Apolipoprotein B gene polymorphisms: prevalence and impact on serum lipid concentrations in hypercholesterolemic individuals from Brazil

Association between apolipoprotein gene polymorphisms and hyperlipidemia: a meta-analysis

BACKGROUND

Hyperlipidemia plays an important role in the etiology of cardio-cerebrovascular disease. Over recent years, a number of studies have explored the impact of apolipoprotein genetic polymorphisms in hyperlipidemia, but considerable differences and uncertainty have been found in their association with different populations from different regions.

RESULTS

A total of 59 articles were included, containing in total 13,843 hyperlipidemia patients in the case group and 15,398 healthy controls in the control group. Meta-analysis of the data indicated that APOA5-1131 T > C, APOA1 -75 bp, APOB XbaI, and APOE gene polymorphisms were significantly associated with hyperlipidemia, with OR values of 1.996, 1.228, 1.444, and 1.710, respectively. All P-values were less than 0.05.

CONCLUSIONS

Meta-analysis of the data indicated that the C allele of APOA5 1131 T > C, the A allele at APOA1-75 bp, the APOB XbaI T allele, and the ε2 and ε4 allele of APOE were each a risk factor for susceptibility for hyperlipidemia.

Association of the 12669G>A Apolipoprotein B Gene Polymorphism with Apo-B Serum Level and Lipid Profile in Patients with Coronary Artery Disease Comparing with Individuals Without Coronary Artery Disease in Zanjan Population of Iran

Atherosclerosis is a pathologic disorder which has an important role in the occurrence of coronary heart disease. It is determined as a focal, inflammatory proliferative response to several types of endothelial damage. Apolipoprotein B which is a requirement in the sustenance of cholesterol homeostasis, and is the major protein component of low density lipoprotein, characterized by multitude polymorphic sites, one of which (12669G>A) is related to the levels of serum lipid profiles, coronary artery disease and/or myocardial infarction. One Common polymorphism which is more important in this process is 12669G>A that is appraised in this research. We recruited 80 patients from the Mousavi hospital, Zanjan, Iran, diagnosed with coronary artery disease by the clinician on the basis of clinical symptoms, echocardiogram result, and angiography. Seventy-seven healthy individuals without any evident symptoms of Coronary stenosis and any past history of the disease were taken as controls from the general population. We carried out PCR using specific primers. Then, we digested PCR product by RFLP. Lipid parameters by biochemical methods and Apolipoprotein B serum level by immunoturbidometry method were done. Genotype frequencies for 12669G>A polymorphism were determined: 55 % R+R+, 45 % R+R- in case group, and 55.8 R+R+, 44.2 % R+R- in controls. The R-R- genotype was not seen. There was no significant relationship between this polymorphism and the risk of Coronary stenosis (P = 0.6). In the present study, higher plasma levels of cholesterol and low density lipoproteins in the subjects with R+R- genotype were found while there was no association between this polymorphism and coronary stenosis with ≥50 % in the Zanjan population.

Influence of ApoB100 3' hypervariable repeats on acute myocardial infarction

BACKGROUND AND OBJECTIVE

The 3' flanking region of apolipoprotein B (ApoB) 100 gene is known to contain short A+T-rich DNA sequences which are hypervariable in nature and called the variable number of tandem repeats (VNTRs). It results in different alleles of ApoB100. The present study extends the investigation of whether there is a correlation between the presence of these alleles and acute myocardial infarction (MI).

METHODS

We examined ApoB genotypes in 230 acute MI patients and 300 healthy controls. PCR based genotyping was done for ApoB 3' VNTRs.

RESULTS

We recoded 3'ApoB-VNTR alleles through three- and five-allelic models based on different sizes and found that large repeats (>37) were significantly associated with acute MI (p<0.0001). These large repeats (>37) were also significantly associated with higher lipid levels in the MI group.

CONCLUSION

Patients with 3'ApoB-VNTR large repeats (>37) are more susceptible to acute MI development.

The roles of genetic polymorphisms and human immunodeficiency virus infection in lipid metabolism

Dyslipidemia has been frequently observed among individuals infected with human immunodeficiency virus type 1 (HIV-1), and factors related to HIV-1, the host, and antiretroviral therapy (ART) are involved in this phenomenon. This study reviews the roles of genetic polymorphisms, HIV-1 infection, and highly active antiretroviral therapy (HAART) in lipid metabolism. Lipid abnormalities can vary according to the HAART regimen, such as those with protease inhibitors (PIs). However, genetic factors may also be involved in dyslipidemia because not all patients receiving the same HAART regimen and with comparable demographic, virological, and immunological characteristics develop variations in the lipid profile. Polymorphisms in a large number of genes are involved in the synthesis of structural proteins, and enzymes related to lipid metabolism account for variations in the lipid profile of each individual. As some genetic polymorphisms may cause dyslipidemia, these allele variants should be investigated in HIV-1-infected patients to identify individuals with an increased risk of developing dyslipidemia during treatment with HAART, particularly during therapy with PIs. This knowledge may guide individualized treatment decisions and lead to the development of new therapeutic targets for the treatment of dyslipidemia in these patients.

Dietary fat and apolipoprotein genotypes modulate plasma lipoprotein levels in Brazilian elderly women

Studies show that genetic polymorphisms in apolipoproteins, which are in charge of lipid transport, predispose to atherogenic dyslipidemia. This study aimed to investigate the impact of apolipoprotein E, A5, and B genotypes and dietary intake on lipid profile in a sample of elderly women in Brazil. Two hundred and fifty-two women (60 years or older) living in the outskirts of the Brazilian Federal District underwent clinical and laboratory assessments to characterize glycemic and lipidemic variables, and also to exclude confounding factors (smoking, drinking, hormone replacement, cognitive impairment, physical activity). Three-day food records were used to determine usual dietary intake, whereas genotypic evaluations were in accordance to established methodologies. Genotype frequencies were consistent with the Hardy-Weinberg equilibrium. Prior to adjustment, individuals carrying the epsilon2 allele showed higher serum levels of triglycerides (P<0.05) and VLDL (P<0.005) compared to epsilon4 carriers, whereas LDL levels were considerably elevated in epsilon4 compared to epsilon2 carriers. In the presence of high intake of total fat or a low ratio of polyunsaturated to saturated fatty acid, epsilon4 carriers lost protection against hypertriglyceridemia. There was no association of the apolipoprotein A5 and B genotypes with lipidemic levels independently of the fat intake regimen. Results are suggestive of a dysbetalipoproteinemic-like phenotype in postmenopausal women, with remarkable gene-diet interaction.

Correlation and Identification of Variable number of Tandem repeats of eNOS Gene in Coronary artery disease (CAD)

Endothelium-derived nitric oxide (NO) is synthesized from l-arginine by endothelial nitric oxide synthase (eNOS) encoded by the NOS3 gene on chromosome7. Since reduced NO synthesis has been implicated in the development of coronary atherosclerosis; polymorphisms of NOS gene might be associated with increased susceptibility to coronary artery disease (CAD). We therefore undertook this study to determine the association between the occurrence of CAD and eNOS4 b/a polymorphism in South Indian patients. We investigated the polymorphisms in the 27 base-pair tandem repeats in intron4 of the eNOS gene in 100 unrelated CAD patients with positive coronary angiograms and 100 age and sex matched control subjects without any history of symptomatic CAD. The eNOS gene intron4 b/a VNTR polymorphism was analyzed by polymerase chain reaction. The plasma lipids levels and other risk factors were also determined. The genotype frequencies for eNOS4b/b, eNOS4a/b and eNOS4a/a were 63, 26 and 11 per cent in CAD subjects, and 72, 20 and 8 per cent in control subjects, respectively. The genotype frequencies did not differ significantly between the two groups. The frequency of the a allele was 0.24 per cent in CAD subjects and 0.18 per cent in control subjects and no significant association was found between patients and control group (P = 0.57, Odds ratio = 3.62). Plasma lipids, glucose and creatinine levels were significantly increased in CAD group. The genotypic frequencies and the allele frequency did not differ significantly between the CAD patients and controls indicating that this polymorphism was not an independent risk factor for the development of CAD in South Indian patients.

Effects of APOE, APOB and LDLR variants on serum lipids and lack of association with xanthelasma in individuals from Southeastern Brazil

Xanthelasma might be a clinical manifestation of dyslipidemia, a recognized risk factor for coronary artery disease. We investigated the association of apolipoprotein E (APOE HhaI), apolipoprotein B (APOB XbaI and Ins/Del) and LDL receptor (LDLR AvaII and HincII) gene polymorphisms with lipid profiles in 100 Brazilians with xanthelasma and 100 controls. Allele frequencies were similar in both groups. APOE, APOB and LDLR genotypes were not correlated with differences in the serum lipid profile. In individuals with xanthelasma, the APOB D allele was associated with less chance of having increased LDL-cholesterol (O.R. = 0.16, CI95% = 0.03-0.94, p = 0.042). In the control group, the APOB X+ allele was associated with less chance of having both increased total cholesterol (O.R. = 0.16, CI95% = 0.03-0.78, p = 0.023) and increased LDL-cholesterol (O.R. = 0.10, CI95% = 0.02-0.60, p = 0.012). Moreover, there was a significantly higher frequency of control individuals (68%) with elevated serum triglyceride levels, compared to patients (48%, p = 0.008). On the other hand, triglyceride levels in controls also seemed to be influenced by all other gene polymorphisms studied, an effect that might be enhanced by environmental factors.

Five polymorphisms in gene candidates for cardiovascular disease in Afro-Brazilian individuals

Associations of polymorphisms in the angiotensin I-converting enzyme (ACE), apolipoprotein B (APOB) and apolipoprotein E (APOE) genes with hypertension and variations in lipid serum levels were evaluated in 184 Afro-Brazilians with a familial history of coronary artery disease (CAD). ACE (Ins/Del) and APOB (Ins/Del, XbaI, and EcoRI) and APOE (HhaI) polymorphisms were determined by polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analyses on agarose, and polyacrylamide gel electrophoresis. Serum lipids were measured by means of routine enzymatic assays. The results showed a high frequency of hypertension (44%) in Afro-Brazilians that was increased in subjects >40 years old and those with a blood mass index (BMI) higher than 25 kg/m(2) (P<0.001). The ACE Del allele was associated with hypertension in men >40 years old (P<0.05). APOE (HhaI) and APOB (XbaI and Ins/Del) polymorphisms were not associated with hypertension or variations in serum concentrations of lipids, while subjects with the APOB E- allele had higher low-density lipoprotein cholesterol (LDL-C) levels than E+ carriers (P<0.05). These results suggest that ACE Ins/Del polymorphism is associated with hypertension, and APOB EcoRI polymorphism is associated with LDL-C variation in Afro-Brazilians.

Functional foods: Latin American perspectives

The perspectives of Latin America as a potential producer and consumer of functional foods will depend largely on the level of information and income of the population, credibility of the products, research investments and regulatory practices. The characteristics of Latin America are diverse at the regional and sub-regional levels. However, as part of the demographic and epidemiological transition currently underway, common trends can be identified such as increasing urbanization and life expectancy, the occurrence of obesity and malnutrition, increasing incidences of chronic diseases and causes of mortality rates, all of which suggests the importance of diet and functional foods in public health policies. The Latin American population in general has no knowledge of functional foods, but in the more urbanized areas there is an increasingly health-conscious consumer, aware of the importance of food for health, due to the media and local traditions. More investment in research is important to explore the existing plant biodiversity that is a rich source of new foods and bioactive compounds, some of which are already used for health improvement and well-being. Clinical validation of functional foods should consider functional food science concepts and also the diverse cultural and genetic background of the local population. In Latin American scientific and regulatory communities, the functional foods concept has been associated with foods having health benefits beyond those of basic nutrition but is not defined officially in the emerging regulatory codes. Regulation existing in some countries is focused on safety and efficacy; both functional and health claims are allowed (risk reduction) provided they have scientific validation. This allowed introduction on the market of several products with health claims, some of them submitted to post-marketing surveillance.

Rapid detection of 3500Q and 3531 mutations and MspI polymorphism in exon 26 at the apolipoprotein B gene

Several environmental and genetic factors are associated with high levels of cholesterol. Hypercholesterolemia is the main phenotype of Familial Defective Apolipoprotein B and Familial Hypercholesterolemia that are caused by mutations at the apolipoprotein (apo) B and LDL receptor genes, respectively. Identification of the specific genetic alteration associated with hypercholesterolemia is an important issue in clinical diagnosis of high risk for CAD. Apo B gene mutations and polymorphisms are usually screened by SSCP, DGGE, and heteroduplex, which must be confirmed by DNA sequencing or by direct detection using PCR techniques. In this study, we have optimized a PCR-RFLP procedure for identification of 3500Q and 3531 mutations and MspI polymorphism at the apo B gene. The technique can be performed in a single reaction, using the restriction endonuclease MspI for simultaneous detection of 3500Q mutation and MspI polymorphism, and NsiI for detection of 3531 mutation. The procedure was validated by analysis of control DNA samples from individuals carrying these mutations. Screening of 186 Brazilian hypercholesterolemic individuals showed that the frequency of the M-allele (7.8%) of MspI polymorphism was similar to that found in other individuals with CAD. However, neither 3500Q nor 3531 mutations were detected in this group. In conclusion, this procedure is simple and rapid, being easily introduced in clinical laboratories for direct detection of the more frequent mutations at the apo B gene associated with hypercholesterolemia.