Impact of 3 Common ABCA1 Gene Polymorphisms on Optimal vs Non-Optimal Lipid Profile in Greek Young Nurses

ABCA1 Polymorphism R1587K in Chronic Hepatitis C Is Gender-Specific and Modulates Liver Disease Severity through Its Influence on Cholesterol Metabolism and Liver Function: A Preliminary Study

Chronic hepatitis C (CHC) progression is highly variable and can be influenced by lipid metabolism. The ATP-binding cassette transporter A1 (ABCA1) is involved in lipid metabolism and mediates cholesterol efflux from liver cells. ABCA1 gene polymorphism rs2230808 (R1587K) modulates lipid levels as it is located in an ABCA1 protein domain, which is essential for cholesterol efflux. We aimed to analyze the role of ABCA1 polymorphism R1587K (rs2230808) in modulating the biochemical parameters of lipid metabolism and liver function and its association with liver disease severity, according to gender. A total of 161 CHC patients were clinically, histologically, and biochemically evaluated. Genotyping was performed by melting-curve analysis and statistical analysis by SPSS 24.0. There were significant differences between ABCA1_rs2230808 genotypes and total cholesterol, γGT (γ-glutamyl-transpeptidase), and HCV-RNA. Gender differences: in females, ABCA1_rs2230808 (GG or GA) was associated with higher HCV-RNA serum levels; in males, ABCA1_rs2230808 (GG or GA) was associated with higher γGT, lower total cholesterol, increased risk for γGT ≥ 38 UI/L, and total cholesterol < 4.92 mmol/L. Only in the case of males were higher γGT and lower total cholesterol associated with severe fibrosis and steatosis. Total cholesterol < 4.92 mmol/L also associates with severe necroinflammation. We conclude that ABCA1_rs2230808 is gender-specific. ABCA1_rs2230808 Allele G was associated with different clinical and biochemical parameters, which are related to more severe liver disease.

Association between the ABCA1 (R219K) polymorphism and lipid profiles: a meta-analysis

Conflicting evidence was found about the relationship between lipid profiles and R219K polymorphism in adenosine triphosphate-binding cassette exporter A1 (ABCA1) gene. In this study, four meta-analyses were conducted to assess the effect of R219K on lipid levels, including high-density lipoprotein cholesterol (HDLC), low-density lipoprotein cholesterol, total cholesterol, and triglycerides (TG). A total of 125 samples of 87 studies (about 60,262 subjects) were included. The effect of each study was expressed using the standard mean difference (SMD) and 95% confidence interval (95% CI) and pooled by meta-analysis in the random-effects model. Subgroup and meta-regression analyses were conducted to explore potential heterogeneity sources. The overall pooled effect showed the following results. (1) The R219K was significantly associated with HDLC level (SMD = - 0.25 mmol/L, 95%CI - 0.32 to - 0.18, z = - 6.96, P < 0.01, recessive genetic model). People with different genotypes had significantly different HDLC levels under the recessive, codominant and dominant genetic models (all Ps < 0.01). (2) A weak and indeterminate relationship between R219K and TG level was observed (SMD = 0.18 mmol/L, 95%CI 0.06-0.30, z = 3.01, P < 0.01, recessive genetic model). These findings suggested that R219K was associated with HDLC and TG levels, which might implicate a promising clinical application for lipid-related disorders, though the influences of race, health status, BMI, and other heterogeneity sources should be considered when interpreting current findings. The protocol was registered at PROSPERO (registration number: CRD42021231178).

Phenotypic severity in a family with MEND syndrome is directly associated with the accumulation of potentially functional variants of cholesterol homeostasis genes

Background

Male EBP disorder with neurologic defects (MEND) syndrome is an X‐linked disease caused by hypomorphic mutations in the EBP (emopamil‐binding protein) gene. Modifier genes may explain the clinical variability among individuals who share a primary mutation.

Methods

We studied four males (Patient 1 to Patient 4) exhibiting a descending degree of phenotypic severity from a family with MEND syndrome. To identify candidate modifier genes that explain the phenotypic variability, variants of homeostasis cholesterol genes identified by whole‐exome sequencing (WES) were ranked according to the predicted magnitude of their effect through an in‐house scoring system.

Results

Twenty‐seven from 105 missense variants found in 45 genes of the four exomes were considered significant (−5 to −9 scores). We found a direct genotype–phenotype association based on the differential accumulation of potentially functional gene variants among males. Patient 1 exhibited 17 variants, both Patients 2 and 3 exhibited nine variants, and Patient 4 exhibited only five variants.

Conclusion

We conclude that APOA5 (rs3135506), ABCA1 (rs9282541), and APOB (rs679899 and rs12714225) are the most relevant candidate modifier genes in this family. Relative accumulation of the deficiencies associated with variants of these genes along with other lesser deficiencies in other genes appears to explain the variable expressivity in MEND syndrome.

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.

Association Study of the ATP - Binding Cassette Transporter A1 (ABCA1) Rs2230806 Genetic Variation with Lipid Profile and Coronary Artery Disease Risk in an Iranian Population

BACKGROUND:

ATP - binding cassette transporter A1 (ABCA1) plays essential roles in the biogenesis of high -density lipoprotein - cholesterol. Variations in the ABCA1 gene may influence the risk of coronary artery disease (CAD).

AIM:

Present study aimed to investigate the association of rs2230806 (R219K) polymorphism of ABCA1 gene with the development and severity of CAD in an Iranian population.

MATERIALS AND METHODS:

Our study population consisted of 100 patients with angiographically confirmed CAD and 100 controls. The genotyping of R219K mutation of ABCA1 gene was determined by PCR - RFLP method. Lipid profile was determined using routine colourimetric assays. Statistical analysis was done by SPSS - 16.

RESULTS:

The genotypic (P = 0.024) and allelic (P = 0.001) distribution of the ABCA1 R219K polymorphism were significantly different between the two groups. In a univariate analysis (with genotype RR as the reference), the RK genotype (OR = 0.46, 95%CI = 0.25-0.86, P = 0.020) and KK genotype (OR = 0.27, 95%CI = 0.11 – 0.66, P = 0.005) was significantly associated with a decreased risk of CAD. A multiple logistic regression analysis revealed that smoking (0.008), diabetes (P = 0.023), triglyceride (P = 0.001), HDL - cholesterol (P = 0.002) and ABCA1 KK genotype (P = 0.009) were significantly and independently associated with the risk of CAD. The association between different genotypes of R219K polymorphism with lipid profile was not significant in both groups (P > 0.05). The R219K polymorphism was significantly associated with severity of CAD (P < 0.05).

CONCLUSION:

The carriage of K allele of ABCA1 R219K polymorphism has a protective effect on CAD risk and correlates with a decreased severity of CAD. This protective effect seems to be mediated independently of plasma lipid levels.

Polysaccharide IV from Lycium barbarum L. Improves Lipid Profiles of Gestational Diabetes Mellitus of Pregnancy by Upregulating ABCA1 and Downregulating Sterol Regulatory Element-Binding Transcription 1 via miR-33

Lycium barbarum L. (LBL) has beneficial effects on gestational diabetes mellitus (GDM) but the related mechanism remains unclear. Polysaccharides of LBL (LBLP) are the main bioactive components of LBL. miR-33, ATP-binding cassette transporter A1 (ABCA1) and sterol regulatory element-binding transcription 1 (SREBF1) affect lipid profiles, which are associated with GDM risk. LBLP may exert protective against GDM by affecting these molecules. Four LBLP fractions: LBLP-I, LBLP-II, LBLP-III, and LBLP-IV were isolated from LBL and further purified by using DEAE-Sephadex column. The effects of purified each fraction on pancreatic beta cells were comparatively evaluated. A total of 158 GDM patients were recruited and randomly divided into LBL group (LG) and placebo group (CG). miR-33 levels, lipid profiles, insulin resistance and secretory functions were measured. The association between serum miR-33 levels and lipid profiles were evaluated by using Spearman's rank-order correlation test. After 4-week therapy, LBL reduced miR-33 level, insulin resistance and increased insulin secretion of GDM patients. LBL increased the levels of ABCA1, high-density lipoprotein cholesterol (HDL-C) and reduced miR-33, SREBF1, low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), triglyceride (TG), and malondialdehyde. Homeostatic model assessment of β-cell function and insulin resistance was lower in LG than in CG, whereas homeostatic model assessment of β-cell function and insulin secretory function was higher in LG than in CG. There was a strong positive association between miR-33 level and TG, or TC and or LDL-C, and a strong negative association between miR-33 level and HDL-C. The levels of miR-33 had negative relation with ABCA1 and positive relation with SREBF1. ABCA1 has negative relation with TG, TC, and LDL-C and positive relation with HDL-C. Inversely, SREBF1 had positive relation with TG, TC, and LDL-C and negative relation with HDL-C. The main bioactive compound LBLP-IV of LBL increased insulin secretion of beta cells and the levels of ABCA1, and reduced miR-33 levels and SREBF1 in beta cells. However, LBLP-IV could not change the levels of these molecules anymore when miR-33 was overexpressed or silenced. LBLP-IV had the similar effects with LBL on beta cells while other components had no such effects. Thus, LBLP-IV from LBL improves lipid profiles by upregulating ABCA1 and downregulating SREBF1 via miR-33.

Associations of the ABCA1 and LPL Gene Polymorphisms With Lipid Levels in a Hyperlipidemic Population

We conducted a cross-sectional study to investigate the effects of the adenosine triphosphate-binding cassette transporter 1 (ABCA1) I883M and lipoprotein lipase (LPL) HindIII polymorphisms on lipid levels in patients with hyperlipidemia. A total of 533 patients were enrolled. Serum lipid parameters were determined by an automatic biochemistry analyzer. Genotyping of the ABCA1 I883M and LPL HindIII was carried out using the polymerase chain reaction-restriction fragment length polymorphism technique. Multiple linear regression analysis was used to estimate the associations between serum lipid levels and the genetic polymorphisms. The frequency distribution of the ABCA1 I883M and LPL HindIII polymorphisms did not deviate from Hardy-Weinberg equilibrium. The major finding of our regression analysis showed that neither the ABCA1 I883M nor the LPL HindIII polymorphism was associated with baseline serum lipid levels in the total population. However, among patients with elevated alanine aminotransferase (ALT) levels (ALT ≥ 40 U/L), carriers of the M allele of the ABCA1 gene had lower levels of high-density lipoprotein cholesterol (HDL-C) and higher levels of low-density lipoprotein cholesterol (LDL-C) after adjusting for age, sex, smoking status, alcohol consumption, education level, occupation, and work intensity ( P < .05 for both). A test on interaction terms between the ABCA1 I833M polymorphism and ALT on HDL-C and LDL-C levels also remained significant ( P = .001 and P = .014, respectively). Our data suggest that there are significant interactive effects between ABCA1 I883M and ALT levels on HDL-C and LDL-C levels. However, the LPL HindIII polymorphism did not influence lipid levels.

Effect of ATP-binding Cassette Transporter A1 (ABCA1) Gene Polymorphisms on Plasma Lipid Variables and Common Demographic Parameters in Greek Nurses

Objective:

The present study is on line with our previous studies evaluating the influence of ATP-binding cassette transporter A1 (ABCA1) gene polymorphisms on the lipid variables of Greek student-nurses. The current study was undertaken to (1) estimate the influence of variant(s) such as rs2066715 (V825I), R219K, R1587K, I883M of ABCA1 gene on lipid variables and (2) evaluate the effect of all four ABCA1 polymorphisms on common demographic parameters.

Methods:

The study population involved 432 unrelated nurses (86 men) who were genotyped for ABCA1 polymorphisms and correlated according to lipid variables [total cholesterol (TC), triglycerides (TGs), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C) and apolipoprotein (apo) A] and demographic parameters (age, gender, BMI, waist circumference).

Results:

According to lipid variables concentration there was no difference between genotypes and alleles of V825I, R219K and I883M polymorphisms. The LDL-C concentration was 13% lower in RR compared with RK genotype (100.7 vs. 113.9 mg/dl, p=0.013) of R1587K gene polymorphism. In regression analysis the effects of age, gender and only R1587K gene polymorphism on LDL-C concentrations were proved significant. Additionally, LDL-C was increased (by 1.29 mg/dl on average) by every year of increase of age. Moreover, females had lower LDL-C concentrations as compared with males.

Conclusion:

Findings suggested that only R1587K polymorphism of ABCA1 gene was associated with lipid variables, age, and gender of Greek nurses. These findings may be helpful in assessing the risk factors for premature coronary heart disease and distinct individuals with lower/higher atherosclerotic burden.

Functional and Structural Impact of ATP-Binding Cassette Transporter A1 R219K and I883M Gene Polymorphisms in Obese Children and Adolescents

INTRODUCTION

Obesity is a serious medical condition that affects children and adolescents. ATP-binding cassette transporter A1 (ABCA1) protein is known to mediate the transport of intracellular cholesterol and phospholipids across the cell membranes. Thus, we aimed to investigate the association between ABCA1 gene polymorphisms and overweight/obesity risk, and to evaluate their relation to the lipid profile.

MATERIALS AND METHODS

The study included in silico analysis of ABCA1 gene and protein. Two genetic variants in ABCA1 gene-R219K (rs2230806; G/A) and I883M (rs2066714; A/G)-were genotyped in 128 normal weight and 128 overweight/obese subjects using polymerase chain reaction-restriction fragment length polymorphism technology. Anthropometric and biochemical assessments were performed.

RESULTS

Our findings suggest that the heterozygote GA genotype of R219K polymorphism increased susceptibility to obesity under the heterozygous model (odds ratio 2.75, 95 % CI 1.01-6.12; p = 0.014) compared with the control group. This susceptibility could be gender-specific, with higher risk among females. In addition, the A variant was associated with a higher degree of obesity (p < 0.001). On the other hand, individuals with the G variant of I883M polymorphism showed lower susceptibility to obesity under all genetic models (allelic, homozygote, heterozygote, dominant, and recessive models; p < 0.05), with no observed association with body mass index or degree of obesity. However, both single nucleotide polymorphisms (SNPs) showed significant differences in lipid levels among patients with different genotypes.

CONCLUSIONS

The study results suggest that R219K and I883M SNPs of the ABCA1 gene may play a role in susceptibility to obesity in our Egyptian population; the former increases susceptibility and phenotype severity, and the latter is protective. Larger epidemiological studies are needed for validation of the results.

The impact of common polymorphisms in CETP and ABCA1 genes with the risk of coronary artery disease in Saudi Arabians

Background

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Many genetic and environmental risk factors including atherogenic dyslipidemia contribute towards the development of CAD. Functionally relevant mutations in the dyslipidemia-related genes and enzymes involved in the reverse cholesterol transport system are associated with CAD and contribute to increased susceptibility of myocardial infarction (MI).

Method

Blood samples from 990 angiographically confirmed Saudi CAD patients with at least one event of myocardial infarction were collected between 2012 and 2014. A total of 618 Saudi controls with no history or family history of CAD participated in the study. Four polymorphisms, rs2230806, rs2066715 (ABCA1), rs5882, and rs708272 (CETP), were genotyped using TaqMan Assay.

Results

CETP rs5882 (OR = 1.45, P < 0.005) and ABCA1 rs2230806 (OR = 1.42, P = 0.017) polymorphisms were associated with increased risk of CAD. However, rs708272 polymorphism showed protective effect (B1 vs. B2: OR = 0.80, P = 0.003 and B2B2 vs. B1B1: OR = 0.68, P = 0.012) while the ABCA1 variant rs2066715 was not associated.

Conclusion

This study is the first to report the association of these polymorphisms with CAD in the population of the Eastern Province of Saudi Arabia. The rs5882 polymorphism (CETP) showed a significant association and therefore could be a promising marker for CAD risk estimation while the rs708272 polymorphism had a protective effect from CAD.