Effect of Two Common Polymorphisms in the ATP Binding Cassette Transporter A1 Gene on HDL-Cholesterol Concentration

A Common R219K Variant of ATP-Binding Cassette Transporter A1 Gene Alters Atherometabolic Traits in Pregnant Women With Gestational Diabetes Mellitus

BACKGROUND

ATP-binding cassette transporter A1 (ABCA1) has important roles in high-density lipoprotein (HDL) metabolism and reverse cholesterol transport, and is implicated in lipid-related disorders. Genetic variants are involved in the pathogenesis of gestational diabetes mellitus (GDM). The objective of this study was to investigate the association of rs2230806 (R219K), a single nucleotide polymorphism (SNP) in the lipid-related gene, with the risk of GDM and related traits.

METHODS

The SNP, rs2230806, was genotyped, and clinical and metabolic parameters were determined in 660 GDM patients and 1,097 control subjects. Genetic associations with related traits were also analyzed.

RESULTS

The genotype distributions were similar in GDM patients and normal controls. However, significant differences in the variables examined in the study subjects were noted across the three genotypes. The genotype at the rs2230806 polymorphism was significantly associated with HDL-cholesterol (HDL-C) levels and atherogenic index (AI) values in GDM patients and total cholesterol (TC) and low-density lipoprotein-cholesterol (LDL-C) levels in control subjects. Subgroup analysis showed that the polymorphism was associated with diastolic blood pressure, in addition to HDL-C levels and AI, in overweight/obese GDM patients, while it was associated with TC levels, AI, pre-pregnancy body mass index (BMI), and BMI at delivery in non-obese GDM patients. In addition, this polymorphism was associated with TC, LDL-C, and apoB levels in overweight/obese control subjects.

CONCLUSIONS

The rs2230806 polymorphism in the ABCA1 gene was associated with variations in atherometabolic traits in GDM patients, with characteristics of BMI dependency, but not with GDM. Our findings highlight a link between related phenotypes in women with GDM and genetic factors.

Association of rs2230806 in ABCA1 with coronary artery disease: An updated meta-analysis based on 43 research studies

BACKGROUND

As a key gene in the reverse transport pathway of cholesterol, ABCA1 (ATP-binding cassette transporter A1) plays an important role in the pathogenesis of coronary artery disease (CAD). In the ABCA1, rs2230806 is the most widely studied polymorphism and its role has been controversial.

METHODS

We performed an updated meta-analysis by searching online electronic databases using the PubMed, Web of Science, Embase, Cochrane Library, EMBASE, Google Scholar, China National Knowledge Infrastructure, and Wan Fang databases before June 28, 2019. STATA12.0 software was used to perform a series of analyses on the data, including genetic effect model, heterogeneity, sensitivity, and publication bias analysis.

RESULTS

Based on our inclusion and exclusion criteria, finally 43 articles including a total of 34,348 subjects (14,085 CAD cases and 20,263 healthy controls) were investigated. Results showed that carrying the K allele in rs223086 in the overall population significantly reduced the risk of CAD (OR = 0.745, 95% CI = 0.687-0.809, P < .001). After the ethnicity stratification analysis, the above phenomenon was found to be significant in Asian populations (OR = 0.686, 95% CI = 0.633-0.744, P < .001), marginally significant in Caucasians (OR = 0.887, 95% CI = 0.786-1.001, P = .051), and not significant in other populations (OR = 0.851, 95% CI = 0.558-1.297, P = .452). Further stratified according to the sample size in the Asian and Caucasian populations, in the Asian the K allele is more protective in small samples than large samples; however, in the Caucasian small samples carrying the K allele play a protective role while large samples are negative. In addition, according to the source of the control population and the geographical location in China, the results showed that rs2230806 was significantly associated with CAD in any group. Five genetic models (allelic, recessive, dominant, homozygote, and heterozygote) were analyzed in the above analysis.

CONCLUSION

The K allele of rs2230806 was significantly associated with decreased risk of CAD, especially in Asian populations and small sample Caucasians.

Associations of the ABCA1 gene polymorphisms with plasma lipid levels: A meta-analysis

BACKGROUND

Studies on the associations of the adenosine triphosphate-binding cassette transporter A1 gene (ABCA1) rs2230806, rs2230808, and rs2066714 polymorphisms with plasma lipid levels have reported apparently conflicting findings. This meta-analysis aimed to clarify the relationships between the 3 polymorphisms and fasting lipid levels.

METHODS

A comprehensive search of the literature was carried out by using the databases including Medline, Google Scholar, Web of Science, Embase, Cochrane Library, CNKI, Wanfang, and VIP. The studies that presented mean lipids and standard deviations or standard errors according to the rs2230806, rs2230808, and/or rs2066714 genotypes were examined and included. The random effects model was used. Standardized mean difference and 95% confidence interval were used to assess the differences in lipid levels between the genotypes. Heterogeneity among studies was tested by Cochran's χ-based Q-statistic, and Galbraith plots were used to detect the potential sources of heterogeneity. Publication bias was assessed by Begg's rank correlation test as well as funnel plots.

RESULTS

Sixty-two studies (48,452 subjects), 12 studies (9853 subjects) and 14 studies (10,727 subjects) were identified for the rs2230806, rs2230808, and rs2066714 polymorphisms, respectively. A dominant model was used for all the polymorphisms in this meta-analysis. The A allele carriers of the rs2230806 polymorphism had higher levels of high-density lipoprotein cholesterol (HDL-C) (P <.001), and lower levels of low-density lipoprotein cholesterol (LDL-C) (P =.03) and triglycerides (TG) (P <.01) than the non-carriers. The A allele carriers of the rs2230808 polymorphism had higher levels of total cholesterol (TC) (P <.001) than the non-carriers. The G allele carriers of the rs2066714 polymorphism had higher levels of TC (P <.01) and HDL-C (P = .02) than the non-carriers.

CONCLUSION

The ABCA1 rs2230806, rs2230808, and rs2066714 polymorphisms are significantly associated with plasma lipid levels in the present meta-analysis.

The C-565T Polymorphism (rs2422493) of the ATP-binding Cassette Transporter A1 Gene Contributes to the Development and Severity of Coronary Artery Disease in an Iranian Population

Objectives

ATP-binding cassette transporter A1 (ABCA1) plays a pivotal role in reverse cholesterol transport from peripheral tissues back to the liver. Abnormalities in ABCA1 function may lead to dyslipidemia and coronary artery disease (CAD). We investigated the role of C-565T (rs2422493) promoter polymorphism of ABCA1 gene in the development and severity of CAD in an Iranian subpopulation.

Methods

Our study population consisted of 110 angiographically-confirmed CAD patients and 110 matched controls. The severity of CAD was expressed based on the number of stenotic vessels. Genotyping of C-565T promoter polymorphism was performed using the polymerase chain reaction followed by restriction fragments length polymorphism analysis methods. Lipid profile was determined by routine colorimetric methods.

Results

The distribution of ABCA1 C-565T genotypes (p = 0.035) and alleles (p = 0.017) was significantly different between the CAD and control groups. In univariate analysis (with genotype CC as reference), the TT genotype was significantly associated with an increased risk of CAD (odds ratio = 3.83; 95% confidence interval: 1.29-11.30, p = 0.014), but the CT genotype was not (p = 0.321). A multiple binary logistic regression analysis revealed that smoking, hypertension, triglyceride, cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and ABCA1 C-565T dominant genotype were significant and independent risk factors for CAD development (p < 0.050). The ABCA1 C-565T polymorphism affected the severity of CAD in TT homozygote state (p = 0.028). However, no significant correlation was seen between this common polymorphism and lipid profile in the study population (p > 0.050). Conclusions: Our study indicated that ABCA1 C-565T polymorphism is a significant risk factor for development and severity of CAD in our population.

Influence of ATP-binding cassette transporter 1 R219K and M883I polymorphisms on development of atherosclerosis: a meta-analysis of 58 studies

Background

Numerous epidemiological studies have evaluated the associations between ATP-binding cassette transporter 1 (ABCA1) R219K (rs2230806) and M883I (rs4149313) polymorphisms and atherosclerosis (AS), but results remain controversial. The purpose of the present study is to investigate whether these two polymorphisms facilitate the susceptibility to AS using a meta-analysis.

Methods

PubMed, Embase, Web of Science, Medline, Cochrane database, Clinicaltrials.gov, Current Controlled Trials, Chinese Clinical Trial Registry, CBMdisc, CNKI, Google Scholar and Baidu Library were searched to get the genetic association studies. All statistical analyses were done with Stata 11.0.

Results

Forty-seven articles involving 58 studies were included in the final meta-analysis. For the ABCA1 R219K polymorphism, 42 studies involving 12,551 AS cases and 19,548 controls were combined showing significant association between this variant and AS risk (for K allele vs. R allele: OR = 0.77, 95% CI = 0.71–0.84, P<0.01; for K/K vs. R/R: OR = 0.60, 95% CI = 0.51–0.71, P<0.01; for K/K vs. R/K+R/R: OR = 0.69, 95% CI = 0.60–0.80, P<0.01; for K/K+R/K vs. R/R: OR = 0.74, 95% CI = 0.66–0.83, P<0.01). For the ABCA1 M883I polymorphism, 16 studies involving 4,224 AS cases and 3,462 controls were combined. There was also significant association between the variant and AS risk (for I allele vs. M allele: OR = 0.85, 95% CI = 0.77–0.95, P<0.01).

Conclusions

The present meta-analysis suggested that the ABCA1 R219K and M883I polymorphisms were associated with the susceptibility to AS. However, due to the high heterogeneity in the meta-analysis, the results should be interpreted with caution.

Genetic variation of the ATP-binding cassette transporter A1 and susceptibility to coronary heart disease

ATP-binding cassette transporter A1 (ABCA1) is a member of a superfamily of membrane proteins that has attracted considerable attention as a candidate gene for coronary heart disease (CHD) based on its enzyme function as a key factor in regulating plasma HDL-C and apo A-I metabolism. It has been suggested that polymorphisms in the ABCA1 gene are risk factors for CHD, but a large number of studies have reported apparently conflicting results. To investigate this inconsistency and derive a more precise estimation of the relationship, a meta-analysis of 14,040 cases and 28,607 controls from 31 published case-control studies was performed. Five potential sources of heterogeneity including ethnicity, source of control, sample size, HWE status and genotyping method of study were also assessed. Overall, significantly decreased CHD risk was associated with 219K allele of R219K polymorphism when all studies were pooled into the meta-analysis. In the subgroup analysis by ethnicity, significantly decreased risks were found in Asians and other ethnic population for the polymorphism in all genetic models; while no significant associations were found among Caucasians. When stratified by source of controls, both population and hospital based studies get consistent positive results. However, no significant results were observed for I883M polymorphism of ABCA1 in all genetic models. In conclusion, this meta-analysis suggests that K allele of ABCA1 R219K polymorphism is a protective factor associated with decreased CHD susceptibility, but these associations vary in different ethnic populations.

Effect of fenofibrate therapy and ABCA1 polymorphisms on high-density lipoprotein subclasses in the Genetics of Lipid Lowering Drugs and Diet Network

BACKGROUND

Previous studies have shown that ATP-binding cassette transporter 1 (ABCA1) polymorphisms associated with increased ABCA1 expression result in increased small HDL (high-density lipoprotein) subclass particle concentration. This study examines the effect of treatment with fenofibrate, a drug known to bind peroxisome proliferator-activated receptor alpha (PPARalpha) which increases the expression of ABCA1 gene, on lipoprotein subclass profiles of individuals stratified by ABCA1 genotypes.

METHODS

Participants of Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) were treated with fenofibrate over a three week period. We analyzed six ABCA1 polymorphisms in 287 GOLDN participants with triglyceride concentrations >or=150mg/dL and studied their associations with HDL subclass particle concentrations, as measured by nuclear magnetic resonance spectroscopy, before and after treatment.

RESULTS

Fenofibrate treatment did not result in significant changes in small HDL subclass particle concentration. When changes in HDL subclasses were stratified by ABCA1 polymorphism genotypes, there were no statistically significant associations between ABCA1 genotypes and small HDL subclasses before fenofibrate treatment. However, after fenofibrate treatment the KK genotype of R1587K (mean 4.40micromol/L; p=0.004) and the RK genotype of R219K (mean 1.60micromol/L; p=0.02) polymorphisms were associated with significantly increased small HDL. The R1587KKK genotype (mean 4.80micromol/L; p=0.0002) and the R219K KK genotype (mean 2.50micromol/L; p=0.02) were also associated with increased HDL particle concentrations.

CONCLUSION

There is a synergistic effect between ABCA1 polymorphisms and fenofibrate. Thus, our study indirectly confirms the role of fenofibrate and genotype in increasing cholesterol efflux, as evidenced by increased small HDL particles.

Associations of genetic variants in ATP-binding cassette A1 and cholesteryl ester transfer protein and differences in lipoprotein subclasses in the multi-ethnic study of atherosclerosis

BACKGROUND

ATP-binding cassette A1 (ABCA1) and cholesteryl ester transfer protein (CETP) play important roles in the reverse cholesterol transport pathway. The associations of ABCA1 and CETP polymorphisms with lipoprotein subclasses have not been extensively studied.

METHODS

We genotyped 2 ABCA1 and 5 CETP polymorphisms in 999 participants of the Multi-Ethnic Study of Atherosclerosis (MESA) and studied their associations with HDL and LDL subclass particle concentrations, measured by nuclear magnetic resonance spectroscopy.

RESULTS

ABCA1 and CETP polymorphisms were associated with different and distinct changes in lipoprotein subclass concentrations. The ABCA1 1051G/A AA genotype, previously found to be associated with cardioprotective effects in this cohort, was associated with a 5.5% higher concentration of small HDL particles (P = 0.024). The CETP TaqIB B2B2, -2505C/A AA, and -629C/A AA genotypes, previously demonstrated to lack cardioprotective effects, were associated with 15.2%, 15.4%, and 11.7% higher HDL cholesterol concentrations, respectively, and 36.5%, 40.7%, and 25.4% higher large HDL particle concentrations (P < 0.0001). The minor alleles of the A373P and R451Q polymorphisms were associated with lower large HDL particle concentrations.

CONCLUSIONS

Our study of the influence of ABCA1 and CETP genetic variants on lipoprotein subclasses demonstrates the importance of interpreting lipoprotein subclasses within the context of the biochemical processes involved in the alterations. In the case of HDL, the study of subclass particle numbers and sizes may not be sufficiently informative. Assays for HDL function may be needed to supplement quantification of HDL cholesterol and HDL particle numbers and sizes.

R219K polymorphism of ATP binding cassette transporter A1 related with low HDL in overweight/obese Thai males

BACKGROUND

ATP binding cassette transporter A1 (ABCA1) plays a role in the initial stage of removing cholesterol from the body via cholesterol efflux. Mutations of this gene cause wide-ranging HDL deficiency, as evident in Tangier disease and familial hypoalphalipoproteinemia. The aim of this study was to elucidate whether the presence of ABCA1 gene polymorphism could be a risk factor for overweight/obesity.

METHODS

The presence of R219K and I883M genetic variant was determined by PCR-RFLP analysis in 112 overweight/obese and 117 control subjects of both sexes. Statistical analysis was performed to find an association between polymorphism and lipid data.

RESULTS

Overweight/obese men carrying the mutant allele of R219K had lower level of HDL than the control (p = 0.006). However, no positive association was observed using bivariate logistic regression analysis. On the contrary, there was no difference in HDL level among genotypes in I883M polymorphism. Both polymorphisms appeared to be common in Thai ethnic groups. No difference was detected in genotype frequency between the two populations for both polymorphisms.

CONCLUSIONS

Although the lower level of HDL in overweight/obese men carrying R219K in comparison to the control suggests the possible involvement of this gene with obesity, further investigations are needed to prove the influence of ABCA1 gene polymorphism on HDL level and to determine whether it could be a genetic determinant of obesity.

Genetic determinants of HDL: monogenic disorders and contributions to variation

PURPOSE OF REVIEW

This review focuses on recent progress towards the characterization of genetic variations that contribute to interindividual variation in plasma high-density lipoprotein cholesterol levels in the general population.

RECENT FINDINGS

Many of the genes that harbor rare mutations leading to extreme high-density lipoprotein cholesterol levels contain common variation that influences plasma high-density lipoprotein cholesterol in several study populations. Candidate gene association studies provide evidence that some of these variations have an effect on high-density lipoprotein cholesterol, dependent on epistatic interactions or environmental context. Both rare and common variations contribute to interindividual high-density lipoprotein cholesterol variation. Recent comparisons of candidate gene sequences between individuals in the tails of the high-density lipoprotein cholesterol distributions (the upper or lower 1-5%) of several study populations indicate that as many as 20% of individuals with low high-density lipoprotein cholesterol harbor a rare mutation in an investigated gene. For example, the ABCA1 gene region harbors rare mutations and common variants that contribute to interindividual high-density lipoprotein cholesterol variation in the general population.

SUMMARY

The genetic control of high-density lipoprotein cholesterol level is complex. Maximizing the utility of genetic knowledge for predicting an individual's high-density lipoprotein cholesterol level or response to intervention will require a better understanding of the action of combinations of genetic variants and environmental exposures.

ABCA1 polymorphisms and Alzheimer's disease

In our search for genetic factors related to the development of Alzheimer's disease, we have genotyped 332 pedigrees for three coding polymorphisms in the ABCA1 gene, two of which are known to alter plasma cholesterol levels, as well as a non-coding polymorphism within the promoter. We show an apparent weak association of rs2230806 (p-value=0.01) with the disease in a sibpair series of Alzheimer's disease that had shown previously evidence for linkage to the chromosome 9 locus where ABCA1 maps.

Enhanced bioavailability of zeaxanthin in a milk-based formulation of wolfberry (Gou Qi Zi; Fructus barbarum L.)

The carotenoid zeaxanthin is concentrated within the macula. Increased macular zeaxanthin is suggested to lower the risk of age-related macular degeneration. The small red berry, wolfberry (Fructus barbarum L.; Gou Qi Zi and Kei Tze), is one of the richest natural sources of zeaxanthin. However, carotenoid bioavailability is low, and food-based products with enhanced bioavailability are of interest. The present study investigated zeaxanthin bioavailability from three wolfberry formulations. Berries were homogenised in hot (80 degrees C) water, warm (40 degrees C) skimmed milk and hot (80 degrees C) skimmed milk, with freeze drying of each preparation into a powdered form. A zeaxanthin-standardised dose (15 mg) of each was consumed, in randomised order, together with a standardised breakfast by twelve healthy, consenting subjects in a cross-over trial, with a 3-5-week washout period between treatments. Blood samples were taken via a venous cannula immediately before (fasting) and 2, 4, 6, 7, 8 and 10 h post-ingestion. Zeaxanthin concentration in the triacylglycerol-rich lipoprotein fraction of plasma was measured by HPLC. Results showed that triacylglycerol-rich lipoprotein zeaxanthin peaked at 6 h post-ingestion for all formulations. Zeaxanthin bioavailability from the hot milk formulation was significantly higher (P < 0.001) than from the others. Mean area under the curve (n 12) results were 9.73 (sem 2.45), 3.24 (sem 0.72) and 3.14 (sem 1.09) nmol x h/l for the hot milk, warm milk and hot water formulations, respectively. Results showed clearly that homogenisation of wolfberry in hot skimmed milk results in a formulation that has a 3-fold enhanced bioavailability of zeaxanthin compared with both the 'classical' hot water and warm skimmed milk treatment of the berries.

Associations between two common polymorphisms in the ABCA1 gene and subclinical atherosclerosis: Multi-Ethnic Study of Atherosclerosis (MESA)

OBJECTIVE

ABCA1 controls the first step in reverse cholesterol transport. The potential associations between G1051A (R219K) and -565C/T genetic polymorphisms in the ABCA1 gene, high-density lipoprotein cholesterol (HDL-C) and subclinical cardiovascular disease in the general population remains unclear. We examined these associations in a sample of Multi-Ethnic Study of Atherosclerosis (MESA) participants.

METHODS

Nine hundred and sixty-nine MESA participants were genotyped and underwent CT examinations for coronary artery calcification (CAC) and carotid ultrasound examinations for intima media thickness. Genetic association analyses were performed.

RESULTS

The AA genotype was associated with a 2.4mg/dl higher HDL-C, adjusting for age, gender, race/ethnicity and clinic site (p=0.04). There was a 28% lower prevalence of CAC (p=0.002) in those with AA genotype that persisted after further adjustment for HDL-C. There were no significant associations between -565C/T genotype and HDL-C. There were trends towards a higher prevalence of CAC in those with CT (PR=1.13, p=0.08) and TT (PR=1.16, p=0.08) genotypes, compared with CC genotype. Neither G1051A nor -565C/T polymorphisms were associated with carotid intima media thickness.

CONCLUSION

The AA genotype of the G1051A polymorphism is associated with slightly higher HDL-C and lower prevalence of CAC and thus may protect against subclinical cardiovascular disease. The T allele of -565 C/T polymorphism may increase risk for subclinical cardiovascular disease.