Association of apolipoprotein B XbaI gene polymorphism and lipid profile in northern Indian obese

The APOB rs693 polymorphism impacts the lipid profile of Brazilian older adults

The apolipoprotein B (APOB) gene contains several polymorphic sites described as risk modifiers for cardiovascular events. The objective of this study was to verify the association of the classic APOB Xba I polymorphism (rs693) with atherosclerotic risk factors in a segment of the Brazilian elderly population considering their usual dietary intake. Clinical and biochemical characteristics as well as total caloric and fat intake data were determined from 644 elderly individuals. Polymorphism analysis was performed by conventional polymerase chain reaction followed by enzyme restriction. Statistical analyses compared measures and proportions according to different APOB genotypic combinations. Statistically significant association was found between Xba I polymorphism and serum LDL, total cholesterol, and total lipid levels, with important elevations among T homozygotes compared to the other genotypes. There was homogeneity in all other parameters analyzed (including intake pattern), with a tendency for reduced levels of circulating apolipoprotein B among TT individuals. Our results pointed out that genetic variation in APOB affected the lipemic profile of elderly individuals in a context not biased by diet, generating a pattern suggestive of secretory disorder of lipoprotein particles, with possible implication in atherosclerotic risk.

Distribution of polymorphism rs693 of ApoB gene in a sample of Colombian Caribbeans

INTRODUCTION

Several studies have reported that the single nucleotide polymorphism rs693 of Apo lipoprotein B gene is associated with high levels of plasma lipids and high body mass index, which are risk factors for cardiovascular diseases. The distribution of this single nucleotide polymorphism and its association with the phenotype depend on the genetic background of each population.

OBJECTIVE

To evaluate the distribution of single nucleotide polymorphism rs693 and its association with lipid profile and body mass index in a sample of Colombian Caribbeans.

METHODS

108 non-related adult subjects of both gender were included in this study. Body mass index and lipid profile that included total cholesterol, triglycerides, Low Density Lipoprotein and High Density Lipoprotein were determined. The single nucleotide polymorphism rs693 was determined by Polymerase Chain Reaction/Restriction Fragment Length Polymorphism from genomic DNA followed by digestion with the restriction enzyme XbaI. The chi-square test was used to analyze the genotype distribution of rs693 and the genotype-phenotype association was evaluated through different inheritance model.

RESULTS

The genotype frequencies for single nucleotide polymorphism rs693 were CC (45.0%), TT (16.5%) and CT (38.5%). The allele frequencies were C (64.0%) and T (36.0%). The single nucleotide polymorphism was in Hardy-Weinberg equilibrium in the studied sample. No association of the single nucleotide polymorphism rs693 with lipid profile nor the body mass index was found (p >0.05).

CONCLUSION

There is no significant association between single nucleotide polymorphism rs693 and body mass index nor lipid profile, in a sample of Colombian Caribbeans.

Associations of the APOB rs693 and rs17240441 polymorphisms with plasma APOB and lipid levels: a meta-analysis

BACKGROUND

The associations of the apolipoprotein B gene (APOB) rs693 and rs17240441 polymorphisms with plasma levels of APOB and lipids have been widely explored, but the results were inconclusive. This meta-analysis aimed to clarify the associations of the rs693 and rs17240441 polymorphisms with fasting APOB and lipid levels.

METHODS

Sixty-one studies (50,018 subjects) and 23 studies (8425 subjects) were respectively identified for the rs693 and rs17240441 polymorphisms by searching in PubMed, Google Scholar, Web of Science, Cochrane Library, Wanfang, VIP and CNKI databases. The following information was collected for each study: first author, age, gender, ethnicity, health condition, sample size, genotyping, lipid assay method, mean and standard deviation or standard error of APOB and lipid variables by genotypes. A dominant model was used for this meta-analysis.

RESULTS

The carriers of the rs693 variant allele (T) had higher levels of APOB [standardized mean difference (SMD) = 0.26, 95% confidence interval (CI) = 0.16-0.36, P < 0.01], triglycerides (TG) (SMD = 0.12, 95% CI = 0.05-0.20, P < 0.01), total cholesterol (TC) (SMD = 0.24, 95% CI = 0.17-0.30, P < 0.01) and low-density lipoprotein cholesterol (LDL-C) (SMD = 0.22, 95% CI = 0.14-0.30, P < 0.01), and lower levels of high-density lipoprotein cholesterol (HDL-C) (SMD = -0.06, 95% CI = -0.11-0.01, P = 0.01) than the non-carriers. The carriers of the rs17240441 deletion allele had higher levels of APOB (SMD = 0.13, 95% CI = 0.06-0.20, P < 0.01), TC (SMD = 0.17, 95% CI = 0.07-0.26, P < 0.01) and LDL-C (SMD = 0.15, 95% CI = 0.07-0.23, P < 0.01) than the non-carriers.

CONCLUSIONS

The rs693 polymorphism is significantly associated with higher levels of APOB, TG, TC and LDL-C, and lower levels of HDL-C. The rs17240441 polymorphism is significantly associated with higher levels of APOB, TC and LDL-C. Further studies are needed to elucidate the underlying mechanisms.

Apolipoprotein B Gene Polymorphisms and Dyslipidemia in HIV Infected Adult Zimbabweans

Background:

Dyslipidemia does not occur in all HIV-infected or antiretroviral therapy-experienced patients suggesting role of host genetic factors but there is paucity of data on association between dyslipidemia and gene polymorphisms in Zimbabwe.

Objective:

To determine association of lipoprotein levels and apolipoprotein B polymorphisms in HIV-infected adults.

Method:

Demographic data were collected from 103 consenting patients; lipoprotein levels were determined and blood samples were successfully genotyped for both apolipoprotein B 2488C>T Xba1 and apolipoprotein B 4154G>A p.Gln4154Lys EcoR1 polymorphisms by real time polymerase chain reaction.

Results:

Mean age of genotyped patients was 40.3 ± 10.1 years, 68% were female; prevalence of dyslipidemia was 67.4%. Of 103 samples genotyped for apolipoprotein B Xba1 polymorphism, 76 (74%) were homozygous C/C, 24 (23%) were heterozygous C/T and only three (3%) were homozygous T/T. Apolipoprotein B EcoR1 polymorphism showed little variability, one participant had rare genotype A/A, 68.3% had wild type genotype G/G.

Conclusion:

Observed frequencies of apolipoprotein B XbaI and EcoRI polymorphisms matched other African studies. In spite of low numbers of rare variants, there was positive association between both total cholestrol and high density lipoprotein with ECoR1 wild type G/G genotype, suggesting that ECoRI 4154 G allele could be more protective against coronary heart disease than EcoR1 4154 A allele. There is need for further research at population level to confirm whether apolipoprotein B ECoR1 genotyping is useful for predicting risk of dyslipidemia in HIV patients in our setting.

Genetics of Obesity

Numerous classical genetic studies have proved that genes are contributory factors for obesity. Genes are directly responsible for obesity associated disorders such as Bardet-Biedl and Prader-Willi syndromes. However, both genes as well as environment are associated with obesity in the general population. Genetic epidemiological approaches, particularly genome-wide association studies, have unraveled many genes which play important roles in human obesity. Elucidation of their biological functions can be very useful for understanding pathobiology of obesity. In the near future, further exploration of obesity genetics may help to develop useful diagnostic and predictive tests for obesity treatment.

Apolipoprotein B polymorphism distribution among a sample of obese Egyptian females with visceral obesity and its influence on lipid profile

Background

Regional distribution of adipose tissue is more important than total amount of body fat in predicting complications associated with obesity. Apolipoprotein B (Apo B) plays a central role in lipid metabolism.

Aim

To investigate the importance of the XbaI polymorphism of Apo B gene (C7673T) as risk factor for visceral obesity and its influence on lipid profile.

Subjects and methods

Total of 122 obese adult females (BMI ⩾ 30 kg/m²): 56 of them with visceral obesity (⩾7 cm by abdominal Ultrasound) and 66 without visceral obesity and 36 age matched non-obese (BMI ⩽ 25 kg/m²) without visceral obesity were studied. Anthropometric assessment, body composition, visceral obesity and lipid profile evaluation were attempted. Genetic analysis of Apo B XbaI was performed using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP).

Results

Visceral obesity was associated significantly with the presence of the heterozygous (CT) genotype of the XbaI Apo B gene (p < 0.001). Frequency of homozygous (CC) was significantly the least genotype found in females with visceral obesity, while homozygote (TT) genotype was more frequent in those without visceral obesity. T allele (about 70%) was more frequent than C allele (about 30%) in all groups. Significant lowest values of visceral obesity, triglyceride and HDL-C were associated with the presence of (CC) genotype and the highest values were associated with the presence of the heterozygous (CT) genotype; except HDL-C with (TT) genotype.

Conclusions

Study reveals considerable association of Apo B XbaI gene polymorphism with visceral obesity and some lipid profile parameters (TG and HDL-C) among Egyptian females.

No association of apolipoprotein B gene polymorphism and blood lipids in obese Egyptian subjects

BACKGROUND

Several environmental and genetic factors are associated with high levels of lipids in obese patients. Apolipoprotein B (ApoB) is the major protein component of low-density lipoproteins (LDL), very-low density lipoproteins (VLDL) and chylomicrons and plays a central role in lipid metabolism. Several apoB restriction fragment length polymorphisms (XbaI, EcoRI, MspI) have been reported to be associated with variation in lipid levels and obesity. To date, no data are available on the relationship between XbaI polymorphism and lipid levels in Egyptian populations. Following clinical profiling, 178 obese (body mass index [BMI] >25 kg/m(2)) and 178 age-matched non-obese (BMI ≤ 25 kg/m(2)) subjects were included in this case-control study. All samples were analysed for total cholesterol, triglycerides and HDL-cholesterol. Genetic analysis of apoB XbaI (X) was performed using Polymerase Chain Reaction-Restriction Fragment Length polymorphism (PCR-RFLP). The aim of this study was to assess the association of apoB XbaI gene polymorphism (X) and lipid profiles in obese and non-obese Egyptian populations.

RESULTS

Obese subjects demonstrated significantly higher values of waist-to-hip ratio, blood pressure, and total lipid. However, in our sample we did not find significant differences in apoB XbaI gene polymorphism (X) genotype or allele frequencies. Moreover, none of the studied lipid parameters showed any association with the gene polymorphism.

CONCLUSION

This study reveals no significant association of apoB XbaI gene polymorphism (X) with obesity or lipid profiles in an Egyptian population.

Relationship between the Apolipoprotein AI, B gene polymorphism and the risk of non-traumatic osteonecrosis

BACKGROUND

Previous studies suggested that Apolipoprotein AI (ApoAI) and apolipoprotein B (ApoB) gene polymorphisms may result in lipid metabolism disorders. Genetic polymorphisms in these genes may be associated with the occurrence of osteonecrosis.

METHODS

We designed a case-control study including 429 patients of osteonecrosis and 368 age- and sex-matched control subjects. Polymerase chain reaction was used to amplify the DNA fragments in promoter -75 G > A of ApoAI gene and EcoR I, Xba I and 3'-VNTR of ApoB gene in osteonecrosis patients and healthy controls. We utilized polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method to genotype these four single nucleotide polymorphisms (SNPs).

RESULTS

For -75 G > A polymorphism of ApoAI, AA genotype frequency (0.501) was significantly higher in patients with osteonecrosis than that in control (0.462) subjects (P <0.001), GA genotype frequency (0.170) was significantly lower than that in the control (0.310) group (P <0.0001). In osteonecrosis patients, the odds ratio (OR) of A allele was 3.932 (95% CI: 3.0847 ~ 5.0123), which suggested that subjects carrying A allele of promoter region -75 G > A of ApoAI gene had higher susceptibility to osteonecrosis than G allele carriers. The genotype and allele frequency distributions showed no significant difference in EcoR I, Xba Iand 3'-VNTR loci of ApoB gene between the osteonecrosis group and control group.

CONCLUSION

Our study suggested that ApoAI gene -75G > A polymorphism may be associated with susceptibility to osteonecrosis in Chinese population. However, our results need further investigation with large sample size and various populations.