G polymorphism and alcohol consumption on serum triglyceride levels

Background

Both apolipoprotein (Apo) C-III gene polymorphism and alcohol consumption have been associated with increased serum triglyceride (TG) levels, but their interactions on serum TG levels are not well known. The present study was undertaken to detect the interactions of the ApoC-III 3238C>G (rs5128) polymorphism and alcohol consumption on serum TG levels.

Methods

A total of 516 unrelated nondrinkers and 514 drinkers aged 15-89 were randomly selected from our previous stratified randomized cluster samples. Genotyping of the ApoC-III 3238C>G was performed by polymerase chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. Interactions of the ApoC-III 3238C>G genotype and alcohol consumption was assessed by using a cross-product term between genotypes and the aforementioned factor.

Results

Serum total cholesterol (TC), TG, high-density lipoprotein cholesterol (HDL-C), ApoA-I and ApoB levels were higher in drinkers than in nondrinkers (P < 0.05-0.001). There was no significant difference in the genotypic and allelic frequencies between the two groups. Serum TG levels in nondrinkers were higher in CG genotype than in CC genotype (P < 0.01). Serum TC, TG, low-density lipoprotein cholesterol (LDL-C) and ApoB levels in drinkers were higher in GG genotype than in CC or CG genotype (P < 0.01 for all). Serum HDL-C levels in drinkers were higher in CG genotype than in CC genotype (P < 0.01). Serum TC, TG, HDL-C and ApoA-I levels in CC genotype, TC, HDL-C, ApoA-I levels and the ratio of ApoA-I to ApoB in CG genotype, and TC, TG, LDL-C, ApoA-I and ApoB levels in GG genotype were higher in drinkers than in nondrinkers (P < 0.05-0.01). But the ratio of ApoA-I to ApoB in GG genotype was lower in drinkers than in nondrinkers (P < 0.01). Multivariate logistic regression analysis showed that the levels of TC, TG and ApoB were correlated with genotype in nondrinkers (P < 0.05 for all). The levels of TC, LDL-C and ApoB were associated with genotype in drinkers (P < 0.01 for all). Serum lipid parameters were also correlated with age, sex, alcohol consumption, cigarette smoking, blood pressure, body weight, and body mass index in both groups.

Conclusions

This study suggests that the ApoC-III 3238CG heterozygotes benefited more from alcohol consumption than CC and GG homozygotes in increasing serum levels of HDL-C, ApoA-I, and the ratio of ApoA-I to ApoB, and lowering serum levels of TC and TG.

Stepwise positive association between APOA5 minor allele frequencies and increasing plasma triglyceride quartiles in random patients with hypertriglyceridemia of unclarified origin

Apolipoprotein A5 (ApoA5) gene and its protein product play a central role in the complex regulation of circulating triglyceride levels in humans. Naturally occurring variants of the apolipoprotein A5 gene have been associated with increased triglyceride levels and have been found to confer risk for cardiovascular diseases. In our study, four polymorphisms, the T-1131C, IVS3+G476A, T1259C, and C56G alleles of APOA5 were analyzed in a total of 436 patients by polymerase chain reaction-restriction fragment length polymorphism methods. The randomly selected patients were classified into four quartile (q) groups based on triglyceride levels (q1: TG<1.31 mmol/l; q2: 1.31-2.90 mmol/l; q3: 2.91-4.85 mmol/l; q4: TG>4.85 mmol/l). We observed significant stepwise increasing association between the four APOA5 minor allele carrier frequencies and plasma triglyceride quartiles: -1131C (q1: 4.44%; q2: 8.95%; q3: 12.9%; q4: 20.6%), IVS3 + 476A (q1: 4.44%; q2: 5.79%; q3: 11.1%; q4: 19.7%), 1259C (q1: 4.44%; q2: 6.84%; q3: 11.1%; q4: 20.6%) and 56G (q1: 5.64%; q2: 6.31%; q3: 11.16%; q4: 11.9%). The serum total cholesterol and high density lipoprotein-cholesterol levels also showed allele-dependent differences in the quartiles. The findings presented here revealed a special arrangement of APOA5 minor alleles in patients with different serum triglyceride ranges in Hungarians.

Association of Interaction Between Smoking and CYP 2C19*3 Polymorphism With Coronary Artery Disease in a Uighur Population

Objectives: Cytochrome P450 (CYP) 2C19 is expressed in vascular endothelium and metabolizes arachidonic acid to biologically active epoxyeicosatrienoic acids (EETs), which are potent endogenous vasodilators and inhibitors of vascular inflammation. The purpose of this study is to explore the relationship between the interaction of CYP2C19*3 polymorphism and smoking and coronary artery disease (CAD) in a Uighur population. Methods: In a Chinese Uighur case-control study of patients with CAD (n = 336) and healthy controls (n = 370), we investigated the roles of polymorphism in the CYP2C19 gene by the use of polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis. Results: The CYP2C19*3 AG + AA genotype was significantly more prevalent in patients with CAD (6.25.0% vs 2.96%; P = .03). Multiple logistic regression analysis showed 4 independent risk factors: the interaction of CYP2C19*3 and smoking (OR 7.22, 95% confidence interval [CI] 2.32-10.23; P = .009), smoking (OR 3.23, 95% CI 1.72-5.44; P = .003), blood sugar (OR 2.12, 95% CI 1.03-4.21; P < .01), and hypertension (OR 1.74, 95% CI 0.98-2.34; P = .013). Conclusions: The CYP2C19*3 polymorphism and CAD were synergistically and significantly associated in Chinese Uighur patients.

West African and Amerindian ancestry and risk of myocardial infarction and metabolic syndrome in the Central Valley population of Costa Rica

Genetic ancestry and environmental factors may contribute to the ethnic differences in risk of coronary heart disease (CHD), metabolic syndrome (MS) or its individual components. The population of the Central Valley of Costa Rica offers a unique opportunity to assess the role of genetic ancestry in these chronic diseases because it derived from the admixture of a relatively small number of founders of Southern European, Amerindian, and West African origin. We aimed to determine whether genetic ancestry is associated with risk of myocardial infarction (MI), MS and its individual components in the Central Valley of Costa Rica. We genotyped 39 ancestral informative markers in cases (n = 1,998) with a first non-fatal acute MI and population-based controls (n = 1,998) matched for age, sex, and area of residence, to estimate individual ancestry proportions. Odds ratios (ORs) and 95% confidence intervals (95% CI) were estimated using conditional (MI) and unconditional (MS and its components) logistic regression adjusting for relevant confounders. Mean individual ancestry proportions in cases and controls were 57.5 versus 57.8% for the Southern European, 38.4 versus 38.3% for the Amerindian and 4.1 versus 3.8% for the West African ancestry. Compared with Southern European ancestry, each 10% increase in West African ancestry was associated with a 29% increase in MI, OR (95% CI) = 1.29 (1.07, 1.56), and with a 30% increase on the risk of hypertension, OR (95% CI) = 1.30 (1.00, 1.70). Each 10% increase in Amerindian ancestry was associated with a 14% increase on the risk of MS, OR (95% CI) = 1.14 (1.00, 1.30), and 20% increase on the risk of impaired fasting glucose, OR (95% CI) = 1.20 (1.01, 1.42). These results show that the high variability of admixture proportions in the Central Valley population offers a unique opportunity to uncover the genetic basis of ethnic differences on the risk of disease.

Association between sequence variant of c.553 G > T in the apolipoprotein A5 gene and metabolic syndrome, insulin resistance, and carotid atherosclerosis

Common polymorphism of the apolipoprotein A5 gene (APOA5, c.553G>T) related to metabolic syndrome components, insulin resistance, and carotid atherosclerosis remains unclear. We investigated the associations of the APOA5 c.553G>T gene with various metabolic syndrome components and carotid artery atherosclerosis among family members. A total of 661 participants who provided complete genotyping and carotid artery measures were included in this study. Participants with APOA5 c.553T carrier (GT and TT) were more likely to have higher levels of triglycerides and apolipoprotein B, as well as lower levels of high-density lipoprotein (HDL) cholesterol, than participants with the GG genotype. Individuals who carried T alleles had an increased risk of a high level of triglycerides (multivariate odds ratio [OR], 3.86; 95% confidence interval [CI], 1.98-7.55; P<0.0001) and low levels of HDL cholesterol (OR, 2.32; 95% CI, 1.40-3.86; P=0.0012) compared with those without T alleles. The age was an effect modifier for the association between APOA5 genotype and smoking, alcohol drinking, obesity, and lipid profiles, including total, HDL, and low-density lipoprotein (LDL) cholesterol; triglycerides; and apolipoproteins. In addition, the association between APOA5 genotype and hypertriglyceridemia was significant only in adult groups (OR, 3.53; 95% CI, 1.79-6.94), and the association between APOA5 genotype and low HDL cholesterol was stable in young adolescents (OR, 2.39; 95% CI, 1.19-4.78) and adults (OR, 2.20; 95% CI, 1.17-4.15). Our findings indicated that the APOA5 c.553G>T polymorphism is associated with high triglycerides and low HDL cholesterol but not with other metabolic syndrome components or carotid atherosclerosis in this ethnic Chinese population.

Haplotype Analysis of the CYP8A1 Gene Associated With Myocardial Infarction

Objective: The aim of this study was to assess the association between the human CYP8A1 gene and myocardial infarction (MI) in Chinese people. Methods: 210 MI patients and 206 age-matched controls were genotyped and constructed haplotypes for 3 SNPs [3982C>T (rs5602), C1117A (rs5629), C251T (rs454-98106)] of the human CYP8A1 gene. Results: The CC genotype of rs5629 was more frequently in MI patients than in control subjects (P = .030). The frequency of the A-C-T haplotype was significantly higher in MI patients than in control subjects (P =.001). The frequency of the C-T-T haplotype was significantly lower in MI patients than in control subjects (P= .011). Conclusions: The present results indicate that MI is associated with the CC genotype of rs5629 in the human CYP8A1 gene. The A-C-T haplotype appears to be a useful genetic marker and the C-T-T haplotype might be a protective factor of MI in Chinese people.

Association of polymorphisms of PTGS2 and CYP8A1 with myocardial infarction

: Cyclooxygenase-2 (COX-2) and prostacyclin synthase (PGIS) are enzymes involved in prostaglandin and prostacyclin synthesis, which have been linked to cardiovascular disease risk. We hypothesized that genetic variations altering the function of these enzymes would modify the risk of myocardial infarction (MI).

: In a Chinese case control study of MI patients (n=356) and healthy controls (n=350), we investigated the roles of polymorphisms in the PGIS gene (

: The CC genotype of

: The CC genotype of

Clin Chem Lab Med 2009;47:347–52.

Genetic studies on the APOA1-C3-A5 gene cluster in Asian Indians with premature coronary artery disease

BACKGROUND

The APOA1-C3-A5 gene cluster plays an important role in the regulation of lipids. Asian Indians have an increased tendency for abnormal lipid levels and high risk of Coronary Artery Disease (CAD). Therefore, the present study aimed to elucidate the relationship of four single nucleotide polymorphisms (SNPs) in the Apo11q cluster, namely the -75G>A, +83C>T SNPs in the APOA1 gene, the Sac1 SNP in the APOC3 gene and the S19W variant in the APOA5 gene to plasma lipids and CAD in 190 affected sibling pairs (ASPs) belonging to Asian Indian families with a strong CAD history.

METHODS & RESULTS

Genotyping and lipid assays were carried out using standard protocols. Plasma lipids showed a strong heritability (h2 48% - 70%; P < 0.0001). A subset of 77 ASPs with positive sign of Logarithm of Odds (LOD) score showed significant linkage to CAD trait by multi-point analysis (LOD score 7.42, P < 0.001) and to Sac1 (LOD score 4.49) and -75G>A (LOD score 2.77) SNPs by single-point analysis (P < 0.001). There was significant proportion of mean allele sharing (pi) for the Sac1 (pi 0.59), -75G>A (pi 0.56) and +83C>T (pi 0.52) (P < 0.001) SNPs, respectively. QTL analysis showed suggestive evidence of linkage of the Sac1 SNP to Total Cholesterol (TC), High Density Lipoprotein-cholesterol (HDL-C) and Apolipoprotein B (ApoB) with LOD scores of 1.42, 1.72 and 1.19, respectively (P < 0.01). The Sac1 and -75G>A SNPs along with hypertension showed maximized correlations with TC, TG and Apo B by association analysis.

CONCLUSION

The APOC3-Sac1 SNP is an important genetic variant that is associated with CAD through its interaction with plasma lipids and other standard risk factors among Asian Indians.

Abdominal obesity and hyperglycemia mask the effect of a common APOC3 haplotype on the risk of myocardial infarction

BACKGROUND

Plasma apolipoprotein (apo) C-III strongly predicts myocardial infarction (MI) and directly activates atherogenic processes in vascular cells. Genetic variation in the insulin response element of the APOC3 promoter is associated with an increased risk of MI.

OBJECTIVE

The objective was to determine whether the APOC3 promoter variation affects plasma apo C-III concentrations and MI only when insulin sensitivity is normal.

DESIGN

The APOC3*222 haplotype, defined by the minor alleles of the single nucleotide polymorphisms 3238C-->G, -455T-->C, and -482C-->T, was studied in 1703 matched nonfatal case-control pairs with MI in the Central Valley of Costa Rica. We used fasting hyperglycemia and abdominal obesity as surrogates for insulin sensitivity.

RESULTS

The APOC3*222 haplotype was associated with higher apo C-III concentrations only in those with the lowest waist circumference or fasting glucose concentration. The association between the APOC3*222 haplotype and nonfatal MI, previously reported in this population, was strongly influenced by fasting hyperglycemia and abdominal obesity. The odds ratios for MI for the APOC3*222 haplotype were 1.72 (95% CI: 1.16, 2.54) and 1.84 (1.31, 2.59) in subjects in the lowest quintiles of abdominal obesity and fasting hyperglycemia, respectively, and were 0.75 (0.54, 1.05) and 1.16 (0.85, 1.59) in subjects in the highest quintiles, respectively (P for interaction <0.05).

CONCLUSION

The results support the concept that mutations in the APOC3 promoter inhibit the down-regulation of APOC3 expression by insulin. This cardioprotective system becomes dysfunctional in abdominal obesity and hyperglycemia.

Apoprotein A-V: an important regulator of triglyceride metabolism

Apolipoprotein A-V (apoA-V) was discovered in 2001 both by comparative sequencing and as a liver regeneration protein. The gene is a located at the APOA1/C3/A4/A5 gene cluster on chromosome 11q23, a locus well known for playing a major role in regulating plasma cholesterol and triglyceride (TG) levels. ApoA-V is produced in the liver and has very low plasma concentrations (0.1-0.4 mug/ml). Mice lacking apoA-V have 4-fold increased TG levels, whereas apoA-V overexpression leads to 40% plasma TG reduction. Based on metabolic studies in vivo, apoA-V enhances the catabolism of TG rich lipoproteins rather than affecting their intestinal or hepatic production. By activating proteoglycans-bound lipoprotein lipase (LPL), apoA-V can accelerate TG hydrolysis from VLDL and chylomicrons independent from other apoproteins. Several variants at the APOA5 gene locus have been detected in humans. Some single nucleotide polymorphisms (SNPs) are associated with significantly higher plasma TG levels in patients (e.g., -1131T > C, S19W, G185C). In addition, these SNPs may affect fibrate response and obesity. However, data for a possible association of APOA5 variants with coronary heart disease are not consistent. Severe structural mutations (Q139X, Q148X, IVS3 + 3G > C) predispose to familial hypertriglyceridaemia and late-onset chylomicronaemia. Thus, despite its low plasma concentration, apoA-V is a major regulator of plasma TG metabolism in humans. However, the precise mechanism of its function is not yet clear.

In vivo characterization of human APOA5 haplotypes

Increased plasma triglyceride concentrations are an independent risk factor for cardiovascular disease. Numerous studies support a reproducible genetic association between two minor haplotypes in the human apolipoprotein A5 gene (APOA5) and increased plasma triglyceride concentrations. We thus sought to investigate the effects of these minor haplotypes (APOA5*2 and APOA5*3) on ApoAV plasma levels through the precise insertion of single-copy APOA5 haplotypes at a targeted location (Hprt) in the mouse genome. While we found no difference in the amount of human plasma ApoAV in mice containing the common APOA5*1 or minor APOA5*2 haplotype, the introduction of the single APOA5*3-defining allele (19W) resulted in three fold lower ApoAV plasma levels, consistent with existing genetic association studies. These results indicate that the S19W polymorphism is likely to be functional and explain the strong association of this variant with plasma triglycerides, supporting the value of sensitive in vivo assays to define the functional nature of human haplotypes.

Apolipoprotein A5 gene promoter region T-1131C polymorphism associates with elevated circulating triglyceride levels and confers susceptibility for development of ischemic stroke

The possible pathogenic role of triglycerides (TG) in the development of ischemic stroke is still under extensive investigation. Recently, apolipoprotein (apo)A5 gene promoter region T-1131C polymorphism has been shown to associate with elevated serum TG levels. In the current work, a total of 302 subjects were classified as being large vessel-associated, small vessel-associated, or belonging to a mixed group of ischemic stroke-affected patients. The level of TG was increased in all groups (p < 0.01). The apoA5-1131C allele frequency was approximately twofold in all groups of stroke patients compared with the controls (5 vs 10-12%; p < 0.05); and the apoA5-1131C allele itself was also found to associate with increased TG levels in all groups. In a multivariate logistic regression analysis model adjusted for differences in age, gender, serum cholesterol, hypertension, presence of diabetes mellitus, smoking and drinking habits, and ischemic heart disease, a significantly increased risk of developing stroke disease was found in patients carrying the apoA5-1131C allele (p < 0.05; odds ratio OR = 2.1 [1.3-4.7]); this association was also proven for all subtypes of the stroke. The results presented here suggest that the apoA5-1131C allele is an independent risk factor for the development of stroke. Being that apoA5 gene is under the control of the peroxisome proliferator-activated receptor alpha, theoretically, the current observations also can have long-term therapeutic consequences.

APOA5 gene variation modulates the effects of dietary fat intake on body mass index and obesity risk in the Framingham Heart Study

Diet is an important environmental factor interacting with our genes to modulate the likelihood of developing lipid disorders and, consequently, cardiovascular disease risk. Our objective was to study whether dietary intake modulates the association between APOA5 gene variation and body weight in a large population-based study. Specifically, we have examined the interaction between the APOA5-1131T>C and 56C>G (S19W) polymorphisms and the macronutrient intake (total fat, carbohydrate, and protein) in their relation to the body mass index (BMI) and obesity risk in 1,073 men and 1,207 women participating in the Framingham Offspring Study. We found a consistent and statistically significant interaction between the -1131T>C single-nucleotide polymorphism (SNP; but not the 56C>G) and total fat intake for BMI. This interaction was dose-dependent, and no statistically significant heterogeneity by gender was detected. In subjects homozygous for the -1131T major allele, BMI increased as total fat intake increased. Conversely, this increase was not present in carriers of the -1131C minor allele. Accordingly, we found significant interactions in determining obesity and overweight risks. APOA5-1131C minor allele carriers had a lower obesity risk (OR, 0.61, 95%; CI, 0.39-0.98; P = 0.032) and overweight risk (OR, 0.63, 95%; CI, 0.41-0.96; P = 0.031) compared with TT subjects in the high fat intake group (>or=30% of energy ) but not when fat intake was low (OR, 1.16, 95%; CI, 0.77-1.74; P = 0.47 and OR = 1.15, 95%; CI, 0.77-1.71; P = 0.48) for obesity and overweight, respectively). When specific fatty acid groups were analyzed, monounsaturated fatty acids showed the highest statistical significance for these interactions. In conclusion, the APOA5-1131T>C SNP, which is present in approximately 13% of this population, modulates the effect of fat intake on BMI and obesity risk in both men and women.

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.

The -1131 T>C and S19W APOA5 gene polymorphisms are associated with high levels of triglycerides and apolipoprotein C-III, but not with coronary artery disease: an angiographic study

High plasma concentrations of triglycerides (TG) and apolipoprotein C-III (ApoC-III) are well-known risk factors for cardiovascular disease. Two variants of the recently discovered APOA5, 1131 C>T and S19W, have been associated with hypertriglyceridemia, whereas their relation with coronary artery disease (CAD) remains controversial. Nine hundred and thirteen angiografically defined patients (669 CAD and 244 CAD-free) were genotyped for APOA5 -1131 C>T and S19W polymorphisms. Carriership of the APOA5 -1131 C allele was identified, by multiple linear regression models, as a significant independent predictor for both TG (standardized beta-coefficient=0.112; p=0.010) and ApoC-III variability (standardized beta-coefficient=0.113; p=0.013). Similarly, APOA5 19W allele carriership was a significant independent predictor for both TG (standardized beta-coefficient=0.113; p=0.007) and ApoC-III variability (standardized beta-coefficient=0.088; p=0.045). Despite the association with at-risk lipid profile, no significant difference was detected in the distribution of both APOA5 gene polymorphisms between subjects with or without CAD. Moreover, homozygous carriers of the APOC3 -455 C, another TG- and ApoC-III raising variant, showed a significant increased risk for CAD (OR 1.90 with 95% CI 1.002-3.62; p=0.049; by multiple logistic regression). Different genotypes, i.e., APOA5 and APOC3 variants, may lead to similar biochemical phenotypes, namely hypertriglyceridemia, but to contrasting clinical phenotypes such as the presence of angiographically proven CAD.

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.