Polymorphism of the apolipoprotein B gene and blood lipid concentrations in Japanese and Caucasian population samples

Can biomarkers be used to improve diagnosis and prediction of metabolic syndrome in childhood cancer survivors? A systematic review

Childhood cancer survivors (CCS) are at increased risk to develop metabolic syndrome (MetS), diabetes, and cardiovascular disease. Common criteria underestimate adiposity and possibly underdiagnose MetS, particularly after abdominal radiotherapy. A systematic literature review and meta-analysis on the diagnostic and predictive value of nine newer MetS related biomarkers (adiponectin, leptin, uric acid, hsCRP, TNF-alpha, IL-1, IL-6, apolipoprotein B (apoB), and lipoprotein(a) [lp(a)]) in survivors and adult non-cancer survivors was performed by searching PubMed and Embase. Evidence was summarized with GRADE after risk of bias evaluation (QUADAS-2/QUIPS). Eligible studies on promising biomarkers were pooled. We identified 175 general population and five CCS studies. In the general population, valuable predictive biomarkers are uric acid, adiponectin, hsCRP and apoB (high level of evidence), and leptin (moderate level of evidence). Valuable diagnostic biomarkers are hsCRP, adiponectin, uric acid, and leptin (low, low, moderate, and high level of evidence, respectively). Meta-analysis showed OR for hyperuricemia of 2.94 (age-/sex-adjusted), OR per unit uric acid increase of 1.086 (unadjusted), and AUC for hsCRP of 0.71 (unadjusted). Uric acid, adiponectin, hsCRP, leptin, and apoB can be alternative biomarkers in the screening setting for MetS in survivors, to enhance early identification of those at high risk of subsequent complications.

The Circulatory Risk in Communities Study (CIRCS): A Long-Term Epidemiological Study for Lifestyle-Related Disease Among Japanese Men and Women Living in Communities

The Circulatory Risk in Communities Study (CIRCS) is an ongoing community-based epidemiological study of lifestyle-related disease involving dynamic prospective cohorts of approximately 12,000 adults from five communities of Japan: Ikawa, Ishizawa and Kita-Utetsu (Akita Prefecture), Minami-Takayasu (Osaka Prefecture), Noichi (Kochi Prefecture), and Kyowa (Ibaraki Prefecture). One of the most notable features of CIRCS is that it is not only an observational cohort study to identify risk factors for cardiovascular diseases (CVD), such as stroke, coronary heart disease, and sudden cardiac death, but it also involves prevention programs for CVD. Using basic, clinical, epidemiological, and statistical techniques, CIRCS has clarified characteristics of CVD and the related risk factors to develop specific methodologies towards CVD prevention in Japanese middle-aged or older adults for more than half a century.

Genetic diversity and natural selection footprints of the glycine amidinotransferase gene in various human populations

The glycine amidinotransferase gene (GATM) plays a vital role in energy metabolism in muscle tissues and is associated with multiple clinically important phenotypes. However, the genetic diversity of the GATM gene remains poorly understood within and between human populations. Here we analyzed the 1,000 Genomes Project data through population genetics approaches and observed significant genetic diversity across the GATM gene among various continental human populations. We observed considerable variations in GATM allele frequencies and haplotype composition among different populations. Substantial genetic differences were observed between East Asian and European populations (F_ST = 0.56). In addition, the frequency of a distinct major GATM haplotype in these groups was congruent with population-wide diversity at this locus. Furthermore, we identified GATM as the top differentiated gene compared to the other statin drug response-associated genes. Composite multiple analyses identified signatures of positive selection at the GATM locus, which was estimated to have occurred around 850 generations ago in European populations. As GATM catalyzes the key step of creatine biosynthesis involved in energy metabolism, we speculate that the European prehistorical demographic transition from hunter-gatherer to farming cultures was the driving force of selection that fulfilled creatine-based metabolic requirement of the populations.

Polymorphism of the apolipoprotein B gene and association with plasma lipid and lipoprotein levels in the Mongolian Buryat

Allele frequencies at six RFLP sites (Ins/Del, ApaLI, AluI, XbaI, MspI, and EcoRI) of the apolipoprotein B gene (APOB) and the relationship of genotypes with plasma lipid and lipoprotein levels in the Mongolian Buryat were investigated. Common alleles at these sites in 110 Buryat subjects were I, G, A-, X-, M+, and E+; the frequencies of 0.809-0.991 differed strikingly from those of a few Asians and most Europeans. Five unambiguous haplotypes of all sites were revealed at 74%; haplotype IGA-X-M+E+ (000000) was the most frequent (67%), followed by IGA+X-M+E+ (001000) (19%). The frequency constitution differed significantly from the Chinese, Malaysians, and Caucasians but resembled the Indians. No APOB polymorphisms were associated with cholesterol levels (total, HDL and LDL). Significant associations of genotypes were shown with the triglyceride level only at the AluI and XbaI sites. The lipid level of A-A+ females or X-X+ males was higher than that of A-A- females or X-X- males, respectively.

ApoB C7623T polymorphism predicts risk for steroid-induced osteonecrosis of the femoral head after renal transplantation

BACKGROUND

Nontraumatic osteonecrosis of the femoral head (ONFH) is caused by disruption of blood flow. This disease often occurs in association with steroid treatment. The pathology of steroid-induced ONFH remains unclear, although abnormalities in lipid metabolism have been reported to be involved. In this study, we examined the differences of gene polymorphism frequencies of apolipoprotein B (ApoB) and apolipoprotein A1 (ApoA1), which are important proteins for lipid transport, as well as of lipid parameters, between ONFH cases and referent patients among those who were subjected to renal transplantation.

METHODS

Subjects were 158 cases who had undergone renal transplant, including 34 cases that were diagnosed as ONFH after renal transplantation and 124 cases that were not. Four single nucleotide polymorphisms including C7623T and G12619A for the ApoB gene and G75A and C83T for the ApoA1 gene were analyzed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Taqman real-time PCR chemistry. Also, serum levels of low-density lipoprotein (LDL), high-density lipoprotein (HDL), ApoB, and ApoA1 were measured. Their relationship to ONFH was statistically evaluated.

RESULTS

A higher frequency of 7623TT or CT of the ApoB gene was observed in ONFH cases than in referent patients (P = 0.033), resulting in an elevated odds ratio that was statistically significant (adjusted odds ratio = 6.37, 95% CI = 1.53-26.5, P = 0.011). No significant relationship was observed between other genes and ONFH. Regarding lipid parameters, a higher value of ApoB/ApoA1 ratio was observed in cases (P = 0.045).

CONCLUSION

For the prediction of ONFH, it is useful to analyze ApoB C7623T and plasma ApoB/ApoA1 ratio before the administration of steroids.

Apolipoprotein B gene variants are involved in the determination of blood glucose and lipid levels in patients with non-insulin dependent diabetes mellitus

We have examined the frequency of the EcoRI, XbaI and MspI RFLPs of the apolipoprotein B (apo B) gene in 110 type 2 diabetic patients and 91 healthy control subjects in order to ascertain whether variation in this gene may influence the development of non-insulin dependent diabetes mellitus (type 2 diabetes). Serum lipids including total-cholesterol (T-Chol), triacylglycerol (TAG), apolipoprotein E (apo E), apolipoprotein AI (apo AI), apolipoprotein B and lipoprotein (a) (Lp(a)) were analysed. Genomic DNA was extracted and the apo B polymorphic regions amplified by the polymerase chain reaction. Regions carrying EcoRI, XbaI, and MspI restriction sites present in the apo B gene were amplified and digested separately by the respective enzymes. No significant difference for genotypic frequencies was observed for the EcoRI, XbaI and MspI restriction sites in type 2 diabetic patients as compared to controls. Type 2 diabetic patients and controls with EcoRI +/+ and XbaI +/+ genotypes had higher apo E levels. The MspI +/+ genotype is more frequent in the patient and control groups with elevated T-Chol. Furthermore, the EcoRI -/-, XbaI -/-, and MspI +/+ genotypes were found to be significantly more frequent in type 2 diabetic patients with higher blood glucose levels. This study identifies the apo B gene polymorphisms in modulating plasma lipid/lipoprotein and glucose levels in patients with type 2 diabetes.

Genetic variations of the apolipoprotein B gene in Turkish patients with coronary artery disease

BACKGROUND

The results of studies that clarify the association of genetic markers at the apolipoprotein B (apo B) gene (EcoRI and XbaI polymorphisms) with coronary artery disease (CAD) are not consistent and suggest that the effect is context dependent (dependent on ethnicity and sex). The present study represents the first investigation of the apo B gene polymorphisms in Turkish patients with CAD and their influence on lipid levels.

AIM

The study investigated the association of apo B gene EcoRI and XbaI polymorphisms with CAD and with variation in lipid levels (total cholesterol (T-Chol), high-density lipoprotein cholesterol (HDL-Chol), low-density lipoprotein cholesterol (LDL-Chol), and triacylglycerol (TAG)).

SUBJECTS AND METHODS

The study group was composed of 150 individuals with angiographically documented CAD and 100 angiographically proven to be healthy controls. PCR-RFLP was used to determine the DNA polymorphisms of the apo B gene.

RESULTS

The frequencies of apo B genotypes detected with EcoRI (AA, AG, GG) and XbaI (CC, CT, TT) did not differ significantly between case and control subjects. A significant association between EcoRI genotypes and T-Chol (p < or = 0.05), and LDL-Chol (p < or = 0.001) was observed only in CAD patients. Patients with the AA genotype had higher levels of serum T-Chol and LDL-Chol compared with AG. With logistic regression analysis the XbaI TT genotype was found to be associated with CAD prevention. However, no significant differences in lipid variables were determined for the XbaI polymorphisms in the patients with CAD.

CONCLUSIONS

Apo B EcoRI genotypes were not found as risk factors for CAD, whereas XbaI TT genotype was detected to prevent against CAD in our study group.

Locus-specific genetic diversity between human populations: an analysis of the literature

The debate over classification of the human species according to racial or continental lines has involved reports on genetic differences in allele frequencies of a number of loci with important biomedical functions. Such differences are in contrast with the fact that, for human beings, intrapopulation genetic diversity is larger than that seen between populations. In an attempt to address the hypothesis that certain genes show high interpopulation diversity due to selective pressure, the literature was surveyed to quantify such diversity using Wrights Fst statistic. The gene-specific Fst values were then compared to pairwise population values of Fst taken over a large number of genes, which presumably reflect mostly neutral mechanisms of genetic diversity such as drift. The results showed that the majority of pairwise population values of Fst for over 30 genes of biomedical significance were either below or within the expected limits of Fst based on published values. These results do not support the idea that positive or diversifying natural selection plays an important role in increasing genetic diversity, even in genes that might be expected to be subject to selection pressure. Balancing selection, whereby the degree of genetic diversity is actually lower than that expected, appears to occur more frequently for these genes. The fact that allele frequency differences between populations might be "statistically significant" does not therefore necessarily imply a degree of genetic diversity greater than would be expected due to nonselective mechanisms.

Molecular variation at the apolipoprotein B gene locus in relation to lipids and cardiovascular disease: a systematic meta-analysis

Apolipoprotein B (apoB) is the sole protein component of low-density lipoprotein (LDL) and is thought to play an important role in atherogenesis. We performed a meta-analysis of the associations between the three most frequently investigated polymorphisms (XbaI, signal peptide insertion/deletion, EcoRI) in the apolipoprotein B (APOB) gene, lipid parameters, and the risk of ischemic heart disease (IHD). We restricted our analysis to Caucasians. Homozygotes for the XbaI X+ allele had significantly elevated levels of LDL cholesterol (LDL-C) and apoB, but a decreased risk (OR=0.80; 95%CI: 0.66-0.96) of IHD. Homozygosity for the signal peptide deletion allele was associated with similarly increased levels of LDL-C and apoB, and with an increased risk of IHD (OR=1.30; 95%CI: 1.08-1.58). Subjects homozygous for the rare EcoRI allele had significantly decreased levels of total and LDL cholesterol, but unaltered risk of IHD. We conclude that all three polymorphic apoB sites are associated with altered lipid levels, but not necessarily with a consistently altered risk of IHD. These data suggest that the relationship between apoB levels, hypercholesterolemia and IHD risk cannot have a simple molecular basis in the apoB gene.