The SNP276G>T polymorphism in the adiponectin (ACDC) gene is more strongly associated with insulin resistance and cardiovascular disease risk than SNP45T>G in nonobese/nondiabetic Korean men independent of abdominal adiposity and circulating plasma adiponectin

Polymorphism analysis of ADIPOQ gene in Greek patients with diabetic retinopathy

BACKGROUND

Several genetic polymorphisms have been identified as risk factors for diabetic retinopathy (DR) onset. The purpose of our study was to determine whether ADIPOQ rs1501299 and rs2241766 gene polymorphisms are associated with DR in a cohort of Greek diabetic patients.

MATERIALS AND METHODS

218 patients with type-2 diabetes mellitus (T2DM) were included in the study; 109 suffered from DR and 109 not. All the participants underwent a complete ophthalmological examination, while clinical and demographic data were assessed. Furthermore, they were genotyped for G276T (rs1501299) and T45G (rs2241766) single nucleotide polymorphisms of ADIPOQ gene.

RESULTS

Between the studied groups, no significant differences were detected regarding the demographic and clinical data (p > .05 for all), except for hemoglobin A1c levels and frequency of insulin treatment (higher in DR patients). We detected that the frequency of rs1501299 GT genotype was significantly elevated in DR patients (53% vs. 34%, p = .004) and was associated with a higher risk of developing retinopathy (OR 2.31, 95% CI 1.30-4.11). Furthermore, we demonstrated that the rs1501299 GT genotype was significantly and independently associated with increased odds for DR development in diabetic subjects (OR 2.68, 95% CI 1.38-5.21, p = .004), regardless of the impact of other known risk factors.

CONCLUSIONS

We documented that rs1501299 GT genotype could be recognized as an independent risk factor of retinopathy in T2DM Greek patients, while no role for rs2241766 polymorphism was identified. Further research in different ethnic groups will clarify the exact association of these polymorphisms with the risk of DR development.

The effect of single-nucleotide polymorphisms at the ADIPOQ gene locus rs1501299 on metabolic parameters after 9 mo of a high-protein/low-carbohydrate versus a standard hypocaloric diet

OBJECTIVE

Some adiponectin gene (ADIPOQ) single-nucleotide polymorphisms (SNPs) have been related to basal and adiponectin levels and metabolic parameters. The aim of this study was to evaluate the effect of the genetic variant rs1501299 ADIPOQ gene on biochemical changes after weight loss secondary to a high-protein and low-carbohydrate diet versus a standard severe hypocaloric diet over 9 mo as the primary endpoint.

METHODS

A white population of 270 obese patients was enrolled in a randomized clinical trial with two hypocaloric diets (high-protein and low carbohydrate diet [HP] versus standard diet [S]) over 9 mo of intervention. The statistical analysis was performed for the combined GT and TT as a group (T-allele carriers) and GG as second group (non-T-allele carriers). Before and after 12 wk on each hypocaloric diet, an anthropometric evaluation, an assessment of nutritional intake, and a biochemical analysis were realized.

RESULTS

With both dietary interventions, body weight, body mass index (BMI), fat mass, waist circumference, systolic blood pressure, and leptin levels decreased. In non-T-allele carriers after both diets, the decrease in total cholesterol levels -12.3 ± 2.2 mg/dL (T-allele carriers -6.9 ± 2.1 mg/dL; P = 0.01 diet HP) and 12.2 ± 3.1 mg/dL (T-allele carriers -4.7 ± 1.2 mg/dL; P = 0.02 after diet S), low-density lipoprotein cholesterol -13.2 ± 2.7 mg/dL (T-allele carriers -6.1 ± 2.1 mg/dL; P = 0.02 after diet HP) and -9.3 ± 1.8 mg/dL (T-allele carriers -4.8 ± 2.9 mg/dL; P = 0.01 after diet S), triacylglycerol levels -12.7 ± 6.1 mg/dL (T-allele carriers -6 ± 2.9 mg/dL; P = 0.01 after diet HP) and -16.3 ± 7.2 mg/dL (T-allele carriers -5.3 ± 1.4 mg/dL; P = 0.03 after diet S), insulin levels -5 ± 1.1 mUI/L (in T-allele -1.7 ± 0.9 mUI/L; P = 0.02 after diet HP) and -3.2 1.1 mUI/L (T-allele carriers -0.7 ± 0.7 mUI/L; P = 0.02 after diet S), and homeostatic model assessment of insulin resistance levels -0.4 ± 0.2 units (T-allele group -0.1 ± 0.1; P = 0.04 after diet HP) and -0.7 ± 0.1 units (T-allele carriers -0.1 ± 0.5 mg/dL; P = 0.01 after diet S) was higher than T-allele carriers. Only no T-allele carriers showed an increase in adiponectin levels after both diets.

CONCLUSION

After two different hypocaloric diets during 9 mo of intervention, the GG genotype of an ADIPOQ gene variant (rs1501299) is related to better improvement in adiponectin levels, insulin resistance, and lipid profile than T-allele carriers.

Role of rs1501299 variant in the adiponectin gene on total adiponectin levels, insulin resistance and weight loss after a Mediterranean hypocaloric diet

BACKGROUND/AIM

Several adiponectin gene (ADIPOQ) single nucleotide polymorphisms (SNPS) have been related with adiponectin levels and risk for obesity. Our aim was to analyze the effects of rs1501299 ADIPOQ gene polymorphism on total adiponectin levels, insulin resistance and weight loss after a Mediterranean hypocaloric diet in obese subjects.

METHODS

A Caucasian population of 82 obese patients was analyzed, before and after 3 months on a Mediterranean hypocaloric diet. Before and after 3 months on a hypocaloric diet, an anthropometric evaluation, an assessment of nutritional intake and a biochemical analysis were performed.

RESULTS

After dietary treatment and in wild type group, weight, BMI, fat mass, leptin levels, systolic blood pressure and waist circumference decreases were similar to the mutant type group. In wild type group, the decrease in total cholesterol was -28.1 ± 15.3 mg/dl (mutant group: -12.6 ± 16.7 mg/dl:p = 0.009), LDL- cholesterol was -31.8 ± 20.5 mg/dl (-12.2 ± 11.5 mg/dl:p = 0.006), fasting glucose plasma -4.8 ± 2.5 mg/dL (-0.5 ± 0.1 mg/dL:p = 0.02), insulin -3.6 ± 1.5 mUI/L (+0.6 ± 1.1 mUI/L:p = 0.02) and HOMA-IR -1.2 ± 0.9 (-0.1 ± 1.1:p = 0.03).

CONCLUSION

The present study suggests that T allele of ADIPO (rs1501299) could be a predictor of a lack of response of HOMA-IR, insulin, fasting glucose and LDL cholesterol secondary to a Mediterranean hypocaloric diet in obese subjects.

The association of SNP276G>T at adiponectin gene with insulin resistance and circulating adiponectin in response to two different hypocaloric diets

BACKGROUND

Several adiponectin gene (ADIPOQ) single nucleotide polymorphisms (SNPS) have been related with adiponectin levels and risk for obesity.

OBJECTIVE

The aim of our study was to analyze the effect of rs1501299 ADIPOQ gene polymorphism and dietary intake on total adiponectin levels and insulin resistance after two hypocaloric diets in obese subjects.

MATERIAL AND METHODS

A Caucasian population of 284 obese patients was enrolled in a randomized clinical trial with two hypocaloric diets (I: moderate carbohydrates vs II: low fat). Before and after 12 weeks on each hypocaloric diet, an anthropometric evaluation, an assessment of nutritional intake and a biochemical analysis were realized. The statistical analysis was performed for the combined GT and TT as a group (mutant) and GG as second group (wild) (dominant model).

RESULTS

The genotype distribution was 149 GG, 124 GT and 21 TT. With caloric restriction strategies, body weight, body mass index (BMI), fat mass, waist circumference, systolic blood pressure, total LDL cholesterol, LDL cholesterol and leptin levels decreased. Only in subjects with GG genotype, diet I and II decreased fasting insulin levels, HOMA-IR and adiponectin levels. The improvement was similar with both diets; insulin concentrations (Diet I: -4.7 ± 1.4 mUI/L vs. Diet II: -5.9 ± 1.9 mUI/L: p = .76), HOMA-IR (Diet I: -1.4 ± 0.6 units vs. Diet II: -2.0 ± 0.7 units: p = .56) and adiponectin levels (Diet I: -10.2 ± 3.4 ng/dl vs. Diet II: -14.0 ± 2.9 ng/dl: p = .33).

CONCLUSION

The GG genotype of ADIPOQ gene variant (rs1501299) is associated with an increase in adiponectin levels and a decrease of insulin and HOMA-IR after weight loss.

T allele at ADIPOQ rs1501299 G/T polymorphism is more susceptible to the influence of circulating adiponectin on arterial stiffness in nondiabetic men

BACKGROUND

Low adiponectin levels are associated with increased insulin resistance (IR) and arterial stiffness in hypertensive patients, but higher adiponectin levels are also found in heart failure patients. This discrepancy has not been fully resolved, but it may be related to the adiponectin gene (ADIPOQ) which regulates adiponectin production. We aimed to investigate whether the relationship between adiponectin and arterial stiffness is associated with ADIPOQ rs1501299 G/T polymorphism in nondiabetic Korean men.

METHODS

In nondiabetic men without disease (n = 301), anthropometric parameters, lipid profiles, IR, circulating adiponectin, and brachial-ankle pulse wave velocity (baPWV) were measured. rs1501299 G/T polymorphism was also analyzed.

RESULTS

Circulating adiponectin levels were negatively correlated with baPWV and homeostatic model assessment-IR in the T allele carriers (n = 167), but this correlation was not observed in the GG subjects (n = 134). However, a positive correlation between baPWV and IR was observed in the GG subjects, but not in the T carriers. These patterns were maintained after the adjustment for confounding factors. A stepwise linear regression analysis revealed that circulating adiponectin and systolic blood pressure (BP) were the main influencing factors on baPWV levels in T carriers, but systolic BP, IR and age were the main contributors to increased baPWV levels in the GG subjects.

CONCLUSIONS

This study demonstrates that the relationship between circulating adiponectin and arterial stiffness is different according to ADIPOQ rs1501299 G/T polymorphism, and suggests that T allele is more susceptible to the influence of adiponectin on arterial stiffness than GG homozygotes. This information may prove to be useful for personal-based early prevention and management of atherosclerotic risk.

Associations between two common single nucleotide polymorphisms (rs2241766 and rs1501299) of ADIPOQ gene and coronary artery disease in type 2 diabetic patients: a systematic review and meta-analysis

ADIPOQ gene polymorphisms were indicated to be associated with coronary artery disease (CAD) in diabetic patients, however, published studies reported inconsistent results. We performed this meta-analysis to reach a more accurate estimation of the relationship between two common ADIPOQ genetic polymorphisms (rs2241766 and rs1501299) and CAD risk in diabetic patients. Eligible studies were retrieved by searching PubMed, Embase, Wangfang, VIP database and China National Knowledge Infrastructure databases. Included and excluded criteria were formulated. The case group was diabetic patients with CAD, and the control group was diabetic subjects without CAD. Summary odds rations (ORs) and 95% confidence intervals (CIs) were used to evaluate ADIPOQ polymorphisms associations with CAD risk in diabetic group. Heterogeneity was evaluated by Q statistic and I² statistic. A total of twelve published articles, involving 3996 cases and 8876 controls were included in this meta-analysis. The pooled results from rs1501299 polymorphism showed decreased risk in homozygote model (TT VS GG: OR=0.67, 95%CI=0.54-0.83). Heterogeneity was detected in our study. Sensitivity analysis and subgroup analysis were conducted in the meta-analysis. For rs2241766 polymorphism, an increased risk was detected in Caucasian subgroup in heterozygote model (CT VS TT: OR=1.19, 95%CI=1.00-1.42). In genotyping method (PCR-RFLP) subgroup, an increased risk was found in recessive model (GG VS GT+TT: OR=2.05, 95%CI=1.23-3.39). In the sensitivity analysis of rs1501299, decreased risk was detected in allelic model (T VS G: OR=0.86, 95%CI=0.76-0.98) and recessive model (TT VS TG+GG: OR=0.47, 95%CI=0.33-0.67). Publication bias is not observed in our results. Our meta-analysis suggests that the rs1501299 polymorphism may play a protective role in CAD in diabetic patients. The rs2241766 polymorphism is found to be associated with a significant increase in CAD risk in Caucasian and genotyping method (PCR-RFLP) subgroups. Further studies are needed to confirm the prediagnostic effect of the two gene polymorphisms in CAD risk in diabetic patients.

Review: Non-alcoholic fatty liver disease: natural history, pathogenesis and treatment

Non-alcoholic fatty liver disease (NAFLD) is the term used to describe the alcohol-like liver injury that occurs in the absence of alcohol abuse. It embraces a range of histological abnormalities including simple steatosis or fatty liver, non-alcoholic steatohepatitis (NASH) and NAFLD induced cirrhosis. The predominant risk factor for NAFLD appears to be insulin resistance. Simple steatosis and NASH are generally asymptomatic and it is only the development of cirrhosis that has clinical consequence. At present, therapy in NAFLD concentrates on managing risk factors but in the future clinical trials may provide robust evidence for the use of insulin sensitising agents and other potential therapies.

Nutrigenetics and nutrigenomics insights into diabetes etiopathogenesis

Diabetes mellitus (DM) is considered a global pandemic, and the incidence of DM continues to grow worldwide. Nutrients and dietary patterns are central issues in the prevention, development and treatment of this disease. The pathogenesis of DM is not completely understood, but nutrient-gene interactions at different levels, genetic predisposition and dietary factors appear to be involved. Nutritional genomics studies generally focus on dietary patterns according to genetic variations, the role of gene-nutrient interactions, gene-diet-phenotype interactions and epigenetic modifications caused by nutrients; these studies will facilitate an understanding of the early molecular events that occur in DM and will contribute to the identification of better biomarkers and diagnostics tools. In particular, this approach will help to develop tailored diets that maximize the use of nutrients and other functional ingredients present in food, which will aid in the prevention and delay of DM and its complications. This review discusses the current state of nutrigenetics, nutrigenomics and epigenomics research on DM. Here, we provide an overview of the role of gene variants and nutrient interactions, the importance of nutrients and dietary patterns on gene expression, how epigenetic changes and micro RNAs (miRNAs) can alter cellular signaling in response to nutrients and the dietary interventions that may help to prevent the onset of DM.

Associations between two single nucleotide polymorphisms of the adiponectin gene, its circulating concentrations and cardiometabolic risk factors in prepubertal children with and without abdominal obesity

BACKGROUND

The adiponectin gene has been identified as a susceptibility locus for metabolic syndrome, diabetes and cardiovascular disease.

AIM

To examine the influence of two single nucleotide polymorphisms (SNPs) of this gene (+276G>T and +45T>G) on circulating adiponectin concentrations, and to evaluate their relationship with adiposity and cardiometabolic risk factors in prepubertal children with and without abdominal obesity.

MATERIAL AND METHODS

168 children (78M, 6-10 yr) were examined, divided into three groups based on waist circumference (WC). Auxological and biochemical parameters were measured by standard procedures. Adiponectin SNPs were genotyped using TaqMan allelic discrimination assays.

RESULTS

Adiponectin concentration correlated inversely with measures of adiposity (rBMIz-score=-0.211, pBMIz-score=0.007; rwc=-0.210, pwc=0.008; rwc/height=-0.215, pwc/height=0.006), and was significantly influenced by blood glucose, insulin and systolic blood pressure (SBP). The +276T-allele carriers had higher SBP and diastolic BP compared to GG-homozygotes (p<0.05), and expressed higher obesity-related measures and lower adiponectin concentrations. As to the +45T>G SNP, the GGsubject had higher total cholesterol and LDL-C concentrations compared to the T-allele carriers (p<0.05), showing worse obesity measures, higher triglyceride, glucose and insulin and lower serum adiponectin values.

CONCLUSION

Genetic variants of the adiponectin gene had an impact on adiposity, adiponectin concentrations and some cardiometabolic variables among prepubertal children.

Association of the + 45T>G adiponectin gene polymorphism with insulin resistance in non-diabetic Saudi women

BACKGROUND

The human adiponectin gene variations are associated with obesity, insulin resistance, and diabetes. However, these associations have not been fully examined in a non-diabetic population in Saudi Arabia. We aimed to investigate the association of 45T>G single nucleotide polymorphism (SNP) in the adiponectin gene with total adiponectin levels, insulin resistance (IR), fasting blood glucose (FBG) and other markers of obesity in non-diabetic Saudi females.

METHODS

One hundred non diabetic Saudi females were enrolled in this study. They were further divided according to their body mass index (BMI) into two groups. Group I, 46 non diabetic subjects with normal body weight and group II, 54 overweight and obese females. Adiponectin 45T/G polymorphism was detected by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serum adiponectin was measured by ELISA.

RESULTS

Obese women exhibited a higher distribution of TG/GG genotype compared with non-obese women. SNP +45T>G genotypes were associated with higher FBG, insulin levels and HOMA-IR with lower total adiponectin levels in obese Saudi women. Otherwise the all estimated variables revealed non-significant differences among the non-obese genotypes. The observed differences in insulin resistance markers were very significant among women with a higher body weight but not among normal body weight women, thus suggesting that SNP +45T>G effects on insulin sensitivity may depend upon body weight and body fat status.

CONCLUSION

SNP +45T>G of adiponectin gene has a significant role in the development of insulin resistance in Saudi women possibly through an interaction with increase body weight and hypoadiponectinemia.

Variants of the adiponectin gene and diabetic microvascular complications in patients with type 2 diabetes

OBJECTIVE

The aim of this study was to examine the association between common polymorphisms of the adiponectin gene (ADIPOQ) and microvascular complications in patients with type 2 diabetes mellitus (T2DM).

RESEARCH DESIGN AND METHODS

Rs2241766 and rs1501299 of ADIPOQ were genotyped in 708 patients with T2DM. Fundus photography, nerve conducting velocity, and urine analysis were performed to check for the presence of microvascular complications including diabetic nephropathy, retinopathy and neuropathy.

RESULTS

The prevalence of diabetic nephropathy tended to be different according to rs2241766 genotype (p=0.057) and the GG genotype of rs2241766 was associated with diabetic nephropathy [urine albumin/creatinine ratio (UACR) greater than 30 mg/g] after adjusting for age, sex, body mass index, duration of diabetes, HDL-cholesterol, smoking status, and blood pressure (odds ratio=1.96; 95% confidence interval=1.01-3.82, p=0.049). Also, the G allele of rs2241766 demonstrated a trend to be associated with an increase in UACR (p=0.087). Rs2241766 genotype was not associated with diabetic retinopathy (p=0.955) and neuropathy (p=0.104) or any diabetic microvascular complications (p=0.104). There was no significant association between the rs1501299 genotype of ADIPOQ and the prevalence of diabetic retinopathy and neuropathy or any diabetic microvascular complications even after adjustment.

CONCLUSION

These data suggest that the GG genotype at rs2241766 is implicated in the pathogenesis of risk for diabetic nephropathy defined as UACR greater than 30 mg/day in patients with T2DM.

Association of ADIPOQ +45T>G polymorphism with body fat mass and blood levels of soluble adiponectin and inflammation markers in a Mexican-Mestizo population

PURPOSE

Obesity is a disease with genetic susceptibility characterized by an increase in storage and irregular distribution of body fat. In obese patients, the decrease in the Adiponectin gene (ADIPOQ) expression has been associated with a systemic low-grade inflammatory state. Our aim was to investigate the relationship between ADIPOQ +45T>G gene simple nucleotide polymorphism (SNP rs2241766) with serum adiponectin (sAdiponectin), distribution of body fat storage, and inflammation markers.

SUBJECTS AND METHODS

In this cross-sectional study, 242 individuals from Western Mexico characterized as Mexican-Mestizo and classified by body mass index (BMI), were included. Anthropometrics, body composition, body fat distribution, and inflammation markers were measured by routine methods. Genotypes were characterized using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique and sAdiponectin by the ELISA method. A P-value <0.05 was considered the statistically significant threshold.

RESULTS

sAdiponectin is associated with BMI (P < 0.001) and the genotypes (P < 0.001 to 0.0046) GG (8169 ± 1162 ng/mL), TG (5189 ± 501 ng/mL), and TT (3741 ± 323 ng/mL), but the SNP ADIPOQ +45T>G is not associated with BMI. However, the detailed analysis showed association of this SNP with a pattern of fat distribution and correlations (P < 0.05) with inflammation markers and distribution of body fat storage (Pearson's r = -0.169 to -0.465) were found.

CONCLUSION

In this study, we have suggested that the ADIPOQ +45G allele could be associated with distribution of body fat storage in obesity. On the other hand, as no association was observed between ADIPOQ +45T>G gene polymorphism and obesity, it cannot be concluded that the ADIPOQ +45G allele is responsible for the increase of adiponectin levels.

A meta-analysis of the association of adiponectin gene polymorphisms with coronary heart disease in Chinese Han population

OBJECTIVE

  Variants of adiponectin gene have been reported to be associated with coronary heart disease (CHD), but the available data on this relationship are inconsistent. A meta-analysis was performed to quantitatively analyse the association of adiponectin gene polymorphisms with coronary artery disease using previous case-control studies in Chinese Han populations.

METHODS

  Several electronic databases were searched for relevant articles up to January 2011. After data collection and gene loci selection, a meta-analysis was performed to assess heterogeneity, combine results and evaluate variations. Publication bias was examined by the Egger's linear regression test. Hardy-Weinberg equilibrium (HWE) test and by omitting one study at a time was employed for the sensitivity analysis.

RESULTS

  Eleven studies covering 4303 subjects focusing on two polymorphisms [+45T→G (rs2241766) and +276G→T (rs1501299)] in the adiponectin gene and risk of CHD were included in the meta-analysis. Combined analyses of studies of the SNP+45 showed no significant overall association with CHD, yielding ORs of 1·03 (0·80, 1·34) and 1·32 (0·86, 2·03) under a dominant and recessive model, respectively, with strong evidence of heterogeneity. Similar results were also obtained in other genetic models. Concerning SNP+276, a significantly decreased CHD risk was observed under a dominant model, a codominant model and a allele contrast model, with an odds ratio of 0·67 (0·54, 0·83), 0·77 (0·62, 0·94) and 0·69 (0·55, 0·86), respectively. Sensitivity analysis confirmed the reliability and stability of this meta-analysis.

CONCLUSIONS

  The accumulated evidence suggested that the adiponectin gene polymorphism, SNP+45, is not associated with CHD, but the SNP+276T allele might be associated with decreased risk of CHD in the Chinese Han population. More well-designed large studies are required for the validation of this association.

Recessive protective effect of ADIPOQ rs1501299 on cardiovascular diseases with type 2 diabetes: a meta-analysis

The association between a common variant of the ADIPOQ gene rs1501299 (+276G>T) and cardiovascular diseases (CVDs) outcomes has been reported with many studies. However, the evidence is insufficient for strong conclusions regarding CVDs and ADIPOQ rs15011299 (+276G>T). We performed a meta-analysis about the association between ADIPOQ rs1501299 (+276G>T) and CVDs risk using a predefined protocol, including 15 published studies with 5868 cases and 10,744 controls. The pooled data suggested a recessive protective effect of ADIPOQ rs1501299 (+276G>T) on CVDs for type 2 diabetes (T2D) population: the TT homozygote individuals had a reduced risk of developing CVDs compared to the carriers of G allele (OR=0.74, 95% confidence interval (CI): 0.58, 0.94; p=0.013). But there is still not enough evidence to indicate the association of the ADIPOQ rs1501299 (+276G>T) and the development of cardiovascular diseases (CVDs) outcomes in general population. In conclusion, our meta-analysis suggested that the ADIPOQ rs1501299 (+276G>T) polymorphism is a low-risk factor for the development of CVDs with T2D, but the association of this polymorphism with the susceptibility to CVDs in other populations remains unknown. It could be presumed that the ADIPOQ rs1501299 (+276G>T) be a potential cause of susceptibility to CVDs in persons with T2D, and it gives a new opportunity to investigate the mechanisms of CVDs susceptibility in T2D patients.

Single-nucleotide polymorphisms at the adiponectin locus and risk of coronary artery disease in Tunisian coronaries

OBJECTIVE

Adiponectin is an adipocyte-derived hormone and an essential modulator of insulin sensitivity. Several studies suggest an important role of adiponectin in the process leading to atherosclerosis, thus indicating the adiponectin gene as a potential candidate for coronary artery disease. Two single-nucleotide polymorphisms (SNPs) at the adiponectin locus (+45T/G and +276G/T) have been associated with low circulating adiponectin levels, insulin resistance and type 2 diabetes. The objective was to examine the association of two SNPs (45T/G and 276G/T) with coronary artery disease in a Tunisian population.

METHODS

We have recruited 316 Tunisian patients, documented by coronary angiography. Significant coronary stenosis (SCS) was defined as a luminal narrowing of at least 50% in at least one major coronary artery. Genotyping was performed by polymerase chain reaction restriction fragment length polymorphism. Lipids and apolipoproteins were measured.

RESULTS

After adjustments for confounder parameters, odds ratio (OR) of SCS associated with 276G/T mutated genotypes was 0.472 [95% confidence interval (CI) 0.195-0.842, P=0.046]. The mutated genotypes at the +45T/G polymorphism were significantly associated with increased SCS only in obese patients (OR 3.31, 95% CI 0.996-11.05, P=0.049 versus OR 1.71, 95% CI 0.467-6.269, P=0.418 in non-obese individuals). A potential protective effect was also observed for the haplogenotype TT/TT (OR 0.548, 0.306-0.982, P=0.043) in all the studied population.

CONCLUSION

Mutated genotypes at +45T/G (GG + TG) were associated with an increase in SCS only in the obese group. Mutated genotypes at +276G/T (TT + GT) seem to reduce the risk of SCS in the studied population. When the two SNPs were combined, the TT/TT haplogenotype (normal genotype at 45T/G and mutated genotype at 276G/T) was associated with a protective effect.

The adiponectin gene, ADIPOQ, and genetic susceptibility to colon cancer

In order to evaluate the contribution of polymorphisms of the adiponectin gene, ADIPOQ, to the risk of colon cancer, we conducted a case-control study of 60 colon cancer patients and 60 age, gender and ethnicity-matched controls in the Saudi population. We tested the hypothesis by analyzing the genotypes for two single nucleotide polymorphisms (SNPs), rs1501299 (G276T) and rs2241766 (T45G), in the ADIPOQ gene. In addition, the study was also designed to assess whether the two SNPs contribute to circulating adiponectin levels. We observed an increased risk of colon cancer associated with the 276T allele. The odds ratio (OR) was 2.64 [95% confidence interval (CI), 0.49-14.6]. The G allele at the T45G polymorphism was associated with a lower risk of colon cancer (OR=0.41; 95% CI, 0.19-0.86). Our results suggest that the risk of developing colon cancer may be partially explained by genetic polymorphisms in the ADIPOQ gene.

Population-specific coding variant underlies genome-wide association with adiponectin level

Adiponectin is a protein hormone that can affect major metabolic processes including glucose regulation and fat metabolism. Our previous genome-wide association (GWA) study of circulating plasma adiponectin levels in Filipino women from the Cebu Longitudinal Health and Nutrition Survey (CLHNS) detected a 100 kb two-SNP haplotype at KNG1-ADIPOQ associated with reduced adiponectin (frequency = 0.050, P = 1.8 × 10(-25)). Subsequent genotyping of CLHNS young adult offspring detected an uncommon variant [minor allele frequency (MAF) = 0.025] located ~800 kb from ADIPOQ that showed strong association with lower adiponectin levels (P = 2.7 × 10(-15), n = 1695) and tagged a subset of KNG1-ADIPOQ haplotype carriers with even lower adiponectin levels. Sequencing of the ADIPOQ-coding region detected variant R221S (MAF = 0.015, P = 2.9 × 10(-69)), which explained 17.1% of the variance in adiponectin levels and largely accounted for the initial GWA signal in Filipinos. R221S was not present in 12 514 Europeans with previously sequenced exons. To explore the mechanism of this substitution, we re-measured adiponectin level in 20 R221S offspring carriers and 20 non-carriers using two alternative antibodies and determined that the presence of R221S resulted in artificially low quantification of adiponectin level using the original immunoassay. These data provide an example of an uncommon variant responsible for a GWA signal and demonstrate that genetic associations with phenotypes measured by antibody-based quantification methods can be affected by uncommon coding SNPs residing in the antibody target region.

Influence of the interaction between the adiponectin G276T polymorphism and body mass index on lipid levels in healthy children

Adiponectin is an adipose tissue-specific hormone which is inversely associated with metabolic alterations related to atherosclerosis. Polymorphisms in the adiponectin gene (AdipoQ) have been related to low adiponectin levels as well as several cardiovascular risk factors, but this association remains controversial. In our study we investigated the relationship between the AdipoQ T45G (rs: 2241766) and G276T (rs: 1501299) polymorphisms and adiponectin concentrations, blood pressure, and lipid and insulin levels, in a population-based sample of 12- to 16-year-old children. The study included 815 healthy Spanish children (388 boys and 427 girls). Plasma glucose and lipid levels were determined by standard methods. Insulin concentrations were measured by RIA, and serum adiponectin levels were determined by ELISA. The AdipoQ T45G and AdipoQ G276T polymorphisms were determined by TaqMan(®) allelic discrimination assays. ANOVA or t test allowed for comparison of the studied parameters across genotypes or genotype groups, respectively. A linear regression analysis was performed to examine the independent relationships of the lipid variables with BMI (body mass index), AdipoQ G276T polymorphism and the interaction between the two. When independently comparing the effect of these polymorphisms in normal-weight and overweight children, we observed that overweight boys carriers of the minor allele T had significantly lower TC, LDL-C and apo A-I levels than non-carriers, but these differences were not apparent in normal-weight boys. Furthermore, linear regression analysis demonstrated that interaction between the BMI and the AdipoQ G276T polymorphism is a significant factor explaining the variations of TC and LDL-C levels. To our knowledge, this is the first study to report an association between the AdipoQ G276T polymorphism and lipid levels in overweight boys alone, thereby suggesting that the influence of the AdipoQ polymorphisms on cardiovascular risk factors may be dependent on BMI.

ADIPOQ Gene Variants Associated with Susceptibility to Obesity and Low Serum Adiponectin Levels in Healthy Koreans

OBJECTIVES

This study aimed to measure the association between the adiponectin, C1Q and collagen domain-containing (ADIPOQ) gene variants and obesity in Koreans.

METHODS

Three single nucleotide polymorphisms located in the ADIPOQ gene were genotyped in a population-based cross-sectional study of 986 healthy Koreans. Three different case-control groups (i.e. G1, G2, and G3) were defined according to body mass index (BMI) and serum adiponectin levels. Allelic and genotypic associations of this gene with obesity were measured using multivariate logistic regression analyses in each group.

RESULTS

The G allele of -11377C>G, a polymorphism located in the promoter region of the ADIPOQ gene (odds ratio (OR), 1.48; 95% confidence interval, 1.13-1.94) and most haplotypes including this allele significantly increased the risk for obesity. However, the OR decreased from 3.98 (G1 group) to 2.90 (G2 group) and 2.30 (G3 group) when a less strict definition of obesity was used. Most haplotypes, including this allele, significantly increased the risk of obesity. The statistical evidence from the GG genotype of -11377C>G (OR, 3.98) and the GT/GT diplotype composed of -11377G>C and +45T>G (OR, 5.20) confirmed the contribution of the G allele toward a predisposition for obesity.

CONCLUSION

These results suggest the contribution of the ADIPOQ gene toward susceptibility to obesity in healthy Koreans. The high-risk genotypes and haplotypes identified here may provide more information for identifying individuals who are at risk of obesity.

Adiponectin gene polymorphisms and their effect on the risk of myocardial infarction and type 2 diabetes: an association study in an Italian population

OBJECTIVE

While many studies have shown an association between the gene coding for adiponectin (ADIPOQ) and adiponectin levels, much more controversy surrounds its association with metabolic traits such as insulin resistance, obesity and type 2 diabetes. Furthermore, very few studies have looked into the relations between ADIPOQ variants and risk of cardiovascular disease. The present study assessed the influence of four common ADIPOQ Single Nucleotide Polymorphisms (SNPs), rs17300539 (-11391G→A), rs266729 (-11377C→G), rs2241766 (+45T→G) and rs1501299 (+276G→T) on the risk of myocardial infarction and type 2 diabetes.

METHODS

and

RESULTS

A large genetic association case-control study was conducted in 2008 Italians, including patients with myocardial infarction, type 2 diabetes, or both, and a reference group of healthy controls. Homozygotes TT for the rs1501299 (+276) had half the risk of either myocardial infarction alone or in association with type 2 diabetes when compared to the carriers of the G allele (OR = 0.58, p =0.01, and OR = 0.55, p =0.006 respectively). SNPs rs17300539 (-11391), rs266729 (-11377) and rs2241766 (+45) showed no significant association with any of the three case groups.

CONCLUSIONS

These results suggest that homozygotes TT for the adiponectin polymorphism rs1501299 (+276) are protected from the risk of myocardial infarction.

Analysis of adiponectin gene polymorphisms in dilated cardiomyopathy in a Han Chinese population

Dilated cardiomyopathy (DCM) is a heart muscle disease characterized by ventricular chamber enlargement and systolic dysfunction with normal left ventricular wall thickness. The pathogenesis of DCM has been extensively studied for many years, but it remains elusive. Adiponectin is an adipocyte-derived cytokine with anti-inflammatory, antidiabetic, and antiatherogenic properties. To assess the role of adiponectin in DCM, we examined two single-nucleotide polymorphisms in the adiponectin gene, rs1501299 and rs2241766. A total of 203 DCM patients and 258 control subjects were recruited in this study and all single-nucleotide polymorphisms were genotyped by polymerase chain reaction-restriction fragment length polymorphism. No statistically significant differences in genotype and allele frequencies were observed between DCM and controls with any of the adiponectin genetic variants. These data may provide evidence that adiponectin polymorphisms do not play a role in the susceptibility of DCM in the Han Chinese population.

Association of genetic variants in the adiponectin encoding gene (ADIPOQ) with type 2 diabetes in Japanese Brazilians

AIM

The objective of this study is to assess the contribution of ADIPOQ variants to type 2 diabetes in Japanese Brazilians.

METHODS

We genotyped 200 patients with diabetes mellitus (100 male and 100 female, aged 55.0 years [47.5-64.0 years]) and 200 control subjects with normal glucose tolerant (NGT) (72 male and 128 female, aged 52.0 years [43.5-64.5 years]).

RESULTS

Whereas each polymorphism studied (T45G, G276T, and A349G) was not significantly associated with type 2 diabetes mellitus, the haplotype GGA was overrepresented in our diabetic population (9.3% against 3.1% in NGT individuals, P=.0003). Also, this haplotype was associated with decreased levels of adiponectin. We also identified three mutations in exon 3: I164T, R221S, and H241P, but, owing to the low frequencies of them, associations with type 2 diabetes could not be evaluated. The subjects carrying the R221S mutation had plasma adiponectin levels lower than those without the mutation (2.10 microg/ml [1.35-2.55 microg/ml] vs. 6.68 microg/ml [3.90-11.23 microg/ml], P=.015). Similarly, the I164T mutation carriers had mean plasma adiponectin levels lower than those noncarriers (3.73 microg/ml [3.10-4.35 microg/ml] vs. 6.68 microg/ml [3.90-11.23 microg/ml]), but this difference was not significant (P=.17).

CONCLUSIONS

We identified in the ADIPOQ gene a risk haplotype for type 2 diabetes in the Japanese Brazilian population.

Association of the +45T>G and +276G>T polymorphisms in the adiponectin gene with insulin resistance in nondiabetic Greek women

OBJECTIVE

We explored potential associations of two single nucleotide polymorphisms (SNPs) in the adiponectin gene (ADIPOQ; +45T>G, rs2241766 and +276G>T, rs1501299) with circulating total and high-molecular weight (HMW) adiponectin, insulin resistance (IR), and markers of obesity in a healthy Greek female population.

DESIGN AND METHODS

The two SNPs were genotyped in 349 women without diabetes (mean age: 47.0+/-12.1 years, mean body mass index: 28.9+/-5.6 kg/m(2)). Total and HMW adiponectin concentrations, body composition variables, IR parameters, and plasma lipid levels were determined.

RESULTS

In single SNP analysis adjusting for several potential confounders, SNP +276G>T was associated with higher fasting insulin levels (P=0.01) and higher homeostasis model assessment index for IR (HOMA-IR; P=0.009), and SNP +45T>G was associated with lower insulin levels and HOMA-IR (P=0.05 and P=0.07 respectively). No association with total or HMW adiponectin, plasma lipid levels, and body composition variables was observed; however, haplotype analysis revealed that subjects homozygous for the most common +45T/+276G haplotype had lower total adiponectin levels than did noncarriers of this haplotype (P=0.02). The observed differences in HOMA-IR were very significant among women with a higher body fat (BF) percentage (>or= the population median of 41%; all P<or=0.005), but not among leaner individuals (P for interactions 0.01-0.07), thus suggesting that ADIPOQ effects on insulin sensitivity may depend upon BF status.

CONCLUSION

Our data suggest a significant role of ADIPOQ variants at positions +45 and +276 in the development of IR in healthy Greek women possibly through an interaction with BF.

The relationship of insulin resistance with SNP 276G>T at adiponectin gene and plasma long-chain polyunsaturated fatty acids in obese children

This study examined the association of insulin resistance with single-nucleotide polymorphism (SNP) 276G>T at adiponectin gene and the plasma long-chain polyunsaturated fatty acids (LCPUFAs) profile in obese children. One hundred thirty-one normolipidaemic obese children aged 8-13 y (53 girls and 68 boys) entered the study. The prevalence of T allele carriers at SNP276 was 48.8%. Mean [SD] values of fasting insulin and homeostasis model assessment-insulin resistance (HOMA-IR) index in noncarriers versus carriers of T allele were 12.4 [6.4] versus 20.6 [6.3] muU/mL (p = 0.039) and 2.6 [1.4] versus 4.5 [1.7] (p = 0.032). Mean [SD] values of plasma C18:3n - 3, C20:5n - 3/C20:4n - 6, and n - 6/n - 3 LCPUFA in phospholipids in noncarriers versus carriers of T allele were 0.10 [0.04] versus 0.08 [0.03] % (p = 0.013), 0.04 [0.01] versus 0.03 [0.01] % (p = 0.045), and 4.4 [0.7] versus 4.9 [0.9] % (p = 0.005), respectively. Insulin resistance was independently associated with SNP 276G>T (p = 0.002) and n - 6/n - 3 LCPUFA (p = 0.042) in plasma phospholipids, and interaction was found between SNP 276G>T and n - 6/n - 3 LCPUFA (p = 0.046). These findings suggest that obese children carriers of the SNP 276G>T may be at increased risk of metabolic complications compared with noncarriers, possibly due in part to a different plasma phospholipids profile.

Plasma adiponectin levels are associated with insulin sensitivity in stroke survivors

OBJECTIVE

Adiponectin is an anti-inflammatory and insulin-sensitizing adipokine produced by adipose tissue. The purpose of this study was to determine the relationships between adiponectin and glucose metabolism in stroke survivors and to compare adiponectin levels between patients with stroke and nonstroke control subjects similar in age, sex, and body mass index.

METHODS

In all, 52 stroke survivors (35 men, 17 women) and 33 nonstroke control subjects (22 men, 11 women) had plasma adiponectin levels measured by RIA, an oral glucose tolerance test, and a peak oxygen consumption-graded treadmill test. Insulin resistance (IR) and insulin sensitivity were assessed using the homeostasis model assessment for IR (HOMA-IR) and insulin sensitivity index (ISI(M)).

RESULTS

Adiponectin levels were positively associated with age (r = 0.32, P < .05) and negatively associated with glucose homeostasis (fasting glucose: r = -0.42; insulin: r = -0.36; Glucose at (120 min): r = -0.39; HOMA-IR: r = -0.45; and ISI(M): r = 0.44, all P < .01) in stroke survivors. Adiponectin levels were significantly different among normal glucose-tolerant, impaired glucose-tolerant, and diabetic patients with stroke (11.1 +/- 0.99 v 9.56 +/- 0.99 v 5.75 +/- 1.55 ng/mL, P < .05). Adiponectin levels were 62% higher in patients with stroke than control subjects (9.29 +/- 0.62 v 5.80 +/- 0.40 ng/mL, P < .001) despite greater fasting insulin levels (81%) and 120-minute insulin (70%) in stroke survivors than control subjects (P < .05). HOMA-IR was 78% higher and ISI(M) was 81% lower in stroke survivors than control subjects (P < .05).

CONCLUSIONS

Plasma adiponectin levels are associated with age and insulin sensitivity but not adiposity in stroke survivors. The paradoxical finding that the more IR stroke survivors had higher adiponectin levels than more insulin-sensitive control subjects suggests that perhaps anti-inflammatory cytokines increase to counter an inflamed and IR state in stroke survivors.

Correlation between adiponectin polymorphisms and non-alcoholic fatty liver disease with or without metabolic syndrome in Chinese population

BACKGROUND

To investigate the effect of single nucleotide polymorphisms (SNP) 45 and 276 of the adiponectin gene on non-alcoholic fatty liver disease (NAFLD) with or without metabolic syndrome.

METHODS

A total of 165 NAFLD, 83 NAFLD with metabolic syndrome and 160 healthy controls from Chinese population were genotyped for the adiponectin gene (+45T>G and +276G>T) by PCR-restriction fragment length polymorphism methods. Plasma adiponectin and insulin levels were determined by enzyme-linked immunosorbent assay and radioimmunoassay, respectively. Insulin resistance (IR) was evaluated by using homeostasis model assessment of IR (HOMA-IR).

RESULTS

NAFLD with metabolic syndrome had further extent of IR and hypoadiponectinemia. No association of SNP45 or SNP276 was found in NAFLD or NAFLD with metabolic syndrome. Subjects carrying the G allele of SNP45 showed higher levels of triglyceride (TG), fasting blood sugar (FBS), HOMA, body mass index (BMI), and alanine transaminase (ALT), as well as lower plasma adiponectin levels. In the normal-weight group of SNP276, subjects carrying the G allele showed higher HOMA and subjects carrying the T allele showed lower BMI.

CONCLUSIONS

Our study observed further hypoadiponectinemia and IR in NAFLD with metabolic syndrome. The T45G and G276T of the adiponectin gene may not be the important determinants of NAFLD in Chinese people, but some of them still influence serum ALT, BMI, IR, lipid, glucose metabolism and plasma adiponectin concentration.

Multimers and adiponectin gene 276G>T polymorphism in the Japanese population residing in rural areas

BACKGROUND

Although it has been shown that high-molecular weight adiponectin is an active form, few studies have attempted to clarify the relationship between high molecular weight adiponectin and markers linked with cardiovascular diseases in the general population.

METHODS

We screened 236 Japanese study participants recruited from the general population, residing in one large and four small islands. In addition to serum lipids and lipoproteins, serum total adiponectin and each multimer were measured. The genotype single-nucleotide polymorphism 276G>T was detected in real-time PCR with LightCycler hybridization probes, using fluorescent-labeled nucleotides.

RESULTS

Multiple linear regression analysis showed that high-molecular weight adiponectin, as well as total adiponectin, were significantly correlated with body weight, body mass index, high-density lipoprotein cholesterol and triglycerides. Total adiponectin and high-molecular weight adiponectin concentrations were not significantly different between GG and TX (GT and TT) genotypes of 276G>T polymorphism in the adiponectin gene. Interestingly, no differences were observed for participants from the large island between GG and TX genotypes with regard to both total adiponectin and high-molecular weight adiponectin, whereas significant differences were observed for those from the small islands.

CONCLUSIONS

Our results show that total adiponectin and high-molecular weight adiponectin are associated with similar factors in the general population. Furthermore, different effects of 276G>T for participants from small and large islands suggest that regional background due to geographic barriers may control the effects of 276G>T on adiponectin concentrations.

Serum adiponectin levels and lifestyle factors in Japanese men

Adiponectin plays an important role in the development of various lifestyle-related diseases such as obesity, hypertension, type II diabetes mellitus, hyperlipidemia, and metabolic syndrome, leading to the development of heart and vascular diseases. However, the determinants that affect circulating adiponectin levels, including lifestyle factors, have still not been thoroughly investigated, in a general male population in particular. A total of 109 healthy Japanese male subjects (mean age, 55 +/- 14 years) with constant lifestyles were enrolled. All were on no medication. Fasting serum adiponectin levels were measured with an enzyme-linked immunosorbent assay. Each subject's lifestyle was assessed by the self-administered Breslow Questionnaire (a well-established method to estimate various lifestyles) with minor modifications. Partial correlation analysis for serum adiponectin levels, after controlling age and all lifestyle factors, revealed a significant and independent negative correlation between serum adiponectin levels and body mass index (BMI) (r = -0.222, P = 0.025), and a significant and independent positive correlation between serum adiponectin levels and sleep duration (r = 0.252, P = 0.011). No significant correlations were observed between adiponectin and other lifestyle factors. These data suggest that increased BMI and shorter sleep duration may be significant independent risks for low serum adiponectin levels in healthy males. Therefore, these factors may be intervention targets to modulate adiponectin to its proper levels for the prevention of cardiovascular disorders.

Adiponectin levels are reduced, independent of polymorphisms in the adiponectin gene, after supplementation with alpha-linolenic acid among healthy adults

Our first aim was to determine whether an isocaloric intervention using alpha-linolenic acid (ALA) in the form of flaxseed oil would alter adiponectin levels among overweight, otherwise healthy, males and females, and our second aim was to test for any potential modification of this intervention by 2 single nucleotide polymorphisms (276 and 45) in the adiponectin gene. Subjects included healthy adult males and females (approximately 81% female; average age, 38 years) with increased waist circumference (mean, 99 cm) and body mass index (mean, 30 kg/m(2)) who were free of chronic disease, not taking medications, and sedentary. Subjects met weekly with a registered dietician for 8 weeks. The control subjects (n = 27) were instructed not to alter their habitual diet and the ALA group (n = 30) was instructed to follow an enriched ALA diet by using flaxseed oil capsules (increasing ALA to 5% of total energy intake) and to lower their dietary fat consumption by a commensurate amount. Diets were analyzed using the Food Intake and Analysis System (v. 3.0, University of Texas School of Public Health, 1998). Fasting blood samples were obtained before and after the 8-week intervention. We found significant decreases (P = .02) in adiponectin (10.12 microg/mL pre, 9.23 microg/mL post) in the ALA group as compared with the control group (7.93 microg/mL pre, 8.10 microg/mL post) after the intervention. We also saw a decline in adiponectin in all genotype groups with the greatest decline among those carrying the rare T allele of single nucleotide polymorphism 276. There were no significant changes in fasting insulin, glucose, or quantitative insulin sensitivity check index values as a result of this intervention. In conclusion, this study suggests that supplementing with ALA for 8 weeks may lower adiponectin levels among healthy individuals, and this effect appears to be independent of polymorphisms in the adiponectin gene. Although the change in adiponectin in response to the omega-3 fatty acids was not accompanied by any change in glucose, insulin, or quantitative insulin sensitivity check index, long-term implications of such a decrease should be considered in future studies.

Genetics of the metabolic syndrome

The concept of a metabolic syndrome (MetS), a cluster of pre-clinical metabolic alterations commonly associated with obesity, is the object of much debate. Genetic studies have the potential to contribute to some of the key questions, including the true nature of the cluster of pre-clinical features and whether it is associated with human genetic variation. This review summarizes the evidence for the presence of familial aggregation for the individual components of MetS and their heritability levels. It also provides an overview of the studies that have dealt with candidate genes for MetS. Potential leads from genome-wide linkage scans are also discussed. The assumption is made that obesity, ectopic fat deposition and abnormal adipose tissue metabolism are responsible for alterations in lipid metabolism, which in turn generates the commonly observed pre-clinical shifts in glucose tolerance, lipids and lipoprotein profile, blood pressure, inflammatory markers, endothelial function, and a prothrombotic state. Progress in the understanding of the genetic basis of MetS should occur as soon as a consensus is reached on the true nature of MetS, its components and diagnostic criteria.

Genetic influences of adiponectin on insulin resistance, type 2 diabetes, and cardiovascular disease

Recent evidence points to molecules secreted by the adipose tissue, or adipokines, as possible links between increased adipose mass and metabolic abnormalities. Among these molecules, adiponectin has drawn much attention because of its insulin-sensitizing and antiatherogenic actions, suggesting that genetic deficits in its production or action may contribute to insulin resistance and coronary artery disease (CAD). A meta-analysis of the data published to date supports this hypothesis. Two independent effects, corresponding to the two linkage disequilibrium blocks that can be identified at the adiponectin locus, appear to be present. In the 5' block, the g.-11391G-->A variant has a modest but significant effect on adiponectinemia, with a mean difference between genotypes of 1.64 ng/ml (95% CI 0.88-2.41). In the 3' block, the g.+276G-->T variant is a strong determinant of insulin resistance and CAD, with minor allele homozygotes having a lower homeostasis model assessment of insulin resistance (HOMA(IR)) index (-0.36 units, 95% CI 0.24-0.47) and a lower cardiovascular risk (odds ratio 0.55, 95% CI 0.38-0.80) than carriers of other genotypes. No consistent effect on BMI or risk of type 2 diabetes is evident. Polymorphisms in the genes coding for the adiponectin receptors may also influence the risk of insulin resistance and CAD, but data on these genes are still too sparse to draw firm conclusions. In summary, the studies published to date indicate that polymorphisms at the adiponectin locus are indeed predictors of circulating adiponectin levels, insulin sensitivity, and atherosclerosis, highlighting the pivotal role of this adipokine in the modulation of metabolism and atherogenesis.

Metabolic syndrome pathophysiology: the role of adipose tissue

Several pathophysiological explanations for the metabolic syndrome have been proposed involving insulin resistance, chronic inflammation and ectopic fat accumulation following adipose tissue saturation. However, current concepts create several paradoxes, including limited cardiovascular risk reduction with intensive glucose control in diabetics, therapies that result in weight gain (PPAR agonists), and presence of some of the metabolic traits among some lipodystrophies. We propose the functional failure of an organ, in this case, the adipose tissue as a model to interpret its manifestations and to reconcile some of the apparent paradox. A cornerstone of this model is the failure of the adipose tissue to buffer postprandial lipids. In addition, homeostatic feedback loops guide physiological and pathological adipose tissue activities. Fat turnover is determined by a complex equilibrium in which insulin is a main factor but not the only one. Chronically inadequate energy balance may be a key factor, stressing the system. In this situation, an adipose tissue functional failure occurs resulting in changes in systemic energy delivery, impaired glucose consumption and activation of self-regulatory mechanisms that extend their influence to whole body homeostasis system. These include changes in adipokines secretion and vascular effects. The functional capacity of the adipose tissue varies among subjects explaining the incomplete overlapping among the metabolic syndrome and obesity. Variations at multiple gene loci will be partially responsible for these interindividual differences. Two of those candidate genes, the adiponectin (APM1) and the perilipin (PLIN) genes, are discussed in more detail.

Common adiponectin gene variants show different effects on risk of cardiovascular disease and type 2 diabetes in European subjects

Alterations in the secretion of adipokines may explain the link between obesity, type 2 diabetes (T2DM) and coronary artery disease (CAD). These conditions have been associated with variation in the adiponectin gene, although evidence for this relationship has been variable, with differences found even in similar samples. This study aims to clarify these inconsistencies by determining the impact of identified adiponectin gene (ADIPOQ) variants (-11391G>A,-1377C>G[promoter] and +45T>G[exon 2] and +276G>T[intron 2]) on the prospective risk of CAD and T2DM in healthy men, and on adverse metabolic markers, in myocardial infarct survivors and controls from different parts of Europe. The hazard ratio for cardiovascular disease varied across the -11391GG/GA/AA(p = 0.03) and -11371CC/CG/GG(p = 0.05) genotypes only. In contrast, only the +45T>G variant (3.80[1.76-8.24]) was associated with T2DM, while two haplotypes GCTT/GCGG (p < 0.05) and +276G>T(p = 0.01) increased risk in interaction with obesity. The variants were associated with a number of biomarkers in Southern but not Northern Europe (p = 0.01), despite no significant differences in allele or haplotype frequencies (p > 0.44). A risk haplotype could not be identified in either sample. Adiponectin gene variants are hence currently poor markers for the development of T2DM and CAD. Their influence on risk depends significantly on interactions that are not currently understood with either genetic variation elsewhere or the environment of the sample studied.

Dietary fat, genes and insulin sensitivity

Both insulin resistance and dyslipidaemia are determined by genetic and environmental factors. Depending on their expression and their function, gene variants may influence either insulin action or dyslipidaemia. The purpose of this review was to give some examples from recent studies of gene variants that influence insulin signalling and the interaction between gene and diet to predispose insulin resistance. Recent findings indicate a major role for genetic susceptibility to the insulin resistance syndrome. Nutrition also plays an important role in the development and progression of the condition. Genetic background may interact with habitual dietary fat composition, affecting predisposition to the insulin resistance syndrome and individual responsiveness to changes in dietary fat intake. Due to the complex nature of gene-environment interactions, therefore, therapeutic dietary therapy may require a 'personalized' nutrition approach in the future. Although results have not always been consistent, gene variants that affect primary insulin action or dyslipidaemia, and particularly their interaction with the environment, are important modulators of glucose metabolism and insulin resistance syndrome.

Identification of adiponectin and its receptors in human osteoblast-like cells and association of T45G polymorphism in exon 2 of adiponectin gene with lumbar spine bone mineral density in Korean women

OBJECTIVE

The role of adiponectin in bone metabolism has been recently reported in in vitro and in vivo studies. There has been no report on the association of adiponectin gene polymorphism and bone mineral density (BMD). Therefore, we investigated whether two single nucleotide polymorphisms (SNPs), T45G and G276T, in the adiponectin gene were related to BMD in Koreans. We also report on the identification of adiponectin and its receptors 1 and 2 in human osteoblast-like cell lines.

PATIENTS AND MEASUREMENTS

MG-63 cells were cultured and osteogenic and adipogenic differentiations from human mesenchymal stem cells (hMSCs) were performed. RNA was then extracted from the cultured cells and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed using primers for adiponectin and for the adiponectin receptor genes. In 249 female and 80 male subjects, measurements were made of their lumbar spine and femoral neck BMDs, and biochemical markers of bone turnover. The genotyping of the T45G polymorphism in exon 2 and the G276T polymorphisms in intron 2 in the adiponectin gene was performed using an allelic discrimination assay with a TaqMan probe. Analyses were performed separately in each cohort.

RESULTS

We found that the mRNAs for adiponectin and for adiponectin receptor 1 (AdipoR1) and 2 (AdipoR2) were expressed in the MG-63 cells. Sequencing of the PCR products revealed that they were identical to human adiponectin, AdipoR1 and AdipoR2, respectively. mRNAs for adiponectin, AdipoR1 and AdipoR2 were also expressed in the osteoblastic and adipogenic cell lines differentiated from hMSCs. For the polymorphism study, the frequencies of T45G and G276T in the adiponectin gene were in compliance with Hardy-Weinberg equilibrium and the two polymorphisms were in complete linkage disequilibrium (D' = -1.0, P < 0.001). In the female cohort, subjects with G alleles at the T45G locus had significantly lower lumbar spine BMD than those subjects with the TT genotype. Although BMD levels showed no association with the G276T locus, the GT genotype group showed significantly higher urine deoxypyridinoline levels than other genotype groups. In the male cohort, no association was observed between adiponectin genotypes and BMD levels.

CONCLUSIONS

We observed the expression of adiponectin, AdipoR1 and AdipoR2 in the MG-63 cell line and the osteoblastic cell line differentiated from hMSCs. T45G polymorphism in exon 2 of the adiponectin gene is associated with lumbar spine BMD and G276T polymorphism in intron 2 of the adiponectin gene is associated with the urine deoxypyridinoline level in Korean women. Additional studies are needed to elucidate the precise contribution of adiponectin to bone mineral metabolism.

Association of adiponectin gene variations with risk of incident myocardial infarction and ischemic stroke: a nested case-control study

BACKGROUND

Adiponectin (ADIPOQ) gene variations are associated with risk of cardiovascular disease in patients with diabetes. No prospective data are available, however, on the risk of atherothrombotic disorders in persons with ADIPOQ variations who do not have diabetes.

METHODS

From a group of DNA samples collected at baseline in a prospective cohort of 14 916 initially healthy American men, we assessed the presence of 5 ADIPOQ genetic variants (rs266729, rs182052, rs822396, rs2241766, and rs1501299) in samples from 600 Caucasian men who subsequently suffered an atherothrombotic event (incident myocardial infarction or ischemic stroke) and from 600 age- and smoking-matched Caucasian men who remained free of reported vascular disease during follow-up (controls).

RESULTS

Genotype distributions for the variations tested were in Hardy-Weinberg equilibrium. Marker-by-marker conditional logistic regression analysis, adjusted for potential risk factors, showed an association of rs266729 [recessive: odds ratio (OR), 0.26; 95% confidence interval (CI), 0.10-0.64; P=0.004] and rs182052 (recessive: OR, 0.40; 95% CI, 0.21-0.76; P=0.006) with decreased risk of ischemic stroke. These findings remained significant after Bonferroni correction. Haplotype-based (constituted by rs266729, rs182052, and rs822396) conditional logistic regression analysis, adjusted for the same potential risk factors, showed an association of haplotype G-A-G (OR, 0.28; 95% CI, 0.09-0.87; P=0.03) with decreased risk of ischemic stroke. Prespecified analysis limited to participants without baseline diabetes showed similar significant findings.

CONCLUSIONS

The present prospective investigation provides further evidence for a protective role of adiponectin gene variation in the risk of ischemic stroke that was independent of the presence of diabetes.