Mutations in the adiponectin gene in lean and obese subjects from the Swedish obese subjects cohort

Association of Adiponectin 45T/G (rs2241766) and Visfatin 4689G/T (rs2110385) Gene Polymorphisms with Susceptibility to Obesity

Background

This study aimed to see whether the adiponectin 45T/G (rs2241766) and visfatin 4689G/T (rs2110385) gene polymorphisms in an Iranian population are linked to obesity and/or obesity-related traits in normal and obese individuals.

Methods

230 obese individuals and 169 healthy controls had their genomic DNA taken. The alleles and genotypes of the rs2241766 and rs2110385 polymorphisms were determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique.

Results

Obese individuals had considerably greater frequencies of the G allele and GG genotypes of the rs2241766 polymorphism than healthy controls (35% vs 21%, Probability (P) <0.0001, odds ratios (OR): 1.99, 95% confidence intervals (CI): 1.45-2.75 and 21% vs 7%, P = 0.002, OR: 3.52, 95% CI: 1.81-6.85, respectively). In comparison to healthy controls, obesity patients had substantially lower frequencies of the T allele and TT genotype of the rs2241766 polymorphism (65% vs 79%, P < 0.0001, OR: 0.50, 95% CI: 0.36-0.69 and 51% vs 65%, P = 0.008, OR: 0.58, 95% CI: 0.39-0.87, respectively). Obese individuals had substantially higher frequencies of the G allele and GG genotype in the rs2110385 polymorphism than healthy controls (77% vs 69%, P = 0.01, OR: 1.47, 95% CI: 1.07-2.0 and 61% versus 51%, P = 0.047, OR: 1.5, 95% CI: 1.0-2.2, respectively). When compared to healthy controls, the frequency of the T allele in the rs2110385 polymorphism was considerably lower in obese individuals (23% vs 31%, P = 0.01, OR: 0.68, 95% CI: 0.5-0.93). Furthermore, these single nucleotide polymorphisms (SNPs) were shown to have a strong link to clinical data in obese individuals. In the case of adiponectin, 45T/G (rs2241766) genotypes, serum low-density lipoprotein, waist circumference, and diastolic blood pressure were substantially different among the rs2241766 genotypes (P = 0.007, P = 0.000, and P = 0.011, respectively). In the instance of the visfatin 4689G/T (rs2110385) gene polymorphism, serum triglycerides was substantially different among the rs2110385 genotypes (P = 0.039).

Conclusions

In the Iranian population, our findings revealed a strong link between adiponectin and visfatin gene polymorphisms and obesity and several obesity-related clinical characteristics. These SNPs might be used to identify those who are at risk of becoming obese.

Is Single Nucleotide Polymorphism ADIPOQ (NM_004797.4):c.214+62G>T (rs1501299) Associated With Uterine Leiomyomas? A Pilot Study

Objective: Although polymorphisms of adiponectin gene (ADIPOQ) in obesity-related conditions have been the target of research efforts, little is known about this genetic marker in uterine leiomyomas. The aim of this pilot study was to analyze the frequencies of alleles and genotypes of Single Nucleotide Polymorphism ADIPOQ (NM_004797.4):c.214+62G>T (rs1501299) and to correlate it with the risk of uterine fibroids. Study Design: The Test Group comprised 90 women treated surgically for uterine leiomyomas in the Department of Operative Gynecology, Endoscopy and Gynecologic Oncology, Polish Mother's Memorial Hospital-Research Institute. 90 disease-free individuals were used as Controls. Patients within both groups were additionally stratified into lean, overweight and obese, according to Body Mass Index. Statistical analysis was performed between the two major groups and, furthermore, within the abovementioned subgroups. Results: The study revealed no statistically significant differences in the distribution of alleles and genotypes of SNP ADIPOQ (NM_004797.4):c.214+62G>T (rs1501299) between the two main groups. A weak correlation within distributions of alleles was observed between obese Test Patients and lean Controls. Conclusion: This pilot study has revealed no association between SNP ADIPOQ (NM_004797.4):c.214+62G>T (rs1501299) and uterine fibroids. Further studies on larger groups are warranted to elucidate whether this SNP may be correlated with uterine leiomyomas.

A genetic analysis identifies a haplotype at adiponectin locus: Association with obesity and type 2 diabetes

Adiponectin is a prime determinant of the status of insulin resistance. Association studies between adiponectin (ADIPOQ) gene single nucleotide polymorphisms (SNPs) and metabolic diseases have been reported earlier. However, results are ambiguous due to apparent contradictions. Hence, we investigated (1) the association between ADIPOQ SNPs: −11377C/G, +10211T/G, +45T/G and +276G/T for the risk towards type 2 diabetes (T2D) and, (2) genotype-phenotype association of these SNPs with various biochemical parameters in two cohorts. Genomic DNA of diabetic patients and controls from Gujarat and, Jammu and Kashmir (J&K) were genotyped using PCR-RFLP, TaqMan assay and MassArray. Transcript levels of ADIPOQ were assessed in visceral adipose tissue samples, and plasma adiponectin levels were estimated by qPCR and ELISA respectively. Results suggest: (i) reduced HMW adiponectin/total adiponectin ratio in Gujarat patients and its association with +10211T/G and +276G/T, and reduced ADIPOQ transcript levels in T2D, (ii) association of the above SNPs with increased FBG, BMI, TG, TC in Gujarat patients and (iii) increased GGTG haplotype in obese patients of Gujarat population and, (iv) association of −11377C/G with T2D in J&K population. Reduced HMW adiponectin, in the backdrop of obesity and ADIPOQ genetic variants might alter metabolic profile posing risk towards T2D.

Adipokine gene variability and plasma levels in patients with chronic periodontitis -a case-control study

Specific variants in genes that encode adipokines and their mRNA and protein expression were previously studied in type 2 diabetes mellitus (T2DM) and obesity, and similar studies have been performed for chronic periodontitis (CP). The aim of this case-control study was to investigate the possible impacts of adiponectin (ADIPOQ), leptin (LEP) and its receptor (LEPR), and resistin (RETN) on the etiopathogenesis of CP. Examinations were performed on 118 non-periodontitis healthy subjects (healthy controls, HC), 205 healthy individuals with CP (H + CP) and 86 type 2 diabetes patients with CP (T2DM + CP). Variants within the ADIPOQ (rs2241766, rs1501299), LEP (rs13228377, rs2167270), LEP receptor (rs1805096), and RETN (rs1862513) genes were determined by qPCR. In addition, the plasma levels of ADIPOQ, LEP, and RETN were analysed by ELISA for 80 individuals. The genotype frequencies of the SNP ADIPOQ +45G/T (rs2241766) differed between the HC and H + CP groups (p=0.03, pcorr>0.05), and carriers of the TT genotype had a lower risk of developing CP compared to carriers of the GG or TG genotypes (p<0.01, pcorr>0.05). However, there were no significant differences in the plasma levels of ADIPOQ, LEP or RETN between the study groups (p > 0.05). Plasma levels of the adipokines were also independent of the gene profiles (p > 0.05). Adipokine plasma levels did not change in patients with H + CP/T2DM + CP compared to HC, but we did identify a specific polymorphism in the ADIPOQ gene that was associated with CP. Although the ADIPOQ +45G/T (rs2241766) gene variant may be a candidate biomarker for CP, further research is required in larger populations with different ethnic backgrounds before any final conclusions can be drawn about the role of this gene in CP.

Association between +45T>G adiponectin polymorphism gene and type 2 diabetes mellitus and metabolic syndrome in a Venezuelan population

Background: Adiponectin (ADIPOQ) is a hormone primarily synthesized by adipocytes and encoded by the ADIPOQ gene, which exerts anti-inflammatory, antiatheratogenic and insulin sensitizing functions. It has been shown that its plasma concentrations are decreased in individuals with metabolic syndrome (MS) and type 2 diabetes mellitus (DM2), which could be due to variations in the gene coding for this protein. The aim of this study was to detect the +45 T>G polymorphism of the ADIPOQ gene in subjects with DM2 and MS in Maracaibo municipality, Zulia state, Venezuela. Methods: A total of 90 subjects who attended the Center for Metabolic Endocrine Research "Dr. Félix Gómez" were enrolled for this study, 46 of which had MS-DM2 and 44 of which were healthy control individuals. Genomic DNA was extracted from blood samples and PCR-restriction fragment length polymorphism analysis was carried out for the promoter region of the ADIPOQ gene. Likewise, the +45 T> G polymorphism was identified and correlated with MS and DM2 in the studied population. Results: The most frequent allele in both groups was the T allele, and the predominant genotype was homozygous T/T (79%). Genotypes with heterozygous T/G and G/G homozygous polymorphism were more frequent in the control group than in the MS-DM2 group. Regarding the individuals with T/G and G/G genotypes, statistically significant lower mean values ​​were found for fasting glucose, total cholesterol, triacylglycerides, abdominal circumference, and for the medians of systolic and diastolic blood pressure. Odds ratio were calculated for the presence or absence of MS and DM2. Conclusions: The results suggested that the presence of the G allele exerts a protective effect on the carrier individuals, thus avoiding the appearance of the aforementioned metabolic alterations.

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.

Prevalence, Risk Factors, and Genetic Traits in Metabolically Healthy and Unhealthy Obese Individuals

Objective. To assess prevalence of metabolically healthy individuals among patients with abdominal obesity (AO) and to determine phenotype and potential genetic traits associated with a benign metabolic status. Methods. 503 AO patients without cardiovascular diseases were examined. Waist circumference (WC), BMI, blood pressure, plasma glucose and serum insulin levels, HOMA-IR, lipid profile, and adiponectin (AN) and leptin (LEP) concentrations in serum were measured. Polymorphisms A19G and Q223R of the LEP and LEP receptor gene, and G276T and T45G of the AN gene were investigated. Results. 91.3% of patients were metabolically unhealthy obese (MUO), and 8.7% metabolically healthy obese (MHO). MHO patients were younger, and had lesser BMI and WC, while duration of obesity, frequency, and duration of physical training were greater than MUO patients (p < 0.05). In MHO and MUO patients distribution of the G19G, G19A, and A19A genotypes of the LEP gene and G276G, G276T, and T276T genotypes of AN gene did not differ. The Т45Т genotype was associated with increase of metabolic disorders' risk for patients with АО (OR = 2.331; 95%  CI = 1.121 ÷ 5.132). Conclusions. Prevalence of MHO individuals among patients with AO is low. Benign metabolic status was associated with younger age, lower waist circumference, and higher physical activity, shorter duration of obesity, and G45G adiponectin genotype carriage.

Gender-specific associations between ADIPOQ gene polymorphisms and adiponectin levels and obesity in the Jackson Heart Study cohort

BACKGROUND

Despite the important role of adiponectin in regulating general metabolic homeostasis, analysis of genetic determinants of adiponectin and the related cardio-metabolic traits in African American population has been limited and inconsistent. Considering the high genetic admixture of African Americans and thus the important population stratification that may confound the genetic-trait associations, the objective of this work was to perform a comprehensive analysis of the associations between ADIPOQ variants and adiponectin levels and obesity phenotypes in a large African American population from the Jackson Heart Study (JHS) cohort.

METHODS

Genotype data was available for 2968 JHS participants (1131men; 1837women). Single Nucleotide Polymorphisms (SNPs) were selected by a Tag-SNP Approach and literature review. The genotype imputation was performed using IMPUTE2 software and reference phased data from the 1000G project. PLINK software was used for the genetic analysis. Plasma specimens were analyzed by ELISA for adiponectin levels. All analyses were controlled for population stratification assessed by Individual Proportions of European Ancestry (PEA) estimates calculated in HAPMIX using ancestry informative markers (AIMs).

RESULTS

We found a gender-dependent association of some ADIPOQ variants and adiponectin levels. In women four of the studied polymorphisms (rs6444174, rs16861205, rs1403697, rs7641507) were associated with adiponectin levels after Bonferroni correction and controlling for the percentage of PEA, age, annual household income and smoking. These results were consistent with the haplotype analysis. The association between the rs12495941 variant and obesity is modulated by the PEA, so that the relationship between the G allele and a higher incidence of obesity was present in those individuals within the lower PEA group. In addition we found an effect modification of obesity on the association between the ADIPOQ rs6444174 SNP and BMI so that the presence of the T allele was negatively and significantly associated with BMI only in participants with a normal weight.

CONCLUSIONS

In this large African American cohort, ADIPOQ variants were associated with adiponectin levels in a gender-dependent manner and the relationship of some of these variants with obesity and BMI was modulated by the PEA and obesity status respectively. This suggests that the effects of these polymorphisms on adiponectin and obesity phenotypes are subject to a strong interaction with genetic and environmental factors in African American population.

Association between dietary patterns and serum leptin-to-adiponectin ratio in apparently healthy adults

OBJECTIVE

Dietary patterns reflect diet and nutritional habits of individuals in a society. Various dietary patterns could influence leptin and adiponectin secretion from adipose tissue. These hormones are associated with metabolic diseases. It is suggested that the leptin-to-adiponectin (L/A) ratio might be a more useful diagnostic marker in predicting chronic diseases than leptin and adiponectin separately. The aim of this study was to investigate the association between various dietary patterns and L/A ratio in Iranian adults.

METHODS

This cross-sectional study was conducted on 150 apparently healthy subjects aged 25-50 years in Tabriz, Iran. Dietary patterns were determined using 132-item semiquantitative food frequency questionnaire on a 5-point scale. Weight, height, waist circumference (WC), as well as fasting serum leptin and adiponectin levels were measured to assess the association between dietary patterns and L/A ratio.

RESULTS

Four major dietary patterns were identified using a factor analysis approach: Western, healthy, mixed, and traditional dietary patterns. Linear regression analysis showed that a Western dietary pattern was negatively associated with serum adiponectin concentration, even after adjusting for the confounders (r = -0.19, p = 0.02). No statistically significant associations were found between any dietary pattern and leptin (r = -0.14, p = 0.06) or L/A ratio (r = -0.10, p = 0.09).

CONCLUSION

Our findings indicate an inverse association between a Western dietary pattern and serum adiponectin levels but not for serum leptin or L/A ratio.

Genetic polymorphisms of cytokine genes in type 2 diabetes mellitus

Diabetes mellitus is a combined metabolic disorder which includes hyperglycemia, dyslipidemia, stroke and several other complications. Various groups all over the world are relentlessly working out the possible role of a vast number of genes associated with type 2 diabetes (T2DM). Inflammation is an important outcome of any kind of imbalance in the body and is therefore an indicator of several diseases, including T2DM. Various ethnic populations around the world show different levels of variations in single nucleotide polymorphisms (SNPs). The present review was undertaken to explore the association of cytokine gene polymorphisms with T2DM in populations of different ethnicities. This will lead to the understanding of the role of cytokine genes in T2DM risk and development. Association studies of genotypes of SNPs present in cytokine genes will help to identify risk haplotype(s) for disease susceptibility by developing prognostic markers and alter treatment strategies for T2DM and related complications. This will enable individuals at risk to take prior precautionary measures and avoid or delay the onset of the disease. Future challenges will be to understand the genotypic interactions between SNPs in one cytokine gene or several genes at different loci and study their association with T2DM.

Association of adiponectin (ADIPOQ) rs2241766 polymorphism and dyslipidemia in HIV/HCV-coinfected patients

BACKGROUND

The adiponectin (ADIPOQ) rs2241766 polymorphism is related to metabolic abnormalities. The aim of this study was to evaluate the association of the ADIPOQ rs2241766 polymorphism with serum dyslipidemia and insulin resistance (IR) in human immunodeficiency virus (HIV)/hepatitis C virus (HCV)-coinfected patients.

METHODS

We carried out a cross-sectional study on 262 patients. ADIPOQ rs2241766 polymorphisms were genotyped by GoldenGate® assay. Generalized linear models (GLMs) were used to compare continuous outcome variables (total cholesterol (TC), triglycerides (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), non-HDL-C and homeostatic model assessment (HOMA)) and categorical outcome variables (TC≥200 mg/dL, TG≥170 mg/dL, LDL-C≥100 mg/dL, HDL-C≤35 mg/dL, non-HDL-C≥120 mg/dL and HOMA≥3·8) according to ADIPOQ genotype under a dominant inheritance model.

RESULTS

Patients with the rs2241766 GG/GT genotype had significantly lower serum TC levels (P=0·038) and percentages of TC≥200 mg/dL (P=0·022) than rs2241766 TT carriers. When adjusted GLM was performed, rs2241766 GG/GT was associated with low serum TC levels (arithmetic mean ratio (AMR)=0·92 [(95% CI=0·85; 0·99) P=0·024]) and low likelihood of TC≥200 mg/dL (odds ratio (OR)=0·32 [(95% CI=0·11; 0·88) P=0·027]. When stratifying by steatosis, no significant values were found for patients without steatosis. However, for patients with steatosis, rs2241766 GG/GT genotypes were related to low TC serum values of TC (AMR=0·89; P=0·027), LDL-C (AMR=0·85; P=0·039) and non-HDL-C (AMR=0·86; P=0·015). No significant associations were found between rs2241766 and HOMA values.

CONCLUSIONS

The presence of the ADIPOQ rs2241766 G allele (GG/GT genotype) was associated with a protective effect against dyslipidemia, primarily in HIV/HCV-coinfected patients with steatosis.

Association of adiponectin gene (ADIPOQ) rs2241766 polymorphism with obesity in adults: a meta-analysis

Background

Adiponectin plays an important role in regulating glucose levels and fatty acid oxidation. Multiple studies have assessed the association between rs2241766 polymorphism in the adiponectin (ADIPOQ) gene and obesity susceptibility. However, the results are inconsistent and inconclusive. The aim of this meta-analysis was to investigate this association in adults.

Method

Several electronic databases were searched for relevant literature published up to November 2013. Statistical analyses were performed using software Review Manager (Version 5.02) and STATA (Version 10.0). The pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated with a random-effects model or a fixed-effect model depending on heterogeneity among studies. Q tests and Egger’s tests were performed to assess heterogeneity and publication bias. Sensitivity analysis was conducted to confirm the reliability and stability of the meta-analysis.

Results

A total of 2,819 obese and 3,024 controls in 18 case-control studies were included in the meta-analysis. The results indicated that compared with TT genotype, the ADIPOQ-rs2241766 GG genotype was associated with an increased risk for obesity (OR = 1.39, 95% CI: 1.11–1.73, P for heterogeneity = 0.520, I² = 0%) in overall studies. Whereas, GT genotype was associated with a borderland increased risk for obesity (OR = 1.13, 95% CI: 0.94–1.36, P for heterogeneity = 0.006, I² = 51%). The susceptibility of obesity was increased based on genotypes of TT<GT<GG (P for trend = 0.011). Subgroup analysis of different regions revealed that the ADIPOQ-rs2241766 GG genotype increased obesity risk in the Chinese studies (OR = 1.54, 95% CI: 1.19–2.00) but not in the non-Chinese studies (OR = 1.02, 95% CI: 0.66–1.58). Similar results were observed in allelic, recessive, and dominant genetic models. There was no significant evidence of publication bias in the overall, Chinese, and non-Chinese studies (P = 0.426, P = 0.935, and P = 0.390, respectively).

Conclusion

The results of this meta-analysis suggest that the ADIPOQ-rs2241766 G/T polymorphism might be associated with obesity in Chinese studies but not in non-Chinese studies in adults. Better-designed studies that consider confounding factors and assess larger sample sizes with a focus on ADIPOQ-rs2241766G/T polymorphisms and obesity are required in the future.

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.

Evidence of a causal relationship between adiponectin levels and insulin sensitivity: a Mendelian randomization study

The adipocyte-secreted protein adiponectin is associated with insulin sensitivity in observational studies. We aimed to evaluate whether this relationship is causal using a Mendelian randomization approach. In a sample of Swedish men aged 71 years (n = 942) from the Uppsala Longitudinal Study of Adult Men (ULSAM), insulin sensitivity (M/I ratio) was measured by the euglycemic insulin clamp. We used three genetic variants in the ADIPOQ locus as instrumental variables (IVs) to estimate the potential causal effect of adiponectin on insulin sensitivity and compared these with results from conventional linear regression. The three ADIPOQ variants, rs17300539, rs3774261, and rs6444175, were strongly associated with serum adiponectin levels (all P ≤ 5.3 × 10(-9)) and were also significantly associated with M/I ratio in the expected direction (all P ≤ 0.022). IV analysis confirmed that genetically determined adiponectin increased insulin sensitivity (β = 0.47-0.81, all P ≤ 0.014) comparable with observational estimates (β = 0.50, all P(difference) ≥ 0.136). Adjustment for BMI and waist circumference partly explained the association of both genetically determined and observed adiponectin levels with insulin sensitivity. The observed association between higher adiponectin levels and increased insulin sensitivity is likely to represent a causal relationship partly mediated by reduced adiposity.

+276 G/T single nucleotide polymorphism of the adiponectin gene is associated with the susceptibility to biliary atresia

BACKGROUND

Biliary atresia (BA) is an intractable neonatal inflammatory and obliterative cholangiopathy, leading to progressive fibrosis and cirrhosis. Adiponectin, an anti-inflammatory adipokine, is known to play a possible role in liver diseases. The objective of our study was to determine the relationship between adiponectin gene polymorphisms and BA susceptibility.

METHODS

A total of 106 BA patients and 107 healthy controls were included in this study. Two single nucleotide polymorphisms (SNPs) of the adiponectin gene, +45T/G (rs2241766) and +276G/T (rs1501299), were genotyped by polymerase chain reaction-restriction fragment length polymorphism analysis.

RESULTS

Genotype distributions of +45 T/G and +276 G/T SNPs were seen in the Hardy-Weinberg equilibrium for both BA patients and controls. The frequency of the G/G genotype at +276G/T was significantly higher in BA patients than in the controls (P=0.009). Regarding +45T/ G in BA patients, the frequency of the T/T genotype tended to be lower than in the controls, but the difference was not significant. Moreover, the G allele at +276G/T in BA patients was more common than in the controls (P=0.0043). In contrast, the frequency of the T allele at +45T/G was not significantly different between BA patients and the controls. None of the haplotypes studied was found to significantly influence the risk of BA.

CONCLUSIONS

+276G/T SNP is strongly associated with BA, particularly with the G allele. We postulate that the +276G/T adiponectin gene polymorphism confers increased susceptibility to BA.

Amerindians show association to obesity with adiponectin gene SNP45 and SNP276: population genetics of a food intake control and "thrifty" gene

Adiponectin gene polymorphisms SNP45 and SNP276 have been related to metabolic syndrome (MS) and related pathologies, including obesity. However results of associations are contradictory depending on which population is studied. In the present study, these adiponectin SNPs are for the first time studied in Amerindians. Allele frequencies are obtained and comparison with obesity and other MS related parameters are performed. Amerindians were also defined by characteristic HLA genes. Our main results are: (1) SNP276 T is associated to low diastolic blood pressure in Amerindians, (2) SNP45 G allele is correlated with obesity in female but not in male Amerindians, (3) SNP45/SNP276 T/G haplotype in total obese/non-obese subjects tends to show a linkage with non-obese Amerindians, (4) SNP45/SNP276 T/T haplotype is linked to obese Amerindian males. Also, a world population study is carried out finding that SNP45 T and SNP276 T alleles are the most frequent in African Blacks and are found significantly in lower frequencies in Europeans and Asians. This together with the fact that there is a linkage of this haplotype to obese Amerindian males suggest that evolutionary forces related to famine (or population density in relation with available food) may have shaped world population adiponectin polymorphism frequencies.

The Human Obesity Gene Map: The 2003 Update

This is the tenth update of the human obesity gene map, incorporating published results up to the end of October 2003 and continuing the previous format. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, quantitative trait loci (QTLs) from human genome-wide scans and animal crossbreeding experiments, and association and linkage studies with candidate genes and other markers is reviewed. Transgenic and knockout murine models relevant to obesity are also incorporated (N = 55). As of October 2003, 41 Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. QTLs reported from animal models currently number 183. There are 208 human QTLs for obesity phenotypes from genome-wide scans and candidate regions in targeted studies. A total of 35 genomic regions harbor QTLs replicated among two to five studies. Attempts to relate DNA sequence variation in specific genes to obesity phenotypes continue to grow, with 272 studies reporting positive associations with 90 candidate genes. Fifteen such candidate genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, more than 430 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful sites can be found at http://obesitygene.pbrc.edu.

The Human Obesity Gene Map: The 2004 Update

This paper presents the eleventh update of the human obesity gene map, which incorporates published results up to the end of October 2004. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTLs) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2004, 173 human obesity cases due to single-gene mutations in 10 different genes have been reported, and 49 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 166 genes which, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 221. The number of human obesity QTLs derived from genome scans continues to grow, and we have now 204 QTLs for obesity-related phenotypes from 50 genome-wide scans. A total of 38 genomic regions harbor QTLs replicated among two to four studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably with 358 findings of positive associations with 113 candidate genes. Among them, 18 genes are supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. Overall, >600 genes, markers, and chromosomal regions have been associated or linked with human obesity phenotypes. The electronic version of the map with links to useful publications and genomic and other relevant sites can be found at http://obesitygene.pbrc.edu.

Effect of interaction between PPARG, PPARA and ADIPOQ gene variants and dietary fatty acids on plasma lipid profile and adiponectin concentration in a large intervention study

Unsaturated fatty acids are ligands of PPAR-γ, which up-regulates genes involved in fatty acid transport and TAG synthesis and the insulin-sensitising adipokine adiponectin, which activates fatty acid β-oxidation via PPAR-α action in liver. We investigated the effect of dietary fatty acid interaction with PPARG, PPARA and ADIPOQ gene variants on plasma lipid and adiponectin concentrations in the Reading Imperial Surrey Cambridge King's study, a five-centre, parallel design, randomised controlled trial of 466 subjects at increased cardiometabolic risk. After a 4-week run-in to baseline, SFA was replaced by MUFA or carbohydrate (low fat) in isoenergetic diets for 24 weeks. Habitual dietary PUFA:SFA ratio×PPARG Pro12Ala genotype interaction influenced plasma total cholesterol (P=0·02), LDL-cholesterol (P=0·002) and TAG (P=0·02) concentrations in White subjects. PPARA Val162Leu×PPARG Pro12Ala genotype interaction influenced total cholesterol (P=0·04) and TAG (P=0·03) concentrations at baseline. After high-MUFA and low-fat diets, total cholesterol and LDL-cholesterol were reduced (P<0·001) and gene×gene interaction determined LDL-cholesterol (P=0·003) and small dense LDL as a proportion of LDL (P=0·012). At baseline, ADIPOQ -10066 G/A A-allele was associated with lower serum adiponectin (n 360; P=0·03) in White subjects. After the high-MUFA diet, serum adiponectin increased in GG subjects and decreased in A-allele carriers (P=0·006 for difference). In GG, adiponectin increased with age after the high MUFA and decreased after the low-fat diet (P=0·003 for difference at 60 years). In conclusion, in Whites, high dietary PUFA:SFA would help to reduce plasma cholesterol and TAG in PPARG Ala12 carriers. In ADIPOQ -10066 GG homozygotes, a high-MUFA diet may help to increase adiponectin with advancing age.

Association between eight adiponectin polymorphisms, obesity, and metabolic syndrome parameters in Tunisian volunteers

BACKGROUND

Adiponectin is a plasma protein produced by the adipose tissue, with insulin sensibility, antiinflammatory and antiatherogenic properties. Many adiponectin gene polymorphisms have been described, and their implication in obesity, metabolic syndrome, and cardiovascular diseases was controversial. Our aim was to study the relationship between eight adiponectin polymorphisms (-1391G/A, -1377C/G, 4522C/T, 395 G/A, 276G/T, 639C/T, 45T/G, and +2019delA), metabolic syndrome parameters, and the risk of obesity in Tunisian volunteers.

METHODS

We have recruited 169 nonobese [sex ratio=0.594, mean age 43.25±13.12 years; mean body mass index (BMI) 24.73±3.50 kg/m(2)] and 160 obese (BMI≥30 kg/m(2)) (sex ratio=0.221, mean age 48.41±10.92 years; mean BMI 36.6±4.8 kg/m(2)). Genotyping was performed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). Glucose, insulin, and lipids were measured. BMI and homeostasis model assessment of insulin resistance (HOMA-IR) were calculated.

RESULTS

The polymorphisms 276G/T, 639 C/T, 11391 G/A, 11374C/G, and +2019delA seem to contribute to obesity. In fact, adjusted odds ratios (ORs) of obesity associated with mutated genotypes of each polymorphism were, respectively: OR=0.64, P=0.039; OR=1.85, P=0.018; OR=1.68, P=0.044; OR=1.77, P=0.038; and OR=1.94, P=0.010). Mutated genotypes at 639 C/T were associated with higher waist circumference, BMI, and systolic and diastolic blood pressure. In addition, the 11391AA genotype was associated with increased BMI. Concerning 2019delA, the delAdelA genotype was associated with increased HOMA-IR and BMI, suggesting a possible effect of these single-nucleotide polymorphisms (SNPs) on insulin resistance parameters. Mutated genotypes at 276G/T were associated with lower serum insulin concentration and lower systolic and diastolic blood pressure. The other genotypes showed no association with metabolic syndrome parameters.

CONCLUSION

Adiponectin gene polymorphisms were associated with obesity and metabolic syndrome parameters in Tunisian volunteers.

Distribution and genotype frequency of adiponectin (+45 T/G) and adiponectin receptor2 (+795 G/A) single nucleotide polymorphisms in Iranian population

The Adiponectin (ADIPOQ) gene encodes adipose tissue-secreted hormone, Adiponectin, which is secreted to the bloodstream by adipocytes. Adiponectin is a hormone with anti-inflammatory and anti-atherogenic properties and plays a significant role in insulin sensitivity and obesity. The genetic variations in ADIPOQ gene change the circulating adiponectin level and may cause insulin resistance. The aim of the present study is to evaluate the frequency of a common single nucleotide polymorphism (SNP) of ADIPOQ gene (+45T/G) and adiponectin receptor-2 (ADIPOR2) gene (+795G/A) in Iranian population and to correlate these data with other populations. A hundred healthy volunteers were enrolled to identify the genotype of ADIPOQ gene (+45T/G) and ADIPOR2 gene (+795G/A). This was performed by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Genotype frequencies for ADIPOQ (+45T/G) were 0.789 for TT, 0.164 for TG, and 0.0468 for GG. Allelic frequencies were 0.87 and 0.13 for T and G, respectively. Genotype frequencies for ADIPOR2 (+795G/A) were 0.09 for AA, 0.3 for AG, and 0.61 for GG; allelic frequencies were 0.24 for A and 0.76 for G. Comparisons between ADIPOQ and ADIPOR2 polymorphisms in Iranian population with those in other populations showed significant differences.

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 level as a consequence of genetic variation, but not leptin level or leptin: adiponectin ratio, is a risk factor for carotid intima-media thickness

BACKGROUND AND PURPOSE

The adipocytokines adiponectin and leptin have been suggested as risk factors for cardiovascular disease, including stroke, acting through atherosclerosis. However, studies have provided conflicting results in underpowered cohorts with some suggesting that the leptin:adiponectin ratio is a better predictor of risk. We examined these associations with carotid intima-media thickness (IMT), a marker of early atherosclerosis and arterial remodeling and an independent predictor of stroke. We also examined association between genetic variants in the leptin and adiponectin genes and IMT.

METHODS

Adiponectin and leptin levels were determined in 990 individuals from the community Carotid Atherosclerosis Progression Study. Five variants in the gene encoding adiponectin and 7 in the gene encoding leptin were genotyped and their effects on circulating levels assessed. Both were then correlated with IMT.

RESULTS

Adiponectin levels negatively correlated with IMT (-0.079, P=0.013). There was no correlation between leptin levels or leptin:adiponectin ratio and IMT. Two variants in the ADIPOQ gene encoding adiponectin were associated with altered adiponectin levels, 1 of which (rs266729) was associated with IMT. There was also an interaction with body mass index (P=0.019) with the association being present in obese subjects (P=0.02).

CONCLUSIONS

Our results support a causal role for adiponectin in early carotid IMT and suggest it may act through interaction with obesity. In contrast, we found no evidence of a role for leptin and no evidence that leptin:adiponectin ratio is a better predictor of risk that adiponectin levels alone.

Polymorphism in a microsatellite of the acrp30 gene and its association with growth traits in goats

Acrp30 plays a critical role in the regulation of glucose and lipid homeostasis. In this study, polymorphism of the Acrp30 gene was detected by PCR-SSCP and DNA sequencing methods in 321 individuals from three goat breeds, and the association of Acrp30 gene polymorphism with growth traits in the three goat breeds was analyzed. A novel insert/deletion (GT)(5) microsatellite sequence was detected in the 5' flanking region of the gene. Three genotypes (AA, AB, and BB) were found in three breeds. There was moderate genetic diversity in the locus in the analyzed populations. Significant associations were observed between the genotypes of the locus and growth traits in the Boer goat population. The chest circumference of individuals with genotype BB was significantly greater than that of individuals with genotype AA.

Variations in Adipokine Genes AdipoQ, Lep, and LepR are Associated with Risk for Obesity-Related Metabolic Disease: The Modulatory Role of Gene-Nutrient Interactions

Obesity rates are rapidly increasing worldwide and facilitate the development of many related disease states, such as cardiovascular disease, the metabolic syndrome, type 2 diabetes mellitus, and various types of cancer. Variation in metabolically important genes can have a great impact on a population's susceptibility to becoming obese and/or developing related complications. The adipokines adiponectin and leptin, as well as the leptin receptor, are major players in the regulation of body energy homeostasis and fat storage. This paper summarizes the findings of single nucleotide polymorphisms in these three genes and their effect on obesity and metabolic disease risk. Additionally, studies of gene-nutrient interactions involving adiponectin, leptin, and the leptin receptor are highlighted to emphasize the critical role of diet in susceptible populations.

Frequency of adiponectin gene polymorphisms in polycystic ovary syndrome and the association with serum adiponectin, androgen levels, insulin resistance and clinical parameters

AIM

Although the association between adiponectin gene polymorphisms and insulin resistance has been investigated in many studies, there are only a few studies, which have investigated adiponectin gene polymorphisms in patients with polycystic ovary syndrome (PCOS). The objectives of this study were to determine the frequency of T45G polymorphisms localised in exon 2 of the adiponectin gene in a Turkish population with PCOS and to determine the association of T45G polymorphisms with insulin resistance and serum adiponectin levels in PCOS.

MATERIALS AND METHODS

Ninety-six patients with PCOS and 93 healthy control subjects were included in the study. Insulin resistance was estimated via HOMA-IR. Serum adiponectin levels were measured by ELISA. For determination of adiponectin gene polymorphisms, PCR was performed with appropriate primers after genomic DNA was obtained from the peripheral blood of the patients and control subjects.

RESULTS

Adiponectin levels were low in patients with PCOS than control subjects. There was no significant statistical difference between the PCOS and control groups with respect to the frequency of polymorphisms and the genotype distribution. Adiponectin gene polymorphisms were not associated with the anthropometric parameters, hyperandrogenism and adiponectin levels in PCOS. However, the fasting insulin level and insulin resistance were significantly higher and more frequent, respectively, in the polymorphic group compared to the other genotypes among patients with PCOS.

CONCLUSION

The risk of PCOS, hyperandrogenism in patients with PCOS and low serum adiponectin levels cannot be directly attributed to T45G adiponectin gene polymorphisms in exon 2, rather these polymorphisms may be associated with insulin resistance and hyperinsulinemia in PCOS.

Metabolic syndrome in primary aldosteronism and essential hypertension: relationship to adiponectin gene variants

BACKGROUND AND AIMS

Evidence shows that aldosterone excess is crucial for the development of cardiac and metabolic complications. Among the possible pathogenetic elements of the metabolic syndrome, adiponectin and its polymorphisms seem to confer a genetic risk for metabolic alterations and type 2 diabetes. Aims of the study were to investigate whether metabolic syndrome represents a common feature in patients with primary aldosteronism (PA) compared with essential hypertensives (EH) and to study the impact of two common adiponectin gene variants on the parameters of metabolic syndrome.

METHODS AND RESULTS

Metabolic syndrome was defined according to ATPIII criteria. Eighty-nine patients with PA and 164 matched EH were studied. In all patients with PA and in 135 EH two single nucleotide polymorphisms of the adiponectin gene, T45G and G276T, were detected. Patients with PA displayed a higher prevalence of metabolic syndrome compared with EH (45% vs. 30%, p<0.05). In patients with PA, genotypes 45T/G+G/G were associated with significantly lower values of waist circumference, HOMA-IR and serum aldosterone. In both PA patients and EH, the 276T/T genotype was associated with significantly worse metabolic profile and a higher risk for the metabolic syndrome (OR=1.5 for PA and OR=1.3 for EH).

CONCLUSIONS

Our data confirm a higher prevalence of metabolic syndrome among patients with PA compared with matched EH. Genetic analysis of T45G and G276T adiponectin gene polymorphisms showed that, while the genotypes 45G/G+G/T seemed to have a protective role on the metabolic complications, the genotype 276T/T defined PA and EH patients with a worse metabolic profile.

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.

Relation between adiponectin 45 T/G polymorphism and dietary composition in the Czech population

In this study on 138 Czech Caucasians, the ADIPOQ 45T/G polymorphism was associated with the dietary composition. As the GG homozygotes were associated with the increased intake of carbohydrates, we suggest that a proportion of the prodiabetogenic effect of the polymorphism might be due to its influence on eating behaviour.

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.

The association of adiponectin allele 45T/G and -11377C/G polymorphisms with Type 2 diabetes and rosiglitazone response in Chinese patients

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT

Rosiglitazone is able to increase serum adiponectin levels significantly in Type 2 diabetic patients. :The role of genetic factors that determine the marked interindividual variability in glucose-lowering efficacy of rosiglitazone in Chinese patients is not known. The current study was designed to evaluate the impact of the adiponectin common allele 45T/G and -11377C/G polymorphisms on the response to rosiglitazone monotherapy in Chinese patients with Type 2 diabetes (T2D).

WHAT THIS STUDY ADDS

The genetic polymorphisms of adiponectin alleles 45T/G and -11377C/G as well as their common diplotypes are significantly associated with an attenuated fasting plasma glucose, postprandial plasma glucose and homeostasis model assessment for insulin resistance as well as an enhanced adiponectin concentration in Chinese patients with T2D after rosiglitazone treatment. AIMS The aim of the present study was to evaluate the impact of adiponectin allele T45G and C-11377G genetic polymorphisms on efficacy of rosiglitazone in Chinese patients with type 2 diabetes (T2D).

METHODS

Patients with T2D (n = 255) and 120 healthy volunteers were enrolled to identify 45T/G and -11377C/G genotypes by polymerase chain reaction-restriction fragment length polymorphism assay. Forty-two T2D patients with different 45T/G or -11377C/G genotypes received orally rosiglitazone as a single-dose therapy (4 mg day-1 p.o.) for 12 weeks. Serum triglyceride, fasting plasma glucose (FPG), postprandial plasma glucose (PPG), glycated hemoglobin, fasting serum insulin, postprandial serum insulin, total cholesterol, homeostasis model assessment for insulin resistance (HOMA-IR), low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol (HDL-c) and adiponectin concentration were determined before and after rosiglitazone treatment.

RESULTS

We showed an attenuated rosiglitazone effect in patients with -11377CG+GG heterozygote genotype on FPG, PPG, HOMA-IR compared with -11377CC homozygote genotype. However, we found an enhanced rosiglitazone effect on serum adiponectin concentration in patients with -11377CC homozygote genotype compared with -11377CG+GG heterozygote genotype (P = 0.000) and in patients with 45TG + GG heterozygote genotype compared with 45TT homozygote genotype (P = 0.018). Finally, our results showed that there was an enhanced effect in patients with -11377/45 CGTT diplotype compared with other discovered diplotypes on FPG (P = 0.001) and PPG (P = 0.003) after rosiglitazone treatment.

CONCLUSIONS

These data suggest that the adiponectin allele 45T/G and -11377C/G polymorphisms are significantly associated with the therapeutic efficacy of multiple-dose rosiglitazone in Chinese patients with T2D.

Association of genetic variation of the adiponectin gene with body fat distribution and carotid atherosclerosis in Japanese obese subjects

AIM

The aim of this study was to investigate the effect of SNP45 of the adiponectin gene on body fat distribution and carotid atherosclerosis in Japanese obese subjects.

METHODS

A total of 64 obese subjects were investigated. Genotypes of SNP45 were assayed by polymerase chain reaction-restriction fragment length polymorphism. Visceral fat area (VFA) and subcutaneous fat area (SFA) were measured using computed tomography. The progression of atherosclerosis was evaluated by plaque score (PS) of carotid artery using B-mode ultrasonography.

RESULTS

Men carrying the G allele of SNP45 showed higher VFA (172.8+/-50.8 vs. 147.1+/-58.7, p=0.005), lower SFA (209.9+/-101.8 vs. 273.4+/-142.2, p=0.007), higher VFA/SFA (V/S) ratio (1.00+/-0.46 vs. 0.60+/-0.26, p <0.001) and higher PS (9.5+/-3.7 vs. 6.8+/-4.2, p=0.012) than those with TT genotype. Multivariate analysis showed that SNP45 was an independent determinant of V/S ratio and PS in men. In subgroup analysis, PS tended to be associated with V/S ratio only in the carrier of 45G allele.

CONCLUSION

These results suggest that the G allele could be a risk factor of metabolic syndrome and the development of atherosclerosis in Japanese obese subjects.

Do low levels of circulating adiponectin represent a biomarker or just another risk factor for the metabolic syndrome?

The metabolic syndrome is currently defined by various combinations of insulin resistance, obesity, dyslipidaemia and hypertension. The tendency for these risk factors to appear simultaneously suggests a single aetiologic basis. A low level of circulating adiponectin is associated with the appearance of each metabolic syndrome risk factor. The following review summarizes a large body of evidence that suggests a low level of circulating adiponectin represents an independent risk factor and a possible biomarker for the metabolic syndrome. An association between the metabolic syndrome and low adiponectin supports the view that the development of the metabolic syndrome may be triggered by a single underlying mechanism. Clinical studies in the future may show that a low level of circulating adiponectin is a primary biomarker for a specific cluster of metabolic syndrome risk factors rather than all the possible combinations of risk factors currently used to identify the metabolic syndrome. The significance of low circulating adiponectin in risk assessment models should ultimately be compared against insulin resistance, obesity, dyslipidaemia, hypertension and other metabolic syndrome risk factors presently under consideration. Adiponectin can be measured reliably in a clinical setting; circulating values of adiponectin do not fluctuate on a diurnal basis as much as insulin, glucose, triglycerides or cholesterol and only 2-4 microl of blood are currently needed for its measurement.

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.

Medical sequencing at the extremes of human body mass

Body weight is a quantitative trait with significant heritability in humans. To identify potential genetic contributors to this phenotype, we resequenced the coding exons and splice junctions of 58 genes in 379 obese and 378 lean individuals. Our 96-Mb survey included 21 genes associated with monogenic forms of obesity in humans or mice, as well as 37 genes that function in body weight-related pathways. We found that the monogenic obesity-associated gene group was enriched for rare nonsynonymous variants unique to the obese population compared with the lean population. In addition, computational analysis predicted a greater fraction of deleterious variants within the obese cohort. Together, these data suggest that multiple rare alleles contribute to obesity in the population and provide a medical sequencing-based approach to detect them.

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.

Adiponectin and adiponectin receptor gene variants in relation to resting metabolic rate, respiratory quotient, and adiposity-related phenotypes in the Quebec Family Study

BACKGROUND

Despite adiponectin's presumed role in fatty acid oxidation and energy homeostasis, little is known about the effect of gene variants on substrate oxidation, energy expenditure, and adiposity-related phenotypes.

OBJECTIVE

We examined the effects of genetic variation in adiponectin (ADIPOQ) and adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2) on resting metabolic rate, respiratory quotient (RQ), and adiposity-related phenotypes.

DESIGN

We studied the associations of ADIPOQ, ADIPOR1, and ADIPOR2 polymorphisms with resting metabolic rate, RQ, and body mass index, percentage body fat, sum of 6 skinfold thicknesses, waist circumference, and total, subcutaneous, and visceral fat in 759 participants in the Québec Family Study.

RESULTS

The ADIPOQ 45T-->G single-nucleotide polymorphism (SNP) was significantly (P = 0.0002 to 0.04) associated with overall adiposity and abdominal adiposity; the rare homozygotes (G/G) had a leaner phenotype than did the carriers of the common allele. One SNP each in the putative promoter of ADIPOR1 (ie, -3882T-->C) and ADIPOR2 (ie, IVS1 -1352G-->A) was associated with RQ (P = 0.03 and 0.04, respectively), and the association was even stronger in nonobese persons (P = 0.02 and 0.003). Carriers of the common alleles (ADIPOR1 T and ADIPOR2 G alleles) had a lower RQ than did the rare homozygotes. A significant genotype-by-genotype interaction (P = 0.0002 to 0.02) was found between SNPs in the promoters of ADIPOQ (-3971A-->G) and ADIPOR1 (-3882T-->C). Subjects carrying the minor ADIPOQ allele (G allele) who were rare homozygotes (C/C) for the ADIPOR1 SNP had a higher RQ (P = 0.003) and greater overall (P < 0.03) and abdominal (P < 0.05) adiposity than did persons with other genotype combinations.

CONCLUSIONS

Previous findings that the ADIPOQ 45T-->G variant contributes to overall fatness and abdominal obesity are confirmed. Moreover, variants in the promoter region of both ADIPOR genes contribute to substrate oxidation.

Investigational therapies in the treatment of obesity

Obesity is a major public health concern and environmental factors are involved in its development. The hypothalamus is a primary site for the integration of signals for the regulation of energy homeostasis. Dysregulation of these pathways can lead to weight loss or gain. Some drugs in development can have favourable effects on body weight, acting on some of these pathways and leading to responses resulting in weight loss. Strategies for the management of weight reduction include exercise, diet, behavioural therapy, drug therapy and surgery. Investigational antiobesity medications can modulate energy homeostasis by stimulating catabolic or inhibiting anabolic pathways. Investigational drugs stimulating catabolic pathways consist of leptin, agonists of melanocortin receptor-4, 5-HT and dopamine; bupropion, growth hormone fragments, cholecystokinin subtype 1 receptor agonist, peptide YY3-36, oxyntomodulin, ciliary neurotrophic factor analogue, beta3-adrenergic receptor agonists, adiponectin derivatives and glucagon-like peptide-1. On the other hand, investigational drugs inhibiting anabolic pathways consist of the ghrelin receptor, neuropeptide Y receptor and melanin-concentrating hormone-1 antagonists; somatostatin analogues, peroxisome proliferator-activated receptor-gamma and -beta/delta antagonists, gastric emptying retardation agents, pancreatic lipase inhibitors, topiramate and cannabinoid-1 receptor antagonists. These differing approaches are reviewed and commented on in this article.

Parental obesity and overweight affect the body-fat accumulation in the offspring: the possible effect of a high-fat diet through epigenetic inheritance

The prevalence of obesity in adults has been rising continually, as has the prevalence of childhood obesity, and a large number of epidemiological studies have demonstrated a direct relationship between parental obesity and childhood obesity. In this paper, we review the effect of diet, the intrauterine environment, and the genetic inheritance on obesity. We described a study in detail that used experimental animals as a model to investigate the effect of a parental high-fat diet on body-fat accumulation in their offspring. Fertilized eggs were transplanted in that study, and body-fat accumulation in the offspring of the parents fed a high-fat diet was found to be greater than in the offspring of the parents fed a low-fat diet, even when the experimental conditions were the same in the intrauterine and subsequent environment. The results suggested that a parental high-fat diet before intrauterine developmental stage may increase body-fat accumulation in the offspring. We discuss the possibility that parental diet may influence the lifelong health of offspring and epigenetic inheritance may be occurred.

Adiponectin and its gene variants as risk factors for insulin resistance, the metabolic syndrome and cardiovascular disease

The increasing prevalence of obesity and metabolic syndrome/insulin resistance has attracted considerable interest due to their identification as risk factors for cardiovascular disease and, hence, targets for cardiovascular disease prevention. This review focuses on adiponectin, the most profusely secreted protein from adipose tissue, which itself is being increasingly recognised as an important and very active endocrine organ, secreting a wide range of biologically active substances known as adipokines or adipocytokines. Adiponectin has been demonstrated to have insulin sensitising effects, and secretion of adiponectin is reduced as adipose tissue mass increases. Adiponectin has also been demonstrated to have anti-inflammatory and anti-atherogenic properties, and is independently associated with cardiovascular disease. The evidence that suggests adiponectin plays a role in the relationship between obesity and insulin resistance, and also insulin resistance and cardiovascular disease, is examined. Variation in the adiponectin gene is one tool to determine whether this relationship is causal. The association of identified variants with human disease, specifically obesity and its consequences, type 2 diabetes and cardiovascular disease is reviewed. This data may enable patients at greater risk of the adverse effects of obesity to be identified and, as such, benefit from more targeted therapy of its consequences.

The human obesity gene map: the 2005 update

This paper presents the 12th update of the human obesity gene map, which incorporates published results up to the end of October 2005. Evidence from single-gene mutation obesity cases, Mendelian disorders exhibiting obesity as a clinical feature, transgenic and knockout murine models relevant to obesity, quantitative trait loci (QTL) from animal cross-breeding experiments, association studies with candidate genes, and linkages from genome scans is reviewed. As of October 2005, 176 human obesity cases due to single-gene mutations in 11 different genes have been reported, 50 loci related to Mendelian syndromes relevant to human obesity have been mapped to a genomic region, and causal genes or strong candidates have been identified for most of these syndromes. There are 244 genes that, when mutated or expressed as transgenes in the mouse, result in phenotypes that affect body weight and adiposity. The number of QTLs reported from animal models currently reaches 408. The number of human obesity QTLs derived from genome scans continues to grow, and we now have 253 QTLs for obesity-related phenotypes from 61 genome-wide scans. A total of 52 genomic regions harbor QTLs supported by two or more studies. The number of studies reporting associations between DNA sequence variation in specific genes and obesity phenotypes has also increased considerably, with 426 findings of positive associations with 127 candidate genes. A promising observation is that 22 genes are each supported by at least five positive studies. The obesity gene map shows putative loci on all chromosomes except Y. The electronic version of the map with links to useful publications and relevant sites can be found at http://obesitygene.pbrc.edu.

Adiponectin and its receptors: partners contributing to the "vicious circle" leading to the metabolic syndrome?

Although already described five years ago, it is only from year 2000, following intensive research in the field of genetics that the adiponectin protein was related with insulin sensitivity, type 2 diabetes and the metabolic syndrome. The story began with a paradox as this protein exclusively secreted by fat tissue was dramatically decreased in patients presenting an excess of fat mass. Later this decrease was reported with insulin resistance and metabolic syndrome associated phenotypes. The search for genetic variants in the adiponectin encoding ACDC gene and epidemio genetic investigations allowed to associate genetic variations of the gene and phenotypic traits of the metabolic syndrome. One of the major points was the correlation of the levels of circulating adiponectin with insulin sensitivity, leading to a better knowledge of the role of adiponectin. Indeed it is now clearly admitted that adiponectin is an insulin sensitizing cytokine. Recently two adiponectin receptors were described and genetic variations in their genes were associated with features of the metabolic syndrome. Interactions of adiponectin with various partners are discussed in view of a better understanding of adiponectin resistance and insulin resistance.