Effects of apolipoprotein A-I genetic variations on plasma apolipoprotein, serum lipoprotein and glucose levels

[－75 G/A Polymorphism of Apolipoprotein A1 Gene Promoter Region in Normal Pregnant Women and Patients With Gestational Diabetes Mellitus]

Objective

To investigate the －75 G/A single-nucleotide polymorphism in the promoter region of apolipoprotein A1 gene (apoA1) and its association with gestational diabetes mellitus (GDM) in pregnant women and to provide references for the exploration in the molecular genetic basis of GDM.

Methods

A total of 626 GDM patients and 1022 normal pregnant women, ie, the controls, were included in the study. The genotyping of apoA1 －75 G/A polymorphism was performed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) analysis. Total cholesterol (TC), triglycerides (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 immunoassay. The protein levels of apoA1 and apoB were measured by the turbidimetric immunoassay.

Results

Allele frequencies of G and A were 0.718 and 0.282 in the GDM group and 0.713 and 0.287 in the control group, respectively. Distribution of the genotype frequencies was found to be in Hardy-Weinberg equilibrium in both the GDM and control groups. There was no significant difference in the frequencies of alleles G and A and the genotypes of apoA1 －75 G/A polymorphism between the GDM and the control group (P>0.05). In the GDM group, the carriers with the genotype AA were associated with significantly higher levels of TC, HDL-C, and apoA1 than those with genotypes GG and GA did (all P<0.05). After the GDM patients were divided into obese and non-obese subgroups, the genotype-related apoA1 variation was observed only in obese patients, while the genotype-related TC and HDL-C variations were evident in non-obese patients (P<0.05). In the control group, carriers of genotypes AA and GA had higher systolic blood pressure (SBP) and HDL-C than the carriers of genotype GG did (all P<0.05). Carriers of genotypes AA had significantly lower Glu levels than carriers of genotypes GG and GA did (P<0.05). The control subjects were further divided into subgroups according to their body mass index (BMI). Analysis of the subgroups showed that AA carriers were associated with higher SBP levels in the obese control women only, while lower Glu levels were evident in both obese and non-obese control women.

Conclusion

These results suggest that －75 G/A polymorphism in the apoA1 gene is not associated with GDM. However, the genetic variation is closed associated with the plasma apoA1, HDL-C, and TC levels in GDM patients and plasma HDL-C, Glu, and SBP levels in the control subjects. The apoA1 variant-associated lipids and SBP variation is BMI dependent in both groups.

[Influence of rs670 variant of APOA1 gene on serum HDL response to an enriched-polyunsaturated vs. an enriched-monounsaturated fat hypocaloric diet]

Introduction

Background and objectives: genetic variants of the APOA1 gene have been related to lipid profile in obese subjects. Our aim was to analyze the effects of the rs670 APOA1 gene polymorphism on metabolic changes secondary to an enriched-polyunsaturated fat vs. an enriched-monounsaturated fat hypocaloric diet. Methods: 360 Caucasian obese subjects were randomly allocated to two groups. One group received an enriched-polyunsaturated fat (diet P) and the other an enriched-monounsaturated fat hypocaloric diet (diet M) during 12 weeks. The effects on serum biomarkers related to lipid and carbohydrate metabolism were evaluated before and after the dietary intervention. Results: after both diets, body mass index, weight, fat mass, waist circumference, systolic blood pressure, plasma leptin concentration, and waist circumference decreased in all patients. After 12 weeks of intervention with diet P, plasma insulin levels and HOMA-IR decreased in A-allele carriers: delta: -7.3 ± 2.2 IU/L (p = 0.01), and delta: -2.8 ± 0.5 units (p = 0.02), respectively. The same changes in delta were observed after diet M in A-allele carriers: insulin delta: -5.9 ± 1.2 IU/L (p = 0.01), and HOMA-IR delta: -2.1 ± 0.8 units (p = 0.02). In A-allele carriers, LDL-cholesterol decreased and HDL-cholesterol increased after the dietary intervention with diet P: delta: -12.1 ± 4.3 mg/dL (p = 0.01), and delta: 2.6 ± 0.7 mg/dL (p = 0.01), respectively. No differences in lipid profile were observed after diet M. These improvements were not observed in non-A-allele carriers after both interventions. Conclusions: our study showed the association of the rs670 ApoA1 polymorphism with insulin resistance changes as induced by both diets. An enriched-polyunsaturated fat diet produced an additional improvement of HDL-cholesterol and LDL-cholesterol in A-allele carriers.

Association of rs670 variant of APOA1 gene with lipid profile and insulin resistance after 9 months of a high protein/low carbohydrate vs a standard hypocaloric diet

BACKGROUND & AIMS

A common G-to-A transition (rs670) in the APOA1 gene has been related with metabolism. We evaluate the association of this SNP with changes in lipid profile and insulin resistance in response to two diets.

METHODS

268 obese patients were randomly allocated to a high protein/low carbohydrate -Diet HP- vs. a standard hypocaloric diet -Diet S- for 9 months. Anthropometric and biochemical status were evaluated at 3 and 9 months.

RESULTS

179 subjects (66.8%) had the genotype GG, 79 patients GA (29.4%) and 10 subjects AA (3,8%). With both diets: the decrease of BMI, weight, waist circumference, fat mass was higher in A allele carriers than non-carriers. Also on both diets A allele carriers showed greater improvements in total cholesterol (-19.0 ± 2.5 mg/dl (non-A allele carriers -12.1 ± 2.0 mg/dl:p = 0.02 after Diet HP) and -13.1 ± 2.1 mg/dl (non-A allele carriers -8.9 ± 1.1 mg/dl:p = 0.02 after Diet S)), LDL-cholesterol (-18.0 ± 2.1 mg/dl (non-A allele carriers -8.3 ± 2.2 mg/dl:p = 0.01 after Diet HP) and -12.0 ± 1.5 mg/dl (non-A allele carriers -6.3 ± 2.3 mg/dl:p = 0.01 after Diet S)), insulin (-2.5 ± 0.2 mUI/L (in non A allele -1.8 ± 0.2 mUI/L:p = 0.01 after Diet HP) and -2.1 ± 0.1 mUI/L (non A allele carriers -1.2 ± 0.3 mUI/L:p = 0.01 after Diet S)), HOMA-IR (-1.3 ± 0.3 units (non A allele group -0.8 ± 0.2:p = 0.03 after Diet HP) and -1.1 ± 0.1 units (non A allele carriers -0.3 ± 0.2 mg/dl:p = 0.01 after Diet S)) than non-A allele carriers.

CONCLUSIONS

A allele carriers of rs670 ApoA1 polymorphism showed a higher decrease of insulin resistance, LDL cholesterol and adiposity induced by two different hypocaloric diet than non A allele carriers.

Role of rs670 variant of APOA1 gene on metabolic response after a high fat vs. a low fat hypocaloric diets in obese human subjects

BACKGROUND & AIMS

A common G-to-A transition located 75 base pairs upstream (rs670) from transcription start site of the APOA1 gene has been related with some metabolic parameters. Our aim was to analyze the effects of rs670 APOA1 gene polymorphism on lipid profile and metabolic changes after two different hypocaloric diets.

METHODS

282 obese subjects were randomly allocated during 12 weeks (Diet HF - high fat diet vs. Diet LF - low fat diet). Anthropometric and biochemical status were evaluated.

RESULTS

Body mass index, weight, fat mass, waist circumference, systolic blood pressure, leptin levels and waist circumference decreased in all patients in average after both diets. In A allele carriers after 12 weeks with both diets, insulin levels (Delta diet HF: -5.3 + 1.2 UI/L; P = 0.02 and Delta diet LF: -5.8 + 1.3 UI/L; P = 0.02) and HOMA-IR (Delta diet HF: -2.9 + 0.8 units; P = 0.01 and Delta diet LF: -2.2 + 0.9 units; P = 0.03) improved in a significant way. With the low fat diet, A allele carriers showed a statistical improvement in HDL-cholesterol levels (Delta: 4 + 1 mg/dl; P = 0.03).

CONCLUSIONS

Our study showed the association of rs670 ApoA1 polymorphism with a decrease of insulin resistance induced by both diets and provided additional evidence on HDL-cholesterol increase after a LF hypocaloric diet in A allele carriers.

Role of rs670 variant of APOA1 gene on lipid profile, insulin resistance and adipokine levels in obese subjects after weight loss with a dietary intervention

OBJECTIVE

The aim of this study was to analyze the effects of rs670 APOA1 gene polymorphism on obesity parameters, lipid profile, glucose metabolism markers, blood pressure and adipokine levels after a hypocaloric diet with Mediterranean pattern.

MATERIAL AND METHODS

A population of 82 obese patients was studied before and after 12 weeks on a hypocaloric diet (500 kcal per day) in an interventional study of one arm. GG and GA + AA subjects receiving the same diet. Anthropometric measures and biochemical parameters (lipid profile, glucose metabolism, blood pressure and adipokine levels) were measured. Genotype of ApoA1 gene polymorphism (rs670) was evaluated. The A allele is the risk allele.

RESULTS

After dietary intervention and in both genotype groups (GG vs. GA + AA), body mass index (BMI) (delta: -1.0 ± 0.8 kg/m² vs. -1.4 ± 1.0 kg/m²: p = 0.02), weight (delta: -2.6 ± 2.1 kg vs. -3.6 ± 2.2 kg: p = 0.03), fat mass (delta: -1.6 ± 1.1 kg vs. -3.2 ± 1.0 kg: p = 0.01) and waist circumference (delta: -1.8 ± 0.6 cm vs. -2.2 ± 1.1 cm: p = 0.02) decreased. The decrease of the anthropometric parameters was higher in A allele carriers than non-A allele carriers. In A allele carriers, total cholesterol (delta: -11.1 ± 7.1 mg/dl vs. -20.1 ± 9.0 mg/dl: p = 0.02), LDL cholesterol (delta: -10.7 ± 4.1 mg/dl vs. -21.2 ± 8.0 mg/dl: p = 0.01), insulin levels (delta: -0.6 ± 0.8 UI/L vs. 3.7 ± 1.1 UI/L; p = 0.002) and insulin resistance with HOMA-IR (delta: -0.2 ± 0.3 units vs. 0.8 ± 0.4 units; p = 0.01) decreased. The improvement of leptin was similar in both genotype groups. Resistin and adiponectin levels remained unchanged after dietary intervention.

CONCLUSION

In this study the APOA1 (rs670) gene showed important effects on body weight, adiposity, LDL-cholesterol levels and insulin resistance after 12 weeks of the dietary intervention.

Implication of the rs670 variant of APOA1 gene with lipid profile, serum adipokine levels and components of metabolic syndrome in adult obese subjects

BACKGROUND & AIMS

A G-to-A transition located 75 base pairs upstream (rs670) from transcription start site of the APOA1 gene is related with metabolic parameters. The aim of the present investigation was to describe the association of rs670 with metabolic syndrome and metabolic parameters.

METHODS

The study involved a population of 1000 obese subjects. Measurements of anthropometric parameters, arterial blood pressure, fasting blood glucose, C-reactive protein (CRP), insulin concentration, insulin resistance (HOMA-IR), lipid profile, adipokines levels and prevalence of MetS was recorded. Genotype of ApoA1 gene polymorphism (rs670) was evaluated.

RESULTS

A sample of 1000 obese subjects with a mean BMI of 36.5 ± 5.0 kg/m² was enrolled. In males, weight (delta: 3.3 ± 1.2 kg; p = 0.01), fat mass (delta: 2.7 ± 1.1 kg; p = 0.01), waist circumference (delta: 2.8 ± 1.1 cm; p = 0.02), fasting glucose (delta: 8.9 ± 2.2 mg/dl; p = 0.01), insulin levels (delta: 3.7 ± 1.2 UI/L; p = 0.04) and HOMA-IR (delta: 1.2 ± 1.1 units; p = 0.02) were higher in non-A allele carriers than A allele carriers. In males without A allele, an increased risk of hyperglycemia (OR = 1.40, 95% CI = 1.09-2.09, p = 0.04), percentage of central obesity (OR = 4.55, 95% CI = 1.36-15.39, p = 0.01), percentage of low HDL-C (OR = 2.02, 95% CI = 1.02-4.03, p = 0.03) and prevalence of diabetes mellitus (OR = 2.14, 95% CI = 1.03-5.04, p = 0.03) were reported.

CONCLUSIONS

rs670 of APOA1 gene has a gender specific influence on serum glucose, insulin, HOMA-IR, fat mass, weight and waist circumference. Males without A allele showed high rates of central obesity, low levels of HDL, hyperglycemia and diabetes mellitus.

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.

Single nucleotide polymorphisms of APOA1 gene and their relationship with serum apolipoprotein A-I concentrations in the native population of Assam

Background

There is a growing interest in the role of allelic variants of the APOA1 gene in relation to a number of disorders. We described two common polymorphisms of the APOA1 gene, G-75A and C+83T and investigated their potential influence on the serum apolipoprotein A-I (apo A-I) levels in the native population of Assam — a region that is ethnically distinct and from where no information is hitherto available.

Methods

Blood samples were collected from 150 healthy volunteers. Apo A-I levels were estimated by immunoturbidometry. Genotyping was done by a PCR-RFLP method that involved DNA extraction from whole blood, followed by polymerase chain reaction and digestion of the PCR product by MspI restriction enzyme, and analysis of fragment sizes in 12% polyacrylamide gel.

Results

The GG variant at G-75A locus and CC variant at C+83T locus were the most prevalent. GG/CC was the most common combination. Homozygous TT genotype was not detected in any of the subjects. The rare allele frequencies for the G-75A and C+83T sites were found to be 0.22 and 0.06 respectively, which significantly differed from those reported in some other populations in neighbouring regions. Serum apo A-I concentrations did not vary significantly across the detected genotypes. These findings were consistent in both sexes.

Conclusion

We described the distribution of the G-75A and C+83T polymorphisms of the APOA1 gene in the population of Assam for the first time. These polymorphisms were not found to directly influence apo A-I concentrations in this population either individually or synergistically.

•

The G-75A and C + 83T polymorphisms of the APOA1 gene are described for the first time in the native population of Assam, north-east India.

•

The minor allelic frequencies of G-75A and C + 83T differ significantly from some populations in the adjoining regions.

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The G-75A and C + 83T polymorphisms do not influence the serum apolipoprotein A-I levels in the current population.

G-protein estrogen receptor as a regulator of low-density lipoprotein cholesterol metabolism: cellular and population genetic studies

OBJECTIVE

Estrogen deficiency is linked with increased low-density lipoprotein (LDL) cholesterol. The hormone receptor mediating this effect is unknown. G-protein estrogen receptor (GPER) is a recently recognized G-protein-coupled receptor that is activated by estrogens. We recently identified a common hypofunctional missense variant of GPER, namely P16L. However, the role of GPER in LDL metabolism is unknown. Therefore, we examined the association of the P16L genotype with plasma LDL cholesterol level. Furthermore, we studied the role of GPER in regulating expression of the LDL receptor and proprotein convertase subtilisin kexin type 9.

APPROACH AND RESULTS

Our discovery cohort was a genetically isolated population of Northern European descent, and our validation cohort consisted of normal, healthy women aged 18 to 56 years from London, Ontario. In addition, we examined the effect of GPER on the regulation of proprotein convertase subtilisin kexin type 9 and LDL receptor expression by the treatment with the GPER agonist, G1. In the discovery cohort, GPER P16L genotype was associated with a significant increase in LDL cholesterol (mean±SEM): 3.18±0.05, 3.25±0.08, and 4.25±0.33 mmol/L, respectively, in subjects with CC (homozygous for P16), CT (heterozygotes), and TT (homozygous for L16) genotypes (P<0.05). In the validation cohort (n=339), the GPER P16L genotype was associated with a similar increase in LDL cholesterol: 2.17±0.05, 2.34±0.06, and 2.42±0.16 mmol/L, respectively, in subjects with CC, CT, and TT genotypes (P<0.05). In the human hepatic carcinoma cell line, the GPER agonist, G1, mediated a concentration-dependent increase in LDL receptor expression, blocked by either pretreatment with the GPER antagonist G15 or by shRNA-mediated GPER downregulation. G1 also mediated a GPER- and concentration-dependent decrease in proprotein convertase subtilisin kexin type 9 expression.

CONCLUSIONS

GPER activation upregulates LDL receptor expression, probably at least, in part, via proprotein convertase subtilisin kexin type 9 downregulation. Furthermore, humans carrying the hypofunctional P16L genetic variant of GPER have increased plasma LDL cholesterol. In aggregate, these data suggest an important role of GPER in the regulation of LDL receptor expression and consequently LDL metabolism.

Gender-specific associations of the APOA1 -75G>A polymorphism with several metabolic syndrome components in Turkish adults

BACKGROUND

Variations in the apolipoprotein A-1 (APOA1) gene, a determinant of plasma high-density lipoprotein cholesterol (HDL-C) and apoA-I levels, may contribute to cardiovascular diseases. We evaluated the effects of a promoter polymorphism (-75G>A) in the APOA1 gene on metabolic syndrome (MetS) components in a Turkish population sample.

METHODS

Randomly selected 1515 Turkish adults (age 49.9±11.8 years, 785 females) were genotyped for -75G>A polymorphism using hybridization probes in Real-Time PCR LC480 device. MetS and atherogenic dyslipidemia were defined using the criteria of ATP III.

RESULTS

The -75AA genotype prevailed in 3.9% of men and 2.4% of women, and was independently associated with significantly higher HDL-C concentrations. Independent associations with the -75GA genotype existed only in men: higher diastolic and systolic blood pressure (BP) levels (p<0.05) were observed in male -75GA heterozygotes. Logistic regression revealed that the GA genotype confers elevated risk for atherogenic dyslipidemia (OR=1.57, 95% Cl 1.06-2.3) after adjustment for associated risk factors. Independent associations with atherogenic dyslipidemia or elevated BP did not emerge in women.

CONCLUSION

APOA1 -75G>A polymorphism is independently related to HDL-C concentrations. Independent associations of the -75GA genotype with elevated BP and atherogenic dyslipidemia were confined to men. These gender-modulated associations suggest novel gene-gender-environmental interactions.

Genetic polymorphisms in the APOA1 gene and their relationship with serum HDL cholesterol levels

Low high density lipoprotein cholesterol (HDL-C) is a known risk factor of coronary artery disease. Apolipoprotein A1 (APOA1) is the most abundant component of HDL-C. This study aimed at identifying sequence variations (rare and common) in the APOA1 gene and its association with serum HDL-C levels. This study was conducted from April 2012 to February 2013 on 79 Tehranians (participants of Tehran Lipid and Glucose Study) with extremely low HDL-C (within the 5th percentile) and 63 individuals with extremely high HDL-C (within the 95th percentile) levels. After DNA amplification by PCR, DNA sequencing of all three exons and 700 bps of promoter region of the APOA1 gene was performed. Sequence results were analyzed and interpreted using the appropriate software and variants were identified. After sequencing 42 common and rare variants were identified, 11 of which were known variants and the others had been unreported so far. Of the exonic variants, 11 were missense, 6 were synonymous and 1 was nonsense. There was a significant association between serum HDL-C and variant of rs2070665 as well as variants Chr.11:116707788, Chr.11:116708059, Chr.11:116708036, Chr.11:116707729, rs201148448, Chr.11:116707018, Chr.11:116707801, Chr.11:116708530, Chr.11:116708088, rs121912724 and Chr.11:116706966 (p < 0.001). Variants Chr.11:116707018, rs121912724 and 2070665 were independent predictors of the HDL-C level (p < 0.001). SNP Chr.11:116707018 was the strongest predictor of the HDL-C level (OR 7.527, p < 0.001). This study identified 42 variants in APOA1 gene, 31 of which were new variants. Three variants of rs2070665, rs121912724 and Chr.11:116707018 could predict the HDL-C level independently. Variant rs2070665 was protective against low-HDL-C levels while variants rs121912724 and Chr.11:116707018 were risk factors for that in our population.

Re-sequencing of the APOAI promoter region and the genetic association of the -75G > A polymorphism with increased cholesterol and low density lipoprotein levels among a sample of the Kuwaiti population

Background

APOAI, a member of the APOAI/CIII/IV/V gene cluster on chromosome 11q23-24, encodes a major protein component of HDL that has been associated with serum lipid levels. The aim of this study was to determine the genetic association of polymorphisms in the APOAI promoter region with plasma lipid levels in a cohort of healthy Kuwaiti volunteers.

Methods

A 435 bp region of the APOAI promoter was analyzed by re-sequencing in 549 Kuwaiti samples. DNA was extracted from blood taken from 549 healthy Kuwaiti volunteers who had fasted for the previous 12 h. Univariate and multivariate analysis was used to determine allele association with serum lipid levels.

Results

The target sequence included a partial segment of the promoter region, 5’UTR and exon 1 located between nucleotides −141 to +294 upstream of the APOAI gene on chromosome 11. No novel single nucleotide polymorphisms (SNPs) were observed. The sequences obtained were deposited with the NCBI GenBank with accession number [GenBank: JX438706]. The allelic frequencies for the three SNPs were as follows: APOAI rs670G = 0.807; rs5069C = 0.964; rs1799837G = 0.997 and found to be in HWE. A significant association (p < 0.05) was observed for the APOAI rs670 polymorphism with increased serum LDL-C. Multivariate analysis showed that APOAI rs670 was an independent predictive factor when controlling for age, sex and BMI for both LDL-C (OR: 1.66, p = 0.014) and TC (OR: 1.77, p = 0.006) levels.

Conclusion

This study is the first to report sequence analysis of the APOAI promoter in an Arab population. The unexpected positive association found between the APOAI rs670 polymorphism and increased levels of LDL-C and TC may be due to linkage disequilibrium with other polymorphisms in candidate and neighboring genes known to be associated with lipid metabolism and transport.

The common apolipoprotein A-1 polymorphism -75A>G is associated with ethnic differences in recurrent coronary events after recovery from an acute myocardial infarction

Since data regarding the relationship between a common polymorphism (SNP) of the apoA1 gene with apoA1 levels and risk of coronary artery disease are inconsistent, we hypothesized that its association with recurrent coronary events differs for White and Black individuals with diagnosed coronary heart disease. The apoA1 -75G>A SNP was genotyped in a cohort of 834 Black (n=129) and White (n=705) post-myocardial infarction patients. Recurrent coronary events (coronary-related death, non-fatal myocardial infarction, or unstable angina) were documented during an average follow-up of 28 months. Thirty percent of White and 21% of Black patients carried the SNP. Cox proportional-hazards regression analysis, adjusting for clinical and laboratory covariates, demonstrated that the SNP was not associated with recurrent events in the total cohort (HR=1.37, 95% CI 0.95-1.97; p= 0.09) but was the only variable associated with an increased risk of recurrent cardiac events in Blacks (HR=2.40, 95% CI 1.07-5.40; p= 0.034). Conversely in Whites, the SNP was not associated with recurrent events (HR=1.12, 95% CI 0.75-1.67; p= 0.59) whereas apoB (HR=1.78, 95% CI 1.20 -2.65; p= 0.0042) and calcium channel blocker use (HR=2.53, 95% CI 1.72-3.72; p<0.001) were associated; p= 0.0024 for interaction between ethnicity and the SNP. A common apoA1 SNP is associated with a significantly increased risk of recurrent cardiac events among Black, but not White, postmyocardial infarction patients. Relationships with lipoproteins may help explain this finding.

Genetic-epidemiological evidence on genes associated with HDL cholesterol levels: a systematic in-depth review

High-density lipoprotein (HDL) particles exhibit multiple antiatherogenic effects. They are key players in the reverse cholesterol transport which shuttles cholesterol from peripheral cells (e.g. macrophages) to the liver or other tissues. This complex process is thought to represent the basis for the antiatherogenic properties of HDL particles. The amount of cholesterol transported in HDL particles is measured as HDL cholesterol (HDLC) and is inversely correlated with the risk for coronary artery disease: an increase of 1mg/dL of HDLC levels is associated with a 2% and 3% decrease of the risk for coronary artery disease in men and women, respectively. Genetically determined conditions with high HDLC levels (e.g. familial hyperalphalipoproteinemia) often coexist with longevity, and higher HDLC levels were found among healthy elderly individuals. HDLC levels are under considerable genetic control with heritability estimates of up to 80%. The identification and characterization of genetic variants associated with HDLC concentrations can provide new insights into the background of longevity. This review provides an extended overview on the current genetic-epidemiological evidence from association studies on genes involved in HDLC metabolism. It provides a path through the jungle of association studies which are sometimes confusing due to the varying and sometimes erroneous names of genetic variants, positions and directions of associations. Furthermore, it reviews the recent findings from genome-wide association studies which have identified new genes influencing HDLC levels. The yet identified genes together explain only a small amount of less than 10% of the HDLC variance, which leaves an enormous room for further yet to be identified genetic variants. This might be accomplished by large population-based genome-wide meta-analyses and by deep-sequencing approaches on the identified genes. The resulting findings will probably result in a re-drawing and extension of the involved metabolic pathways of HDLC metabolism.

Association of apolipoprotein A1-C3 gene cluster polymorphisms with gallstone disease

INTRODUCTION

Genetic polymorphisms in apolipoprotein genes may be associated with alteration in lipid profile and susceptibility to gallstone disease.

AIM

To determine the association between apolipoprotein A1 (APOA1) -75 guanine [G] to adenine [A] and +83/84 M2(+/-), MspI) and apolipoprotein C3 (APOC3) (SstI) polymorphisms with gallstone disease.

METHODS

MspI polymorphisms of the APOA1 gene and SstI polymorphisms of APOC3 were analyzed in DNA samples of 214 gallstone patients and 322 age- and sex-matched healthy controls. All statistical analyses were performed using SPSS version 11.5 (SPSS, USA) and Arlequin version 2.0 (Arlequin, Switzerland).

RESULTS

The APOA1 -75 G/A polymorphism was significantly associated with gallstone disease. Patients with the GG genotype (P=0.015) and G allele carriers (P=0.004) had a significantly higher risk of gallstone disease (1.087-fold and 1.561-fold, respectively), whereas patients with AA genotypes (P=0.011) and A allele carriers (P=0.004) were protected (OR 0.230 and 0.641, respectively) against gallstone disease. APOA1 +83 M2(+/-) and APOC3 SstI polymorphisms were not associated with gallstone disease. Case-control analysis of haplotypes showed a significant association in males only. G-M2(+)-S1 conferred risk for gallstone disease (P=0.036; OR 1.593, 95% CI 1.029 to 2.464), while A-M2(+)-S1 was protective (P=0.002; OR 0.370, 95% CI 0.197 to 0.695) against gallstone disease. In APOA1(-75)-APOA1(+83) bilocus haplotypes, G-M2(+) was associated (P=0.0001) with very high risk (OR 3.173, 95% CI 1.774 to 5.674) for gallstone disease in males only. APOA1(-75)-APOC3(SstI) haplotypes also showed significant association while APOA1(+83)-APOC3(SstI) haplotypes showed no association with gallstone disease.

CONCLUSIONS

The APOA1 -75 G/A polymorphism is associated with gallstone disease and shows sex-specific differences. On the other hand, APOA1 M2(+/-) and APOC3 SstI polymorphisms may not be associated with gallstone disease. Haplotype analysis is a better predictor of risk for gallstone disease.

Genetic association study of APOA1/C3/A4/A5 gene cluster and haplotypes on triglyceride and HDL cholesterol in a community-based population

BACKGROUND

Polymorphism of apolipoprotein A1/C3/A4/A5 gene cluster affected lipid profiles in general population. We reported 6 polymorphisms, APOA1 -75G>A, APOA1 83C>T, APOC3 3175C>G, APOC3 3206G>T, APOA4 127A>G, and APOA5 553G>T in APOA1/C3/A4/A5 gene and the haplotype structures on triglyceride and HDL traits among ethnic Chinese.

RESULTS

Overall, there were statistically significant differences in the distribution of APOA1 -75G>A and APOA5 +553G>T genotypes comparing cases with control subjects. For the APOA1 -75 SNP, a lower risk of triglyceride/HDL among subjects with A/A genotype compared with those with the G/G genotype (odds ratio, OR=0.39, 95% CI 0.16-0.92, P=0.04). However, the risk magnitude reduced after multivariate adjustments. For continuous traits, we found that only in APOA5 +553 T allele carriers showed a significant higher triglyceride and a significant lower HDL cholesterol level than subjects with APOA5 +553 G/G genotypes. There were significant differences in overall haplotype frequencies between case and control subjects (P<0.001).

CONCLUSION

There is an important role of APOA1/C3/A4/A5 gene polymorphisms and haplotypes in the development of high triglyceride/HDL ratio in Chinese.

Proteomic identification of lower apolipoprotein A-I in Alzheimer's disease

Many researches have been trying to find the potential biomarkers for Alzheimer's disease (AD). We hereby used the proteomics method to search for protein expression differences in the serum between AD patients and controls. We enrolled 59 AD patients and 74 age- and sex-matched controls in this study. Ten AD patients and 10 controls were selected for proteomic analysis. Apolipoprotein A-I (ApoA-I) was found to have a lower expression in the AD group by a proteomics two-dimensional gel electrophoresis study. We further measured the serum ApoA-I level which was significantly lower in the AD patients (112.29 +/- 21.33 mg/dl) in comparison to the controls (144.53 +/- 19.91 mg/dl; p < 0.0002). Lower serum ApoA-I levels might be a potential biomarker for AD.

The contribution of individual and pairwise combinations of SNPs in the APOA1 and APOC3 genes to interindividual HDL-C variability

Apolipoproteins (apo) A-I and C-III are components of high-density lipoprotein-cholesterol (HDL-C), a quantitative trait negatively correlated with risk of cardiovascular disease (CVD). We analyzed the contribution of individual and pairwise combinations of single nucleotide polymorphisms (SNPs) in the APOA1/APOC3 genes to HDL-C variability to evaluate (1) consistency of published single-SNP studies with our single-SNP analyses; (2) consistency of single-SNP and two-SNP phenotype-genotype relationships across race-, gender-, and geographical location-dependent contexts; and (3) the contribution of single SNPs and pairs of SNPs to variability beyond that explained by plasma apo A-I concentration. We analyzed 45 SNPs in 3,831 young African-American (N=1,858) and European-American (N=1,973) females and males ascertained by the Coronary Artery Risk Development in Young Adults (CARDIA) study. We found three SNPs that significantly impact HDL-C variability in both the literature and the CARDIA sample. Single-SNP analyses identified only one of five significant HDL-C SNP genotype relationships in the CARDIA study that was consistent across all race-, gender-, and geographical location-dependent contexts. The other four were consistent across geographical locations for a particular race-gender context. The portion of total phenotypic variance explained by single-SNP genotypes and genotypes defined by pairs of SNPs was less than 3%, an amount that is miniscule compared to the contribution explained by variability in plasma apo A-I concentration. Our findings illustrate the impact of context-dependence on SNP selection for prediction of CVD risk factor variability.

Polymorphisms in APOA1 and LPL genes are statistically independently associated with fasting TG in men with CAD

The objective of this paper was to identify the single nucleotide polymorphisms (SNPs) that show unshared effects on plasma triglyceride (TG) levels and to investigate whether these SNPs show statistically independent effects on plasma TG levels. In total, 59 polymorphisms in 20 genes involved in lipid metabolism were investigated. Polymorphisms were selected for a multivariate ANOVA model if they showed an univariate association with TG (after adjustment for HDL-C and LDL-C) in more than 50% of bootstrap samples that were made from the original data. The multivariate model included 512 men with coronary artery disease from the REGRESS study who were completely genotyped for eight polymorphisms selected in the univariate procedure (ie, APOA1 G(-75)A, ABCA1 C(-477)T, ABCA1 G1051A, APOC3 T3206G, APOE Arg158Cys, LIPC C(-514)T, LPL Asn291Ser and LPL Ser447Stop). The gene variants APOA1 G(-75)A (P=0.04) and LPL Asn291Ser (P=0.03) were significantly associated with plasma TG levels in this multivariate analysis. The eight polymorphisms explained 8.9% of the variation in plasma TG levels. In conclusion, this study showed statistically independent effects of gene variants in the APOA1 and LPL genes on fasting plasma levels of TG. Nevertheless, only a small part of variation in TG levels could be explained by the polymorphisms.

Gender-specific effects of estrogen receptor α gene haplotype on high-density lipoprotein cholesterol response to atorvastatin: interaction with apolipoprotein AI gene polymorphism

Statins can modestly raise the levels of HDL cholesterol and apolipoprotein A-I (APOA1). Recently, associations between polymorphisms in the estrogen receptor alpha (ESR1) and the HDL cholesterol response to hormone replacement therapy were reported. To test the hypothesis that common polymorphisms in ESR1 and APOA1 genes are associated with the response to statin therapy, two ESR1 (PvuII and XbaI) and two APOA1 (G-75A and +83) polymorphisms were examined in 338 hypercholesterolemic patients treated with atorvastatin 10mg. The ESR1 PvuII-XbaI+ haplotype was significantly, and independently, associated with a greater response of HDL raising in women (+13% versus +7%, p=0.010) but not in men (+9% versus +7%, p=0.248). Effects of the APOA1+83 variant allele on HDL cholesterol response also differed significantly by gender (p=0.012). The APOA1+83 variant allele was associated with higher basal LDL cholesterol levels in men as well, but not in women. Finally, significant interactions were observed between the ESR1 PvuII-XbaI+ haplotype and the APOA1+83 variant allele regarding both HDL (p=0.042) and LDL (p=0.031) cholesterol responses. In conclusion, the ESR1 haplotype was associated with a greater HDL-raising to atorvastatin in a gender-specific manner, and the interactions between ESR1 and APOA1 genotypes regarding HDL and LDL cholesterol response were also gender specific.

APOA1 polymorphisms are associated with variations in serum triglyceride concentrations in hypercholesterolemic individuals

Background: Apolipoprotein A-I gene (

Methods:

Results: G–75A polymorphism was associated with differences in serum concentrations of triglyceride and very low-density lipoprotein (VLDL)-cholesterol (p=0.026) in HC men. After atorvastatin treatment, women carrying the

Conclusion: Our data suggest that

Genetic variation at the hormone sensitive lipase: gender-specific association with plasma lipid and glucose concentrations

Hormone-sensitive lipase (HSL) catalyzes the intracellular hydrolysis of triacylglycerols and cholesteryl esters, and it is involved in regulating body fat, steroidogenesis, and insulin secretion. Thus, genetic variability at the HSL locus (LIPE) may play a significant role on lipid metabolism and the risk of obesity and type 2 diabetes. Therefore, we have examined two LIPE single nucleotide polymorphism (SNP) [14672C>G in the promoter region and 17948C>T (rs1206034) on intron 2] in relation to plasma lipids, anthropometrical and glucose-related phenotypes in a population of mostly overweight and obese men (373) and women (361). In women, the 17948T allele was associated with decreased total cholesterol (TC, p = 0.001), LDL-cholesterol (LDLc, p < 0.001) and apoE concentrations (p = 0.041). Conversely, female carriers of the LIPE 14672G allele had significantly higher TC (p = 0.047), LDLc (p = 0.041), and apoE (p = 0.041) levels. Although we did not find significant associations in men, we observed that male carriers of the LIPE 14672G who did not drink alcohol showed higher glucose levels than non-carriers (p = 0.008), whereas there were no allele-related differences among drinkers (p = 0.019 for the interaction). These SNPs were not significantly associated with anthropometrical variables. In summary, variation at this locus showed gender-specific associations with lipids and glucose measures, and the latter was influenced by alcohol drinking.