A case-control study of apoA5 -1131T-->C polymorphism that examines the role of triglyceride levels in diabetic nephropathy

Apolipoprotein A5 gene polymorphism (rs662799) and cardiovascular disease in end-stage kidney disease patients

Background

Plasma triglyceride (TG) levels are a significant risk factor for cardiovascular disease (CVD). The APOA5 gene is one of the crucial factors in plasma TG metabolism regulation. The rs662799 polymorphism in the APOA5 gene has been reported to be associated with cardiovascular disease. The goal of this study was to evaluate the potential association of this variant with CVD in patients with end-stage kidney disease. 

Methods

In this case–control study the polymorphism was analyzed using the PCR–RFLP method in 800 consecutive patients with ESKD and 500 healthy controls. The genotype and allele distribution was compared between subgroups of patients with CVD (552) versus those without CVD (248).

Results

The frequency of the minor allele (C) in the healthy individuals was 9% compared to 12% in ESRD group (p = 0.09). The difference between groups was slightly higher for CC homozygote (3.5% versus 1.6%, p = 0.042). The ESKD patient group was analyzed according to the presence or absence of CVD. The significant differences in the polymorphism distribution were revealed in this analysis. The frequency of the C allele in the CVD + subgroup was 14% compared to 6% in CVD- patients (p = 0.001). In the CVD + subgroup the ORs (95% CI) for the C allele and CC genotype were 2.41 (1.61–3.6), p < 0.001 and 3.13 (1.07–9.14), p = 0.036, respectively. This indicates to the association of the variant C allele with cardiovascular disease in ESKD patients. The CC homozygotes have a threefold higher odds of CVD compared to TT homozygotes. The highest frequency of the C allele (18%) was observed in subgroup of patients with diabetic nephropathy, with OR (95% CI) 3.40 (2.13–5.43), p < 0.001.The presence of minor allele (CC and CT genotypes) was significantly associated with increased plasma triglyceride levels (p < 0.001 for both CVD + and CVD- groups).

Conclusion

The present study demonstrated the effect of rs662799 polymorphism on plasma TG levels and its association with the development of cardiovascular disease in ESKD patients.

Association of APOA5 Gene Promoter Region -1131T>C Polymorphism (rs662799) to Plasma Triglyceride Level in Patients with Type 2 Diabetic Nephropathy

INTRODUCTION

Diabetic Nephropathy (DN), a serious complication of Type 2 Diabetic Mellitus (T2DM), is progressive and susceptibility to DN varies among T2DM patients. ApoA5-1131T>C polymorphism revealed that is strongly associated with triglyceride levels and proposed as a predisposing factor for DN.

AIM

The purpose of this study was to investigate the association -1131T>C ApoA5 gene polymorphism with serum lipids levels in Type 2 diabetic (DM) patients with or without DN in north of Iran (Mazandaran province).

MATERIALS AND METHODS

This study comprised patients with established T2DM (n=161) and controls (n=58). Genotyping of APOA5 -1131T>C polymorphisms was performed by PCR-RFLP. Diabetic patients were divided into two groups: with nephropathy (DN+, n = 90) and without nephropathy (DN-, n = 71). Lipids and lipoproteins were assessed by enzymatic methods.

RESULTS

The genotype frequencies were 63.8 % TT, 31 % TC, 5.2 % CC in controls, 33.8% TT, 52.1 % TC, 14.1 % CC in DN- and 44.4 % TT, 36.7 % TC, 18.9 % CC in DN+ patients. The TC genotype and the CC genotype were overexpressed among DN+ and DN-population in comparison to the control group. The highest and the lowest TG levels in both diabetic patients and controls belonged to CC+TC and TT genotypes, respectively. Furthermore in both patients TG increased with this order: TT< TC<CC.

CONCLUSION

These results suggest that APOA5 -1131T>C polymorphisms influence lipid levels in type 2 diabetic patients.

Genetic polymorphism of apolipoprotein A5 gene and susceptibility to type 2 diabetes mellitus: a meta-analysis of 15,137 subjects

BACKGROUND

Several studies have investigated whether the polymorphism in the apolipoprotein A5 (APOA5) is associated with type 2 diabetes mellitus (T2DM) risk. However, those studies have produced inconsistent results. The purpose of this study was to investigate whether the APOA5 -1131T/C polymorphism (rs662799) confers significant susceptibility to T2DM using a meta-analysis.

METHODS

PubMed, Embase, Web of Science, Cochrane database, CBMdisc, CNKI and Google Scholar were searched to get the genetic association studies. All statistical analyses were done with Stata 11.0.

RESULTS

A total of 19 studies included 4,767 T2DM cases and 10,370 controls (four studies involving 555 T2DM cases and 2958 controls were performed among Europeans and 15 studies involving 4212 T2DM cases and 7412 controls were performed among Asians) were combined showing significant association between the APOA5 -1131T/C polymorphism and T2DM risk (for C allele vs. T allele: OR = 1.28, 95% CI = 1.17-1.40, p<0.00001; for C/C vs. T/T: OR = 1.57, 95% CI = 1.35-1.83, p<0.00001; for C/C vs. T/C+T/T: OR = 1.36, 95% CI = 1.18-1.57, p<0.0001; for C/C+T/C vs. T/T: OR = 1.32, 95% CI = 1.16-1.51, p<0.0001). In the subgroup analysis by ethnicity, significant association was also found among Asians (for C allele vs. T allele: OR = 1.31, 95% CI = 1.22-1.40, p<0.00001; for C/C vs. T/T: OR = 1.61, 95% CI = 1.38-1.88, p<0.00001; for C/C vs. T/C+T/T: OR = 1.39, 95% CI = 1.20-1.61, p<0.0001; for C/C+T/C vs. T/T: OR = 1.42, 95% CI = 1.25-1.62, p<0.00001). However, no significant association was found between the APOA5 -1131T/C polymorphism and T2DM risk among Europeans.

CONCLUSIONS

The present meta-analysis suggests that the APOA5 -1131T/C polymorphism is associated with an increased T2DM risk in Asian population.

Association of APOA5 -1131T>C polymorphism and serum lipid levels in patients with type 2 diabetes

Significant abnormalities in lipid metabolism are frequently present in patients with type 2 diabetes mellitus (T2DM). Hypertriglyceridemia, a highly proatherogenic state, is associated with increased risk of coronary artery disease. Genetic polymorphism APOA5 -1131T>C has been recognized as a significant contributor to hypertriglyceridemia in both healthy and diabetic populations. The aim of the study was to investigate the association of APOA5 -1131T>C polymorphism with the serum levels of triglycerides, total cholesterol, high-density lipoprotein (HDL) cholesterol, and low-density lipoprotein (LDL) cholesterol in patients with T2DM. In total, 234 DNA samples from patients with T2DM were genotyped using the PCR-RFLP method. Serum lipid levels were measured using standard laboratory methods. Obtained APOA5 -1131T>C genotype frequencies were 89% (T/T) and 11% (T/C+C/C). There was no significant association between APOA5 -1131T>C genotypes and triglyceride levels (1.90 mM [1.32-2.74] vs. 1.78 mM [1.54-3.05] for T/T vs. T/C+C/C genotype; p=0.553), HDL cholesterol levels (1.30 mM [1.10-1.40] vs. 1.30 mM [1.05-1.40] for T/T vs. T/C+C/C; p=0.534), and LDL cholesterol levels (3.1 mM [2.3-3.8] vs. 3.0 mM [2.2-3.5] for T/T vs. T/C+C/C; p=0.313). Our results suggest that hypertriglyceridemia in patients with T2DM is not likely to be associated with the APOA5 -1131T>C polymorphism.

Effects of APOA5 -1131T>C (rs662799) on fasting plasma lipids and risk of metabolic syndrome: evidence from a case-control study in China and a meta-analysis

The apolipoprotein A5 (APOA5) gene −1131T>C (rs662799) has been suggested to be involved in the pathway of lipid homeostasis and the development of metabolic syndrome (MetS). However, the findings are not consistent. To systematically evaluate the associations between −1131T>C polymorphism and fasting lipid parameters and the risk of MetS, we conducted a case-control study in a Chinese population and a meta-analysis. The findings from 1840 Chinese participants indicated that the C allele carriers had significantly higher fasting total cholesterol (TC), triglycerides (TG) and lower HDL-cholesterol (HDL-C) than the TT homozygotes carriers. The −1131C allele was also found to be significantly associated with increased risk of MetS (OR  =  1.40, 95% confidence interval (CI)  =  1.15, 1.69) compared to the TT homozygotes. In the meta-analysis of 51,868 participants from 46 East Asian studies, 26 European studies and 19 studies of other ethnic groups, the −1131C allele was associated with higher fasting TC (weighted mean difference (WMD)  =  0.08 mmol/L, 95% CI  =  0.05, 0.10, P = 1.74×10⁻⁹), TG (WMD  =  0.30 mmol/L, 95% CI  =  0.26, 0.33, P =  1.87×10⁻⁵⁵), LDL-cholesterol (LDL-C) (WMD  =  0.04 mmol/L, 95% CI  =  0.02, 0.07, P = 0.002), and lower HDL-C (WMD  =  −0.05 mmol/L, 95% CI  =  −0.06,−0.04, P = 1.88×10⁻²¹), respectively. Based on 12 studies with 5,573 MetS cases and 8,290 controls from 5 East Asian studies, 5 European studies and 2 studies of other ethnic groups, the −1131C allele was associated with increased risk of MetS with an OR (95% CI)  =  1.33 (1.16, 1.53) in the overall population, 1.43 (1.29, 1.58) in East Asian and 1.30 (0.94, 1.78) in European populations. In conclusion, the −1131C allele may be associated with elevated levels of fasting TG, TC, LDL-C and decreased HDL-C, and increased risk of MetS, especially in East Asians.

Role of triglyceride-rich lipoproteins in renal injury

Dyslipidemia is implicated as a risk factor for the development of atherosclerosis. Specifically triglyceride-rich lipoproteins and their lipolysis products are shown to be proinflammatory and proapoptosis in both in vivo and in vitro studies with endothelium. However, the role of triglyceride-rich lipoproteins in the progression of kidney diseases is not clear. Epidemiology studies demonstrated a correlation between renal disease and blood lipids. Recent evidence suggests that the mechanism may involve cellular uptake of lipid and de novo lipogenesis. Further studies are needed to establish the relevance of these mechanistic studies in human pathophysiology.

Association of the apolipoprotein A5 gene -1131 T>C polymorphism with fasting blood lipids: a meta-analysis in 37859 subjects

BACKGROUND

Studies examining the association of apolipoprotein A5 (APOA5) gene -1131 T>C polymorphism with blood lipids produced inconsistent results. In this meta-analysis encompassing all the relevant studies, we aimed to investigate the association of the -1131 T>C polymorphism with fasting blood lipids.

METHODS

We limited our analysis to the following four blood lipid variables: total cholesterol (TC), triglycerides (TG), low density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C). Subjects were confined to adults who were at least 18 years old. A dominant model was used for this meta-analysis. 37 studies with 37859 subjects were included in this meta-analysis.

RESULTS

The results showed that the carriers of -1131C allele have higher blood TC and TG than the non-carriers: standardized mean difference (SMD) = 0.08, 95% confidence interval (CI, 0.05, 0.11), P < 0.00001, P(heterogeneity) = 0.42, and SMD = 0.31, 95% CI (0.27, 0.34), P < 0.00001, P(heterogeneity) = 0.0003, respectively. Significant association between the -1131 T>C polymorphism and lower blood HDL-C was also detected under the dominant model: SMD = -0.17, 95% CI (-0.21, -0.14), P < 0.00001, P(heterogeneity) = 0.003.

CONCLUSIONS

Our meta-analysis supports the strong association of the APOA5 -1131 T>C polymorphism with higher levels of TC and TG, and lower levels of HDL-C.

Clinical significance of apolipoprotein A5

PURPOSE OF REVIEW

We have examined the evidence from recent human studies examining the role of apolipoprotein A-V in triglyceride-rich lipoprotein metabolism and cardiovascular disease risk. Special emphasis was placed on the evidence emerging from the association between genetic variability at the apolipoprotein A5 locus, lipid phenotypes and disease outcomes. Moreover, we address recent reports evaluating apolipoprotein A5 gene-environment interactions in relation to cardiovascular disease and its common risk factors.

RECENT FINDINGS

Several genetic association studies have continued to strengthen the position of APOA5 as a major gene that is involved in triglyceride metabolism and modulated by dietary factors and pharmacological therapies. Moreover, genetic variants at this locus have been significantly associated with both coronary disease and stroke risks.

SUMMARY

Apolipoprotein A-V has an important role in lipid metabolism, specifically for triglyceride-rich lipoproteins. However, its mechanism of action is still poorly understood. Clinical significance at present comes largely from genetic studies showing a consistent association with plasma triglyceride concentrations. Moreover, the effects of common genetic variants on triglyceride concentrations and disease risk are further modulated by other factors such as diet, pharmacological interventions and BMI. Therefore, these genetic variants could be potentially used to predict cardiovascular disease risk and individualize therapeutic options to decrease cardiovascular disease risk.