Association of two apolipoprotein A-I gene MspI polymorphisms with lipid and blood pressure levels

Genetics of Cholesterol-Related Genes in Metabolic Syndrome: A Review of Current Evidence

Metabolic syndrome (MetS) refers to a cluster of metabolic dysregulations, which include insulin resistance, obesity, atherogenic dyslipidemia and hypertension. The complex pathogenesis of MetS encompasses the interplay between environmental and genetic factors. Environmental factors such as excessive nutrients and sedentary lifestyle are modifiable and could be improved by lifestyle modification. However, genetic susceptibility to MetS, a non-modifiable factor, has attracted the attention of researchers, which could act as the basis for future diagnosis, prognosis, and therapy for MetS. Several cholesterol-related genes associated with each characteristic of MetS have been identified, such as apolipoprotein, lipoprotein lipase (LPL), cholesteryl ester transfer protein (CETP) and adiponectin. This review aims to summarize the genetic information of cholesterol-related genes in MetS, which may potentially serve as biomarkers for early prevention and management of MetS.

Importance of Polymorphisms in the Gene of Paraoxonase-1 (SNP rs662) and Apolipoprotein A-I (SNP rs670 and rs5069) in Non-Smoking and Smoking Healthy Subjects and Patients with Acute Pancreatitis

Oxidative stress has been implicated in the initiation of acute pancreatitis (AP). HDL is considered to be a preventing factor against cell membrane oxidation, thanks to the presence on its surface of apolipoprotein A-I (apoA-I) and paraoxonase-1 (PON1), which activity can be modified by genetic and environmental factors. The impact of SNP rs662 in the PON1 gene and SNP rs670 and rs5069 in the APOAI gene on PON1 activities and its concentration in the population of AP patients and healthy volunteers was investigated. In the group of patients with AP, a decreased HDL concentration and PON1 activities were observed. A decrease in the aryloesterase and lactonase activities of PON1 in AP patients with the TT genotype for SNP rs662 (especially in smokers) was found. In the group of patients with the AA genotype (rs670), the highest concentrations of HDL and apoA-I were observed, which were gradually decreasing in the course of AP. Changes in the concentration of apoA-I were associated with the changes in the concentration and activities of PON1 in the AP patients with the AA genotype for SNP rs670. A decreasing apoA-I concentration contributing to lowering PON1 concentration and its activities during the hospitalization of AP patients with the CC genotype for SNP rs5069 were shown. Therefore, more susceptibility of persons with the CC genotype for SNP rs5069 to pro/antioxidative imbalance was shown. In this process, an important role was played by the HDL level and its interaction with PON1 and apoA-I.

Association of SNP rs5069 in APOA1 with Benign Breast Diseases in a Mexican Population

Breast cancer (BCa) is the most common type of cancer affecting women worldwide. Some histological subtypes of benign breast disease (BBD) are considered risk factors for developing BCa. Single nucleotide polymorphisms (SNPs) in the genes encoding apolipoproteins A-I (APOA1) and B (APOB) have been associated with BCa in Tunisian, Chinese, and Taiwanese populations. The objective of this pilot study is to evaluate the possible contribution of APOA1 and APOB polymorphisms to BCa and BBD in the Mexican population. We analyzed the association of 4 SNPs in genes encoding apolipoproteins: rs670 and rs5069 in the APOA1 gene, and rs693 and rs1042031 in the APOB gene, by performing PCR-RFLP with DNA extracted from the biopsy tissue of Mexican women with BCa or BBD and whole blood samples obtained from the general population (GP). Our results showed an association between the CT + TT genotypes of the SNP rs5069 and BBD (p = 0.03201). In the A-T haplotype, the frequency of the SNPs rs670 and rs5069 differed significantly between the BBD group and the GP and BCa groups (p = 0.004111; p = 0.01303). In conclusion, the SNP rs5069 is associated with BBD but not with BCa in the Mexican population.

Serum apolipoprotein A1 rather than apolipoprotein B is associated with hypertension prevalence in Chinese people with coronary artery disease

OBJECTIVE

Studies on the association of apolipoprotein A1 (ApoA1) and apolipoprotein B (ApoB) with hypertension (HTN) prevalence in patients with coronary artery disease (CAD) are limited. This cross-sectional study aimed to investigate this association in Chinese people in Wuhan, China.

METHODS

Serum ApoA1 and ApoB levels were measured by immunoturbidimetry assay. Logistic regression analysis was used to estimate the associations of ApoA1 and ApoB level and ApoB/A1 ratio with HTN prevalence.

RESULTS

We included 5192 individuals (3060 men, mean age 61 years; 4412 HTN cases) in this study. After adjusting for covariates, serum ApoA1 but not ApoB level or ApoB/A1 ratio was inversely associated with HTN prevalence. HTN prevalence was reduced with the fifth versus first quintile of ApoA1 level [odds ratio = 0.78 (95% confidence interval 0.62-0.98)]. In stratified analyses based on sex, the probability of HTN with the fifth versus first ApoA1 level was 0.71 (0.53-0.96) for men. The probability of HTN with the fifth versus first quintile of ApoB/A1 ratio was 1.54 (1.11-2.13) after adjustment. With quintiles 2-5 versus of ApoB level, the probability of HTN did not differ in both men and women. On path analyses, the association of ApoA1 level and ApoB/A1 ratio with HTN was mediated by BMI (β coefficients: -0.179 to 0.133).

CONCLUSION

In general, high serum ApoA1 level may be associated with a reduced probability of HTN prevalence in patients with CAD in China, and this association may be mediated by BMI.

Associations of serum apolipoprotein A1, B levels and their ratio with blood pressure in Chinese adults with coronary artery disease

OBJECTIVE

We examined the relationships of apolipoprotein A1 (ApoA1), ApoB levels and ApoB/A1 ratio with blood pressure (BP) in Chinese adults with coronary artery disease (CAD).

METHODS

This cross-sectional study included 4921 adults with CAD. SBP, DBP, serum ApoA1 and ApoB levels were measured. The associations between Apo and BP were assessed by analyses of covariance.

RESULTS

Serum ApoA1 was inversely associated with BP, whereas ApoB and the ApoB/A1 ratio exhibited positive associations with BP. For all subjects, a higher ApoA1 level was associated with lower SBP. Subjects in the fourth quartile for ApoA1 exhibited - 2.85 and - 2.63% lower DBP and mean arterial pressure (MAP), respectively than those in the third quartile. In contrast, higher ApoB and ApoB/A1 ratios were associated with higher SBP, DBP and MAP. The mean differences between ApoB quartiles 4 and 1 were 1.54% for SBP, 2.92% for DBP and 2.29% for MAP. The mean differences between the ApoB/A1 ratio quartiles 4 and 1 were 1.94% for SBP, 3.53% for DBP and 2.80% for MAP. In analyses stratified by gender, graded and inverse associations of ApoA1 with SBP, DBP and MAP were observed in both men and women, but positive associations were observed for ApoB and the ApoB/A1 ratio. Path analysis showed that BMI mediated the associations between ApoB and the ApoB/A1 ratio and SBP.

CONCLUSIONS

In general, serum ApoA1 was inversely associated with BP in persons with CAD. In contrast, serum ApoB and the ApoB/A1 ratio were positively associated with BP, and these associations were mediated by BMI.

Association of the Apolipoprotein A-I Gene Polymorphisms with Cardiovascular Disease Risk Factors and Atherogenic Indices in Patients from Assam, Northeast India

Cardiovascular disease (CVD) risk factors, and particularly decreased high density lipoprotein cholesterol (HDL-C) dyslipidemia are prevalent in Assam, India. This study was undertaken to investigate whether Apolipoprotein A-I (APOA1) gene polymorphisms (G-75A and C+83T) were associated with i) the risk for decreased HDL-C, and ii) other CVD risk factors, viz. serum lipids, atherogenic indices, obesity, and blood pressure (BP). A total of 649 subjects were screened, from which 200 eligible individuals, classified as case group with decreased HDL-C levels (100 subjects) and control group with normal HDL-C levels (100 subjects) were enrolled and genotyped using polymersase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing. Lipid fractions [HDL-C, total cholesterol (TC), low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), triglycerides (TG)] and atherogenic indices [Castelli's Risk Indices-I and -II (CRI-I and -II), non-HDL-C fraction, atherogenic index of plasma (AIP), atherogenic coefficient (AC)] were estimated. The G-75A and C+83T loci were not associated with decreased HDL-C risk. This was confirmed across different genetic models (dominant, recessive, additive and allelic). Association was also absent with BP and obesity. However, the G-75A locus was associated with LDL-C, whereas the C+83T locus was associated with TG and VLDL-C. Furthermore, these sites had effects on atherogenic indices. The rare A allele at the G-75A locus was associated with adverse CRI-I, CRI-II, non-HDL-C and AC values, while the major C allele at the C+83T locus was associated with adverse AIP values. Thus, the pro-atherogenic G-75A polymorphism and the anti-atherogenic C+83T polymorphism represent important genetic loci that modulate CVD risk factors in subjects from Assam.

Screening and identification of apolipoprotein A-I as a potential hepatoblastoma biomarker in children, excluding inflammatory factors

The aim of the present study was to identify a child hepatoblastoma serum biomarker that is unaffected by inflammatory factors, with the ultimate aim of finding an effective method for the early diagnosis of hepatoblastoma. The magnetic bead-based weak cation exchange chromatography technique was used to process serum harvested from 30 children with hepatoblastoma, 20 children with systemic inflammatory response syndrome (SIRS) and 20 healthy children. Proteins differentially expressed in SIRS were excluded from consideration as biomarkers for hepatoblastoma. Proteins differentially expressed in hepatoblastoma and healthy controls were screened using surface-enhanced laser desorption/ionization-time of flight-mass spectrometry (SELDI-TOF-MS). Target proteins were purified by SDS-PAGE, and matrix-assisted laser desorption/ionization (MALDI)-TOF-MS was used to determine their amino acid sequences. Protein matches were searched in the SwissProt database. Quantitative polymerase chain reaction (qPCR) and ELISA were employed to confirm the expression of target proteins. Following screening to exclude inflammatory factors, SELDI-TOF-MS revealed a protein with a mass-to-charge ratio of 9,348 Da that was expressed at significantly lower levels in the serum of children with hepatoblastoma compared with healthy controls (P<0.01). Sequence analysis identified this protein as apolipoprotein A-1 (Apo A-I). qPCR and ELISA confirmed that the expression of Apo A-I mRNA and protein were significantly lower in children with hepatoblastoma compared with healthy controls (P<0.05). These results indicate that Apo A-I is a non-inflammatory protein marker for hepatoblastoma with the potential for use in early diagnosis of hepatoblastoma. In addition, the present study demonstrates the feasibility of proteomic screening for the identification of proteins that can serve as markers for a specific tumor.

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.

Polymorphism in apoA1 Influences High-Density Lipoprotein Cholesterol Levels but Is Not a Major Risk Factor of Alzheimer's Disease

BACKGROUND

Apolipoprotein A1 (apoA1) is the major apolipoprotein constituent of the high-density lipoprotein (HDL) and is involved in reverse cholesterol transport. Variation in the apoA1 gene might influence the function of the protein and, thus, brain cholesterol metabolism, leading to an increased risk for Alzheimer's disease (AD).

AIM

In the current report, we investigated the role of the functional apoA1 polymorphism (-75 G/A) as a genetic risk factor for AD in a Tunisian population.

METHODS

173 AD patients and 150 healthy controls were studied.

RESULTS

No association was found between this genetic variation in apoA1 gene and the risk of AD. The presence of the (-75 G/A) A allele appeared, however, to be associated with lower levels of cerebrospinal fluid Aβ42 and HDL cholesterol levels in sera.

CONCLUSION

Our data support the observation that apoA1 polymorphism influences cholesterol metabolism and Aβ42 deposition in the brain.

Apolipoprotein A1 -75 G/A and +83 C/T polymorphisms: susceptibility and prognostic implications in breast cancer

Apolipoprotein A1 (ApoA1) is the major apoprotein constituent of high-density lipoprotein that can play important roles in tumor invasion and metastasis. In the current report, we evaluated the role of the functional ApoA1 polymorphisms (-75 G/A and +83 C/T) as genetic markers for breast cancer susceptibility and prognosis. We used the polymerase chain reaction and restriction enzyme digestion (RFLP-PCR) to characterize the variations of the ApoA1 gene in 295 unrelated Tunisian patients with breast carcinoma and 197 healthy control subjects. No association was found between the +83 C/T genetic variation in ApoA1 gene and the risk of breast cancer occurrence. The presence of the (+83) T allele appeared however to be associated with an increased risk of lymph node metastasis occurrence (OR = 2.94; P = 0.01). Furthermore, a positive association was found between ApoA1 -75 A allele carriers and breast cancer risk (OR = 1.57; P = 0.02). Regarding prognostic indicators, a significant association was found between ApoA1 (-75) A allele carriers and the premenopausal status of breast cancer patients (OR = 1.73; P = 0.03). Additionally, the presence of the -75 A allele was correlated with the oestrogen receptor status among premenopausal women (OR = 2.45; P = 0.02). This is the first report on the studies of ApoA1 single nucleotide polymorphisms (SNPs) in breast carcinomas. Our data suggest that these genetic variations of ApoA1 may represent a marker for the increased risk of breast cancer.