Variation in the resistin gene is associated with obesity and insulin-related phenotypes in Finnish subjects

Association between the RETN -420C/G polymorphism and type 2 diabetes mellitus susceptibility: A meta-analysis of 23 studies

BACKGROUND

The published findings on the link between the resistin (RETN) gene polymorphism and type 2 diabetes mellitus (T2DM) risk are still contradictory. Here, through a meta-analysis, we summarized a more precise evaluation of their connection by synthesizing existing research.

METHODS

PubMed, Google Scholar, and Web of Science were electronically searched, and all cited sources were manually searched. The heterogeneity of effects was tested and all statistical analyses were performed in Stata 12.0.

RESULTS

A total of 23 studies with 10,651 cases and 14,366 controls on RETN -420C/G polymorphism were included. The overall results showed that the association of RETN -420C/G polymorphism and T2DM susceptibility was not significant [for the allelic model: odds ratio (OR) = 0.98, 95% confidence interval (CI) = 0.87-1.10, p_{heterogeneity} <.001; I ² = 84.6%; for the dominant model: OR = 0.96, 95% CI = 0.80-1.15, p_{heterogeneity} <.001; I ² = 87.1%; and for the recessive model: OR = 0.96, 95% CI = 0.82-1.12, p_{heterogeneity} <.001; I ² = 56.9%] but with high heterogeneity across studies (p <.0001). Meta-regression found that the median age of T2DM participants (using age 50 as the cutoff) could be a factor in the observed variation. The RETN -420C/G polymorphism seems to be linked to an increased risk of T2DM in younger individuals [for dominant: OR = 0.84 (95% CI, 0.72-0.98; p_{heterogeneity} <.001; I ² = 80.9%)] and decreased risk in older people [for dominant: OR = 3.14 (95% CI, 2.35-4.19; p_{heterogeneity} = .98; I ² = 0.0%)].

CONCLUSIONS

Current results found no evidence that the RETN -420C/G variant was linked to T2DM susceptibility, but the patient's age appears to be a potential factor that contributed to high heterogeneity across studies. Additional high-quality and well-designed investigations are required to confirm these results.

Association of resistin (rs3745367) and urotensin II (rs228648 and rs2890565) gene polymorphisms with risk of type 2 diabetes mellitus in Indian population

Insulin resistance may become the most powerful predictor of future development of type 2 diabetes mellitus (T2DM) and a therapeutic target for the treatment of the same. Both Resistin, an adipose derived peptide hormone and Urotensin II a potent vasoconstrictor, are reported to be involved in the development of insulin resistance and T2DM but the results remain contradictory. Therefore, investigations were carried out to study the association of T2DM and single nucleotide polymorphism (SNP) in Resistin (RETN) gene at rs3745367 (+ 299 G > A) and Urotensin II (UTS2) gene at rs228648 (+ 143 G > A) and rs2890565 (+ 3836 C > T) in a North Indian population. Method: The present case-control study, conducted from August 2017 to July 2020, involved 168 T2DM patients and 102 healthy controls. SNPs rs3745367, rs228648 and rs2890565 were amplified from genomic DNA in the studied samples by polymerase chain reaction (PCR) using specific primers. The amplified products were genotyped by restriction fragment length polymorphism (RFLP) using particular restriction endonucleases. Clinical parameters viz. glycosylated haemoglobin (HbA1c), fasting blood glucose (FBG), high density lipoprotein cholesterol (HDL-C), triglycerides (TG), total cholesterol (CHL) and fasting insulin were determined by enzymatic methods. Result and conclusion: A statistically significant association between T2DM and RETN gene at SNP rs3745367 (p = 0.001) and UTS2 gene at SNP rs2890565 (p = 0.001) was observed. In RETN gene SNP rs3745367, insulin and homeostasis model assessment of insulin resistance (HOMA-IR) were found to be higher in GA + AA combined genotype than in GG genotype for T2DM subjects. Regression analysis revealed that SNP rs2890565 and HOMA-IR were independently associated with the risk of development of T2DM when three SNPs were taken as independent variable adjusted for clinical variables. Among four haplotypes, A/T was found associated with increased risk of T2DM as determined for rs228648 and rs2890565 of UTS2 gene. It can be concluded from these results that polymorphism at rs3745367 of RETN gene and at rs2890565 of UTS2 gene are associated with risk of T2DM in North Indian population.

The Relevance of Single-nucleotide Polymorphism +62 G>A to the Expression of Resistin Gene Affecting Serum Resistin Levels in Metabolic Syndrome in the Egyptian Population

BACKGROUND

Metabolic Syndrome (MS) is a clinical condition consisting of risk factors associated with type two diabetes and developing cardiovascular disease. It has been suggested that resistin is a linkage between obesity, inflammation and type two diabetes. This study aims to investigate whether Resistin Gene (RETN) polymorphism (+62G>A) is linked to MS and resistin levels among the Egyptian population.

METHODS

This study was performed with 310 Egyptian volunteers: 160 MS subjects and 150 controls. Anthropometric parameters and biochemical variables were determined. The RETN +62G>A polymorphism was genotyped by PCR-RFLP technique.

RESULTS

The resistin levels of the MS group were significantly higher than those of the control group. Resistin levels were positively correlated with anthropometric parameters and liver biomarkers in the MS group. According to RETN +62G>A polymorphism, carriers with the A allele (GA/AA) had significantly increased resistin levels than subjects with the GG genotype, consequently, the RETN +62G >A polymorphism was found to be related to MS, biochemical parameters and anthropometric variables.

CONCLUSION

These findings propose that the RETN +62G>A polymorphism has a great impact on the circulating resistin concentrations, and that resistin levels are strongly related to MS. Therefore, this RETN polymorphism is related to the risk of the prevalence of MS in the Egyptians.

Type 2 diabetes mellitus risk and exercise: is resistin involved?

Obesity and associated disorders such as type 2 diabetes mellitus (T2DM) pose an increasing risk to the health of both individuals and society. Adipose tissue is an active endocrine organ, secreting many hormones, known as adipokines. Evidence suggests that one suggest adipokine, resistin, may be elevated in the plasma of individuals with T2DM, and early reports indicated that this may contribute to the impaired glucose tolerance and insulin resistance observed in T2DM, hence its name, resistin, however subsequent evidence suggests it may have a proinflammatory role. Performing regular exercise and dietary interventions improve insulin sensitivity and glucose tolerance in the majority of individuals with T2DM, and we hypothesized that plasma resistin levels may drop in individuals following a long term aerobic and/or resistance exercise intervention program. Articles analyzing the effects of exercise on serum resistin levels were therefore analyzed. Articles were selected and analyzed based on a minimum aerobic and/or resistance training program of 2 sessions per week for 12 weeks. Plasma resistin levels decreased following either endurance aerobic exercise and/or resistance training plans in individuals with obesity and/or insulin resistance, although this was not related to BMI change. Exercise intervention programs generally showed potentially beneficial changes in plasma resistin concentrations. It is possible these effects are mediated through exercise-induced decreases in inflammation via anti-inflammatory cytokine release rather than alterations in glucose metabolism and reductions in BMI per se. A possible link between resistin, exercise and T2DM is discussed.

Resistin polymorphims, plasma resistin levels and obesity in Tunisian volunteers

BACKGROUND

Adipose tissue is an important endocrine organ that secretes a number of adipokines, like Resistin (RETN); it's an adipocytes-secreted cytokine and has been proposed as a link between obesity and diabetes. Many resistin gene polymorphisms were described and their implication in obesity was controversial. This study was to investigate the prevalence of single nucleotide polymorphisms (SNPs) in RETN gene 420C/G; 44G/A; 62G/A; 394C/G and 299 G/A and their association with Resistin level and obesity in Tunisian volunteers.

METHODS

We recruited 169 nonobese (mean age=42.16-14.26 years; mean body mass index [BMI]=24.51-3.69 kg/m² ) and 160 obese (mean age=47.86-11.17 years; mean BMI=36-4.78 kg/m² ). Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism. Anthropometric parameters, lipid levels, Glycemia and insulinemia were measured, BMI was calculated and insulinresistance was evaluated with the homeostasis model assessment insulin resistance (HOMA-IR) and resistin level was measured by ELISA. Statistical analyses were performed by SPSS19.0.

RESULTS

After adjustment for confounding parameters; the Odds Ratio (OR) of obesity associated with mutated genotypes at 420C/G compared with normal genotype was as: OR=2.17; 95% CI [1.28-3.68], P=.004. The serum Resistin levels present no significant association with all RETN polymorphisms and it was significantly associated with BMI (P=.047). In our haplotype analysis, one haplotype seems to be protective and one other seems to be the highest risk to obesity.

CONCLUSION

The 420 C/G Polymorphism were associated with obesity and Leptin concentration in our population.

Association of ADIPOQ, leptin, LEPR, and resistin polymorphisms with obesity parameters in Hammam Sousse Sahloul Heart Study

BACKGROUND

Adipose tissue is an important endocrine organ that secretes a number of adipokines, such as adiponectin (ADIPOQ), leptin (LEP), leptin receptor (LEPR), and resistin (RETN) which may be implicated in obesity. Some adipokines' polymorphisms of genes might influence their concentrations and/or activities. Our aim was to study the relationship between seven SNPs in ADIPOQ (+45T<G (rs2241766); +276G<T (rs1501299); -4255C<T (rs822393); -395G<T (rs17366568)), LEP (2548G<A (rs7799039)), LEPR (223Q<R (rs1137101)), and RETN (-420C<G (rs1862513)) and obesity in Hammam Sousse Sahloul Heart Study (HSHS).

METHODS

The study, carried out between February and June 2009, is mainly focused on 1121 respondents in HSHS which is a population-based epidemiological study of type "community-based" on cardiovascular risk. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). Serum lipids and anthropometric parameters were measured. Statistic analysis was performed on SPSSv19.

RESULTS

The polymorphisms of ADIPOQ 4522C<T and 276G<T, LEP 2548G<A, and RETN 420C<G seem to contribute to obesity. In fact, adjusted odds ratios (ORs) of obesity associated with mutated genotypes of each polymorphism were respectively OR=1.38, P=.037; OR=0.608, P<.001; OR=2.23, P=.034; and OR=2.18, P<.001. The 276G<T, 4522C<T, and 420C<G were associated with increased BMI (P=.010, P=.028, and P<.001). A significant association was found between the 276G<T; 4522C<T, LEP 2548G<A and 420C<G, and the waist circumference and hip measurements.

CONCLUSION

ADIPOQ, LEP, and RETN gene polymorphisms were associated with obesity parameters in HSHS population.

Relevance Study on Cerebral Infarction and Resistin Gene Polymorphism in Chinese Han Population

Recent research on genome-wide associations has implicated that the serum resistin level and its gene polymorphism are associated with cerebral infarction (CI) morbidity and prognosis, and could thereby regulate CI. This study aimed to investigate the association between the resistin single nucleotide polymorphism (SNP) and the susceptibility to CI in the Chinese Han population. A total of 550 CI patients and 313 healthy controls were genotyped. Nine SNPs of the resistin gene previously shown were sequenced and assessed for an association with CI. The numbers of GG genotype carriers of rs3219175 and rs3486119 in the CI group were significantly higher than those in the control group among the middle-aged group (aged 45-65), at 76% vs 67.9% (P=0.025) and 75.5% vs 67.9% (P=0.031). rs3219175 and rs34861192 were associated with CI in the dominant and superdominant models according to the genetic model analysis (P<0.05). Meanwhile, there was strong linkage disequilibrium among the rs34124816, rs3219175, rs34861192, rs1862513, rs3745367, 180C/G and rs3745369 sites. In a haplotype analysis, the occurrence rate of the haplotype AGGCAGC was 1.97 times (P<0.05) higher in the patient group than in the control group. In addition, the numbers of GG genotype carriers of rs3219175 and rs3486119 in the middle-aged male CI patients and the middle-aged small artery occlusion (SAO) CI patients were higher than those in the control group (P<0.05). In the Chinese Han middle-aged population, the GG gene type carriers of the resistin gene sites rs3219175 and rs34861192 had a high risk for CI onset, especially in middle-aged male patients and SAO CI in all middle-aged patients.

Resistin: insulin resistance to malignancy

Adipose tissue is recognized as an endocrine organ that secretes bioactive substances known as adipokines. Excess adipose tissue and adipose tissue dysfunction lead to dysregulated adipokine production that can contribute to the development of obesity-related co-morbidities. Among the various adipokines, resistin, which was initially considered as a determinant of the emergence of insulin resistance in obesity, has appeared as an important link between obesity and inflammatory processes. Several experimental and clinical studies have suggested an association between increased resistin levels and severe conditions associated with obesity such as cardiovascular disease and malignancies. In this review, we present the growing body of evidence that human resistin is an inflammatory biomarker and potential mediator of obesity-associated diseases. A common pathway seems to involve the combined alteration of immune and inflammatory processes that favor metabolic disturbances, atherosclerosis and carcinogenesis. The mode of action and the signaling pathways utilized by resistin in its interactions with target cells could involve oxidative and nitrosative stress. Therefore, resistin could function as a key molecule in the complications of obesity development and could potentially be used as a diagnostic and prognostic marker.

Association of resistin polymorphisms with resistin levels and lipid profile in children

Previous research has found a correlation between resistin and lipid level variations. Polymorphisms in the resistin gene (RETN) could be involved in this relationship, but the results of the different studies are contradictory. The aim of this study was to examine the association between resistin and lipid levels, and to determine whether resistin polymorphisms are associated with resistin levels and lipid profile in prepubertal children and adolescents. The single nucleotide polymorphisms (SNPs) rs1862513 and rs10401670 were analyzed in 442 randomly selected 6- to 8-year-old children and 827 children aged 12-16 years. Anthropometric data were recorded. Lipid profile was determined using standard methods. Serum resistin levels were measured using a multiplexed bead immunoassay. Resistin polymorphisms were determined by TaqMan(®) allelic discrimination assays. A relationship was found between serum levels of resistin and the SNP rs10401670 in 6- to 8-year-old boys. SNP rs10401670 was also related to TC and LDL-cholesterol in 12- to 16-year-old boys and to HDL-C in 12- to 16-year-old girls. SNP rs1862513 was not related to any of the studied variables. Serum resistin levels were significantly and negatively associated with ApoAI levels in 12- to 16-year-old girls. A SNP in the 3'UTR region of RETN (rs10401670) is associated with resistin levels and lipid profile in children, showing different associations depending on age and gender.

Visfatin -948G/T and resistin -420C/G polymorphisms in Egyptian type 2 diabetic patients with and without cardiovascular diseases

Diabetes mellitus is one of the main threats to human health in the 21st century. Visfatin/Nampt and resistin are novel adipokines that have been implicated in the pathogenesis of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD) complication. Several genetic studies have shown inconsistent results regarding association of visfatin/Nampt gene (NAMPT) and resistin gene (RETN) polymorphisms with T2DM and CVD complications. Here, we investigate whether NAMPT -948G/T and RETN -420C/G polymorphisms are associated with T2DM, its CVD complications, and serum adipokines levels in 90 Egyptian diabetic patients (44 without CVD and 46 with CVD) along with 60 healthy control subjects. Higher frequencies of NAMPT -948G/G and RETN -420G/G were observed among T2DM patients compared with controls. Furthermore, the frequencies of these genotypes were significantly higher in T2DM patients with CVD than those without CVD. Both NAMPT -948G/G and RETN -420G/G genotypes and G alleles were significantly associated with T2DM and CVD in Egyptian diabetic patients. Moreover, serum visfatin/Nampt and resistin levels were markedly elevated in T2DM patients, with the highest values observed in G/G genotypes among T2DM patients with CVD. In addition, positive correlations were observed between plasma adipokines levels and CVD risk factors. In conclusion, our data suggests that genetic variations in NAMPT -948G/T and RETN -420C/G may contribute to the disposition for T2DM and its CVD complications in Egyptian patients. However, further studies with greater sample size should be performed to verify these results.

Resistin gene variations are associated with the metabolic syndrome in Japanese men

SUMMARY

OBJECTIVES

Metabolic syndrome is defined as a cluster of risk factors for cardiovascular disease and is intimately related to insulin resistance. Resistin, a hormone secreted by adipocytes, may play an important role in communication between adiposity and insulin resistance. We investigated whether variations in the resistin gene associated with metabolic syndrome in a Japanese population.

METHOD

We analyzed five SNPs, two of which were located in the promoter region (-420C > G, -358G > A), two in intron 2 (+157C > T, +299G > A), and one in the 3'-untranslated region (3'UTR) (+1263G > C) across the resistin gene in 2968 residents from an urban Japanese cohort. The associations of SNPs and haplotypes with metabolic syndrome were analyzed.

RESULTS

The GAC and CGC haplotypes (comprising -420C > G, -358G > A, and +157C > T) had opposite influences on metabolic syndrome susceptibility in men; the former was associated with an increased risk and the latter with a decreased risk. We also found that the -420G allele was significantly associated with an increased risk of metabolic syndrome and significantly correlated with high diastolic blood pressure, high HOMA-IR values, high serum triglyceride levels, low HDL-cholesterol levels and high serum levels of adiponectin.

CONCLUSION

We identified a risk-conferring SNP and haplotype of the resistin gene for metabolic syndrome in a Japanese population. Our data suggested that resistin gene is a susceptibility gene for metabolic syndrome in Japanese men.

Rapid cloning and comparative sequence analysis of full-length cDNA of Rhesus monkey (Macaca mulatta) resistin

Resistin protein is thought to link insulin resistance in murine models of obesity and type-2 diabetes, but the role of resistin in human studies of inflammatory metabolic disorders have generated conflicting data. Here, we describe the structure of the resistin gene using adipose tissue from non-human primates (NHPs), which have been used extensively to model a host of human diseases. Full-length cDNA from rhesus macaque resistin obtained by rapid amplification of cDNA ends (RACE) is comprised of 526 nucleotides covering an open-reading frame (ORF) that encodes a 108-amino-acid protein that is 92% homologous with the human counterpart but only 60% homologous with the murine counterpart. Using a modified polymerase chain reaction technique, we identified single nucleotide polymorphisms and a 78-bp deletion within resistin cDNA of nine rhesus macaques. Comparisons of the full-length cDNA sequence and an amplified 569-bp genomic DNA sequence revealed an error in published predictions arising from genomic studies about the gene's exon 3 region. Our data show, for the first time, the full-length macaque resistin cDNA sequence (GenBank: JF740676.1). These findings will illuminate future studies into the role of resistin in NHP models of inflammatory metabolic diseases.

Association between resistin gene -420 C/G polymorphism and the risk of type 2 diabetes mellitus: a meta-analysis

Epidemiological studies on the association between the single nucleotide polymorphism (SNP) at -420 C/G (rs1862513) in the human resistin gene (RETN) and the risk of type 2 diabetes mellitus (T2DM) are conflicting. In order to derive a more precise estimation of the association, a meta-analysis was conducted. Twelve studies with 5,935 cases and 5,959 controls were enrolled by searching the databases of Medline, EMBASE, and Cochrane. Summary odds ratios (ORs) with 95% confidence intervals (CIs) were calculated. The heterogeneity and publication bias were investigated. The main analysis indicated no significant association [for allelic model: OR = 0.97 (0.92-1.03); for additive model: OR = 0.95 (0.83-1.09); for recessive model: OR = 0.98 (0.86-1.12); for dominant model: OR = 0.95 (0.88-1.04)]. Overall, no significant heterogeneity was found. Subgroup analysis by race and source of controls indicated no significant association. In conclusion, the current meta-analysis did not observe any association between the polymorphism of RETN -420 C/G and the risk of T2DM. The study may help us further understand the genetics of T2DM. However, larger and prospective studies are warranted to confirm this finding.

Significant interaction between RETN -420 G/G genotype and lower BMI on decreased risk of type 2 diabetes mellitus (T2DM) in Japanese--the J-MICC Study

We examined the association of the RETN (resistin) -420 C>G polymorphism (rs1862513) with risk of diabetes mellitus (DM), considering lifestyle factors, in Japanese. Subjects were participants of J-MICC Study, where 2,651 participants aged 35-69 years provided their blood for genotyping and lifestyle data after informed consent. Odds ratio (OR) of DM for RETN-420 G/G genotype was estimated using unconditional logistic regression model. Statistically significant interaction on risk of DM was observed between RETN-420 G/G genotype and BMI<25 (OR for interaction = 0.12; P = 0.046), and when subjects with RETN-420 C/C+C/G and BMI ≥ 25 (n = 69 for DM and 544 for non-DM) were defined as the reference, the adjusted ORs for subjects with RETN-420 G/G genotype and BMI>25 (n = 10 for DM and 111 for non-DM), RETN-420 C/C+C/G and BMI<25 (n = 81 for DM and 1,605 for non-DM), and RETN-420 G/G and BMI<25 (n = 1 for DM and 230 for non-DM) were demonstrated to be 0.72 (95% confidence interval: 0.36-1.46), 0.40 (0.28-0.56) and 0.03 (0.005-0.25), respectively. The present study revealed the significant interaction of RETN-420 G/G genotype with lower BMI on the decreased risk of DM, but the direction was opposite to the reported ones in Japanese. We should be careful in interpretation of the present study results because of the limited sample sizes. Further investigation of this association as well as of the actual biological roles of RETN in the genesis of human metabolic disorders including DM will be required.

Resistin polymorphisms show associations with obesity, but not with bone parameters in men: results from the Odense Androgen Study

Resistin is an obesity-related adipokine which has also been implicated in bone metabolism. Therefore, we designed a study to investigate the possible role of resistin gene variation in both obesity and bone mineral density. We included 1,155 individuals from the Odense Androgen Study (663 young subjects and 492 older subjects), a population-based, prospective, observational study on the inter-relationship between endocrine status, body composition, muscle function, and bone metabolism in men, in an association study with resistin (RETN) polymorphisms. Three RETN variants (rs1862513, rs3745367 and rs3745369) were genotyped with TaqMan Pre-Designed Genotyping assays. Linear regression was performed to investigate the possible association of these variants with several obesity- and bone-related parameters. After genotyping 1,155 Danish men, 663 young subjects and 492 older subjects, we found that rs3745367 was associated with several obesity-related measures in both the young and elderly cohort. Rs3745369 was only associated with obesity-phenotypes in the elderly cohort. When studying the combined cohorts, we could confirm the associations of rs3745367 with several obesity-related parameters. We were unable to identify any association between RETN polymorphisms and bone-related measurements. Together, these results illustrate resistin's role in the development of obesity. Rs3745367 gives the most consistent results in the current study and these should be confirmed in other populations. Research into its possible functional effect might also be required. A role for RETN variants in determining bone mineral density seems unlikely from our results.

Association of resistin gene polymorphisms with insulin resistance in Egyptian obese patients

BACKGROUND

Obesity associated insulin resistance is a major risk factor for type 2 diabetes mellitus. Resistin is recently reported to provide a link between obesity, insulin resistance and type 2 diabetes mellitus. We aimed to investigate the possible associations of resistin gene (RETN) polymorphisms with obesity, and to detect whether these polymorphisms are associated with glucose intolerance and type 2 diabetes mellitus in obese patients.

METHODS

One hundred and forty-five Egyptian obese patients with or without glucose intolerance and 155 unrelated healthy controls were enrolled in this study. Polymorphisms of RETN +299G>A and RETN -420 C>G gene were detected by polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP). Serum resistin was measured by ELISA.

RESULTS

RETN +299 AA and RETN -420 GG genotypes were significantly associated with obesity in Egyptian population. Moreover, the mutant alleles or genotypes of both examined polymorphisms were associated with impaired glucose tolerance and diabetes mellitus compared to normal glucose tolerant obese patients. Furthermore, our results revealed elevated waist/hip ratio, BMI, blood pressure, fasting blood glucose level, HOMA-IR, triglycerides, total cholesterol, resistin level, and decreased HDL cholesterol level in homozygote mutant genotypes carriers of both RETN polymorphisms among obese patients.

CONCLUSION

Resistin gene polymorphisms may play an important role in pathogenesis and susceptibility to obesity, impaired glucose tolerance, and type 2 diabetes mellitus in Egyptian population.

Association between four resistin polymorphisms, obesity, and metabolic syndrome parameters in Tunisian volunteers

Resistin is an adipocyte-secreted cytokine recently discovered and has been proposed as a link between obesity and diabetes. Many resistin gene polymorphisms were described and their implication in obesity and metabolic syndrome (MetS) was controversial. Our aim was to study the relationship between four resistin polymorphisms (420C/G, 44G/A, 62G/A, and 394C/G), MetS parameters, and the risk of obesity in Tunisian volunteers. We 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 subjects (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. Anthropometric parameters, lipid levels, glycemia, and insulinemia were measured. BMI was calculated and insulin resistance was evaluated with the homeostasis model assessment insulin resistance (HOMA-IR). Statistical analyses were performed by SPSS 17.0. The 420C/G seems to contribute to obesity. In fact adjusted odds ratio (OR) of obesity associated to mutated genotypes was 2.17 and 95% confidence interval was 1.28-3.68 (p=0.004). Mutated genotypes at 420C/G were associated with higher waist circumference and BMI. In addition, 44G/A polymorphism was associated with increased total cholesterol and low-density lipoprotein-cholesterol levels. The other genotypes showed no association with MetS parameters. Concerning association between single-nucleotide polymorphisms and MetS risk, only mutated genotypes at 44G/A increase the risk of MetS after adjustment to confounding parameters (OR=1.93, p=0.023). In conclusion, resistin gene polymorphisms 420C/G and 44G/A were associated with obesity and MetS parameters in Tunisian volunteers.

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.

Common variants of IL6, LEPR, and PBEF1 are associated with obesity in Indian children

The increasing prevalence of obesity in urban Indian children is indicative of an impending crisis of metabolic disorders. Although perturbations in the secretion of adipokines and inflammatory molecules in childhood obesity are well documented, the contribution of common variants of genes encoding them is not well investigated. We assessed the association of 125 common variants from 21 genes, encoding adipocytokines and inflammatory markers in 1,325 urban Indian children (862 normal weight [NW group] and 463 overweight/obese [OW/OB group]) and replicated top loci in 1,843 Indian children (1,399 NW children and 444 OW/OB children). Variants of four genes (PBEF1 [rs3801266] [P = 4.5 × 10(-4)], IL6 [rs2069845] [P = 8.7 × 10(-4)], LEPR [rs1137100] [P = 1.8 × 10(-3)], and IL6R [rs7514452] [P = 2.1 × 10(-3)]) were top signals in the discovery sample. Associations of rs2069845, rs1137100, and rs3801266 were replicated (P = 7.9 × 10(-4), 8.3 × 10(-3), and 0.036, respectively) and corroborated in meta-analysis (P = 2.3 × 10(-6), 3.9 × 10(-5), and 4.3 × 10(-4), respectively) that remained significant after multiple testing corrections. These variants also were associated with quantitative measures of adiposity (weight, BMI, and waist and hip circumferences). Allele dosage analysis of rs2069845, rs1137100, and rs3801266 revealed that children with five to six risk alleles had an approximately four times increased risk of obesity than children with less than two risk alleles (P = 1.2 × 10(-7)). In conclusion, our results demonstrate the association of the common variants of IL6, LEPR, and PBEF1 with obesity in Indian children.

Human resistin: found in translation from mouse to man

The discovery of resistin 10 years ago as a fat cell-secreted factor that modulates insulin resistance suggested a link to the current obesity-associated epidemics of diabetes and cardiovascular disease, which are major human health concerns. Although adipocyte-derived resistin is indisputably linked to insulin resistance in rodent models, the relevance of human resistin is complicated because human resistin is secreted by macrophages rather than adipocytes, and because of the descriptive nature of human epidemiology. In this review, we examine the recent and growing evidence that human resistin is an inflammatory biomarker and a potential mediator of diabetes and cardiovascular disease.

Role of adipokines in obesity-associated hypertension

It has been well documented that obesity is a major risk factor for the development of the hypertensive state. The correlation between body mass index and blood pressure level is well established. Nevertheless, the exact mechanisms which contribute to obesity-related hypertension remain poorly understood. In the last years, we have realized that the white adipose tissue is not just an inert organ for nutrient storage and isolation but rather depending on the body mass index the biggest endocrinological organ. Thus, the possible contribution of adipokines to the blood pressure elevation becomes an attractive hypothesis to explain the hypertensive state that often occurs in obesity. In this review, we consider direct and indirect effects of main adipokines on structural and functional changes in the cardiovascular system.

Association of resistin promoter polymorphisms with plasma resistin levels and type 2 diabetes in women and men

This study's objective was to examine the associations between resistin (RETN) polymorphisms, plasma resistin levels, and type 2 diabetes risk. We conducted two nested case-control studies in postmenopausal women (359 incident cases and 359 controls) and middle-aged/elderly men (170 incident cases and 170 controls). Controls were matched (1:1) to cases by age, race, duration of follow-up, and time of blood draw. Circulating resistin levels were higher among carriers of the variant allele for rs34861192 (p<0.0001 for women, p=0.002 for men) but not rs1862513 (p=0.15 for women, p=0.14 for men). Neither polymorphism was significantly associated with risk of type 2 diabetes after adjusting for diabetes risk factors (exercise, smoking status, alcohol intake, family history of diabetes, and matching factors) among women (rs1862513: OR=1.19, 95% CI=0.80-1.77; rs34861192: OR=0.41, 95% CI=0.14-1.19) and men (rs1862513: OR=1.05, 95% CI=0.57-1.95; rs34861192: OR=0.64, 95% CI=0.14-2.89). In conclusion, RETN promoter polymorphism rs34861192 was associated with elevated circulating resistin levels, but rs1862513 was not. Neither polymorphism was associated with an increased risk for type 2 diabetes.

Plasma resistin concentration determined by common variants in the resistin gene and associated with metabolic traits in an aged Japanese population

AIMS/HYPOTHESIS

Resistin is a cytokine derived from adipose tissue and is implicated in obesity-related insulin resistance and type 2 diabetes mellitus. Polymorphisms of the resistin gene (RETN) have been shown to affect the plasma resistin concentration. The aims of this study were to identify polymorphisms of RETN that influence plasma resistin concentration and to clarify the relation between plasma resistin level and metabolic disorders in an aged Japanese cohort.

METHODS

The study participants comprised 3133 individuals recruited to a population-based prospective cohort study (KING study). Plasma resistin concentration, BMI, abdominal circumference, blood pressure, fasting plasma glucose and serum insulin concentrations, HbA(1c) content and serum lipid profile were measured in all participants. The HOMA index of insulin resistance (HOMA-IR) was also calculated. Eleven polymorphisms of RETN were genotyped.

RESULTS

A combination of ANOVA and multiple linear regression analysis in screening and large-scale subsets of the study population revealed that plasma resistin concentration was significantly associated with rs34861192 and rs3745368 polymorphisms of RETN. Multiple linear regression analysis with adjustment for age and sex also showed that the plasma resistin level was significantly associated with serum concentrations of HDL-cholesterol, triacylglycerol and insulin, as well as with BMI.

CONCLUSIONS/INTERPRETATION

Our results implicate the rs34861192 and rs3745368 polymorphisms of RETN as robust and independent determinants of plasma resistin concentration in the study population. In addition, plasma resistin level was associated with dyslipidaemia, serum insulin concentration and obesity.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00262691.

The contributions of resistin and adiponectin gene single nucleotide polymorphisms to the genetic risk for polycystic ovary syndrome in a Japanese population

Polycystic ovary syndrome (PCOS) is a heterogeneous group of disorders that occur fairly commonly in women of reproductive age and are characterized by a variety of clinical manifestations, including insulin resistance that is independent of obesity. Recent studies suggest that altered adipocytokine gene expression is closely associated with insulin resistance and that single nucleotide polymorphisms (SNPs) modulate the expression and/or function of these genes, thereby affecting insulin sensitivity. With that in mind, we investigated whether SNPs at position -420 of the resistin gene (RETN) and/or -11377 of the adiponectin gene (ADIPOQ) modulate the susceptibility to PCOS. We evaluated the genotypes of 117 women with PCOS and 380 healthy fertile controls and measured the index of insulin resistance and hormonal profiles in the PCOS women. The RETN-420G/G homozygous variant genotype occurred significantly more frequently among the PCOS group than among the control group (15.4% vs. 8.4%, p = 0.035). PCOS women with the RETN-420G/G genotype also showed significantly higher BMIs and greater insulin resistance than those with RETN-420 C/C or C/G genotypes. The ADIPOQ SNP at -11377 showed no association with PCOS. We conclude that the RETN G/G at -420 genotype is associated with PCOS in Japanese women.

Genetic variation in adipokine genes and risk of colorectal cancer

OBJECTIVE

Obesity has been related to an increased risk of colorectal cancer (CRC). Adipokines produced by the adipose tissue are directly linked to obesity and may thus contribute to the pathogenesis of CRC. We hypothesized that potentially functional polymorphisms in the adipokine genes leptin (LEP), leptin receptor (LEPR), resistin (RETN), and adiponectin (ADIPOQ) may be associated with CRC.

DESIGN AND METHODS

We studied the association of four putatively functional single nucleotide polymorphisms (SNPs) with CRC risk using a hospital-based study design with 702 cases and 752 controls from the Czech Republic. We used likelihood ratio tests to select the best model to represent the relationship between genotypes and risk of CRC. Age-adjusted odds ratios (ORs) under the best model were calculated for each SNP. Previous genotyping data on insulin (INS)-related genes were used to explore interactions between genes in obesity- and diabetes-related pathways by using two independent methods, logistic regression, and multifactor-dimensionality reduction.

RESULTS

A trend to associate between the RETN SNP rs1862513 (C-420G) and CRC risk was observed (per allele OR 1.18, 95% confidence interval (0.99-1.40). Statistically, significant interactions were observed between the INS SNP rs3842754 (+1127INSPstI) genotypes and both the LEPR SNP rs1137101 (Q223R) and the ADIPOQ SNP rs266729 (C-11374G) genotypes.

CONCLUSIONS

Our results suggest that variants in the adipokine genes may affect CRC risk in combination with variants in diabetes-related genes.

Resistin gene variation is associated with systemic inflammation but not plasma adipokine levels, metabolic syndrome or coronary atherosclerosis in nondiabetic Caucasians

OBJECTIVE

Resistin causes insulin resistance and diabetes in mice whereas in humans it is linked to inflammation and atherosclerosis. Few human genetic studies of resistin in inflammation and atherosclerosis have been performed. We hypothesized that the -420C>G putative gain-of-function resistin variant would be associated with inflammatory markers and atherosclerosis but not with metabolic syndrome or adipokines in humans.

DESIGN AND METHODS

We examined the association of three resistin polymorphisms, -852A>G, -420C>G and +157C>T, and related haplotypes with plasma resistin, cytokines, C-reactive protein (CRP), adipokines, plasma lipoproteins, metabolic syndrome and coronary artery calcification (CAC) in nondiabetic Caucasians (n = 851).

RESULTS

Resistin levels were higher, dose-dependently, with the -420G allele (CC 5.9 +/- 2.7 ng/ml, GC 6.5 +/- 4.0 ng/ml and GG 7.2 +/- 4.8 ng/ml, trend P = 0.04) after age and gender adjustment [fold higher for GC + GG vs. CC; 1.07 (1.00-1.15), P < 0.05)]. The -852A>G single nucleotide polymorphism (SNP) was associated with higher soluble tumour necrosis factor-receptor 2 (sol-TNFR2) levels in fully adjusted models [1.06 (95% CI 1.01-1.11), P = 0.01)]. The estimated resistin haplotype (GGT) was associated with sol-TNFR2 (P = 0.04) and the AGT haplotype was related to CRP (P = 0.04) in the fully adjusted models. Resistin SNPs and haplotypes were not associated with body mass index (BMI), fasting glucose, insulin resistance, metabolic syndrome, adipokines or CAC scores.

CONCLUSIONS

Despite modest associations with plasma resistin and inflammatory biomarkers, resistin 5' variants were not associated with metabolic parameters or coronary calcification. This suggests that resistin is an inflammatory cytokine in humans but has little influence on adiposity, metabolic syndrome or atherosclerosis.

Polymorphism in resistin promoter region at -420 determines the serum resistin levels and may be a risk marker of stroke in Japanese type 2 diabetic patients

Resistin, which appears to be related to insulin resistance, is secreted mainly from macrophages in human and some of its polymorphisms have been reported. Based on recent in vitro studies, resistin may be associated with atherosclerosis by mediating endothelial hyperactivity. We investigated whether resistin polymorphism at -420C>G is associated with serum resistin levels and diabetic macroangiopathy (coronary heart disease, arteriosclerosis obliterans, and stroke) in 349 Japanese type 2 diabetic patients (DM) and 286 non-diabetic controls (non-DM). Serum resistin levels in DM with a history of stroke were significantly higher than those without, 19.6+/-2.1 and 12.4+/-0.5 ng/ml (P<0.001), respectively. Furthermore, the levels were significantly increased in a genotype-dependent manner (CC, CG, GG) based on the polymorphism at -420C>G (P<0.001) in both DM and non-DM. The prevalence of stroke in DM significantly increased according to the presence of mutations (P<0.035). In multivariate logistic-regression analysis, individuals with the CG or GG genotypes were significantly more likely to have had a stroke than individuals with the CC genotype (vs. CG; OR 2.99, P=0.024, vs. GG; OR 4.49, P=0.010). These data suggested that the genotyping of resistin polymorphism at -420(C>G) can be a risk marker for stroke susceptibility in Japanese type 2 diabetic patients.

Association of -394C>G and -420C>G polymorphisms in the RETN gene with T2DM and CHD and a new potential SNP might be exist in exon 3 of RETN gene in Chinese

Genetic variations of the human RETN gene are associated with metabolic phenotypes, including obesity, insulin sensitivity, diabetes, and coronary heart disease (CHD). There are few studies of two gene variants, -394C>G and -420C>G, in Chinese population. This study investigated the distribution of RETN gene, single nucleotide polymorphisms (SNPs), in Chinese Han population and the association of the polymorphisms with type 2 diabetes mellitus (T2DM) and CHD. In a population-based, case-control genetic association study, a total of 961 subjects were recruited from the community, including 318 T2DM patients, 273 CHD patients, and 370 unrelated healthy control individuals. Serum lipid levels were detected. Two SNPs of RETN gene, -394C>G and -420C>G, were genotyped by PCR-RFLP. Unknown Polymorphisms were screened with the technique of denaturing high performance liquid chromatography (DHPLC). The frequencies of RETN -394G allele in T2DM group, CHD group, and control group were 0.3066, 0.3555, and 0.3481, respectively, which are met with the Hardy-Weinberg equilibrium. There is a significant difference of the comparison of sex in T2DM group of RETN gene SNP-394C>G (P < 0.05). Compared with controls, there was no significant difference in the distribution of genotypes and allele frequencies of -394C>G polymorphic site in T2DM patients and CHD patients, respectively. No direct association was found between the -394C>G polymorphism and T2DM or CHD. The frequencies of RETN -420G allele in T2DM group, CHD group, and control group were 0.4009, 0.3725, and 0.3859, respectively, which are met with the Hardy-Weinberg equilibrium. The frequencies of RETN -420G allele in T2DM groups and control groups of Chinese population are significantly different from those in European population (0.40 vs. 0.27, 0.39 vs. 0.26) (P < 0.01). Compared with controls, there was no significant difference in distribution of genotypes and allele frequencies of -420C>G polymorphic site in T2DM patients and CHD patients, respectively. No direct association was found between the -420C>G polymorphism and T2DM or CHD. In addition, we found new potential SNP +593G>C in exon 3 of RETN gene using DHPLC. The RETN gene exhibits sex and ethnic differences. +593G>C of RETN gene might be a new potential SNP in exon 3 of RETN gene. Association between SNP -394C>G and -420C>G of RETN gene with T2DM and CHD in Chinese needs more exploration.

Association of variants in RETN with plasma resistin levels and diabetes-related traits in the Framingham Offspring Study

OBJECTIVE

The RETN gene encodes the adipokine resistin. Associations of RETN with plasma resistin levels, type 2 diabetes, and related metabolic traits have been inconsistent. Using comprehensive linkage disequilibrium mapping, we genotyped tag single nucleotide polymorphisms (SNPs) in RETN and tested associations with plasma resistin levels, risk of diabetes, and glycemic traits.

RESEARCH DESIGN AND METHODS

We examined 2,531 Framingham Offspring Study participants for resistin levels, glycemic phenotypes, and incident diabetes over 28 years of follow-up. We genotyped 21 tag SNPs that capture common (minor allele frequency >0.05) or previously reported SNPs at r2 > 0.8 across RETN and its flanking regions. We used sex- and age-adjusted linear mixed-effects models (with/without BMI adjustment) to test additive associations of SNPs with traits, adjusted Cox proportional hazards models accounting for relatedness for incident diabetes, and generated empirical P values (Pe) to control for type 1 error.

RESULTS

Four tag SNPs (rs1477341, rs4804765, rs1423096, and rs10401670) on the 3' side of RETN were strongly associated with resistin levels (all minor alleles associated with higher levels, Pe<0.05 after multiple testing correction). rs10401670 was also associated with fasting plasma glucose (Pe = 0.02, BMI adjusted) and mean glucose over follow-up (Pe = 0.01; BMI adjusted). No significant association was observed for adiposity traits. On meta-analysis, the previously reported association of SNP -420C/G (rs1862513) with resistin levels remained significant (P = 0.0009) but with high heterogeneity across studies (P < 0.0001).

CONCLUSIONS

SNPs in the 3' region of RETN are associated with resistin levels, and one of them is also associated with glucose levels, although replication is needed.

Adipocyte-specific expression of murine resistin is mediated by synergism between peroxisome proliferator-activated receptor gamma and CCAAT/enhancer-binding proteins

Resistin antagonizes insulin action in mouse, making it a potential therapeutic target for treating metabolic diseases such as diabetes. To better understand how mouse resistin gene (Retn) expression is restricted to fat tissue, we identified an adipocyte-specific enhancer located approximately 8.8-kb upstream of the transcription start site. This region contains a binding site for the master adipogenic regulator peroxisome proliferator-activated receptor gamma (PPARgamma), and binds endogenous PPARgamma together with its partner retinoid-X receptor alpha (RXRalpha). It also contains three binding sites for CCAAT/enhancer-binding protein (C/EBP), and is bound by endogenous C/EBPalpha and C/EBPbeta in adipocytes. Exogenous expression of PPARgamma/RXRalpha and C/EBPalpha in non-adipocyte cells synergistically drives robust expression from the enhancer. Although PPARgamma ligands repress Retn transcription in adipocytes, rosiglitazone paradoxically stimulates the enhancer activity, suggesting that the enhancer is not directly involved in negative regulation. Unlike expression of Retn in mouse, human resistin (RETN) is expressed primarily in macrophages. Interestingly, the region homologous to the mouse Retn enhancer in the human gene contains all three C/EBP elements, but is not conserved for the sequence bound by PPARgamma. Furthermore, it displays little or no binding by PPARgamma in vitro. Taken together, the data suggest that a composite enhancer binding both PPARgamma and C/EBP factors confers adipocyte-specific expression to Retn in mouse, and its absence from the human gene may explain the lack of adipocyte expression in humans.

Serum levels of resistin and its correlation with adiponectin and insulin in healthy full term neonates

Resistin and adiponectin are two adipokines involved in the regulation of insulin sensitivity, and have been suggested as mediators of adult metabolic syndrome.

AIM

The aim of this study was to investigate cord blood levels of resistin, and their postnatal changes in full-term appropriate for gestational age (AGA) neonates. Interrelations between resistin, adiponectin, and insulin, and between resistin and neonatal and maternal anthropometric parameters were also assessed.

DESIGN

Blood samples were obtained from 30 full term AGA neonates at birth and on the 4th day of life. Anthropometric variables studied included birth weight, length, body mass index (BMI), neonatal weight loss, and mother's BMI. Resistin and adiponectin were determined by ELISA, and insulin by radioimmunoassay method. Data were analyzed using Wilcoxon test and Spearman's correlation coefficient.

RESULTS

Resistin levels were high at birth and did not change on the 4th day of life. Resistin levels were not correlated to insulin, nor adiponectin levels, nor any anthropometric parameter of neonates or their mothers. Instead, adiponectin levels increased on the 4th day of life, and were correlated to insulin levels.

CONCLUSION

High levels of resistin in full-term AGA neonates suggest that this hormone may play a role in maintenance of metabolic neonatal homeostasis, but its physiological significance needs further investigation.

The +299(G>A) resistin gene polymorphism and susceptibility to type 2 diabetes in Thais

The prevalence of type 2 diabetes has been increased in Thais. Resistin is an adipokine that involve in glucose homeostasis and is a candidate gene for type 2 diabetes. We performed a case-control study in representative sample of 200 Thai volunteers, 105 controls and 95 type 2 diabetes subjects. The purposes of the present study were to investigate the association between two SNPs (single nucleotide polymorphisms) in the resistin gene, at positions +299(G>A) and -420(C>G), and biochemical parameters; to determine whether these polymorphisms are linked to increased risk of type 2 diabetes. At position +299(G>A) of the resistin gene, the resistin concentration among type 2 diabetes subjects was significantly higher in GA/AA genotypes (3.40 ng/ml) than the GG genotype (1.99 ng/ml). Resistin gene polymorphism at position +299(G>A) in type 2 diabetes patients was significantly more frequent than in the control group (p = 0.004). Polymorphism at position -420(C>G) showed no significant relationship with type 2 diabetes (p = 0.095). Logistic regression analysis was shown that +299(G>A) gene polymorphism was increased risk factors for type 2 diabetes (p = 0.013). In conclusion, these finding suggest that resistin gene polymorphism at position +299(G>A) has impact on the increased resistin concentrations and may influence susceptibility to type 2 diabetes in Thais.

Genetic analysis implicates resistin in HIV lipodystrophy

OBJECTIVES

To investigate the role of genetic variation in influencing the risk of metabolic complications associated with highly active antiretroviral therapy (HAART).

METHODS

Cluster analysis of metabolic traits of 189 patients enrolled in ACTG5005s, the metabolic substudy of ACTG384, a clinical trial of HAART, was performed to identify a subgroup of individuals with increased risk of developing a cluster of metabolic abnormalities after exposure to HAART. Almost 300 single nucleotide polymorphisms in 135 candidate genes were evaluated for their association with this subgroup.

RESULTS

A subgroup of patients was identified that had a normal metabolic profile at baseline but developed significantly elevated lipids and insulin resistance on HAART. This high-risk subgroup of patients also experienced significant body composition changes, particularly limb fat loss. Candidate gene analysis revealed that a single nucleotide polymorphism in resistin, a gene previously implicated in obesity and insulin resistance, was associated with this high-risk group (P = 0.0003).

CONCLUSION

Genetic variation in resistin is associated with metabolic complications caused by HAART.

Absence of evidence for an association between resistin gene variants and insulin resistance in an Asian population with low and high blood pressure

AIMS

Although the function of resistin in human biology is unclear, some evidence suggests resistin gene variants influence insulin resistance, and insulin resistance-related hypertension. We searched for associations between common resistin gene variants and factors related to insulin resistance in Asian individuals with high or low blood pressure (BP).

METHODS

Non-diabetic Chinese or Japanese sibling pairs were included if one had extreme hypertension and the other was either hypertensive or hypotensive. Four common, non-coding single nucleotide polymorphisms (SNPs) were identified by sequencing the resistin gene in 24 hypertensive probands. Generalized estimating equations (GEEs)-based regressions were then performed to test for SNP associations using the entire study population (n=1556).

RESULTS

Of 72 tests, only one was significant at the 0.05 level; 3.5 significant tests were expected by chance alone. High variability in insulin and triglyceride levels created wide confidence intervals, thus the negative results are not conclusive for these phenotypes. However, the large sample size resulted in narrow confidence intervals for BMI, fasting and 120min post-load glucose, and high and low density lipoprotein cholesterol (LDL-C).

CONCLUSION

Several factors associated with insulin resistance are not likely influenced by the resistin gene in non-diabetic Asian individuals with high and low blood pressure.

Genetic variants at the resistin locus are associated with the plasma resistin concentration and cardiovascular risk factors

OBJECTIVE

To examine the relation of the single nucleotide polymorphisms (SNPs) of the resistin gene on the plasma resistin concentration and cardiovascular risk factors.

METHODS AND RESULTS

Plasma resistin concentrations were measured and SNP -420C>G, +157C>T, and +299G>A genotyped in our Finnish population-based cohort. Association analyses were performed in the control group of the cohort (n=515). In addition, the hypertension group (n=505), representing a high-risk group, was analyzed for these SNP's and the frequencies were compared with the low-risk control group. Resistin concentration differed significantly between the SNP genotypes, the common homozygotes having the lowest concentration in every SNP (p<0.01). After adjustment for age, sex, and BMI SNP -420C-C homozygotes had the lowest IGFBP-1 (p=0.001), the highest GHbA1c (p=0.028) in all the subjects and the lowest quick index (p<0.001) and the highest insulin (p<0.001) among female subjects of the control cohort. Plasma triglycerides were the lowest among G-G homozygotes (p=0.006). In addition, the SNP -420C allele was more frequent among hypertensive than control cohort (p=0.018).

CONCLUSIONS

The results imply that genetic variation seems to have a role in the determination of plasma resistin level. SNP -420C-C homozygozity status seems to be associated with more deleterious metabolic profile.

Bioinformatic analysis of functional proteins involved in obesity associated with diabetes

The twin epidemic of diabetes and obesity pose daunting challenges worldwide. The dramatic rise in obesity-associated diabetes resulted in an alarming increase in the incidence and prevalence of obesity an important complication of diabetes. Differences among individuals in their susceptibility to both these conditions probably reflect their genetic constitutions. The dramatic improvements in genomic and bioinformatic resources are accelerating the pace of gene discovery. It is tempting to speculate the key susceptible genes/proteins that bridges diabetes mellitus and obesity. In this regard, we evaluated the role of several genes/proteins that are believed to be involved in the evolution of obesity associated diabetes by employing multiple sequence alignment using ClustalW tool and constructed a phylogram tree using functional protein sequences extracted from NCBI. Phylogram was constructed using Neighbor-Joining Algorithm a bioinformatic tool. Our bioinformatic analysis reports resistin gene as ominous link with obesity associated diabetes. This bioinformatic study will be useful for future studies towards therapeutic inventions of obesity associated type 2 diabetes.

Adipokines and the peripheral and neural control of energy balance

Adipokines are secreted by adipose tissue and control various physiological systems. Low leptin levels during fasting stimulate feeding, reduce energy expenditure, and modulate neuroendocrine and immune function to conserve energy stores. On the other hand, rising leptin levels in the overfed state prevent weight gain by inhibiting food intake and increasing energy expenditure. These actions are mediated by neuronal circuits in the hypothalamus and brainstem. Leptin also controls glucose and lipid metabolism by targeting enzymes such as AMP-activated protein kinase and stearoyl-coenzyme A desaturase-1 in liver and muscle. Likewise, adiponectin and resistin control energy balance and insulin sensitivity via central and peripheral targets. As highlighted in this review, there are distinct as well as common signaling pathways for adipokines. Understanding adipokine signaling in the brain and other organs will provide insights into the pathogenesis and treatment of obesity, diabetes and various metabolic disorders.

A polymorphism in the resistin gene promoter and the risk of coronary artery disease in a Chinese population

OBJECTIVE

Resistin, a novel adipocyte-derived peptide, has been linked to the pathogenesis of atherosclerosis. Recently, -420C>G, a variant located in the promoter region of the resistin gene (RETN) was identified. The aim of this study was to investigate the association between this RETN-420C>G polymorphism and the risk of coronary artery disease (CAD).

DESIGN

A hospital-based case-control study.

PATIENTS

A total of 225 CAD patients and 225 age- and sex-matched control subjects.

MEASUREMENTS

Genotyping was performed by polymerase chain reaction (PCR) and restriction enzyme analysis to detect the presence of the RETN-420C>G polymorphism.

RESULTS

The frequencies of RETN-420C>G genotypes in the CAD group were significantly different from those in the control group (P = 0.024). Subjects with the variant genotypes (CG and GG) had a 62% increased risk of CAD compared to CC carriers [adjusted odds ratio (OR) = 1.62, 95% confidence interval (CI) = 1.09-2.41, P = 0.016]. However, there were no significant differences between the genotypes with respect to weight, body mass index (BMI) and lipid profiles in CAD patients, and no significant association was found between the RETN-420C>G polymorphism and the severity of CAD.

CONCLUSIONS

Our data suggest that the RETN-420C>G polymorphism might be associated with an increased risk of CAD in a Chinese population.

Effect of the -420C/G variant of the resistin gene promoter on metabolic syndrome, obesity, myocardial infarction and kidney dysfunction

OBJECTIVE

Resistin is an adipokine that has been suggested to be correlated with markers of inflammation and to be predictive of coronary atherosclerosis and type II diabetes in humans. A common single nucleotide polymorphism (SNP) (-420C/G) in the promoter of resistin is associated with increased resistin plasma levels and susceptibility to type II diabetes. The aim of this study was to investigate the association of the -420C/G polymorphism with metabolic syndrome, obesity, myocardial infarction and kidney disease.

DESIGN AND RESULTS

First we studied 1542 subjects from the PLIC study (a population based cohort). GG carriers showed an higher prevalence of obesity and metabolic syndrome as well as increased plasma triglycerides levels, BMI, systolic and diastolic blood pressure and cardiovascular risk according to Framingham algorithm (P < 0.05 for all). Next we investigated the presence of the -420C/G resistin polymorphism in a case-control study that included 300 subject with myocardial infarction and 300 age and sex matched controls and then we studied the role of the -420C/G SNP in 88 patients with mild to moderate renal dysfunction. No statistically significant differences in allele frequencies between the PLIC study, the myocardial infarction (MI) cases and the subjects with renal dysfunction were observed. Pro-inflammatory gene expression profiling of peripheral blood mononuclear cells failed to detect any difference between wild type subjects and carriers of the rare allele.

CONCLUSION

Our data suggest that the presence of the -420C/G SNP of the resistin gene is associated with increased obesity and metabolic syndrome, although it is not different in subjects at high cardiovascular risk such as patients with myocardial infarction or patients with renal dysfunction compared with controls.

Association of Resistin Gene 3'-Untranslated Region EX4-44G-->A Polymorphism with Obesity- and Insulin-Related Phenotypes in Turkish Type 2 Diabetes Patients

Resistin, an adipocyte-secreted hormone, has been associated with obesity, insulin resistance and type 2 diabetes mellitus (T2DM) in some, but not all, rodent models. In humans, the exact function of resistin is unkown. Because 3'-untranslated region (3'-UTR) single nucleotide substitutions (SNPs) have been shown to affect gene expression, we examined the EX4-44G-->A SNP in the 3'-UTR of exon 3 within the resistin gene. The objective of this study was to investigate, for the first time in a Turkish study group, whether the 3'-UTR EX4-44G-->A variation in the resistin gene influences the development of T2DM, obesity and insulin-related phenotypes. We analyzed the genotype frequencies of the EX4-44G-->A polymorphism of the resistin gene in 116 type 2 diabetic and 102 normal subjects. Serum lipids, obesity-related and insulin-related phenotypes were analyzed. No significant difference for genotypic frequencies were observed for the BseRI restriction site in type 2 diabetic patients as compared to controls. Waist-to-hip ratio, BMI, body fat and apoAI levels were found to be affected by resistin genotype. In the control group, BMI (p < 0.01), HIS (p < 0.05) and BF (p < 0.05) levels were found to be elevated, whereas HOMA beta-cell index (p < 0.01) and apo AI (p < 0.05) levels were found to be decreased in GG genotype carriers. In the diabetic group, the GG genotype carriers were found to have higher BMI levels (p < 0.001), waist-to-hip ratio (p < 0.05), body fat (p < 0.01), HOMA (p < 0.001) and fasting insulin (p < 0.05), but lower HbA1c levels in comparison to GC + AA carriers. These data suggest that, in the Turkish study group, the EX4-44G-->A polymorphism of the resistin gene is associated with insulin and obesity-related phenotypes.