Association of sequence variations in the gene encoding adiponectin receptor 1 (ADIPOR1) with body size and insulin levels. The Finnish Diabetes Prevention Study

Polymorphism in Adiponectin and Adiponectin Receptor Genes in Diabetes Mellitus Pathogenesis

The role played by hereditary factors in the development of diabetes mellitus type 2 (DM2) has not yet been fully established. Therefore, the purpose of our study was to investigate the prevalence of adiponectin and polymorphism in its gene receptors in connection with the primary symptoms of DM2 pathogenesis. Genomic DNA was isolated from the whole blood of 94 patients with an established diagnosis of DM2 using the phenol–chloroform method. Gene polymorphisms were determined using real-time polymerase chain reaction (PCR). The most common polymorphic variants in patients with DM2 were the genotypes AA (rs11061971) and GG (rs16928751) on the ADIPOR2 gene. A strong correlation was found between the rs16928751 polymorphism on the ADIPOR2 gene and increased body mass index (BMI). TG (rs2275737) ADIPOR1 gene genotype carriers were found to have the highest levels of glycosylated hemoglobin (HbA1), whereas TT (rs2275738) caused stable hyperglycemia. In addition, the rs16928751 ADIPOR2 gene polymorphism showed an association with the development of key mechanisms of DM2 in the Russian population, although a number of genomic searches failed to show any association of this gene with DM2. Unique gene variants associated with the risk of developing DM2 in the Crimean population were established.

Adiponectin receptor 1 gene is potentially associated with severity of postoperative pain but not cancer pain

Adiponectin is an adipose tissue-derived cytokine that exerts its antiinflammatory effects by binding to 2 adiponectin receptors, adiponectin receptor 1 (ADIPOR1) and adiponectin receptor 2 (ADIPOR2). However, the role of these adiponectin receptors on inflammatory pain remains unclear. We investigated the association between single nucleotide polymorphisms (SNPs) of these genes and inflammatory pain, such as postoperative pain and cancer pain.We analyzed 17 SNPs of the ADIPOR1 gene and 27 SNPs of the ADIPOR2 gene in 56 adult patients with postlaparotomy pain. We compared these genotypes with pain intensity and opioid consumption, adjusting for multiple testing. We analyzed the genotypes of 88 patients with cancer pain and examined the association of the relevant SNP(s) with pain intensity and opioid consumption.One variant of the ADIPOR1 gene (rs12045862) showed significant association with postoperative pain intensity; patients with minor allele homozygote (n = 7) demonstrated significantly worse pain intensity than that of combined patient group exhibiting major allele homozygote or the heterozygote (n = 49; Mann-Whitney test, P < .00002), although their opioid consumptions were comparable. Cancer pain intensity between minor allele homozygote patients (n = 7) and other 2 genotype patients (n = 81) were comparable.The rs12045862 SNP of the ADIPOR1 gene was associated with postoperative pain but not cancer pain. This might result from functional alteration of the ADIPOR1 signalling pathways, which influence the inflammatory process. ADIPOR1 may be a novel potential target for developing analgesics of postoperative pain.

ADIPOR1 is essential for vision and its RPE expression is lost in the Mfrprd6 mouse

The knockout (KO) of the adiponectin receptor 1 (AdipoR1) gene causes retinal degeneration. Here we report that ADIPOR1 protein is primarily found in the eye and brain with little expression in other tissues. Further analysis of AdipoR1 KO mice revealed that these animals exhibit early visual system abnormalities and are depleted of RHODOPSIN prior to pronounced photoreceptor death. A KO of AdipoR1 post-development either in photoreceptors or the retinal pigment epithelium (RPE) resulted in decreased expression of retinal proteins, establishing a role for ADIPOR1 in supporting vision in adulthood. Subsequent analysis of the Mfrprd6 mouse retina demonstrated that these mice are lacking ADIPOR1 in their RPE layer alone, suggesting that loss of ADIPOR1 drives retinal degeneration in this model. Moreover, we found elevated levels of IRBP in both the AdipoR1 KO and the Mfrprd6 models. The spatial distribution of IRBP was also abnormal. This dysregulation of IRBP hypothesizes a role for ADIPOR1 in retinoid metabolism.

Adiponectin Receptor gene Polymorphisms are Associated with Kidney Function in Elderly Japanese Populations

Aim: Adiponectin exhibits its biological effects through adiponectin receptors (AdipoR1 and AdipoR2), which are distributed in the kidneys, and activation of those receptors could prevent or ameliorate diabetic nephropathy. This study aimed to evaluate the associations between AdipoR single nucleotide polymorphisms (SNPs) and kidney function in an elderly Japanese population.

Methods: A total of 271 elderly Japanese volunteers underwent anthropometric and laboratory tests (cystatin C-based eGFR and total and high molecular weight adiponectin levels at baseline and a follow-up visit). Genotype data were obtained for the selected 7 and 5 AdipoR1 and AdipoR2 SNPs, respectively.

Results: In a cross-sectional analysis at baseline, we found a significant association between the AdipoR2 SNP rs12230440 and kidney function; eGFRcys tended to increase as the number of carriers of T alleles increased after adjustment for covariates and Bonferroni correction, although the association of the SNP and annual eGFR decline could not be identified in the longitudinal data. Regarding the variants rs16850797, rs11061925, and rs10773983, each of the allele G, allele C, and allele G showed nominally significant associations with higher eGFRcys. However, this failed to reach significance after Bonferroni correction.

Conclusion: Here, an AdipoR2 SNP was associated with kidney function, suggesting that the effects of this polymorphism on adiponectin receptor may affect kidney function in the elderly Japanese population.

Association of adiponectin receptor 1 gene - 106 C > T variant with susceptibility to colorectal cancer

Background

Colorectal cancer (CRC) is the fourth leading cause of cancer-related death around the world and accumulated evidence indicates the association between CRC and obesity and insulin resistance.

Objectives

Regarding the role of adiponectin in obesity and insulin resistance, we explored whether genetic variants in adiponectin (ADIPOQ) and adiponectin receptor 1 (ADIPOR1) are associated with CRC risk.

Materials and methods

ADIPOQ (rs2241766) and ADIPOR1 (rs2275738) gene variants were genotyped in 261 cases with CRC and 339 controls using PCR-RFLP method.

Results

In this study, no significant difference was observed for ADIPOQ gene rs2241766 variant between the cases and controls. However, carriers of the ADIPOR1 (rs2275738) “CC + CT” genotype compared with “TT” genotype occurred more frequently in the cases with CRC than the controls, and the difference remained significant after adjustment for age, BMI, sex, smoking status, NSAID use, and family history of CRC (P = 0.048; OR = 1.49, 95%CI = 1.01–2.20). Interestingly, after adjustment for confounding factors the ADIPOR1 “CC + TC” genotype compared with “TT” genotype was also associated with an increased risk for obesity in the cases (P = 0.040; OR = 1.86, 95%CI = 1.03–3.36).

Conclusions

Our findings suggest for the first time that the − 106 C > T (rs2275738) variant of ADIPOR1 gene may be a genetic contributor to CRC and obesity risk in the cases with CRC. However, further studies with bigger sample size are needed to validate these findings.

Non-coding functions of alternative pre-mRNA splicing in development

A majority of messenger RNA precursors (pre-mRNAs) in the higher eukaryotes undergo alternative splicing to generate more than one mature product. By targeting the open reading frame region this process increases diversity of protein isoforms beyond the nominal coding capacity of the genome. However, alternative splicing also frequently controls output levels and spatiotemporal features of cellular and organismal gene expression programs. Here we discuss how these non-coding functions of alternative splicing contribute to development through regulation of mRNA stability, translational efficiency and cellular localization.

Adiponectin receptor 1 (ADIPOR1) rs1342387 polymorphism and risk of cancer: a meta-analysis

Many studies have indicated possible associations between a polymorphism of adiponectin receptor 1 (ADIPOR1) rs1342387 and risk of cancer, but contradictory results have been reported. The main aim of this study was to draw a reliable conclusion about the relationship between the rs1342387 polymorphism and cancer incidence, by conducting a literature search of Pubmed, Embase, Wanfang and Cochrane libraries. Eleven studies including 3, 738 cases and 4, 748 controls were identified in this meta-analysis. The ADIPOR1 rs1342387 polymorphism was associated with risk of colorectal cancer for all genetic comparison models (GG vs AA, OR: 1.44, 95%CI: 1.21 -1.70; G carriers vs A carriers, OR: 1.23, 95%CI: 1.11 -1.36; dominant model, OR: 1.28, 95%CI: 1.10 -1.49 and recessive model, OR: 1.31, 95%CI: 1.12 -1.55). Stratified by ethnicity, the rs1342387 polymorphism was significantly associated with risk of colorectal cancer in Asian ancestry for all genetic comparison models (GG vs AA, OR: 1.56, 95%CI: 1.26-1.92; G carriers vs. A carriers OR: 1.30, 95%CI: 1.18 -1.43; dominant model OR: 1.31, 95%CI: 1.08 -1.60 and recessive model OR: 1.44, 95%CI: 1.26 -1.64), but not in Caucasian or mixed (Caucasian mainly) groups. In summary, the ADIPOR1 rs1342387 polymorphism is significantly associated with risk of colorectal cancer among individuals of Asian ancestry.

Association of polymorphisms of the ADIPOQ, ADIPOR1 and ADIPOR2 genes with type 2 diabetes mellitus

The study of hereditary predisposition to multifactorial diseases is essential for diagnosis and selection of the optimal treatment. The study of polymorphisms of candidate genes whose products are involved in the pathogenesis of multifactorial diseases is of great clinical importance. Aim. The aim of this study was to investigate the association of rs2241766 and rs1501299 polymorphisms in the ADIPOQ gene, rs2275737 and rs2275738 polymorphisms in the ADIPOR1 gene and rs11061971 and rs16928751 polymorphisms in the ADIPOR2 gene with the development of type 2 diabetes mellitus (T2DM) in the Russian population. Materials and methods. The study included a group of 500 patients with T2DM diagnosed based on standard diagnostic criteria (T2DM+). The control group (T2DM-) was a random sample of 500 patients with no evidence of the disease and was matched to the T2DM+ group for gender, age and body mass index. The determination of alleles and genotypes was performed using real-time polymerase chain reaction with TaqMan probes. The X2 test and contingency tables were used to compare the distribution of allele and genotype frequencies. A p-value of

Associations between variants on ADIPOQ and ADIPOR1 with colorectal cancer risk: a Chinese case-control study and updated meta-analysis

Background

Epidemiological studies have suggested that variants on adiponectin (ADIPOQ) and its receptor ADIPOR1 (adiponectin receptor 1) are associated with colorectal cancer (CRC) risk; however, the results were inconclusive. The aim of the study was to evaluate the associations between the variants on ADIPOQ and ADIPOR1 and the CRC risk with a hospital-based case-control study in the Chinese population along with meta-analysis of available epidemiological studies.

Methods

With a hospital-based case-control study of 341 cases and 727 controls, the associations between the common variants on ADIPOQ (rs266729, rs822395, rs2241766 and rs1501299) and ADIPOR1 (rs1342387 and rs12733285) and CRC susceptibility were evaluated. Meta-analysis of the published epidemiological studies was performed to investigate the associations between the variants and CRC risk.

Results

For the population study, we found that variant rs1342387 of ADIPOR1 was associated with a reduced risk for CRC [adjusted odds ratio (OR) = 0.74, 95% confidential intervals (95% CI) = 0.57-0.97; CT/TT vs. CC]. The meta-analysis also suggested a significant association for rs1342387 and CRC risk; the pooled OR was 0.79 (95% CI = 0.66-0.95) for the CT/TT carriers compared to CC homozygotes under the random-effects model (Q = 8.06, df = 4, P = 0.089; I² = 50.4%). The case-control study found no significant association for variants rs266729, rs822395, rs2241766, and rs1501299 on ADIPOQ or variant rs12733285 on ADIPOR1 and CRC susceptibility, which were consistent with results from the meta-analysis studies.

Conclusions

These data suggested that variant rs1342387 on ADIPOR1 may be a novel CRC susceptibility factor.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-014-0137-y) contains supplementary material, which is available to authorized users.

Differential gene expression of the key signalling pathway in para-carcinoma, carcinoma and relapse human pancreatic cancer

Pancreatic cancer (PC) has a high rate of mortality and a poorly understood mechanism of progression. Investigation of the molecular mechanism of PC and exploration of the specific markers for early diagnosis and specific targets of therapy are key points to prevent and treat PC effectively and to improve their prognosis. In our study, expression profiles experiment of para-carcinoma, carcinoma and relapse human PC was performed using Agilent human whole genomic oligonucleotide microarrays with 45 000 probes. Differentially expressed genes related with PC were screened and analysed further by Gene Ontology term analysis and Kyoto encyclopaedia of genes and genomes pathway analysis. Our results showed that there were 3853 differentially expressed genes associated with pancreatic carcinogenesis and relapse. In addition, our study found that PC was related to the Jak-STAT signalling pathway, PPAR signalling pathway and Calcium signalling pathway, indicating their potential roles in pancreatic carcinogenesis and progress.

Single-nucleotide polymorphisms in adiponectin, AdipoR1, and AdipoR2 genes: insulin resistance and type 2 diabetes mellitus candidate genes

It has already been a decade and a half since the discovery of adiponectin and its role as an insulin sensitizer and only 7 years since its receptors, AdipoR1 and AdipoR2, were described. A single-nucleotide polymorphism (SNP) is a DNA sequence variation that affects only one nucleotide; it may vary from one population to another with different predisposing factors to diseases and other ailments. Once some of the effects of adiponectin and its receptors were known, it was not long until an effort was made to find the associations between specific SNPs of the genes of this hormone and its receptors as genetic risk factors for insulin resistance, type 2 diabetes mellitus, and metabolic syndrome, although these genes were investigated as possible candidates related to the development of these metabolic disorders. All of these possible associations were studied in different populations from France, Finland, the United Kingdom, North America, and Japan, showing hardly concluding results, and because of that it is highly controversial to directly associate one of the genes mentioned above to insulin resistance, type 2 diabetes mellitus, and metabolic syndrome. All of these inconsistencies lead to a review that summarizes the SNPs of the genes of adiponectin, AdipoR1, and AdipoR2 that are mostly related to insulin resistance syndrome, type 2 diabetes mellitus, and metabolic syndrome, although presenting the possible factors that should be taken into account to homogenize the results obtained until now.

Association between adiponectin receptor 1 gene polymorphism and insulin resistance in Chinese patients with polycystic ovary syndrome

BACKGROUND/AIMS

Adiponectin receptor 1 (ADIPOR1) is an identified receptor for adiponectin, an adipocytokine with anti-inflammatory and insulin-sensitizing properties. The ADIPOR1 gene is a potential candidate gene in polycystic ovary syndrome (PCOS). The aim of this study is to assess the association between single-nucleotide polymorphism (SNP) rs1539355 in the ADIPOR1 gene and PCOS in Chinese women.

METHODS

302 patients with PCOS and 312 healthy controls were included in this study. The ADIPOR1 genotype distribution was detected using the polymerase chain reaction melting temperature shift method.

RESULTS

The genotypic distributions of SNP rs1539355 did not differ in patients with PCOS compared to controls. However, the frequency of the G allele in the PCOS group was significantly higher than that in the control group (p = 0.037). Patients with the AG or GG genotype had a higher homeostasis model assessment for insulin resistance (HOMA-IR) (p < 0.05) compared to patients with the AA genotype. The fasting insulin levels in subjects with the GG genotype were significantly higher than those in patients with the AA genotype (p < 0.05).

CONCLUSION

SNP rs1539355 in the ADIPOR1 gene is associated with insulin resistance in Chinese PCOS patients.

Clinical and genetic predictors of weight gain in patients diagnosed with breast cancer

Background:

Post-diagnosis weight gain in breast cancer patients has been associated with increased cancer recurrence and mortality. Our study was designed to identify risk factors for this weight gain and create a predictive model to identify a high-risk population for targeted interventions.

Methods:

Chart review was conducted on 459 breast cancer patients from Northwestern Robert H. Lurie Cancer Centre to obtain weights and body mass indices (BMIs) over an 18-month period from diagnosis. We also recorded tumour characteristics, demographics, clinical factors, and treatment regimens. Blood samples were genotyped for 14 single-nucleotide polymorphisms (SNPs) in fat mass and obesity-associated protein (FTO) and adiponectin pathway genes (ADIPOQ and ADIPOR1).

Results:

In all, 56% of patients had >0.5 kg m^–2 increase in BMI from diagnosis to 18 months, with average BMI and weight gain of 1.9 kg m^–2 and 5.1 kg, respectively. Our best predictive model was a primarily SNP-based model incorporating all 14 FTO and adiponectin pathway SNPs studied, their epistatic interactions, and age and BMI at diagnosis, with area under receiver operating characteristic curve of 0.85 for 18-month weight gain.

Conclusion:

We created a powerful risk prediction model that can identify breast cancer patients at high risk for weight gain.

No conclusive evidence for association of polymorphisms in the adiponectin receptor 1 gene, AdipoR1, with common obesity

AdipoR1 is one of the adiponectin receptors which are important for adiponectin signaling. Because adiponectin is a candidate gene for common obesity, it is also hypothesized that variations in AdipoR1 may be involved in the development of complex obesity. Therefore, we designed an association study for the AdipoR1 gene. We performed a case-control association study including 1,021 obese subjects (mean age 42 ± 12 years; mean BMI 38.2 ± 6.2 kg/m²) and 226 lean, healthy individuals (mean age 36 ± 7 years; mean BMI 22.1 ± 1.7 kg/m²). Nine tagSNPs were selected to cover the entire AdipoR1 gene and surrounding 7 kb region (based on HapMap data). TagSNPs were genotyped using AcycloPrime-Fluorescence Polarization (FP) SNP Detection kits and TaqMan Pre-Designed SNP Genotyping assays according to manufacturer's protocols. We found that the rs1075399 non-reference allele decreases obesity risk by 45 % in men only [odds ratio (OR) = 0.55, 95 % CI 0.35-0.87, nominal P = 0.010]. However, after Bonferroni correction for multiple testing, this association is lost. None of the other tagSNPs were associated with obesity when studying the entire population, nor when looking at men and women separately. Quantitative analysis of the effect of each SNP on height, weight, and BMI revealed that none of the tagSNPs are associated with weight or BMI. We report here that we found no decisive evidence for association between AdipoR1 tagSNPs and complex obesity in our Belgian Caucasian population.

Variants of the adiponectin and adiponectin receptor-1 genes and posttransplantation diabetes mellitus in renal allograft recipients

CONTEXT

Posttransplantation diabetes mellitus (PTDM) is a major metabolic complication in renal transplant recipients. Adiponectin (ADIPOQ) and adiponectin receptor-1 (ADIPOR1) gene polymorphisms have been associated with type 2 diabetes. However, it is unknown whether these polymorphisms are also risk factors for PTDM.

OBJECTIVE

We investigated the association between PTDM and single-nucleotide polymorphisms of ADIPOQ and ADIPOR1 in a cohort of renal allograft recipients.

DESIGN, SETTING, AND PARTICIPANTS

Five hundred seventy-five patients (367 men and 208 women) who received kidney transplants between 1989 and 2007, without a history of diabetes and with a pretransplant fasting glucose concentration less than 5.5 mmol/liter. Patients were followed up for a median 10 yr. Genotypes included single-nucleotide polymorphisms of the following: ADIPOQ rs266729, rs822395, rs822396, rs2241766, and rs1501299 and ADIPOR1 rs2232853, rs12733285, and rs1342387.

RESULTS

TT-homozygotes in ADIPOQ rs1501299 [hazard ratio (HR) = 1.70, P = 0.032] had greater risk of PTDM after adjusting for age, sex, amount of weight gain, and type of immunosuppressant. There was a significant interaction between sex and ADIPOQ rs1501299 genotype (P = 0.037). In men, but not in women, TT-homozygotes in ADIPOQ rs1501299 were more likely to develop PTDM than the wild GG-homozygotes (HR = 2.50, P = 0.002), whereas GT-heterozygotes had nonsignificantly elevated risk (HR = 1.41, P = 0.128).

CONCLUSION

Genetic variation in ADIPOQ rs1501299 is associated with PTDM in a sex-specific manner.

Effects of genetic variations in the adiponectin pathway genes on the risk of colorectal cancer in the Chinese population

Background

Decreased expression of adiponectin (ADIPOQ) is associated with an increased risk for developing colorectal cancer (CRC) in humans. This study was designed to determine whether polymorphisms present in the ADIPOQ and its type 1 receptor (ADIPOR1) could affect the risk of CRC.

Methods

We measured five polymorphisms in the ADIPOQ and two polymorphisms in ADIPOR1, and analyzed their associations with CRC risk in 420 CRC patients and 555 age- and gender-matched healthy individuals.

Results

Multivariate logistic regression analyses revealed that the CRC risks (adjusted odds ratio and 95% confidence interval) associated with the ADIPOR1 genotypes were 0.53 (95% CI, 0.35-0.81) for rs12733285C/T, 0.59 (95% CI, 0.45-0.78) for rs1342387A/G, and 0.59 (95% CI, 0.39-0.89) for rs1342387A/A, respectively. Furthermore, the risks were more significant in carriers of the allele A of rs1342387A/G (adjusted OR, 0.59; 95% CI, 0.46-0.77) than noncarriers (G/G). In a further subgroup analysis, we observed that rs266729G/C was associated with an increased risk for colon cancer (adjusted OR, 1.50; 95% CI, 1.05-2.14) but not for rectal cancer (adjusted OR, 0.88; 95% CI, 0.63-1.22), and that carriers of the G allele had an increased risk for developing colon cancer (adjusted OR, 1.45; 95% CI, 1.03-2.05).

Conclusions

We conclude that the rs12733285C/T genotype and the carriage of the A allele of rs1342387 (A/G or A/A) in ADIPOR1 are the protective factors for CRC, while that rs266729G/C and G allele of ADIPOQ are the risk factors for colon cancer after excluding rectal cancer cases.

Genetic variation in adiponectin (ADIPOQ) and the type 1 receptor (ADIPOR1), obesity and prostate cancer in African Americans

Background

Adiponectin is a protein derived from adipose tissue suspected to play an important role in prostate carcinogenesis. Variants in the adiponectin gene (ADIPOQ) and its type I receptor (ADIPOR1) have been recently linked to risk of both breast and colorectal cancer. Therefore, we set out to examine the relationship between polymorphisms in these genes, obesity and prostate cancer in study of African American men.

Methods

Ten single nucleotide polymorphisms (SNPs) in ADIPOQ and ADIPOR1 were genotyped in DNA samples from 131 African American prostate cancer cases and 344 controls participating in the Flint Men's Health Study. Logistic regression was then used to estimate their association with prostate cancer and obesity.

Results

While no significant associations were detected between any of the tested SNPs and prostate cancer, the rs1501299 SNP in ADIPOQ was significantly associated with body mass (p=0.03).

Conclusions

Genetic variation in ADIPOQ and ADIPOR1 did not predict risk of prostate cancer in this study of African American men. However, the rs1501299 SNP in ADIPOQ was associated with obesity. Further investigation is warranted to determine if racial differences exist in the influence of the adiponectin pathway on prostate cancer risk.

Association study of the single nucleotide polymorphisms in adiponectin-associated genes with type 2 diabetes in Han Chinese

Single-nucleotide polymorphisms (SNPs) of ADIPOQ, ADIPOR1, and ADIPOR2 have been associated with type 2 diabetes mellitus (T2DM), but there are many conflicting results especially in Chinese populations. To investigate the contribution of the adiponectin genes and their receptors to T2DM, a case-control study was performed and 11 SNPs of ADIPOQ, ADIPOR1, and ADIPOR2 were genotyped in 985 T2DM and 1,050 control subjects. rs16861194 (-11426 A>G) in the putative promoter of ADIPOQ was associated with T2DM (P = 0.007; OR = 1.29, 95%CI 1.08-1.55). None of the other 10 SNPs were associated with T2DM in this study, although rs2241766 and rs1501299 were reported to be associated with T2DM in previous Chinese studies. There was also no significant difference found from the ADIPOQ haplotype analysis, which contains rs16861194. In addition, we also assessed potential gene-gene interactions in three genes and no interactions were found. In conclusion, our results supported the ADIPOQ gene as a possible risk factor for type 2 diabetes in Han Chinese population.

Association of polymorphisms at the ADIPOR1 regulatory region with type 2 diabetes and body mass index in a Brazilian population with European or African ancestry

Association studies between ADIPOR1 genetic variants and predisposition to type 2 diabetes (DM2) have provided contradictory results. We determined if two single nucleotide polymorphisms (SNP c.-8503G>A and SNP c.10225C>G) in regulatory regions of ADIPOR1 in 567 Brazilian individuals of European (EA; N = 443) or African (AfA; N = 124) ancestry from rural (quilombo remnants; N = 439) and urban (N = 567) areas. We detected a significant effect of ethnicity on the distribution of the allelic frequencies of both SNPs in these populations (EA: -8503A = 0.27; AfA: -8503A = 0.16; P = 0.001 and EA: 10225G = 0.35; AfA: 10225G = 0.51; P < 0.001). Neither of the polymorphisms were associated with DM2 in the case-control study in EA (SNP c.-8503G>A: DM2 group -8503A = 0.26; control group -8503A = 0.30; P = 0.14/SNP 10225C>G: DM2 group 10225G = 0.37; control group 10225G = 0.32; P = 0.40) and AfA populations (SNP c.-8503G>A: DM2 group -8503A = 0.16; control group -8503A = 0.15; P = 0.34/SNP 10225C>G: DM2 group 10225G = 0.51; control group 10225G = 0.52; P = 0.50). Similarly, none of the polymorphisms were associated with metabolic/anthropometric risk factors for DM2 in any of the three populations, except for HDL cholesterol, which was significantly higher in AfA heterozygotes (GC = 53.75 +/- 17.26 mg/dL) than in homozygotes. We conclude that ADIPOR1 polymorphisms are unlikely to be major risk factors for DM2 or for metabolic/anthropometric measurements that represent risk factors for DM2 in populations of European and African ancestries.

Polymorphisms of ADIPOR1 and ADIPOR2 are associated with phenotypes of type 2 diabetes in Koreans

OBJECTIVE

Adiponectin receptors 1 and 2 (ADIPOR1 and ADIPOR2) are considered as candidate genes for type 2 diabetes because they mediate the metabolic effects of adiponectin on target tissues. We investigated whether common polymorphisms of ADIPOR1 and ADIPOR2 are associated with type 2 diabetes or its related phenotypes in Koreans.

DESIGN AND PATIENTS

By sequencing of the DNA samples from 24 unrelated Korean subjects, we selected seven single nucleotide polymorphisms (SNPs) from ADIPOR1 and four SNPs from ADIPOR2 for genotyping in 757 type 2 diabetic patients and 644 nondiabetic subjects.

RESULTS

None of the SNPs were associated with the risk of type 2 diabetes. However, g.-7309A>G (rs75172865) in ADIPOR1 was associated with lower insulin resistance, measured by the homeostasis model assessment of insulin resistance (HOMA-IR). Thereafter, we transfected three different human cell lines with plasmids harbouring g.-7309A>G and found that this variant reduced the promoter activity of ADIPOR1. In ADIPOR2, g.-63442G (novel SNP) and g.33447T (rs1044471) were associated with smaller waist circumference.

CONCLUSIONS

None of the SNPs in either ADIPOR1 or ADIPOR2 were associated with the risk of type 2 diabetes in Koreans. However, the altered activity of the ADIPOR1 promoter was associated with insulin resistance and SNPs of ADIPOR2 were associated with waist circumference.

Diabetes-specific genetic effects on obesity traits in American Indian populations: the Strong Heart Family Study

Background

Body fat mass distribution and deposition are determined by multiple environmental and genetic factors. Obesity is associated with insulin resistance, hyperinsulinemia, and type 2 diabetes. We previously identified evidence for genotype-by-diabetes interaction on obesity traits in Strong Heart Family Study (SHFS) participants. To localize these genetic effects, we conducted genome-wide linkage scans of obesity traits in individuals with and without type 2 diabetes, and in the combined sample while modeling interaction with diabetes using maximum likelihood methods (SOLAR 2.1.4).

Methods

SHFS recruited American Indians from Arizona, North and South Dakota, and Oklahoma. Anthropometric measures and diabetes status were obtained during a clinic visit. Marker allele frequencies were derived using maximum likelihood methods estimated from all individuals and multipoint identity by descent sharing was estimated using Loki. We used variance component linkage analysis to localize quantitative trait loci (QTLs) influencing obesity traits. We tested for evidence of additive and QTL-specific genotype-by-diabetes interactions using the regions identified in the diabetes-stratified analyses.

Results

Among 245 diabetic and 704 non-diabetic American Indian individuals, we detected significant additive gene-by-diabetes interaction for weight and BMI (P < 0.02). In analysis accounting for QTL-specific interaction (P < 0.001), we detected a QTL for weight on chromosome 1 at 242 cM (LOD = 3.7). This chromosome region harbors the adiponectin receptor 1 gene, which has been previously associated with obesity.

Conclusion

These results suggest distinct genetic effects on body mass in individuals with diabetes compared to those without diabetes, and a possible role for one or more genes on chromosome 1 in the pathogenesis of obesity.

Adiponectin and adiponectin receptor gene variants in relation to type 2 diabetes and insulin resistance-related phenotypes

BACKGROUND

Alterations in adiponectin-mediated pathways are known to be associated with glucose intolerance, insulin resistance (IR), obesity, and type 2 diabetes (T2D) mellitus. Genetic variations in adiponectin (ADIPOQ) and adiponectin 1 and 2 receptor (ADIPOR1 and ADIPOR2) could have effects on IR-related phenotypes and T2D. Here we examine whether the polymorphic markers rs2241766 (ADIPOQ), rs22753738 (ADIPOR1), rs11061971 and rs16928751 (both in ADIPOR2) are implicated in susceptibility to T2D in a Russian population.

METHODS

The polymorphic markers were genotyped in 129 T2D patients, and 117 non-diabetic controls, by polymerase chain reaction (PCR) restriction fragment length polymorphism approach. In the subjects, biochemical characteristics including serum insulin, plasma glucose and serum lipids/lipoproteins were measured and compared for correlation with the genetic variations studied.

RESULTS

Allele T of rs11061971 and allele A of rs16928751 showed association with higher risk of diabetes providing odds ratios (OR) of 2.05 (p = 0.0025) and 1.88 (p = 0.018), respectively. Haplotype A-G consisting of allele A of rs11061971 and allele G of rs16928751 was associated with reduced risk of T2D (OR = 0.59, pc = 0.0224). Compared to other variants, diabetic patients double homozygous for A/A of rs16928751 and G/G of rs16928751 had decreased homeostasis model assessment-insulin resistance (pc = 0.0375) and serum triglycerides (pc = 0.0285).

CONCLUSIONS

The variants of ADIPOR2 confer susceptibility to T2D and are associated with some IR-related phenotypes in the Russian study population.

Associations between glucose tolerance, insulin sensitivity and insulin secretion phenotypes and polymorphisms in adiponectin and adiponectin receptor genes in the Quebec Family Study

AIMS

Studies suggest that adiponectin (APM1) and its receptors 1 and 2 (AdipoR1 and AdipoR2) play an important role in the development of insulin resistance (IR). Our objective was to examine associations between APM1 (+45T>G, +276G>T and -3971A>G), AdipoR1 (-100G>T and -3882T>C) and AdipoR2 (-35361A>G and -1352G>A) genes single-nucleotide polymorphisms (SNPs) and adiponectin plasma levels, indicators of glucose tolerance, insulin sensitivity (IS) and insulin secretion.

METHODS

Six hundred and twenty-two non-diabetic subjects from the Quebec Family Study (QFS) underwent a 75-g oral glucose tolerance test (OGTT), with measurement of fasting adiponectin, glucose, insulin and C-peptide levels. Indices of glucose tolerance, IS and insulin secretion were derived from fasting and OGTT measurements.

RESULTS

Significant evidence of association was found between indices of IS and APM1 and AdipoR1 SNPs. The APM1 -3971G/G homozygotes exhibited a reduced area under the curve of insulin during the OGTT (P = 0.007) and higher Cederholm index (P = 0.01) compared to the A/A homozygotes. The APM1+45T>G variant was also associated with fasting (P = 0.002) and 2-h (P = 0.007) glucose values as well as with higher Cederholm index (P = 0.04) and disposition index (P = 0.02). Finally, the AdipoR1-3882T>C SNP was associated with fasting glucose (P = 0.03), the homeostasis model assessment for insulin resistance (P = 0.04) and an index of insulin secretion (P30/G30, P = 0.02). No evidence of association was found with plasma adiponectin levels.

CONCLUSIONS

These results provide evidence for an influence of common SNPs in the APM1 and AdipoR1 genes on different phenotypes of glucose and insulin metabolism associated with increased risk of type 2 diabetes.

Within-family outliers: segregating alleles or environmental effects? A linkage analysis of height from 5815 sibling pairs

Most information in linkage analysis for quantitative traits comes from pairs of relatives that are phenotypically most discordant or concordant. Confounding this, within-family outliers from non-genetic causes may create false positives and negatives. We investigated the influence of within-family outliers empirically, using one of the largest genome-wide linkage scans for height. The subjects were drawn from Australian twin cohorts consisting of 8447 individuals in 2861 families, providing a total of 5815 possible pairs of siblings in sibships. A variance component linkage analysis was performed, either including or excluding the within-family outliers. Using the entire dataset, the largest LOD scores were on chromosome 15q (LOD 2.3) and 11q (1.5). Excluding within-family outliers increased the LOD score for most regions, but the LOD score on chromosome 15 decreased from 2.3 to 1.2, suggesting that the outliers may create false negatives and false positives, although rare alleles of large effect may also be an explanation. Several regions suggestive of linkage to height were found after removing the outliers, including 1q23.1 (2.0), 3q22.1 (1.9) and 5q32 (2.3). We conclude that the investigation of the effect of within-family outliers, which is usually neglected, should be a standard quality control measure in linkage analysis for complex traits and may reduce the noise for the search of common variants of modest effect size as well as help identify rare variants of large effect and clinical significance. We suggest that the effect of within-family outliers deserves further investigation via theoretical and simulation studies.

Challenges in studies of the genetic basis of Type 2 diabetes

The prevalence of diabetes is increasing worldwide in epidemic proportions. This increase is mainly due to increased incidence and prevalence of Type 2 diabetes, which accounts for 80-90% of all cases of diabetes. The susceptibility to develop Type 2 diabetes is determined by genetic and environmental factors. Major genes responsible for Type 2 diabetes have not yet been identified. The most replicated susceptibility gene for Type 2 diabetes is TCF7L2, recently published by investigators from Iceland. The second most widely replicated association between a genetic variation and the risk of Type 2 diabetes is that of the Pro12Ala polymorphism in the peroxisome proliferator-activated receptor γ2 gene. Furthermore, the common E23K polymorphism in the KCJN11 gene, encoding the ATP-sensitive potassium-channel subunit Kir6.2, and variants in the calpain-10 gene have been associated with increased susceptibility to Type 2 diabetes in meta-analyses. Several studies have investigated the possibility that rare, highly penetrant mutations in the maturity-onset diabetes of the young genes lead to monogenic diabetes, while common polymorphisms increase the susceptibility to Type 2 diabetes. Indeed, there is increasing evidence that single nucleotide polymorphisms in hepatic nuclear factor-4α are significantly associated with the risk of Type 2 diabetes. In this review, different approaches to identify susceptibility genes for Type 2 diabetes are discussed. In particular, the importance of prospective population-based cohort studies and prospective intervention studies are emphasized. Finally, genome-wide association studies using single nucleotide polymorphisms randomly spaced across the entire genome may be useful in the identification of susceptibility genes for Type 2 diabetes.

Variations in adiponectin receptor genes and susceptibility to type 2 diabetes in women: a tagging-single nucleotide polymorphism haplotype analysis

Adiponectin has been associated with low diabetes risk. The metabolic effects of adiponectin are mediated by adiponectin receptors 1 (ADIPOR1) and 2 (ADIPOR2). We conducted a prospective, nested case-control study of 714 cases of type 2 diabetes and 1,120 control subjects. Six polymorphisms in ADIPOR1 and 16 polymorphisms in ADIPOR2 were determined. Haplotypes inferred from ADIPOR1 polymorphisms were significantly associated with diabetes risk (overall test, -2log-likelihood = 15.1 on 5 df; P = 0.0098). A single copy of haplotype 001100 (0, common allele; and 1, minor allele) was associated with 24% decreased risk (odds ratio [OR] 0.76 [95% CI 0.61-0.96], P = 0.02) compared with the most common haplotype, 110000, adjusting for age, BMI, and other covariates. A 3' untranslated region (UTR) polymorphism, rs1139646, showed the strongest and nominally significant association with greater diabetes risk (unadjusted OR 1.26 [1.03-1.53] and adjusted OR 1.36 [1.10-1.70]). However, such an association became marginal after controlling for multiple comparisons by permutation test (P = 0.08 on the basis of 10,000 permutations). There were not significant associations between ADIPOR2 polymorphisms, individually or in haplotypes, and the risk of type 2 diabetes. In conclusion, our data indicate significant associations between ADIPOR1 haplotypes and diabetes risk but do not support a relation between ADIPOR2 variability and the disease.

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.

Adiponectin receptor genes: mutation screening in syndromes of insulin resistance and association studies for type 2 diabetes and metabolic traits in UK populations

AIMS/HYPOTHESIS

Adiponectin is an adipokine with insulin-sensitising and anti-atherogenic properties. Several reports suggest that genetic variants in the adiponectin gene are associated with circulating levels of adiponectin, insulin sensitivity and type 2 diabetes risk. Recently two receptors for adiponectin have been cloned. Genetic studies have yielded conflicting results on the role of these genes and type 2 diabetes predisposition. In this study we aimed to evaluate the potential role of genetic variation in these genes in syndromes of severe insulin resistance, type 2 diabetes and in related metabolic traits in UK Europid populations.

MATERIALS AND METHODS

Exons and splice junctions of the adiponectin receptor 1 and 2 genes (ADIPOR1; ADIPOR2) were sequenced in patients from our severe insulin resistance cohort (n=129). Subsequently, 24 polymorphisms were tested for association with type 2 diabetes in population-based type 2 diabetes case-control studies (n=2,127) and with quantitative traits in a population-based longitudinal study (n=1,721).

RESULTS

No missense or nonsense mutations in ADIPOR1 and ADIPOR2 were detected in the cohort of patients with severe insulin resistance. None of the 24 polymorphisms (allele frequency 2.3-48.3%) tested was associated with type 2 diabetes in the case-control study. Similarly, none of the polymorphisms was associated with fasting plasma insulin, fasting and 2-h post-load plasma glucose, 30-min insulin increment or BMI.

CONCLUSIONS/INTERPRETATION

Genetic variation in ADIPOR1 and ADIPOR2 is not a major cause of extreme insulin resistance in humans, nor does it contribute in a significant manner to type 2 diabetes risk and related traits in UK Europid populations.

Effect of genotype on success of lifestyle intervention in subjects at risk for type 2 diabetes

Lifestyle intervention programs including increased physical activity and healthy nutrition have been proven to delay the onset of type 2 diabetes. This is achieved mainly by reducing body weight and improving insulin sensitivity. However, response to lifestyle or dietary interventions does differ between individuals, and the genetic or environmental factors that may account for these differences are not yet precisely characterized. Identification of these factors would be desirable in order to provide an individually tailored preventive strategy for patients at risk of developing diabetes. This review summarizes the so far known genetic variations, which determine responders and nonresponders to a lifestyle intervention. In addition, general methodological approaches to study gene-lifestyle interactions are described.