Apolipoprotein C3 SstI polymorphism and triglyceride levels in Asian Indians

Exploring apolipoprotein C-III: pathophysiological and pharmacological relevance

The availability of pharmacological approaches able to effectively reduce circulating LDL cholesterol (LDL-C) has led to a substantial reduction in the risk of atherosclerosis-related cardiovascular disease (CVD). However, a residual cardiovascular (CV) risk persists in treated individuals with optimal levels of LDL-C. Additional risk factors beyond LDL-C are involved, and among these, elevated levels of triglycerides (TGs) and TG-rich lipoproteins are causally associated with an increased CV risk. Apolipoprotein C-III (apoC-III) is a key regulator of TG metabolism and hence circulating levels through several mechanisms including the inhibition of lipoprotein lipase activity and alterations in the affinity of apoC-III-containing lipoproteins for both the hepatic receptors involved in their removal and extracellular matrix in the arterial wall. Genetic studies have clarified the role of apoC-III in humans, establishing a causal link with CVD and showing that loss-of-function mutations in the APOC3 gene are associated with reduced TG levels and reduced risk of coronary heart disease. Currently available hypolipidaemic drugs can reduce TG levels, although to a limited extent. Substantial reductions in TG levels can be obtained with new drugs that target specifically apoC-III; these include two antisense oligonucleotides, one small interfering RNA and an antibody.

[Association Between Apolipoprotein C-3 SstⅠ Polymorphism and Serum Lipids in Patients With Gestational Diabetes Mellitus]

Objective

To investigate the apolipoprotein C-3 (APOC3) gene Sst Ⅰ polymorphism and its relationship with changes in serum lipids in patients with gestational diabetes mellitus (GDM).

Methods

A total of 630 pregnant women with GDM and 1027 normal pregnant controls were covered in the study. The genotype and allele frequencies of APOC3 Sst Ⅰ polymorphism were analyzed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP). Total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and glucose (Glu) were measured by enzymatic methods. Plasma insulin (INS) was measured by chemiluminescence. Apolipoproteins A 1 (apoA1) and B (apoB) levels were measured by turbidimetric immunoassay.

Results

The allele frequencies of S1 and S2 of the APOC3 polymorphism at the SstⅠ locus were 0.704 and 0.296 in the GDM group and 0.721 and 0.279 in the control group, respectively. There was no significant difference in genotype frequency and allele frequency of APOC3 Sst Ⅰ polymorphism between the GDM and the control groups ( P>0.05). In the GDM group, those with S2S2 and S1S2 genotypes had higher plasma HDL-C levels and lower atherogenic index (AI) values than those with S1S1 genotype did, with the differences being statistically significant (all P<0.05). GDM patients were then divided into obesity and non-obesity subgroups. Further subgroup analysis showed that the association of APOC3 genotype with changes in HDL-C levels was observed only in obese GDM patients, while the association of APOC3 genotype with changes in AI values was observed in both obese and nonobese patients. In addition, in obese GDM patients, those with S2S2 genotype had significantly higher plasma TG levels than those with S1S1 and S1S2 genotypes did ( P<0.05 and P<0.01, respectively). In non-obese GDM patients, those with S2S2 genotype had significantly lower apoB/apoA1 ratio than S2S2 carriers did ( P<0.05). No genotype-related effect on lipid and apolipoprotein variations was evident in the normal controls.

Conclusion

APOC3 Sst Ⅰ polymorphism in GDM patients is associated with HDL-C and TG levels as well as AI value and apoB/apoA1 ratio. The changes in lipid levels and apolipoprotein ratio showed BMI-dependent features. However, association between polymorphism at the locus and the development of GDM was not observed.

Polymorphism in Genes Apolipoprotein C3 (APOC3) and Fatty Acid-Binding Proteins (FABP2) in Nondiabetic Dyslipidemics: A Tertiary Care Hospital-Based Pilot Study

Context  Dyslipidemia is a multifactorial disease in which lipoproteins play an important role as one of the early markers for coronary heart disease (CHD). Mixed dyslipidemia is common in people with diabetes mellitus, but nondiabetic dyslipidemics (NDD) remain unidentified for the risk of developing dyslipidemia and eventually CHD.

Objectives  This pilot study attempts to analyze the genetic basis of lipid metabolism alterations, emphasizing the association between fatty acid-binding protein-2 (FABP2-Ala54Thr) and apolipoprotein-C3 (APOC3-rs5128) genetic polymorphism, as a risk for developing dyslipidemia and CHD in NDD.

Methods and Design  Total 90 subjects—30 DD, 30 NDD, and 30 apparently healthy subjects representing Central India—were included. Biochemical analysis and DNA genotyping were done by polymerase chain reaction restriction fragment length polymorphism.

Statistical Analysis  The biochemical parameters were reported as means ± standard deviation. One-way analysis of variance test was used to compare biochemical parameters of three groups. Chi-squared test was done to compare genotype distributions. The strength of association was assessed by odds ratios (ORs) with 95% confidence intervals (CIs). All statistical analysis was done using SPSS-PC software and Graph Pad.

Results  In NDD, maximum polymorphism was observed followed by DD and least polymorphism was observed in controls. There was a significant association of APOC3 G allele with occurrence of hypertriglyceridemia ( p  < 0.05); however, no such association was found for FABP2 A allele ( p > 0.05). Logistic regression analysis revealed APOC3 polymorphism to be significantly associated with dyslipidemia (OR = 2.6667, 95% CI = 1.0510–6.7663, p  = 0.0341); no such association was found for FABP2 polymorphism (OR = 0.4643, 95% CI = 0.1641–1.3136, p  = 0.1347). The triglyceride and cholesterol values in individuals with homozygous genotype indicate that genetic study is comparable to the biochemical findings in carriers of polymorphic allele than noncarriers, especially in NDD patients.

Conclusions  Pilot study indicates that the presence of APOC3 gene polymorphism is associated with pro-atherogenic dyslipidemia in nondiabetic patients and may raise risk of CHD. This information could be used for preventive strategies in NDD group that may otherwise go unnoticed.

Sequence analysis and variant identification at the APOC3 gene locus indicates association of rs5218 with BMI in a sample of Kuwaiti's

Background

APOC3 is important in lipid transport and metabolism with limited studies reporting genetic sequence variations in specific ethnic groups. The present study aimed to analyze the full APOC3 sequence among Kuwaiti Arabs and test the association of selected variants with lipid levels and BMI.

Methods

Variants were identified by Sanger sequencing the entire APOC3 gene in 100 Kuwaiti Arabs. Variants and their genotypes were fully characterized and used to construct haplotype blocks. Four variants (rs5128, rs2854117, rs2070668, KUAPOC3N3 g.5196 A > G) were selected for testing association with serum lipid levels and BMI in a cohort (n = 733).

Results

APOC3 sequence (4.3 kb) of a Kuwaiti Arab was deposited in Genbank (accession number KJ437193). Forty-two variants including 3 novels were identified including an “A” insertion at genomic positions 116,700,599–116,700,600 (promoter region) and two substitutions in intron 1 at genomic positions 116,700,819 and 116,701,159. Only three variants, (rs5128, rs2854117, and rs2070668) were analyzed for association of which rs5128 showed a trend for association with increased BMI, TG and VLDL levels that was further investigated using multivariate analysis. A significant association of rs5128 with BMI (p <  0.05) was observed following a dominant genetic model with increased risk by an OR of 4.022 (CI: 1.13–14.30).

Conclusion

The present study is the first to report sequence analysis of APOC3 in an Arab ethnic group. This study supports the inclusion of rs5128 as a marker for assessing genetic risk to dyslipidemia and obesity and the inclusion of the novel variant g.5196 A > G for population stratification of Arabs.

Non-fasting triglyceride levels in the Korean population with and without ischemic heart disease and cerebrovascular disease

BACKGROUND/AIMS

Associations between non-fasting triglyceride (TG) levels and a risk of ischemic heart disease (IHD) and cerebrovascular accident (CVA) have been suggested in Caucasians. We aimed to investigate whether non-fasting TG levels reflect the risk of IHD/CVA in Koreans.

METHODS

We conducted an analysis of patients aged ≥ 30 years from the nationwide survey database. Fasting TG was defined as a measurement taken ≥ 12 hours since the last meal. Non-fasting TG was categorized by fasting duration of 0 to 3, 4 to 7, and 8 to 11 hours.

RESULTS

In subjects without history of IHD/CVA, diabetes, or lipid-lowering medication, the TG level was significantly elevated for 7 hours in men compared to fasting TG levels (p = 0.011); the mean TG levels were 154.9 mg/dL (standard error [SE], 13.0), 177.0 mg/dL (SE, 12.1), 148.8 mg/dL (SE, 2.8), and 141.5 mg/dL (SE, 1.4) for 0 to 3, 4 to 7, 8 to 11, and ≥12 hours' fasting, respectively. In women, there was no difference in TG level according to fasting duration after adjustment for confounders. In men without diabetes, the TG level from 4 to 7 hours' fasting showed a significant difference between subjects with or without IHD/CVA even after adjustments for age, body mass index, lipid medication, exercise, and dietary factors (215.1 mg/dL vs. 177.3 mg/dL, p < 0.001).

CONCLUSION

In men, non-fasting TG levels from 4 to 7 hours' fasting were significantly associated with IHD/CVA, and were superior to fasting TG levels level in the significant association with the history of IHD or CVA.

A Review of Clinical Practice Guidelines for the Management of Hypertriglyceridemia: A Focus on High Dose Omega-3 Fatty Acids

Cardiovascular (CV) disease remains the leading cause of preventable death in the US. Hyperlipidemia is a major modifiable risk factor for CV disease, and after numerous clinical trials have demonstrated that reductions in low-density lipoprotein (LDL) cholesterol with statin therapy can prevent major adverse CV events, statins have emerged as the drug of choice to lower LDL cholesterol and reduce CV risk. However, some statin-treated patients remain at high residual risk of CV events despite achieving low LDL cholesterol levels, especially if their triglyceride (TG) levels are elevated or their high-density lipoprotein (HDL) cholesterol levels low. Evidence from genetic and observational studies has linked elevated TG levels to an increased risk of CV events. Furthermore, very high TG levels are associated with acute pancreatitis. Consequently, several clinical practice guidelines provide recommendations for the management and treatment of high and very high TG levels. This review focuses on the clinical practice guidelines for the management of hypertriglyceridemia and the role of prescription omega-3 fatty acids in preventing pancreatitis and CV disease in individuals with high and very high TG levels.

Association of serum lipids and coronary artery disease with polymorphisms in the apolipoprotein AI-CIII-AIV gene cluster

Genetic variants are considered as one of the main determinants of the concentration of serum lipids and coronary artery disease (CAD). Polymorphisms in the Apolipoprotein (Apo) AI-CIII-AIV gene cluster has been known to affect the concentrations of various lipid sub-fractions and the risk of CAD. The present study assessed associations between polymorphisms of the Apo AI-CIII-AIV gene cluster, [ApoA-I,-75G > A, (rs1799837); ApoC-III 3238C > G, (SstI), (rs5128) and ApoA-IV, Thr347Ser(347A > T), (rs675)] with serum lipids and their contributions to CAD in North Indian population. We recruited age, sex matched, 200 CAD patients and 200 healthy controls and tested them for fasting levels of serum lipids. We genotyped selected polymorphisms using polymerase chain reaction-restriction fragment length polymorphism. There were no statistically significant association of selected polymorphisms (or their combinations) with CAD even after employing additive, dominant and recessive models. However there was significant association of selected polymorphisms with various lipid traits amongst the control cohort (p < 0.05). Mean levels of high density lipoprotein cholesterol and triglycerides were found to be significantly higher among controls carrying at least one mutant allele at ApoA1-75G > A (p = 0.019) and ApoCIII SstI (p < 0.001) polymorphism respectively. Our study observed that the selected polymorphisms in the ApoAI-CIII-AIV gene cluster although significantly affect various lipid traits but this affect does not seem to translate into association with CAD, at least among North Indian population.

Hypertriglyceridemia: the importance of identifying patients at risk

This review aims to explain risk factors, consequences, and management strategies recommended for patients with hypertriglyceridemia. A search of PubMed was performed: 'Hypertriglyceridemia'[Majr], limited to English-language and published in the 5 years up to April 2016. Abstracts of the 680 results were screened for inclusion. Reference lists of publications included were also screened for inclusion. Approximately 25% of the United States population has elevated (≥150 mg/dL) triglycerides (TG) putting them at an increased risk of cardiovascular disease, non-alcoholic fatty liver disease, and pancreatitis. Risk factors for hypertriglyceridemia include genetics, lifestyle and diet, renal disease, endocrine disorders, and certain medications. Guidelines recommend that all patients with hypertriglyceridemia are advised on lifestyle modification to reduce TG to <150 mg/dL; a reduction in body weight of 5-10% can reduce TG by approximately 20%. For patients with TG <400 mg/dL, the primary goal is to reduce low-density lipoprotein cholesterol (LDL-C) and non-high-density lipoprotein cholesterol, with most guidelines recommending statin therapy. When TG is ≥500 mg/dL the primary goal is to reduce TG levels to lower the risk of pancreatitis. Statin therapy (if LDL-C is elevated) in combination with a fibrate, or long-chain omega-3 fatty acid may be required. The Food and Drug Administration withdrew approval for niacin and some fibrates in combination with statins in April 2016 citing unfavorable benefit-risk profiles. With the increasing incidence of associated conditions (e.g. obesity, metabolic syndrome, and type 2 diabetes mellitus), it is likely that primary care physicians will encounter more patients with hypertriglyceridemia.

Genetic epidemiology of coronary artery disease: an Asian Indian perspective

Coronary artery disease (CAD) has emerged as a major cause of morbidity and mortality worldwide. Recent findings on the role of genetic factors in the aetiopathology of CAD have implicated novel genes and variants in addition to those involved in lipid and lipoprotein metabolism. However, our present knowledge is limited due to lack of clarity on their exact identity and the quantum of impact on disease susceptibility, and incident risk. It is a matter of great interest to understand the role of genetic factors in ethnic populations that have a strong underlying predisposition to CAD such as the South Asian populations, particularly among Asian Indians living in India and abroad. Although, a number of isolated studies do implicate certain gene polymorphisms towards enhanced disease susceptibility, the available data remains scanty and inconclusive as they have not been validated in large, prospective cohorts. The present review aims to consolidate the available literature on the genetics of CAD in Asian Indians and seeks to provide insights on the concerns that need to be addressed in future studies to generate information having clinical value.

Interactions of Environmental Factors and APOA1-APOC3-APOA4-APOA5 Gene Cluster Gene Polymorphisms with Metabolic Syndrome

OBJECTIVE

The present study investigated the prevalence and risk factors for Metabolic syndrome. We evaluated the association between single nucleotide polymorphisms (SNPs) in the apolipoprotein APOA1/C3/A4/A5 gene cluster and the MetS risk and analyzed the interactions of environmental factors and APOA1/C3/A4/A5 gene cluster polymorphisms with MetS.

METHODS

A study on the prevalence and risk factors for MetS was conducted using data from a large cross-sectional survey representative of the population of Jilin Province situated in northeastern China. A total of 16,831 participations were randomly chosen by multistage stratified cluster sampling of residents aged from 18 to 79 years in all nine administrative areas of the province. Environmental factors associated with MetS were examined using univariate and multivariate logistic regression analyses based on the weighted sample data. A sub-sample of 1813 survey subjects who met the criteria for MetS patients and 2037 controls from this case-control study were used to evaluate the association between SNPs and MetS risk. Genomic DNA was extracted from peripheral blood lymphocytes, and SNP genotyping was determined by MALDI-TOF-MS. The associations between SNPs and MetS were examined using a case-control study design. The interactions of environmental factors and APOA1/C3/A4/A5 gene cluster polymorphisms with MetS were assessed using multivariate logistic regression analysis.

RESULTS

The overall adjusted prevalence of MetS was 32.86% in Jilin province. The prevalence of MetS in men was 36.64%, which was significantly higher than the prevalence in women (29.66%). MetS was more common in urban areas (33.86%) than in rural areas (31.80%). The prevalence of MetS significantly increased with age (OR = 8.621, 95%CI = 6.594-11.272). Mental labor (OR = 1.098, 95%CI = 1.008-1.195), current smoking (OR = 1.259, 95%CI = 1.108-1.429), excess salt intake (OR = 1.252, 95%CI = 1.149-1.363), and a fruit and dairy intake less than 2 servings a week were positively associated with MetS (P<0.05). A family history of diabetes (OR = 1.630, 95%CI = 1.484-1.791), cardiovascular disease or cerebral diseases (OR = 1.297, 95%CI = 1.211-1.389) was associated with MetS. APOA1 rs670, APOA5 rs662799 and rs651821 revealed significant differences in genotype distributions between the MetS patients and control subjects. The minor alleles of APOA1 rs670, APOA5 rs662799 and rs651821, and APOA5 rs2075291 were associated with MetS (P<0.0016). APOA1 rs5072 and APOC3 rs5128, APOA5 rs651821 and rs662799 were in strong linkage disequilibrium to each other with r2 greater than 0.8. Five haplotypes were associated with an increased risk of MetS (OR = 1.23, 1.58, 1.80, 1.90, and 1.98). When we investigated the interactions of environmental factors and APOA1/C3/A4/A5 gene cluster gene polymorphisms, we found that APOA5 rs662799 had interactions with tobacco use and alcohol consumption (PGE<0.05).

CONCLUSIONS

There was a high prevalence of MetS in the northeast of China. Male gender, increasing age, mental labor, family history of diabetes, cardiovascular disease or cerebral diseases, current smoking, excess salt intake, fruit and dairy intake less than 2 servings a week, and drinking were associated with MetS. The APOA1/C3/A4/A5 gene cluster was associated with MetS in the Han Chinese. APOA5 rs662799 had interactions with the environmental factors associated with MetS.

Interactions between the apolipoprotein a1/c3/a5 haplotypes and alcohol consumption on serum lipid levels

BACKGROUND

The interactions between apolipoprotein (Apo) A1/C3/A5 haplotypes and alcohol consumption on serum lipid profiles have not been previously explored. The present study was undertaken to detect the polymorphisms of ApoA1 -75 bp G>A (rs1799837), ApoC3 3238C>G (rs5128), ApoA5 -1131T>C (rs662799), ApoA5 c.553G>T (rs2075291), and ApoA5 c.457G>A (rs3135507) and the interactions between their haplotypes and alcohol consumption on serum lipid levels.

METHODS

Genotyping was performed in 1,030 unrelated subjects (516 nondrinkers and 514 drinkers) aged 15 to 89. The interactions between ApoA1/C3/A5 haplotypes and alcohol consumption on serum lipid levels were detected by factorial regression analysis after controlling for potential confounders.

RESULTS

The frequencies of ApoC3 3238 CG/GG genotypes and ApoA1 -75 bp A allele in nondrinkers were higher in females than in males (p < 0.05). The frequencies of ApoC3 3238 CG/GG genotypes and G allele in drinkers were higher in females than in males (p < 0.05). The frequencies of ApoA1 -75 bp GA/AA genotypes and A allele in males were higher, and those of ApoC3 3238 CG/GG genotypes were lower in drinkers than in nondrinkers (p < 0.05 to 0.01). The frequency of ApoC3 3238 GG genotype in male drinkers was also higher in ≥25 g/d than in <25 g/d subgroups (p < 0.05). There were 11 haplotypes with a frequency >1% in our study population. The haplotypes of G-G-T-C-G (in the order of c.553G>T, c.457G>A, -1131T>C, 3238C>G, and -75 bp G>A), G-G-T-C-A, and G-G-C-G-G were shown consistent interactions with alcohol consumption to increase serum total cholesterol, high-density lipoprotein cholesterol (HDL-C), and ApoA1 levels (p < 0.05 to 0.001). The interactions between G-G-T-G-G (HDL-C and ApoA1), G-G-C-C-A (ApoA1), G-A-T-C-G (triglyceride), G-G-T-C-G (ApoA1/ApoB ratio), and G-G-C-G-G (ApoB) haplotypes and alcohol consumption on serum lipid levels were also detected (p < 0.05 to 0.001); the levels of these serum lipid parameters were significantly higher in drinkers than in nondrinkers.

CONCLUSIONS

The differences in serum lipid parameters between drinkers and nondrinkers might partly result from different interactions between the ApoA1/C3/A5 haplotypes and alcohol consumption.

Apolipoprotein A1/C3/A5 haplotypes and serum lipid levels

Background

The association of single nucleotide polymorphisms (SNPs) in the apolipoprotein (Apo) A1/C3/A4/A5 gene cluster and serum lipid profiles is inconsistent. The present study was undertaken to detect the association between the ApoA1/C3/A5 gene polymorphisms and their haplotypes with serum lipid levels in the general Chinese population.

Methods

A total of 1030 unrelated subjects (492 males and 538 females) aged 15-89 were randomly selected from our previous stratified randomized cluster samples. Genotyping of the ApoA1 -75 bp G>A, ApoC3 3238C>G, ApoA5 -1131T>C, ApoA5 c.553G>T and ApoA5 c.457G>A was performed by polymerse chain reaction and restriction fragment length polymorphism combined with gel electrophoresis, and then confirmed by direct sequencing. Pair-wise linkage disequilibria and haplotype analysis among the five SNPs were estimated.

Results

The levels of high-density lipoprotein cholesterol (HDL-C) and ApoA1 were lower in males than in femailes (P < 0.05 for each). The allelic and genotypic frequencies of the SNPs were no significant difference between males and females except ApoC3 3238C>G. There were 11 haplotypes with a frequency >1% identified in the cluster in our population. At the global level, the haplotypes comprised of all five SNPs were significantly associated with all seven lipid traits. In particular, haplotype G-G-C-C-A (6%; in the order of ApoA5 c.553G>T, ApoA5 c.457G>A, ApoA5 -1131T>C, ApoC3 3238C>G, and ApoA1 -75bp G>A) and G-A-T-C-G (4%) showed consistent association with total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), ApoA1, ApoB, and the ApoA1/ApoB ratio. In addition, carriers of haplotype G-G-T-C-G (26%) had increased serum concentration of HDL-C and ApoA1, whereas carriers of G-G-C-G-G (15%) had high concentrations of TC, triglyceride (TG) and ApoB. We also found that haplotypes with five SNPs explain much more serum lipid variation than any single SNP alone, especially for TG (4.4% for haplotype vs. 2.4% for -1131T>C max based on R-square) and HDL-C (5.1% for haplotype vs. 0.9% for c.553G>T based on R-square). Serum lipid parameters were also correlated with genotypes and several environment factors.

Conclusions

Several common SNPs and their haplotypes in the ApoA1/C3/A5 gene cluster are closely associated with modifications of serum lipid parameters in the general Chinese population.

Association of a DNA polymorphism of the apolipoprotein AI-CIII-AIV gene cluster with myocardial infarction in a Tunisian population

BACKGROUND

Apolipoproteins AI-CIII-AIV play important roles in the metabolism of triglycerides and high-density lipoprotein cholesterol. However, whether genetic variations in the ApoAI-CIII-AIV gene cluster are associated with the risk of myocardial infarction (MI) remains uncertain. In the present study, we examined a possible association of the ApoCIII SacI polymorphism in the ApoAI-CIII-AIV gene cluster with lipid parameters and MI in a sample of the Tunisian population.

METHODS

A total of 326 Tunisian patients with MI and 361 controls were included in the study. Genotypes were determined by polymerase chain reaction--restriction fragment length polymorphism (PCR-RFLP) analysis.

RESULTS

A significant difference in genotype distribution and allele frequency was observed between patients and controls. At the multivariate analysis after adjustment for traditional vascular risk factors, the ApoCIII SacI polymorphism was significantly associated with MI, according to co-dominant and dominant models (co-dominant model odds ratio [OR]: 1.53, 95% confidence interval [CI]: 1.0-2.35, p=0.04; dominant model OR: 2.02, 95% CI: 1.11-3.67, p=0.02). The MI patient group showed a significant higher frequency of the S2 allele compared to the controls (10.2% vs. 6.5%; OR: 1.64, 95% CI: 1.10-2.47, p=0.01). There was no statistically significant association between ApoAI-CIII-AIV cluster gene polymorphism and lipid, lipoprotein, and apolipoprotein levels in both MI patients and controls.

CONCLUSION

In the current study, a significant association between the ApoCIII SacI polymorphism (presence of S2 allele) and MI in the Tunisian population was found.

SstI Polymorphism of the Apolipoprotein CIII Gene in Iranian Hyperlipidemic Patients: A Study in Semnan Province

OBJECTIVES

The Sst-I polymorphic site on the 3' untranslated region of the apo CIII gene, has been previously reported to be associated with hypertriglyceridemia. The aim of the present study was to explore the association between Sst-I polymorphism with plasma lipid and lipoprotein levels in hyperlipidemic (HLP) patients from Semnan province, Iran.

MATERIALS AND METHODS

Genomic DNA was prepared from 76 patients with HLP and 75 matched healthy subjects. DNA samples were amplified by polymerase chain reaction. The samples were analyzed by restriction fragment length polymorphism (RFLP) method using SstI enzyme.

RESULTS

The genotype and allelic frequencies for this polymorphism were significantly different between HLP and normolipidemic groups (P< 0.002). Plasma triglyceride (TG) level was higher in both groups, in S2S2 genotype was more than in the S1S1and S1S2 genotypes, however, there was no significant difference in comparison with the control group. Subjects with S1S2 + S2S2 genotypes in compare to S1S1 genotype had odd ratio of 2.8 (95% CI: 1.41-5.56, P< 0.003) for developing hypertriglyceridemia.

CONCLUSION

The results showed that the presence of rare S2 allele was associated with change in TG level in the selected population.

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.

Genetic variants on apolipoprotein gene cluster influence triglycerides with a risk of coronary artery disease among Indians

Apolipoprotein C3 and apolipoprotien A5 are proteins coded from the APOA1/C3/A4/A5 gene cluster. Sst I polymorphism on apolipoprotein C3 and -1131C polymorphism of apolipoprotien A5 are key variants involved in triglyceride metabolism and cause a significant cardio-metabolic risk. Here, we have evaluated these two variants for their roles in coronary artery disease in patients of the Indian population. The apolipoprotein gene cluster variants were analysed in 416 angiographically determined coronary artery disease patients and matched 416 controls using polymerase chain reaction-restriction fragment length polymorphism. The characteristics of the study subjects were analyzed statistically for their association with the polymorphisms. The alleles were combined as haplotypes and their combined risks were evaluated. The minor allele genotypes of both apolipoprotein C3 (S2) and apolipoprotien A5 (C) had a significant risk for coronary artery disease. The S2 allele genotyped patients had a significantly increased triglyceride level (P < 0.001) and increased triglycerides were observed among both patient and control CC genotype carriers. We identified the haplotype S2/C with a significant increased risk (P < 0.001) to coronary artery disease with increased levels of circulating triglycerides compared to other haplotypes in patients. We conclude that the variants on apolipoprotein C3 and apolipoprotien A5 modulate serum triglyceride levels and increase the risk of coronary artery disease.

Disparities in allele frequencies and population differentiation for 101 disease-associated single nucleotide polymorphisms between Puerto Ricans and non-Hispanic whites

Background

Variations in gene allele frequencies can contribute to differences in the prevalence of some common complex diseases among populations. Natural selection modulates the balance in allele frequencies across populations. Population differentiation (F_ST) can evidence environmental selection pressures. Such genetic information is limited in Puerto Ricans, the second largest Hispanic ethnic group in the US, and a group with high prevalence of chronic disease. We determined allele frequencies and population differentiation for 101 single nucleotide polymorphisms (SNPs) in 30 genes involved in major metabolic and disease-relevant pathways in Puerto Ricans (n = 969, ages 45–75 years) and compared them to similarly aged non-Hispanic whites (NHW) (n = 597).

Results

Minor allele frequency (MAF) distributions for 45.5% of the SNPs assessed in Puerto Ricans were significantly different from those of NHW. Puerto Ricans carried risk alleles in higher frequency and protective alleles in lower frequency than NHW. Patterns of population differentiation showed that Puerto Ricans had SNPs with exceptional F_ST values in intronic, non-synonymous and promoter regions. NHW had exceptional F_ST values in intronic and promoter region SNPs only.

Conclusion

These observations may serve to explain and broaden studies on the impact of gene polymorphisms on chronic diseases affecting Puerto Ricans.

Synergistic effect between apolipoprotein E and apolipoprotein A1 gene polymorphisms in the risk for coronary artery disease

Alterations in lipid metabolism and genetic predisposition are major risk factors for coronary artery disease (CAD). Variations in genes involved in lipid metabolism may act synergistically to confer risk or protection against CAD. The objective of the present study was to determine such interactions in variants of apolipoprotein E and apolipoprotein A1 genes. One hundred and forty subjects with clinically confirmed CAD and 100 unrelated normal subjects participated in the study. Multiple regression analysis was used to relate lipid and apolipoprotein profiles with genotypes. Odd ratios were calculated for various combinations of ApoE and ApoA1 genotypes. Prevalence of ApoE 'E4' and ApoA1 'A' and 'T' alleles was significantly higher in patients than controls. Serum apolipoprotein E and apolipoprotein A1 levels were significantly lower in CAD patients than controls. When lipid parameters were related to genotypes, the polymorphisms associated to various markers were in agreement with previous reports. ApoE 2/4 genotype in combination with either ApoA1 heterozygous GA or CT genotype conferred higher risk of CAD. E3 allele in homozygous or heterozygous state in combination with ApoA1+83 CC genotype conferred highest protection (P < 0.05). Thus, it appears that ApoE and ApoA1 gene variants may act synergistically to associate with risk and protection against CAD.

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.

Effect of SstI polymorphism of the apolipoprotein CIII gene and environmental factors on risks of hypertriglyceridemia in Taiwan aborigines

BACKGROUND

Hypertriglyceridemia (HTG) is a heterogeneous metabolic disorder. The aim of this study was to examine associations among genetic polymorphisms, SstI polymorphism of apolipoprotein CIII (ApoCIII) and Hind III polymorphism of lipoprotein lipase (LPL), environmental factors and risks of HTG.

METHODS AND RESULTS

Two hundred and forty-nine southern Taiwanese aborigines were recruited for a cross-sectional study, which included 90 subjects with triglyceride (TG)>150 mg/dl (HTG) and 159 with TG<or=150 mg/dl (NTG). The frequencies of SstI major allele (S1) and minor allele (S2) of ApoCIII were 66.1% and 33.9% in HTG and 73.6% and 26.4% in NTG (p<0.1). In female subjects, the frequencies of the S2 allele was significantly higher in HTG (0.38) than NTG (0.27) (p<0.04). The frequencies of the LPL HindIII major allele (H+) and minor allele (H-) were similar between HTG (H+ 84.3%; H- 15.7%) and NTG (H+ 78.9%; H- 21.1%). In a multivariate adjusted logistic model, education<or=6 year (odds ratio (OR)=3.71, 95% confidence interval (CI): 1.24-8.13), Amis tribe (OR=3.08, 95% CI: 1.41-6.77), body mass index (BMI)>or=25 (OR=2.22, 95% CI: 1.18-4.16), starchy food consumption>or=3 times/week (OR=1.89, 95% CI: 1.00-3.59) and ApoCIII S2S2 genotype (OR=3.35, 95% CI: 1.10-10.19) were independently (p<0.05) associated with HTG risks. Among ApoCIII S1S1, S1S2 and S2S2 genotypes, ApoCIII and TG concentrations increased (p<0.01) in a dose-responsive manner.

CONCLUSIONS

The ApoCIII S2 variant and environmental factors, including education, tribal background, BMI and starchy food intake, modulate the risks of HTG in aboriginal Taiwanese. Interaction between genetic and environmental factors warrants further investigation.

Genome-wide linkage scan for loci influencing plasma triglycerides

BACKGROUND

Plasma triglyceride concentration is known to be a significant risk factor for cardiovascular disease (CVD). Previous studies have found that the level of triglycerides is strongly influenced by genetic factors.

METHODS

To identify quantitative trait loci influencing triglycerides, we conducted a genome-wide linkage scan on data from 485 Australian adult dizygotic twin pairs. Prior to linkage analysis, triglyceride values were adjusted for the effects of covariates including age, sex, time since last meal, time of blood collection (CT) and time to plasma separation.

RESULTS

The heritability estimate for ln(triglyceride) adjusted for all above fixed effects was 0.49. The highest multipoint LOD score observed was 2.94 (genome-wide p=0.049) on chromosome 7 (at 65 cM). This 7p region contains several candidate genes. Two other regions with suggestive multipoint LOD scores were also identified on chromosome 4 (LOD score=2.26 at 62 cM) and chromosome X (LOD score=2.01 at 81 cM).

CONCLUSIONS

The linkage peaks found represent newly identified regions for more detailed study, in particular the significant linkage observed on chromosome 7p13.

Variations in plasma apolipoprotein C-III levels are strong correlates of the triglyceride response to a high-monounsaturated fatty acid diet and a high-carbohydrate diet

The objective of this study was to examine how a diet rich in carbohydrates (high-CHO) vs a diet rich in monounsaturated fatty acids (high MUFA) consumed ad libitum modulated plasma apolipoprotein C-III (apo C-III) levels and to examine the extent to which diet-induced changes in plasma apo C-III were associated with concurrent variations in plasma triglyceride (TG) levels. Forty-seven men (mean age, 35.7 +/- 11.4 years; body mass index, 29.0 +/- 5.1 kg/m2) were randomly assigned to either a high-CHO diet (CHO, 58%; fat, 26%; n = 23) or a high-MUFA diet (CHO, 45%; fat, 40%; MUFA, 22.5%; n = 24), which they consumed for 6 to 7 weeks. Fasting and postprandial lipemia after an oral fat load and fasting plasma apo C-III were measured at the beginning and at the end of the dietary intervention. Ad libitum consumption of the high-CHO diet induced a significant reduction in body weight (-2.6%, P < .0001), but had no impact on plasma apo C-III concentrations and on fasting and postprandial plasma TG levels. In contrast, ad libitum consumption of the high-MUFA diet also resulted in a significant reduction in body weight (-2.3%, P < .01) as well as in significant reductions in plasma apo C-III (-11%, P = .05) and fasting plasma TG (-17%, P < .01). Diet-induced variations in plasma apo C-III concentrations were correlated with changes in fasting and postprandial TG levels both in the high-CHO (r > 0.70, P < .001) and the high-MUFA groups (r > 0.42, P < .05). These results indicate that variations in plasma apo C-III levels are strong correlates of the fasting and postprandial plasma TG responses to high-MUFA and high-CHO diets.

Apolipoprotein C3 SstI polymorphism in the risk assessment of CAD

Various population studies have reported the association of rare S2 allele of apolipoprotein C3 (APOC3) SstI polymorphism with hypertriglyceridemia (HTG) and coronary artery disease (CAD). We were the first to report an association of S2 allele with high triglyceride (TG) levels in healthy volunteers from Northern India. Since HTG is suggested to be a predominant risk factor for CAD among Indians, we have elucidated the relationship of APOC3 SstI polymorphism with the lipid profile and CAD. A total of 158 patients with > or = 70% stenosis in one or more coronary artery (angiographically proven CAD patients), 35 subjects with < 70% stenosis (NCAD) and 151 normal controls (free of heart disease) from Northern plains of India were recruited in the study. DNA samples were analyzed by polymerase chain reaction (PCR) followed by SstI digestion. Lipid profile was estimated by enzymatic kit. We found a strong association of S2 allele with high TG levels, which was more significant in patients. Prevalence of S2 allele in normal controls and CAD patients were comparable, despite the fact that mean TG level was significantly higher in patients. A greater insight into this observation revealed that the prevalence of high TG, if not coupled with other risk factors (like high total cholesterol, low HDL), was comparable in patients and controls. Thus, our study reveals that rare S2 allele may be employed as a susceptibility marker for high TG. However, high TG or S2 allele alone may not contribute to the etiology of CAD.

Polymorphisms in Four Genes Related to Triglyceride and HDL-cholesterol Levels in the General Japanese Population in 2000

We studied the association of six common polymorphisms of four genes related to lipid metabolism with serum lipid levels. We selected single-nucleotide polymorphisms (SNPs) in the genes for cholesteryl ester transfer protein (CETP), lipoprotein lipase (LPL), hepatic lipase (LIPC), and apolipoprotein CIII (APOC3), and studied 2267 individuals randomly selected from the participants of Serum Lipid Survey 2000. There was a significant association of CETP polymorphism (D442G, Int14 +1 G --> A, and TaqIB), LPL polymorphism (S447X), and LIPC polymorphism (-514 --> CT) with HDL-cholesterol levels. We also found a significant association of LPL polymorphism (S447X) and APOC3 polymorphism (SstI) with triglyceride levels. This is the largest database showing the association of common genetic variants in lipid metabolism with serum lipid levels in the general Japanese population. Further study is necessary to elucidate the role of these gene polymorphisms in cardiovascular events.

Apolipoprotein C-III SstI genotypes modulate exercise-induced hypotriglyceridemia

PURPOSE

To investigate whether the efficacy of exercise as an antitriglyceridemic treatment was dependent on the apolipoprotein (apo) C-III SstI gene polymorphism.

METHODS

A subgroup of 100 Korean men, who were prescreened by genotypes (S1S1 = 40, S1S2 = 40, S2S2 = 20), participated in a 6-d moderate-exercise intervention using either a motor-driven treadmill or a cycle ergometer. Height and weight for body mass index and waist circumference were measured. Fasting total cholesterol, triglycerides (TG), high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, glucose, and insulin were measured. Univariate analysis of variance and ANCOVA followed by Bonferroni post hoc tests were used to compare the preintervention values and the pre- to postexercise change (delta) scores in the measured variables across the genotypes, respectively. Multivariate linear regressions were carried out with age, smoking, waist circumference, body mass index, and genotype as independent variables and lipids, glucose, and insulin as dependent variables.

RESULTS

Subjects with the S2S2 genotype had a significantly higher preintervention TG concentration than subjects with the S1S1 genotype (P = 0.022). Waist circumference and genotype were the only significant predictors for the preintervention TG (P < 0.001). With respect to the delta scores, the subjects with the S2S2 genotype had a greater reduction in TG than the subjects with the S1S1 genotype, adjusted for the preintervention difference (P = 0.047).

CONCLUSION

This study suggests that the apo C-III SstI gene polymorphism might be useful for determining who is most susceptible to intervention by exercise in lowering fasting TG concentration.

Study of apolipoproteinc3 Sstl polymorphism in healthy volunteers from Northern India

Several studies including a small case-control (hypertriglyceridemic/normotriglyceridemic individuals) study by us revealed close association between rare S2 allele ofAPOC3 Sstl polymorphism and hypertriglyceridemia. With the understanding that Asian Indians are highly vulnerable to the adverse effects of hypertriglyceridemia, we extended the investigation and studied the frequency distribution of this polymorphism in 216 healthy volunteers from Northern plains of India. We found that more than 50% of the study population had one or two S2 allele. This may suggest that a larger fraction of this population is genetically predisposed to hypertriglyceridemia.