Effect of an FTO polymorphism on fat mass, obesity, and type 2 diabetes mellitus in the French MONICA Study

Sex-based differences in short- and longer-term diet-induced metabolic heart disease

Sex-based differences in the development of obesity-induced cardiometabolic dysfunction are well documented, however, the specific mechanisms are not completely understood. Obesity has been linked to dysregulation of the epitranscriptome, but the role of N6-methyladenosine (m6A) RNA methylation has not been investigated in relation to the sex differences during obesity-induced cardiac dysfunction. In the current study, male and female C57BL/6J mice were subjected to short- and long-term high-fat/high-sucrose (HFHS) diet to induce obesogenic stress. Cardiac echocardiography showed males developed systolic and diastolic dysfunction after 4 mo of diet, but females maintained normal cardiac function despite both sexes being metabolically dysfunctional. Cardiac m6A machinery gene expression was differentially regulated by duration of HFHS diet in male, but not female mice, and left ventricular ejection fraction correlated with RNA machinery gene levels in a sex- and age-dependent manner. RNA-sequencing of cardiac transcriptome revealed that females, but not males may undergo protective cardiac remodeling early in the course of obesogenic stress. Taken together, our study demonstrates for the first time that cardiac RNA methylation machinery genes are regulated early during obesogenic stress in a sex-dependent manner and may play a role in the sex differences observed in cardiometabolic dysfunction.NEW & NOTEWORTHY Sex differences in obesity-associated cardiomyopathy are well documented but incompletely understood. We show for the first time that RNA methylation machinery genes may be regulated in response to obesogenic diet in a sex- and age-dependent manner and levels may correspond to cardiac systolic function. Our cardiac RNA-seq analysis suggests female, but not male mice may be protected from cardiac dysfunction by a protective cardiac remodeling response early during obesogenic stress.

Interaction Effects of FTO and MC4R Polymorphisms on Total Body Weight Loss, Post-Surgery Weight, and Post-Body Mass Index after Bariatric Surgery

Bariatric surgery (BS) is considered the most effective intervention for patients with severe obesity and is used to maintain long-term weight loss and glycemic control. The aim of this study was to analyze the effects of genotypes and haplotypes of the fat mass and obesity-associated (FTO) and melanocortin 4 receptor (MC4R) genes on total body weight loss (TBWL), post-surgery weight, and post-BMI after bariatric surgery. We retrospectively selected 101 patients from Bajio High Specialty Regional Hospital, León Guanajuato, México, who underwent Roux-en-Y gastric bypass (RYGB) to determine their body mass index (BMI), blood pressure, biochemical characteristics, and comorbidities. Post-surgery, patients were referred for registered anthropometry and blood pressure. Glucose, lipid and hepatic profiles, and insulin, leptin, and ghrelin levels were measured, and rs9939609, rs9930506, and rs1421085 FTO and rs17782313 MC4R polymorphisms were genotyped. Six (4-8) years after BS, post-surgery weight was greater in carriers of the rs9939609 and rs1421085 risk genotypes. TBWL was lower for the rs9930506 and rs1421085 risk genotypes. Insulin and HOMA-IR were greater in patients with the three FTO polymorphisms. There were significant interaction effects of the rs9930506 and rs1421085 FTO risk genotypes on weight and BMI in response to BS. No association was found with the MC4R polymorphism. The genotypes and haplotypes of the FTO gene influence post-surgery weight, TBWL, insulin levels, and HOMA-IR.

Lactylation-driven FTO targets CDK2 to aggravate microvascular anomalies in diabetic retinopathy

Diabetic retinopathy (DR) is a leading cause of irreversible vision loss in working-age populations. Fat mass and obesity-associated protein (FTO) is an N6-methyladenosine (m6A) demethylase that demethylates RNAs involved in energy homeostasis, though its influence on DR is not well studied. Herein, we detected elevated FTO expression in vitreous fibrovascular membranes of patients with proliferative DR. FTO promoted cell cycle progression and tip cell formation of endothelial cells (ECs) to facilitate angiogenesis in vitro, in mice, and in zebrafish. FTO also regulated EC-pericyte crosstalk to trigger diabetic microvascular leakage, and mediated EC-microglia interactions to induce retinal inflammation and neurodegeneration in vivo and in vitro. Mechanistically, FTO affected EC features via modulating CDK2 mRNA stability in an m6A-YTHDF2-dependent manner. FTO up-regulation under diabetic conditions was driven by lactate-mediated histone lactylation. FB23-2, an inhibitor to FTO's m6A demethylase activity, suppressed angiogenic phenotypes in vitro. To allow for systemic administration, we developed a nanoplatform encapsulating FB23-2 and confirmed its targeting and therapeutic efficiency in mice. Collectively, our study demonstrates that FTO is important for EC function and retinal homeostasis in DR, and warrants further investigation as a therapeutic target for DR patients.

Minor alleles of FTO rs9939609 and rs17817449 polymorphisms confer a higher risk of type 2 diabetes mellitus and dyslipidemia, but not coronary artery disease in a Chinese Han population

Background

Relationships of the polymorphisms in fat mass and obesity-associated gene (FTO) and peroxisome proliferator-activated receptor delta gene (PPARD) with metabolic-related diseases remain to be clarified.

Methods

One thousand three hundred and eighty-one subjects were enrolled. Metabolic-related diseases including obesity, dyslipidemia, hyperhomocysteinemia, hyperuricemia, hypertension, type 2 diabetes mellitus (T2DM) and coronary artery disease (CAD) were defined based on diagnostic criteria. FTO rs9939609 and rs17817449, and PPARD rs2016520 and rs2267668 polymorphisms were genotyped by using polymerase chain reaction-restricted fragment length polymorphism method.

Results

Patients with T2DM or dyslipidemia had a higher frequency of AA, AT or AA + AT genotypes as well as A allele of FTO rs9939609 polymorphism than those free of T2DM or dyslipidemia (P ≤ 0.04 for all). Patients with T2DM or dyslipidemia had a higher frequency of GG, GT or GG + GT genotypes as well as G allele of FTO rs17817449 polymorphism than those free of T2DM or dyslipidemia (P ≤ 0.03 for all). Multivariate logistic regression analyses showed that FTO rs9939609 and rs17817449 polymorphisms were independently associated with T2DM as well as dyslipidemia after adjustment for age, sex, smoking and other metabolic diseases. FTO rs9939609 and rs17817449 polymorphisms were not associated with obesity, hyperhomocysteinemia, hyperuricemia, hypertension and CAD. Obese or T2DM carriers of the AA or AT genotype of the FTO rs9939609 polymorphism had a higher prevalence of dyslipidemia compared to non-obese or non-T2DM carriers of the AA or AT genotype (P = 0.03 for both). Among the carriers of GG or GT genotype of the FTO rs17817449 polymorphism, the prevalence of dyslipidemia in obese patients was higher than that in non-obese subjects (P < 0.01). PPARD rs2016520 and rs2267668 polymorphisms were not correlated with any of the metabolic-related diseases in the study population.

Conclusion

Minor alleles of FTO rs9939609 and rs17817449 polymorphisms confer a higher risk of T2DM and dyslipidemia, and the risk is further increased among obese individuals. PPARD rs2016520 and rs2267668 polymorphisms are not associated with metabolic-related diseases.

FTO Gene Polymorphisms and Their Roles in Acromegaly

The major causes of both morbidity and mortality in patients with acromegaly are cardiovascular diseases (CVDs). The polymorphisms of the fat mass and obesity-associated gene (FTO) are associated with obesity, as well as with an increased risk of CVDs. The aim of the study was to determine the relationship of risk alleles of four FTO gene polymorphisms with selected parameters of lipid and glucose metabolism as well as with IGF-1 and GH levels in the group of patients with acromegaly compared to the control group. The study group consisted of 104 patients with acromegaly and 64 healthy subjects constituting the control group. In the whole acromegaly group, the data reveal that the homozygous for risk allele carriers (rs1421085, rs9930506, rs9939609) as well as carriers of only one risk allele have lower IGF-1 concentrations. In the well-controlled acromegaly group, the homozygous for three risk allele carriers of FTO gene polymorphisms have lower HDL cholesterol concentration (rs1121980, rs1421085, rs993609). In the cured acromegaly group, homozygous risk allele carriers rs9930506 tend to have higher levels of total cholesterol and LDL cholesterol. These associations are not observed in the control group. Conclusion: there is an association between FTO gene polymorphisms and the metabolism of lipids, suggesting that the FTO gene may be associated with higher CVD risk in patients with acromegaly. In addition, there is an association between FTO gene polymorphisms and IGF-1, implying that FTO gene may influence/modify IGF-1 synthesis. Further investigation on a larger scale is required to provide more precise evidence.

The Analysis of a Genome-Wide Association Study (GWAS) of Overweight and Obesity in Psoriasis

There is evidence that the concomitance of psoriasis and obesity may originate from the interplay between multiple genetic pathways and involve gene−gene interactions. The aim of this study was to compare the genetic background related to obesity among psoriatic patients versus healthy controls by means of a Genome-Wide Association Study (GWAS). A total of 972 psoriatic patients and a total of 5878 healthy donors were enrolled in this study. DNA samples were genotyped for over 500,000 single nucleotide polymorphisms (SNPs) using Infinium CoreExome BeadChips (Illumina, San Diego, CA, USA). Statistical analysis identified eleven signals (p < 1 × 10−5) associated with BMI across the study groups and revealed a varying effect size in each sub-cohort. Seven of the alternative alleles (rs1558902 in the FTO gene, rs696574 in the CALCRL gene, as well as rs10968110, rs4551082, rs4609724, rs9320269, and rs2338833,) are associated with increased BMI among all psoriatic patients and four (rs1556519 in the ITLN2 gene, rs12972098 in the AC003006.7 gene, rs12676670 in the PAG1 gene, and rs1321529) are associated with lower BMI. The results of our study may lead to further insights into the understanding of the pathogenesis of obesity among psoriatic patients.

Regulation of Activating Transcription Factor 4 (ATF4) Expression by Fat Mass and Obesity-Associated (FTO) in Mouse Hepatocyte Cells

Context

Abnormally increased hepatic glucose production contributes to hyperglycemia in diabetes. Interventions that suppress hepatic gluconeogenesis should be beneficial in improving glycemic control in patients with diabetes.

Objectives

It has been suggested that hepatic FTO is involved in glycemic control by regulating gluconeogenesis. Both FTO and activating transcription factor 4 (ATF4) positively regulate the expression of gluconeogenic genes in the liver, suggesting the possibility that ATF4 mediates the stimulatory effect of FTO on hepatic gluconeogenesis. The present study aimed to determine the effect of altered expression or activity of FTO on Atf4 and gluconeogenic gene expression in hepatocyte cells.

Methods

Mouse hepatocyte AML12 cells were treated with the FTO inhibitor rhein or transfected with an FTO-expressing plasmid. Levels of gluconeogenic glucose-6-phosphatase (G6pc) and Atf4 mRNA and protein were measured.

Results

Rhein treatment significantly reduced G6pc mRNA levels as well as Atf4 mRNA and protein levels. Conversely, enhanced FTO expression caused an increase in G6pc and Atf4 mRNA levels.

Conclusions

These findings support the hypothesis that hepatic FTO participates in the regulation of hepatic gluconeogenic gene and ATF4 expression. Reducing the activity of the hepatic FTO-ATF4 pathway may be beneficial in reducing hepatic glucose production and ameliorating hyperglycemia in diabetes.

Fat mass and obesity-associated (FTO) and leptin receptor (LEPR) gene polymorphisms in Egyptian obese subjects

BACKGROUND

Several studies addressed the contribution of fat mass and obesity-associated (FTO) and leptin receptor (LEPR) polymorphisms for the susceptibility to obesity among different ethnic subjects. The main purpose of this work is to evaluate the association of these polymorph\isms with obesity among Egyptian subjects.

SUBJECTS AND METHODS

This case-control study was carried out on 110 unrelated obese Egyptian subjects who were compared with 122 controls. Their genomic DNA was genotyped using the PCR technique.

RESULTS

The allelic frequencies of FTO rs9939609 (A) and LEPR rs1137101 (223R) were significantly higher in obese subjects compared with non-obese controls (p < .001). Comparing different phenotype frequencies including clinical, anthropometric, and biochemical parameters in obese subjects revealed no significant difference in relation to their genotype frequencies (p> .05).

CONCLUSIONS

This study designates a strong association for FTO and LEPR variants with the risk of obesity among Egyptian subjects.

Effect of MTHFR (rs1801133) and FTO (rs9939609) genetic polymorphisms and obesity in T2DM: a study among Bengalee Hindu caste population of West Bengal, India

Type 2 diabetes mellitus (T2DM) susceptibility has increased due to the independent risks of genetic polymorphism and obesity as well as combinations of these. Despite recent advancements in T2DM management and diagnosis, the challenges of susceptibility and prognosis still remain. The present work is attempted to understand the association of methylenetetrahydrofolate reductase (MTHFR) (rs1801133) and FTO (rs9939609) genetic polymorphisms and obesity with T2DM among the Bengalee Hindu caste population of West Bengal, India. One hundred and four clinically diagnosed T2DM male patients and 176 healthy males, without family history of T2DM, (control group) of the endogamous linguistic group (Bengalee Hindu caste) participated. Genotyping was performed using the PCR-RFLP method following the isolation of genomic DNA. MTHFR (rs1801133) genetic polymorphism with CT genotype revealed significantly higher risk (OR = 3.44; p = .01) of T2DM compared to the CC genotype. The attenuation of MTHFR-T2DM risk after adjustment for age and waist circumference revealed obesity and age effects in progression of T2DM. T2DM patients also had significantly (p < .05) higher overall obesity, central obesity, and SBP compared to the controls. However, FTO (rs9939609) genetic polymorphism demonstrated no significant (p= .854) effect on T2DM and obesity. The present study identified that MTHFR genetic polymorphism and obesity might be used as screening tools for early prognosis of T2DM.

Double diabetes: A distinct high-risk group?

The term double diabetes (DD) has been used to refer to individuals with type 1 diabetes (T1D) who are overweight, have a family history of type 2 diabetes and/or clinical features of insulin resistance. Several pieces of evidence indicate that individuals who display features of DD are at higher risk of developing future diabetes complications, independently of average glucose control, measured as glycated haemoglobin (HbA1c) concentration. Given the increased prevalence of individuals with features of DD, pragmatic criteria are urgently required to identify and stratify this group, which will help with subsequent implementation of more effective personalized interventions. In this review, we discuss the potential criteria for the clinical identification of individuals with DD, highlighting the strengths and weaknesses of each definition. We also cover potential mechanisms of DD and how these contribute to increased risk of diabetes complications. Special emphasis is placed on the role of estimated glucose disposal rate (eGDR) in the diagnosis of DD, which can be easily incorporated into clinical practice and is predictive of adverse clinical outcome. In addition to the identification of individuals with DD, eGDR has potential utility in monitoring response to different interventions. T1D is a more heterogeneous condition than initially envisaged, and those with features of DD represent a subgroup at higher risk of complications. Pragmatic criteria for the diagnosis of individuals with DD will help with risk stratification, allowing a more personalized and targeted management strategy to improve outcome and quality of life in this population.

Association of Omentin rs2274907 and FTO rs9939609 gene polymorphisms with insulin resistance in Iranian individuals with newly diagnosed type 2 diabetes

Background

Insulin resistance (IR) and fat accumulation in visceral adipose tissue are key players in developing type 2 diabetes (T2D). Several adipose tissue derived-gene polymorphisms are related to higher body mass index (BMI), insulin resistance and T2D. The association of omentin rs2274907 (Val109Asp) and fat-mass and obesity-associated (FTO) rs9939609 gene polymorphisms with overweight/obesity and T2D is controversial. The aim of this study was to determine the association between omentin Val109Asp and FTO rs9939609 polymorphisms and insulin resistance in newly-diagnosed T2D patients.

Methods

The case-control study included 83 newly-diagnosed T2D patients and 85 healthy matched controls, aged 20–80 years. Fasting blood glucose and insulin levels were measured by the enzymatic method and enzyme-linked-immunosorbent assay, respectively. Insulin resistance was calculated using the homeostasis model assessment (HOMA) index. Genotyping was examined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP).

Results

There are significant differences between both omentin Val109Asp and FTO rs9939609 polymorphisms and studied individuals (P = 0.011 and P = 0.0001, respectively). Both genetic polymorphisms of omentin Val109Asp and FTO rs9939609 (T/A) are significantly related to higher HOMA index (P = 0.030 and P = 0.046, respectively). However, omentin Val109Asp polymorphism was only related to individuals who were overweight/obese. Additionally, both omentin Val109Asp and FTO rs9939609 polymorphisms were significantly positively correlated to familial history of diabetes (P = 0.046 and P = 0.024, respectively).

Conclusions

Omentin V109D and FTO rs9939609 genetic variations may change insulin metabolism and have key roles in developing T2D through insulin resistance. Thus, the evaluation of these polymorphic regions may be helpful for predicting type 2 diabetes.

Exposing the Causal Effect of Body Mass Index on the Risk of Type 2 Diabetes Mellitus: A Mendelian Randomization Study

Introduction: High body mass index (BMI) is a positive associated phenotype of type 2 diabetes mellitus (T2DM). Abundant studies have observed this from a clinical perspective. Since the rapid increase in a large number of genetic variants from the genome-wide association studies (GWAS), common SNPs of BMI and T2DM were identified as the genetic basis for understanding their associations. Currently, their causality is beginning to blur. Materials and Methods: To classify it, a Mendelian randomisation (MR), using genetic instrumental variables (IVs) to explore the causality of intermediate phenotype and disease, was utilized here to test the effect of BMI on the risk of T2DM. In this article, MR was carried out on GWAS data using 52 independent BMI SNPs as IVs. The pooled odds ratio (OR) of these SNPs was calculated using inverse-variance weighted method for the assessment of 5 kg/m2 higher BMI on the risk of T2DM. The leave-one-out validation was conducted to identify the effect of individual SNPs. MR-Egger regression was utilized to detect potential pleiotropic bias of variants. Results: We obtained the high OR (1.470; 95% CI 1.170 to 1.847; P = 0.001), low intercept (0.004, P = 0.661), and small fluctuation of ORs {from -0.039 [(1.412 - 1.470) / 1.470)] to 0.075 [(1.568- 1.470) / 1.470)] in leave-one-out validation. Conclusion: We validate the causal effect of high BMI on the risk of T2DM. The low intercept shows no pleiotropic bias of IVs. The small alterations of ORs activated by removing individual SNPs showed no single SNP drives our estimate.

The Influence of FTO Polymorphism rs9939609 on Obesity, Some Clinical Features, and Disturbance of Carbohydrate Metabolism in Patients with Psoriasis

Background

Psoriasis is often accompanied by obesity, hyperlipidemia, diabetes, and metabolic syndrome as risk factors of cardiovascular conditions and premature mortality.

Objective

The study was aimed at investigating whether psoriatic patients, who carry risk allele of obesity-related FTO gene, are more predisposed to obesity and metabolic disturbances and whether it influences the severity of psoriasis.

Methods

197 patients with psoriasis, representing Lower Silesia region of Poland, underwent physical examination and anthropometric measurements. Blood samples for biochemical and genetic analysis were collected. All patients were genotyped for FTO gene rs9939609 variant. Identification of SNP was conducted with the use of minisequencing method.

Results

Around 63% of patients were carriers of at least one risk allele A and 20% were AA homozygotes. The A allele was associated with increased BMI and hip and waist circumferences. The carriers of risk allele had increased PASI and CRP values and tended to have an increased insulin concentration.

Conclusion

Psoriatic patients, carriers of risk allele of FTO gene rs9939609, have an increased risk for more severe psoriasis and obesity and may develop obesity-induced insulin resistance.

N 6-Methyladenosine modification: a novel pharmacological target for anti-cancer drug development

N⁶-Methyladenosine (m⁶A) modification is the most pervasive modification of human mRNA molecules. It is reversible via regulation of m⁶A modification methyltransferase, demethylase and proteins that preferentially recognize m⁶A modification as “writers”, “erasers” and “readers”, respectively. Altered expression levels of the m⁶A modification key regulators substantially affect their function, leading to significant phenotype changes in the cell and organism. Recent studies have proved that the m⁶A modification plays significant roles in regulation of metabolism, stem cell self-renewal, and metastasis in a variety of human cancers. In this review, we describe the potential roles of m⁶A modification in human cancers and summarize their underlying molecular mechanisms. Moreover, we will highlight potential therapeutic approaches by targeting the key m⁶A modification regulators for cancer drug development.

The rs9939609 polymorphism in the fat mass and obesity associated (FTO) gene is associated with obesity in Tunisian population

CONTEXT

Variations in the fat mass and obesity-associated gene (FTO) has been associated with obesity in many populations, but the results are conflicting.

OBJECTIVE

The aim of this study was to evaluate the effect of the rs9939609 polymorphism in the FTO gene on obesity risk and plasma leptin, adiponectin, insulin and lipid concentrations in Tunisians.

MATERIALS AND METHODS

Four hundred and ninety-four subjects with obesity and 334 non-obese participated in this study. The rs9939609 (T/A) genotype was determined by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

RESULTS

Significant differences in genotype frequencies were observed between cases and controls. In the separate analysis by gender, the association between the AA genotype and obesity was statistically significant in women but not in men. After stratification by obesity class this association remains only with obesity class III.

DISCUSSION

Our study is in agreement with studies on Caucasian, Portuguese and Cebu Filipino populations where a gender-specific association was found between rs9939609 polymorphism and obesity. It is also in agreement with studies on Mexican, Spanish and European populations, where an association was found with obesity class III.

CONCLUSION

The rs9939609 polymorphism of FTO gene is associated with obesity, especially obesity class III in women.

The evaluation of the effectiveness of diet therapy for obese patients basing on studying of the polymorphism rs9939609 of the FTO gene

The Aim. The aim of the study was to develop and evaluate the effectiveness of dietary therapy in obese patients on the basis of studying the polymorphism rs9939609 of the FTO gene. Materials and methods. 100 patients with obesity of I-III degree aged from 18 to 55 years were examined. All patients underwent genotyping using allele-specific amplification with real-time detection of results. Depending on the genotypes of the FTO gene, obese patients received different diet therapy and were divided into 3 groups: patients with the TT and AT genotype received a standard low-calorie diet, and with the AA genotype a personalized diet. Results. It was found that a decrease in the caloric content of the diet contributed to a decrease in body weight in obese patients, mainly due to muscle mass in carriers of the genotype AT, and in carriers of genotypes TT and AA - mainly due to the fat component. Conclusions. Thus, the carriers of the mutant allele A in the homozygous and heterozygous variant require the selection of only a personalized diet. Therefore, in the appointment of dietary therapy to obese patients, it is recommended to carry out molecular genetic studies that will not only identify individuals with increased need for personalization of dietary therapy, but also increase the effectiveness of treatment for obesity and prevent the development of its complications.

The FTO variant is associated with chronic complications of diabetes mellitus in Czech population

BACKGROUND

Genome-wide association studies have resulted in the identification of the FTO gene as an important genetic determinant of diabetes mellitus. The aim of this study was to confirm the role of this gene in the development of DM in the Czech-Slavonic population and to analyse whether this gene is associated with common DM complications.

METHODS

Two groups of patients (814 with T1DM and 848 with T2DM) and a group of healthy controls (2339 individuals) - both of Czech origin - were genotyped for the FTO rs17817449 SNP. ANOVA and logistic regression were used for the statistical evaluations.

RESULTS

The frequency of the GG genotype was significantly higher in T2DM (25.4% vs. 16.7%, P<0.0005) but not in T1DM patients (19.3% vs. 16.7%, P=0.20) than in controls. The increased risk of development of diabetic nephropathy was observed both for T1DM patients (GG vs. TT homozygotes, P<0.01) and T2DM patients (G carriers vs. TT homozygotes, P<0.05). FTO genotype predicted the development of diabetic neuropathy (GG vs. TT comparison; P<0.01) in the T2DM patients only. No association between FTO genotype and development of retinopathy was detected. All presented values are after adjustment for age, sex, BMI and duration of diabetes.

CONCLUSIONS

We confirm the association between the FTO rs17817449 SNP and susceptibility to T2DM in the Czech-Slavonic population. The same variant is associated with a spectrum of chronic complications in both types of diabetes.

Association between ACE (rs4646994), FABP2 (rs1799883), MTHFR (rs1801133), FTO (rs9939609) Genes Polymorphism and Type 2 Diabetes with Dyslipidemia

Diabetic dyslipidemia is one of the leading causes of coronary artery disease (CAD) death. Genetic and environmental factors play an important role in the development of type 2 diabetes mellitus (T2DM) and dyslipidemia. The present study was aimed to investigate the association of ACE (rs4646994), FABP2 (rs1799883), MTHFR (rs1801133) and FTO (rs9939609) genes polymorphism in T2DM with dyslipidemia. Totally, 559 subjects including 221 T2DM cases with dyslipidemia, 158 T2DM without dyslipidemia and 180 controls were enrolled. ACE genes polymorphism was evaluated by polymerase chain reaction (PCR), while MTHFR, FABP2, FTO genes polymorphisms were evaluated by PCR and restriction fragment length polymorphism (RFLP). Significant association of ACE and MTHFR genes polymorphisms were found in both group of cases [T2DM with dyslipidemia (P<0.001, and P=0.008, respectively) and T2DM without dyslipidemia (P=0.003, and P=0.010, respectively)] while FABP2 and FTO genes polymorphisms were significantly associated with T2DM without dyslipidemia (P=0.038, and P= 0.019, respectively). This study concludes that ACE, FABP2, FTO and MTHFR genes are associated with T2DM. Additionally, it also seems that ACE and MTHFR genes might be further associated with the development of dyslipidemia in T2DM cases.

Association of KALRN, ADIPOQ, and FTO gene polymorphism in type 2 diabetic patients with coronary artery disease: possible predisposing markers

OBJECTIVES

Recently, several genes have been introduced as potential genetic markers for diabetes mellitus and coronary artery diseases (CAD).

METHODS

In this case-control study, the associations of rs2241766 T/G of ADIPOQ, rs9289231 T/G of KALRN, and rs9939609 A/T of FTO polymorphisms with genetic susceptibility to CAD in type 2 diabetic (T2D) patients were investigated. A total of 224 T2D patients undergoing coronary angiography were randomly recruited into the study. Of the total diabetic patients, 152 were also diagnosed with CAD, whereas the rest were control participants. Genotyping of single-nucleotide polymorphisms was performed by high-resolution melting analysis.

RESULTS

Genotype analysis showed that the minor allele (G) frequency of rs2241766 ADIPOQ was statistically significant in the CAD group compared with the control group [odds ratio (OR), 2.779; 95% confidence interval (CI), 1.403-5.504; P=0.003]. Also, it was found that the minor allele (G) frequency of rs9289231 KALRN was significantly associated with the risk of CAD (OR, 2.098; 95% CI, 1.096-4.017; P=0.025). In addition, no significant association was observed between the minor allele (A) of the FTO rs9939609 polymorphism and CAD (OR, 1.088; 95% CI, 0.578-2.015; P=0.788). It is speculated that the GG genotype and the G allele of the rs9289231 polymorphism of KALRN and the rs224766 polymorphism of ADIPOQ genes may be considered genetic risk factors for CAD in T2D patients and genetic variations of these genes may play a major role in the process of these disorders.

CONCLUSION

Our case-control study in the Iranian population suggested a possible association between the mentioned single-nucleotide polymorphisms and CAD in T2D patients. However, further replication studies and comprehensive meta-analyses are required.

Type 2 diabetes-associated genetic variants of FTO, LEPR, PPARg, and TCF7L2 in gestational diabetes in a Brazilian population

Objective

Gestational diabetes mellitus (GDM) is a metabolic disorder that shares pathophysiologic features with type 2 diabetes mellitus. The aim of this study was to investigate the association of the polymorphisms fat mass and obesity-associated (FTO) rs1421085, leptin receptor (LEPR) rs1137100, rs1137101, peroxisome proliferator-activated receptor gamma (PPARg) rs1801282, and transcription factor 7-like 2 (TCF7L2) rs7901695 with GDM.

Subjects and methods

252 unrelated Euro-Brazilian pregnant women were classified into two groups according to the 2015 criteria of the American and Brazilian Diabetes Association: healthy pregnant women (n = 125) and pregnant women with GDM (n = 127), matched by age. The polymorphisms were genotyped using fluorescent probes (TaqMan®).

Results

All groups were in Hardy-Weinberg equilibrium. The genotype and allele frequencies of the studied polymorphisms did not show significant differences between the groups (P > 0.05). In the healthy and GDM groups, the C allele frequencies (95% CI) of the FTO rs1421085 polymorphism were 36.8% [31-43%] and 35.0% [29-41%]; the G allele frequencies (95% CI) of the LEPR rs1137100 polymorphism were 24.8% [19-30%] and 22.8% [18-28%]; the G allele frequencies (95% CI) of the LEPR rs1137101 polymorphism were 43.6% [37-50%] and 42.9% [37-49%]; the G allele frequencies (95% CI) of the PPARg rs1801282 polymorphism were 7.6% [4-11%] and 8.3% [5-12%]; and the C allele frequencies (95% CI) of the TCF7L2 rs7901695 polymorphism were 33.6% [28-39%] and 39.0% [33-45%], respectively.

Conclusion

The studied polymorphisms were not associated with GDM in a Brazilian population.

FTO Genotype and Type 2 Diabetes Mellitus: Spatial Analysis and Meta-Analysis of 62 Case-Control Studies from Different Regions

Type 2 diabetes mellitus (T2DM) is a global health problem that results from the interaction of environmental factors with genetic variants. Although a number of studies have suggested that genetic polymorphisms in the fat mass and obesity-associated (FTO) gene are associated with T2DM risk, the results have been inconsistent. To investigate whether FTO polymorphisms associate with T2DM risk and whether this association is region-related, we performed this spatial analysis and meta-analysis. More than 60,000 T2DM patients and 90,000 controls from 62 case-control studies were included in this study. Odds ratios (ORs), 95% confidence intervals (CIs) and Moran's I statistic were used to estimate the association between FTO rs9939609, rs8050136, rs1421085, and rs17817499, and T2DM risk in different regions. rs9939609 (OR = 1.15, 95% CI 1.11-1.19) and rs8050136 (OR = 1.14, 95% CI 1.10-1.18) conferred a predisposition to T2DM. After adjustment for body mass index (BMI), the association remained statistically significant for rs9939609 (OR = 1.11, 95% CI 1.05-1.17) and rs8050136 (OR = 1.08, 95% CI 1.03-1.12). In the subgroup analysis of rs9939609 and rs8050136, similar results were observed in East Asia, while no association was found in North America. In South Asia, an association for rs9939609 was revealed but not for rs8050136. In addition, no relationship was found with rs1421085 or rs17817499 regardless of adjustment for BMI. Moran's I statistic showed that significant positive spatial autocorrelations existed in rs9939609 and rs8050136. Studies on rs9939609 and rs8050136 focused on East Asia and South Asia, whereas studies on rs1421085 and rs17817499 were distributed in North America and North Africa. Our data suggest that the associations between FTO rs9939609, rs8050136 and T2DM are region-related, and the two single-nucleotide polymorphisms contribute to an increased risk of T2DM. Future studies should investigate this issue in more regions.

Milk: an epigenetic amplifier of FTO-mediated transcription? Implications for Western diseases

Single-nucleotide polymorphisms within intron 1 of the FTO (fat mass and obesity-associated) gene are associated with enhanced FTO expression, increased body weight, obesity and type 2 diabetes mellitus (T2DM). The N⁶-methyladenosine (m⁶A) demethylase FTO plays a pivotal regulatory role for postnatal growth and energy expenditure. The purpose of this review is to provide translational evidence that links milk signaling with FTO-activated transcription of the milk recipient. FTO-dependent demethylation of m⁶A regulates mRNA splicing required for adipogenesis, increases the stability of mRNAs, and affects microRNA (miRNA) expression and miRNA biosynthesis. FTO senses branched-chain amino acids (BCAAs) and activates the nutrient sensitive kinase mechanistic target of rapamycin complex 1 (mTORC1), which plays a key role in translation. Milk provides abundant BCAAs and glutamine, critical components increasing FTO expression. CpG hypomethylation in the first intron of FTO has recently been associated with T2DM. CpG methylation is generally associated with gene silencing. In contrast, CpG demethylation generally increases transcription. DNA de novo methylation of CpG sites is facilitated by DNA methyltransferases (DNMT) 3A and 3B, whereas DNA maintenance methylation is controlled by DNMT1. MiRNA-29s target all DNMTs and thus reduce DNA CpG methylation. Cow´s milk provides substantial amounts of exosomal miRNA-29s that reach the systemic circulation and target mRNAs of the milk recipient. Via DNMT suppression, milk exosomal miRNA-29s may reduce the magnitude of FTO methylation, thereby epigenetically increasing FTO expression in the milk consumer. High lactation performance with increased milk yield has recently been associated with excessive miRNA-29 expression of dairy cow mammary epithelial cells (DCMECs). Notably, the galactopoietic hormone prolactin upregulates the transcription factor STAT3, which induces miRNA-29 expression. In a retrovirus-like manner milk exosomes may transfer DCMEC-derived miRNA-29s and bovine FTO mRNA to the milk consumer amplifying FTO expression. There is compelling evidence that obesity, T2DM, prostate and breast cancer, and neurodegenerative diseases are all associated with increased FTO expression. Maximization of lactation performance by veterinary medicine with enhanced miRNA-29s and FTO expression associated with increased exosomal miRNA-29 and FTO mRNA transfer to the milk consumer may represent key epigenetic mechanisms promoting FTO/mTORC1-mediated diseases of civilization.

Effect of the Common Fat Mass and Obesity Associated Gene Variants on Obesity in Pakistani Population: A Case-Control Study

Background/Objective. Obesity has become a global epidemic due to an increase in the number of obese individuals worldwide. There is little research in the field of obesity genetics in Pakistan. The aim of the current study was to analyze the association of common variants in Fat Mass and Obesity associated (FTO) gene with obesity in Pakistan, to find out the effect of the selected SNPs on anthropometric and biochemical traits, and to observe whether these variants act synergistically. Methods. Samples from 631 subjects were taken after informed consent and were used for serum parameters and genetic analysis. Lipid profile was determined, tetra-ARMS PCR was used for genotyping, and allele/genotype frequencies and genescore were calculated. Results. All FTO variants were associated with obesity, and some biochemical and anthropometric measures and had higher minor allele frequencies than those reported for Asian populations previously. The risk allele of each single nucleotide polymorphism resulted in an increase in BMI in a quantitative manner. Conclusion. Common forms of obesity are due to a combined net effect of many variants presented in same or different genes. The more the number of risk alleles present, the higher the risk and severity of obesity resulting from an increase in BMI.

Association of SNP rs9939609 in FTO gene with metabolic syndrome in type 2 diabetic subjects, rectruited from a tertiary care unit of Karachi, Pakistan

Objective:

To determine the association of SNP in FTO gene, rs9939609, with Metabolic Syndrome (MS) in type 2 diabetic subjects at a tertiary care unit of Karachi, Pakistan.

Methods:

We genotyped FTO rs9939609 SNP in 296 patients with type 2 diabetes from the Out Patient Department (OPD) of Baqai Institute of Diabetology and Endocrinology (BIDE). MS was defined on the basis of International Diabetes Federation (IDF) and National Cholesterol Education program (NCEP) criterion. Association between the rs9939609 SNP and MS was tested through chi-square and Z-tests by using odds ratio (OR) with 95% confidence intervals.

Results:

The frequency of MS as defined by IDF criterion was significantly higher in female subjects as compared to male subjects (p= 0.006). Carriers of ≥ 1 copy of the rs9939609 A allele were significantly more likely to had MS (69.6%) than non-carriers (30.4%), corresponding to a carrier odds ratio (OR) of 0.52 (95% confidence interval [CI] (0.29-0.93), with a similar trend for the ATP III-defined MS.“A” allele carriers under dominant model, carry all the criterion of MS more significantly as compared to non-carriers.

Conclusion:

The FTO rs9939609 SNP was associated with an increased risk for Metabolic Syndrome in type 2 diabetic populations at a tertiary care unit of Karachi, Pakistan.

Gene polymorphisms and increased DNA damage in morbidly obese women

Obesity is characterized by increased adipose tissue mass resulting from a chronic imbalance between energy intake and expenditure. Furthermore, there is a clearly defined relationship among fat mass expansion, chronic low-grade systemic inflammation and reactive oxygen species (ROS) generation; leading to ROS-related pathological events. In the past years, genome-wide association studies have generated convincing evidence associating genetic variation at multiple regions of the genome with traits that reflect obesity. Therefore, the present study aimed to evaluate the relationships among the gene polymorphisms ghrelin (GHRL-rs26802), ghrelin receptor (GHSR-rs572169), leptin (LEP-rs7799039), leptin receptor (LEPR-rs1137101) and fat mass and obesity-associated (FTO-rs9939609) and obesity. The relationships among these gene variants and the amount of DNA damage were also investigated. Three hundred Caucasian morbidly obese and 300 eutrophic (controls) women were recruited. In summary, the results demonstrated that the frequencies of the GHRL, GHSR, LEP and LEPR polymorphisms were not different between Brazilian white morbidly obese and eutrophic women. Exceptions were the AA-FTO genotype and allele A, which were significantly more frequent in obese women than in the controls (0.23% vs. 0.10%; 0.46 vs. 0.36, respectively), and the TT-FTO genotype and the T allele, which were less frequent in morbidly obese women (p<0.01). Furthermore, significant differences in the amount of genetic lesions associated with FTO variants were observed only in obese women. In conclusion, this study demonstrated that the analyzed SNPs were not closely associated with morbid obesity, suggesting they are not the major contributors to obesity. Therefore, our data indicated that these gene variants are not good biomarkers for predicting risk susceptibility for obesity, whereas ROS generated by the inflammatory status might be one of the causes of DNA damage in obese women, favoring genetically related diseases as obesity comorbidities.

GNB3 and FTO Polymorphisms and Pregnancy Weight Gain in Black Women

BACKGROUND

Gestational weight gain (GWG) is a modifiable risk factor for obesity in women. Black women have the greatest prevalence of high body mass, which predisposes them to excessive GWG. Increased understanding of genetic influences on GWG has implications for the health of women. The purpose of this study was to explore the associations of GNB3 and FTO risk alleles in pregnant women with prepregnancy body mass index (BMI), GWG, and postpartum and infant birth weights.

RESEARCH DESIGN AND METHODS

This was an observational, prospective candidate gene association study. Pregnant, low-income Black women (N = 97) were enrolled in early pregnancy and followed until 6 months postpartum.

RESULTS

GWG differed depending on number of FTO risk alleles. The mean 6-month postpartum BMI differed, although not significantly, by 4 kg/m(2) between homozygous women. There was an interaction between the FTO risk allele and prepregnancy BMI (p = .022), with obese homozygote AA women having significantly higher mean GWG than obese TT women. When controlling for age and smoking, the FTO gene and physical activity predicted GWG (p = .032). Although not statistically significant, women who carried the GNB3 T risk allele gained 6 pounds more than noncarriers, and mean 6-month postpartum BMI differed by 2.2 kg/m(2) between homozygous women. Neither the GNB3 nor FTO gene predicted prepregnancy BMI, infant birth weight, or postpartum weight.

CONCLUSION

Obese women homozygous for the FTO risk allele were at greater risk of excessive GWG compared to nonrisk allele homozygous obese women or nonobese women. This study provides evidence of the FTO gene's effect on GWG in Black women.

Associations of genetic variants in/near body mass index-associated genes with type 2 diabetes: a systematic meta-analysis

OBJECTIVE

Genome-wide association studies have identified many obesity/body mass index (BMI)-associated loci in Europeans and East Asians. Since then, a large number of studies have investigated the role of BMI-associated loci in the development of type 2 diabetes (T2D). However, the results have been inconsistent. The objective of this study was to investigate the associations of eleven obesity/BMI loci with T2D risk and explore how BMI influences this risk.

METHODS

We retrieved published literature from PubMed and Embase. The pooled odds ratios (OR) with 95% confidence intervals (CI) were calculated using fixed- or random-effect models.

RESULTS

In the meta-analysis of 42 studies for 11 obesity/BMI-associated loci, we observed a statistically significant association of the FTO rs9939609 polymorphism (66 425 T2D cases/239 689 normoglycaemic subjects; P = 1·00 × 10(-41) ) and six other variants with T2D risk (17 915 T2D cases/27 531 normoglycaemic individuals: n = 40 629-130 001; all P < 0·001 for SH2B1 rs7498665, FAIM2 rs7138803, TMEM18 rs7561317, GNPDA2 rs10938397, BDNF rs925946 and NEGR1 rs2568958). After adjustment for BMI, the association remained statistically significant for four of the seven variants (all P < 0·05 for FTO rs9939609, SH2B1 rs7498665, FAIM2 rs7138803, GNPDA2 rs10938397). Subgroup analysis by ethnicity demonstrated similar results.

CONCLUSIONS

This meta-analysis indicates that several BMI-associated variants are significantly associated with T2D risk. Some variants increase the T2D risk independent of obesity, while others mediate this risk through obesity.

FTO is a relevant factor for the development of the metabolic syndrome in mice

The metabolic syndrome is a worldwide problem mainly caused by obesity. FTO was found to be a obesity-risk gene in humans and FTO deficiency in mice led to reduction in adipose tissue. Thus, FTO is an important factor for the development of obesity. Leptin-deficient mice are a well characterized model for analysing the metabolic syndrome. To determine the relevance of FTO for the development of the metabolic syndrome we analysed different parameters in combined homozygous deficient mice (Lep(ob/ob);Fto(-/-)). Lep(ob/ob);Fto(-/-) mice showed an improvement in analysed hallmarks of the metabolic syndrome in comparison to leptin-deficient mice wild type or heterozygous for Fto. Lep(ob/ob);Fto(-/-) mice did not develop hyperglycaemia and showed an improved glucose tolerance. Furthermore, extension of beta-cell mass was prevented in Lep(ob/ob);Fto(-/-)mice and accumulation of ectopic fat in the liver was reduced. In conclusion this study demonstrates that FTO deficiency has a protective effect not only on the development of obesity but also on the metabolic syndrome. Thus, FTO plays an important role in the development of metabolic disorders and is an interesting target for therapeutic agents.

FTO Gene Variants Are Associated with PCOS Susceptibility and Hyperandrogenemia in Young Korean Women

BACKGROUND

The fat mass and obesity-associated (FTO) gene is associated with obesity and type 2 diabetes mellitus. Obesity and insulin resistance are also common features of polycystic ovary syndrome (PCOS). Therefore, the FTO gene might be a candidate gene for PCOS susceptibility. The aim of the present study was to evaluate the effects of FTO gene variants on PCOS susceptibility and metabolic and reproductive hormonal parameters.

METHODS

We recruited 432 women with PCOS (24±5 years) and 927 healthy women with regular menstrual cycles (27±5 years) and performed a case-control association study. We genotyped the single nucleotide polymorphisms rs1421085, rs17817449, and rs8050136 in the FTO gene and collected metabolic and hormonal measurements.

RESULTS

Logistic regression revealed that the G/G genotype (rs1421085, 1.6%), the C/C genotype (rs17817449, 1.6%), and the A/A genotype (rs8050136, 1.6%) were strongly associated with an increased risk of PCOS (odds ratio, 2.551 to 2.559; all P<0.05). The strengths of these associations were attenuated after adjusting for age and BMI. The women with these genotypes were more obese and exhibited higher free androgen indices (P<0.05) and higher free testosterone levels (P=0.053 to 0.063) compared to the other genotypes. However the significant differences disappeared after adjusting for body mass index (BMI). When we analyzed the women with PCOS and the control groups separately, there were no significant differences in the metabolic and reproductive hormonal parameters according to the FTO gene variants.

CONCLUSION

The rs1421085, rs17817449, and rs8050136 variants of the FTO gene were associated with PCOS susceptibility and hyperandrogenemia in young Korean women. These associations may be mediated through an effect of BMI.

A gene variant in the transcription factor 7-like 2 (TCF7L2) is associated with an increased risk of gestational diabetes mellitus

OBJECTIVE

Adipokines play an important role in the pathogenesis of insulin resistance during pregnancy. We studied the association of genetic variants linked with type 2 diabetes in gestational diabetes mellitus (GDM) subjects and its influence on maternal adipokines.

STUDY DESIGN

We recruited 25 healthy pregnant women (Controls) and 45 women with GDM at 24-28 weeks of gestation. Maternal blood samples were collected at recruitment and delivery. Adipokines were determined at both sampling times. Genomic DNA was extracted from recruitment samples and FTO rs9939609, TCF7L2 rs4506565, rs7901695, rs12243326, rs12255372 and rs7903146, INSIG2 rs7566605, SREBF1 rs114001633, rs45535737 and rs12941356 and FATP4 rs2003560 genotyped.

RESULTS

Serum adiponectin was significantly lower in GDM than Controls at recruitment and showed a similar trend at delivery (p=0.060). In contrast, resistin tended to higher levels in GDM only at recruitment. TCF7L2 rs4506565 (OR=2.31, 95% CI: 1.97-5.01; p=0.031) and FTO rs9939609 (OR=2.17, 95% CI: 1.07-4.41; p=0.039) were associated with GDM risk. Women carrying the T allele of TCF7L2 rs4506565 had increases in plasma resistin of 9.38 μg/L (95% CI 1.39-17.37; p=0.022) per allele; this association remained significant after adjusting for pre-gestational body weight.

CONCLUSION

TCF7L2 rs4506565 variant (T/T) is associated with increased risk of GDM and plasma resistin concentrations in women with GDM.

FTO gene variant and risk of hypertension: a meta-analysis of 57,464 hypertensive cases and 41,256 controls

OBJECTIVES

Recent studies have suggested that fat mass and obesity-associated gene (FTO) may predispose individuals to develop hypertension. However, the results have been inconsistent. We performed a meta-analysis to investigate the relationship of FTO gene variant with risk of hypertension and influence of body mass index (BMI) on this risk.

MATERIALS/METHODS

A systematic literature search in PubMed, Embase and ISI web of science databases was performed to identify eligible published literatures. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated.

RESULTS

A total of seven studies comprising 57,464 hypertensive cases and 41,256 controls met the inclusion criteria and were included in the meta-analysis. The FTO gene variant(s) showed significant association with the risk of hypertension (OR=1.16, 95% CI=1.07-1.25, P<0.001) which disappeared on adjustment for BMI (OR=1.04, 95% CI=0.98-1.10, P=0.162). In addition, stratified analysis demonstrated a significant association of the FTO variant with the risk of hypertension in obese subjects (OR=1.10, 95% CI=1.01-1.19, P=0.032) but not in non-obese individuals (OR=1.00, 95% CI=0.97-1.03, P=0.832). Subgroup analysis based on ethnicity showed significant association between FTO variant and hypertension in both European (OR=1.07, 95% CI=1.01-1.14, P=0.028) and Asian populations (OR=1.37, 95% CI=1.23-1.53, P<0.001). However, the association remained significant only in Asians (OR=1.17, 95% CI=1.01-1.35, P=0.035) but not in the Europeans (OR=1.02, 95% CI=0.97-1.07, P=0.390) on adjustment for BMI.

CONCLUSIONS

The present meta-analysis confirms that FTO genotype mediates obesity-related hypertension.

Relation of the rs9939609 gene variant in FTO with metabolic syndrome in obese female patients

OBJECTIVES

Common polymorphisms of the fat mass and obesity associated gene (FTO) have been linked to obesity and diabetes mellitus type 2 in some populations. The aim of our study was to analyze the relationship of the rs9939609 FTO gene polymorphism with metabolic syndrome and its components.

MATERIAL AND METHODS

A population of 457 obese Caucasian females was analyzed in a cross-sectional survey. To estimate the prevalence of Metabolic Syndrome, the definitions of the ATPIII were considered. Genotype of FTO gene polymorphism (rs9939609) was studied.

RESULTS

One hundred and thirty patients (28.4%) had the genotype TT (wild group), whereas 227 patients (49.7%) had the genotype TA and 100 patients (21.9%) had the genotype AA. Prevalence of metabolic syndrome (MS) with ATP III definition was 40.7% (186 patients) and 59.3% patients had no MS (n = 271). Prevalence of mutant FTO genotypes was similar in patients with metabolic syndrome (27.4% wild genotype and 72.6% mutant genotype) and without metabolic syndrome (29.2% wild genotype and 70.8% mutant genotype).Odds ratio of metabolic syndrome in wild vs mutant genotype was 1.04 (95% CI: 0.87-1.22). Insulin levels (13.9±6.3 mUI/L vs. 12.6 ± 3.4 mUI/L; p<0.05), HOMA-R (3.3 ± 1.6 vs. 2.8 ± 1.4; p < 0.05) and triglycerides concentrations (110.8 ± 27.3 mg/dl vs. 103.1 ± 47.3 mg/dl; p < 0.05) were lower in the mutant type group than the wild type group in patients without metabolic syndrome.

CONCLUSION

The FTO gene polymorphism (rs9939609) was found to be associated with increased insulin resistance, insulin and triglyceride levels in obese females with TT variant and without metabolic syndrome. MS or its components were not associated with this polymorphism in obese females.

The expression of FTO in human adipose tissue is influenced by fat depot, adiposity, and insulin sensitivity

OBJECTIVE

The fat mass and obesity associated (FTO) gene is related to obesity, but the regulation of FTO expression in adipose tissue is not fully understood. We investigated FTO expression in paired subcutaneous and omental adipose tissues (SAT and OAT) from healthy women undergoing gynecological surgeries, and its relation with adiposity and insulin sensitivity.

DESIGN AND METHODS

FTO expression in SAT of type 2 diabetic patients treated or not with Rosiglitazone was also compared.

RESULTS

Both the mRNA and protein levels of FTO were higher in OAT from women than in SAT. Only OAT FTO protein levels negatively correlated with BMI and body fat mass, whereas SAT FTO mRNA levels were negatively correlated with subcutaneous fat deposition. In addition, SAT FTO mRNA and protein levels were increased in insulin resistant women (high HOMA) compared to insulin sensitive women (low HOMA), whereas OAT FTO expression was not different between these two subgroups. Interestingly, FTO mRNA levels were increased in SAT of type 2 diabetic patients, and treatment of diabetics with Rosiglitazone improved insulin sensitivity and reduced SAT FTO mRNA levels. Lastly, FTO expression was transiently increased in the early phase of 3T3-L1 cell differentiation, which coincides with the induction of PPARγ2 expression. However, partial reduction of FTO did not impact PPARγ2 expression and adipocyte differentiation.

CONCLUSION

Therefore, FTO gene expression is higher in OAT than in SAT in lean to moderately obese women. OAT FTO expression is associated with adiposity, whereas SAT FTO expression is associated with insulin sensitivity. These associations are independent of an effect of FTO on adipocyte differentiation.

The impact of intronic single nucleotide polymorphisms and ethnic diversity for studies on the obesity gene FTO

In 2007, the first common genetic variants were identified, which undoubtedly affect our susceptibility to obesity. These variants are located in the fat mass and obesity-associated gene FTO. Since then, over 50 loci for common obesity have been identified. As the research on these loci is still at an early stage, there is a great need to review, for clarification purposes, the current research on FTO, as this is likely to influence future studies. Based on the current knowledge, FTO seems to be directly involved in the regulation of energy intake, but there is an urgent need for the identification of regulatory polymorphisms. Thus, herein, we discuss current knowledge and highlight putative functional regions in FTO based on published data and computer-based analysis.

Associations of the FTO rs9939609 and the MC4R rs17782313 polymorphisms with type 2 diabetes are modulated by diet, being higher when adherence to the Mediterranean diet pattern is low

Background

Although the Fat Mass and Obesity (FTO) and Melanocortin-4 Receptor (MC4R) genes have been consistently associated with obesity risk, the association between the obesity-risk alleles with type 2 diabetes is still controversial. In some recent meta-analyses in which significant results have been reported, the associations disappeared after adjustment for body mass index (BMI). However gene-diet interactions with dietary patterns have not been investigated. Our main aim was to analyze whether these associations are modulated by the level of adherence to the Mediterranean Diet (MedDiet).

Methods

Case-control study in 7,052 high cardiovascular risk subjects (3,430 type 2 diabetes cases and 3,622 non-diabetic subjects) with no differences in BMI. Diet was assessed by validated questionnaires. FTO-rs9939609 and MC4R-rs17782313 were determined. An aggregate genetic score was calculated to test additive effects. Gene-diet interactions were analyzed.

Results

Neither of the polymorphisms was associated with type 2 diabetes in the whole population. However, we found consistent gene-diet interactions with adherence to the MedDiet both for the FTO-rs9939609 (P-interaction=0.039), the MC4R-rs17782313 (P-interaction=0.009) and for their aggregate score (P-interaction=0.006). When adherence to the MedDiet was low, carriers of the variant alleles had higher type 2 diabetes risk (OR=1.21, 95%CI: 1.03-1.40; P=0.019 for FTO-rs9939609 and OR=1.17, 95%CI:1.01-1.36; P=0.035 for MC4R-rs17782313) than wild-type subjects. However, when adherence to the MedDiet was high, these associations disappeared (OR=0.97, 95%CI: 0.85-1.16; P=0.673 for FTO-rs9939609 and OR=0.89, 95%CI:0.78-1.02; P=0.097 for MC4R-rs17782313). These gene-diet interactions remained significant even after adjustment for BMI. As MedDiet is rich in folate, we also specifically examined folate intake and detected statistically significant interaction effects on fasting plasma glucose concentrations in non-diabetic subjects. However these findings should be interpreted with caution because folate intake may simply reflect a healthy dietary pattern.

Conclusions

These novel results suggest that the association of the FTO-rs9939609 and the MC4R-rs17782313 polymorphisms with type 2 diabetes depends on diet and that a high adherence to the MedDiet counteracts the genetic predisposition.

FTO gene is related to obesity in Chilean Amerindian children and impairs HOMA-IR in prepubertal girls

OBJECTIVE

The objective of this study was to investigate the allelic frequency of the fat mass and obesity-associated (FTO) gene (rs9939609) and its influences on obesity and metabolic risk biomarkers in a cohort of normal weight and obese Chilean children determining its ethnicity.

METHODS

A total of 136 normal weight children and 238 obese children (between 6 and 11 yr old) from an urban setting were recruited for this case-control study. The children were classified as normal weight [body mass index (BMI) ≥ 5th and < 85th percentiles] or obese (BMI >95th percentile), according to the international age- and gender-specific percentiles defined by the Center for Disease Control and Prevention. The analysis of serum markers was carried out using commercial kits. The FTO polymorphism was determined through a high-resolution melting enabled real time polymerase chain reaction. Ethnicity was determined by analyzing mitochondrial DNA by the restriction fragment length polymorphism method.

RESULTS

As much as 85% of the cohort was Amerindian. The minor A allele of rs9939609 was associated with obesity (odds ratio (OR): 1.422 [95% confidence interval (CI) 1.068-1.868] p = 0.015), calculated using an additive model. In sex-stratified analysis we found that the risk variant (A) of rs9939609 was associated with a higher homeostasis model of assessment for insulin (HOMA-IR) in prepubertal obese girls. In male carriers of the A allele, HOMA-IR showed no further deterioration than that already associated with obesity.

CONCLUSIONS

In summary, we confirm the association of the FTO gene single-nucleotide polymorphism rs9939609 with obesity in Chilean Amerindian children. Furthermore we show an association between the risk allele (A) and insulin resistance-related markers in prepubertal obese girls.

Association between FTO 1st intron tagging variant and telomere length in middle aged females. 3PMFs study

The FTO gene plays an important role in the determination of body weight and BMI and it has been suspected of being associated with all-cause mortality, cardiovascular disease, cancer and end stage renal disease, but the causal mechanism of these effects is still unknown. One of the possibilities is the potential association with telomere length. Telomeres are repetitive DNA-sequences located at the ends of eukaryotic chromosomes' length of which is reduced in all somatic cells during ageing. Out of the 908 females (3PMFs study), in 783 females both FTO 1st intron tagging polymorphism (G>T, rs17817449) and the relative telomere length were successfully analysed. The relative telomere length was calculated as the ratio of telomere repeats to single-copy gene copies. The frequencies of the FTO genotypes were similar to other populations (GG=18.3%, GT=49.1% and TT=32.6%). We have detected, that the relative telomere length was significantly shorter (P<0.02, P<0.01 after adjustment for age, BMI, waist and subcutaneous fat), in carriers of at least one FTO risky (G) allele (0.85±0.39) in comparison to the carriers of the protective TT genotype (0.93±0.48). We have demonstrated that the FTO variant could be associated with the relative telomere length. Whether this represents a causality of association between the FTO variant and the non-communicable diseases needs to be further analysed.

Interactions between the FTO rs9939609 polymorphism, body mass index, and lifestyle-related factors on metabolic syndrome risk

Whether the FTO polymorphisms interact with environmental factors has not yet been evaluated in associations with metabolic syndrome (MS) risk. The present study investigated the association of the FTO rs9939609 genotypes, body mass index (BMI), and lifestyle-related factors including smoking, alcohol drinking, physical activity, and diet with MS incidence. A population-based prospective cohort study comprised 3,504 male and female Koreans aged 40 to 69 years. At the beginning of the study, all individuals were free of MS and known cardiovascular disease. Incident cases of MS were identified by biennial health examinations during a follow-up period from April 17, 2003 to April 15, 2009. Pooled logistic regression analysis was applied to obtain relative odds (RO) of MS with its 95% confidence interval (CI). After controlling for potential MS risk factors, we observed no association between the rs9939609 genotypes and MS incidence. In analysis stratified by BMI, however, carriers with the FTO risk allele whose BMI is 29 kg/m² or greater showed an approximately 6-fold higher RO (95% CI: 3.82 to 9.30) compared with non-carriers with BMI less than 25 kg/m². In particular, the association between the rs9939609 variants and MS risk was significantly modified by high BMI (P-value for interaction < 0.05). Such significant interaction appeared in associations with central obesity and high blood pressure among the MS components. Because carriers of the FTO risk alleles who had BMI of 29 kg/m² or greater are considered a high risk population, we suggest that they may need intensive weight loss regimens to prevent MS development.

A high intake of saturated fatty acids strengthens the association between the fat mass and obesity-associated gene and BMI

Evidence that physical activity (PA) modulates the association between the fat mass and obesity-associated gene (FTO) and BMI is emerging; however, information about dietary factors modulating this association is scarce. We investigated whether fat and carbohydrate intake modified the association of FTO gene variation with BMI in two populations, including participants in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN) study (n = 1069) and in the Boston Puerto Rican Health (BPRHS) study (n = 1094). We assessed energy, nutrient intake, and PA using validated questionnaires. Genetic variability at the FTO locus was characterized by polymorphisms rs9939609 (in the GOLDN) and rs1121980 (in the GOLDN and BPRHS). We found significant interactions between PA and FTO on BMI in the GOLDN but not in the BPRHS. We found a significant interaction between SFA intake and FTO on BMI, which was stronger than that of total fat and was present in both populations (P-interaction = 0.007 in the GOLDN and P-interaction = 0.014 in BPRHS for categorical; and P-interaction = 0.028 in the GOLDN and P-interaction = 0.041 in BPRHS for continuous SFA). Thus, homozygous participants for the FTO-risk allele had a higher mean BMI than the other genotypes only when they had a high-SFA intake (above the population mean: 29.7 ± 0.7 vs. 28.1 ± 0.5 kg/m²; P = 0.037 in the GOLDN and 33.6. ± 0.8 vs. 31.2 ± 0.4 kg/m²; P = 0.006 in BPRHS). No associations with BMI were found at lower SFA intakes. We found no significant interactions with carbohydrate intake. In conclusion, SFA intake modulates the association between FTO and BMI in American populations.

Genotype risk score of common susceptible variants for prediction of type 2 diabetes mellitus in Japanese: the Shimanami Health Promoting Program (J-SHIPP study). Development of type 2 diabetes mellitus and genotype risk score

Recent genomewide association studies have successfully identified several genotypes susceptible to type 2 diabetes mellitus (T2DM). However, only a few studies have investigated whether these variations confer a risk of the future development of T2DM. We conducted a longitudinal genetic epidemiological study to clarify the prognostic significance of the T2DM-associated variants. The sample population consisted of 2037 middle-aged to elderly community residents. Personal health records were obtained from a clinical database administered by the local government. Genotype risk score was calculated by the following variants, namely, KCNQ1, TCF7L2, CDKAL1, HHEX, IGF2BP2, CDKN2AB, SLC30A8, KCNJ11, PPARG, and GCKR. Susceptibility of these variants in Japanese has been confirmed by association analysis. Among the 1824 subjects who did not have T2DM at baseline, 95 cases of T2DM were newly diagnosed during the 9.4-year follow-up period. Mean genotype risk score in these subjects was significantly higher than that in the subjects who remained nondiabetic (9.5 ± 1.8 vs 9.1 ± 2.0, P = .042). Although the initial mean body mass index (24.7 ± 3.2 vs 23.0 ± 2.8, P < .001) and initial glucose (106 ± 18 vs 90 ± 13, P < .001) were also significantly higher in those subjects who developed T2DM, the genotype risk score remained an independent determinant of the development of T2DM even after adjustment for these parameters and possible confounding factors. Per-allele odds ratio for the development of T2DM was 1.12 (95% confidence interval, 1.00-1.25; P = .049). Type 2 diabetes mellitus-susceptible genetic variants identified by a cross-sectional genomewide association study were significantly associated with the future development of T2DM in a general population sample.

Variations in the fat mass and obesity-associated (FTO) gene are related to glucose levels and higher lipid accumulation product in postmenopausal women from southern Brazil

OBJECTIVE

To test the association between polymorphisms rs9939609 T>A and rs8050136 A>C of the fat mass and obesity-associated (FTO) gene and metabolic and cardiovascular variables in postmenopause.

DESIGN

Cross-sectional study.

SETTING

University hospital.

PATIENT(S)

A total of 135 postmenopausal women (mean age 52 ± 4 years).

INTERVENTION(S)

Anthropometric measurements and collection of blood samples.

MAIN OUTCOME MEASURE(S)

Blood pressure, metabolic variables, and FTO genotype.

RESULT(S)

The frequency of polymorphism rs9939609 was 43.7% for the wild TT genotype, 43.0% for TA, and 13.3% for AA. The frequency of the rs8050136 polymorphism was 12.6% for the wild AA genotype, 39.3% for AC, and 48.1% for CC. The polymorphic AA genotype of the SNP rs9939609 was associated with higher glucose levels and lipid accumulation product (LAP) index, whereas the wild AA genotype of the SNP rs8050136 was associated with higher LAP.

CONCLUSION(S)

The rs9939609 polymorphism in the FTO gene is related to abnormal glucose levels and with LAP, a surrogate marker of diabetes and cardiovascular risk in postmenopause. Further studies are needed in different ethnic backgrounds to confirm the clinical relevance of these associations.

Common variants of FTO and the risk of obesity and type 2 diabetes in Indians

Common variants of fat mass and obesity-associated gene (FTO, fat mass- and obesity-associated gene) have been shown to be associated with obesity and type 2 diabetes in population of European and non-European ethnicity. However, studies in Indian population have provided inconsistent results. Here, we examined association of eight FTO variants (rs1421085, rs8050136, rs9939609, rs9930506, rs1861867, rs9926180, rs2540769 and rs708277) with obesity and type 2 diabetes in 5364 North Indians (2474 type 2 diabetes patients and 2890 non-diabetic controls) in two stages. None of the variants including previously reported intron 1 variants (rs1421085, rs8050136, rs9939609 and rs9930506) showed body mass index (BMI)-dependent/independent association with type 2 diabetes. However, rs1421085, rs8050136 and rs9939609 were associated with obesity status and measures of obesity (BMI, waist circumference and waist-to-hip ratio) in stage 2 and combined study population. Meta-analysis of the two study population results also revealed that rs1421085, rs8050136 and rs9939609 were significantly associated with BMI both under the random- and fixed-effect models (P (random/fixed)=0.02/0.0001, 0.004/0.0006 and 0.01/0.01, respectively). In conclusion, common variants of FTO were associated with obesity, but not with type 2 diabetes in North Indian population.

FTO gene polymorphisms and obesity risk: a meta-analysis

BACKGROUND

The pathogenesis of obesity is reportedly related to variations in the fat mass and an obesity-associated gene (FTO); however, as the number of reports increases, particularly with respect to varying ethnicities, there is a need to determine more precisely the effect sizes in each ethnic group. In addition, some reports have claimed ethnic-specific associations with alternative SNPs, and to that end there has been a degree of confusion.

METHODS

We searched PubMed, MEDLINE, Web of Science, EMBASE, and BIOSIS Preview to identify studies investigating the associations between the five polymorphisms and obesity risk. Individual study odds ratios (OR) and their 95% confidence intervals (CI) were estimated using per-allele comparison. Summary ORs were estimated using a random effects model.

RESULTS

We identified 59 eligible case-control studies in 27 articles, investigating 41,734 obesity cases and 69,837 healthy controls. Significant associations were detected between obesity risk and the five polymorphisms: rs9939609 (OR: 1.31, 95% CI: 1.26 to 1.36), rs1421085 (OR: 1.43, 95% CI: 1.33 to 1.53), rs8050136 (OR: 1.25, 95% CI: 1.13 to 1.38), rs17817449 (OR: 1.54, 95% CI: 1.41 to 1.68), and rs1121980 (OR: 1.34, 95% CI: 1.10 to 1.62). Begg's and Egger's tests provided no evidence of publication bias for the polymorphisms except rs1121980. There is evidence of higher heterogeneity, with I2 test values ranging from 38.1% to 84.5%.

CONCLUSIONS

This meta-analysis suggests that FTO may represent a low-penetrance susceptible gene for obesity risk. Individual studies with large sample size are needed to further evaluate the associations between the polymorphisms and obesity risk in various ethnic populations.

An FTO variant is associated with Type 2 diabetes in South Asian populations after accounting for body mass index and waist circumference

AIMS

A common variant, rs9939609, in the FTO (fat mass and obesity) gene is associated with adiposity in Europeans, explaining its relationship with diabetes. However, data are inconsistent in South Asians. Our aim was to investigate the association of the FTO rs9939609 variant with obesity, obesity-related traits and Type 2 diabetes in South Asian individuals, and to use meta-analyses to attempt to clarify to what extent BMI influences the association of FTO variants with diabetes in South Asians.

METHODS

We analysed rs9939609 in two studies of Pakistani individuals: 1666 adults aged ≥40 years from the Karachi population-based Control of Blood Pressure and Risk Attenuation (COBRA) study and 2745 individuals of Punjabi ancestry who were part of a Type 2 diabetes case-control study (UK Asian Diabetes Study/Diabetes Genetics in Pakistan; UKADS/DGP). The main outcomes were BMI, waist circumference and diabetes. Regression analyses were performed to determine associations between FTO alleles and outcomes. Summary estimates were combined in a meta-analysis of 8091 South Asian individuals (3919 patients with Type 2 diabetes and 4172 control subjects), including those from two previous studies.

RESULTS

In the 4411 Pakistani individuals from this study, the age-, sex- and diabetes-adjusted association of FTO variant rs9939609 with BMI was 0.45 (95%CI 0.24-0.67) kg/m(2) per A-allele (P=3.0 × 10(-5) ) and with waist circumference was 0.88 (95% CI 0.36-1.41) cm per A-allele (P=0.001). The A-allele (30% frequency) was also significantly associated with Type 2 diabetes [per A-allele odds ratio (95%CI) 1.18 (1.07-1.30); P=0.0009]. A meta-analysis of four South Asian studies with 8091 subjects showed that the FTO A-allele predisposes to Type 2 diabetes [1.22 (95%CI 1.14-1.31); P=1.07 × 10(-8) ] even after adjusting for BMI [1.18 (95%CI 1.10-1.27); P=1.02 × 10(-5) ] or waist circumference [1.18 (95%CI 1.10-1.27); P=3.97 × 10(-5) ].

CONCLUSIONS

The strong association between FTO genotype and BMI and waist circumference in South Asians is similar to that observed in Europeans. In contrast, the strong association of FTO genotype with diabetes is only partly accounted for by BMI.

Where to go with FTO?

An understanding of the mechanisms underlying body-weight regulation is crucial to tackle the growing problem of obesity. Recent technological advances in the analysis of genetic variation have given novel insights into the molecular basis of common disease. In particular, genomic variants in the fat mass and obesity-associated (FTO) gene have been consistently associated with human adiposity and metabolic disorders. Studies of the product of this previously mysterious gene have formed a vanguard in the quest to turn statistical association into hard biology. In this review, we examine data from human genetic and murine studies that explore the potential role of FTO, a member of the Fe(II)- and 2-oxoglutarate-dependent oxygenase superfamily, in the regulation of energy homeostasis and metabolism.

Conditional expression of the FTO gene product in rat INS-1 cells reveals its rapid turnover and a role in the profile of glucose-induced insulin secretion

Common polymorphisms within the FTO (fat mass and obesity-associated) gene correlate with increased BMI (body mass index) and a rising risk of Type 2 diabetes. FTO is highly expressed in the brain but has also been detected in peripheral tissues, including the endocrine pancreas, although its function there is unclear. The aim of the present study was to investigate the role of FTO protein in pancreatic β-cells using a conditional expression system developed in INS-1 cells. INS-1 cells were stably transfected with FTO–HA (haemagluttinin) incorporated under the control of a tetracycline-inducible promoter. Induction of FTO protein resulted in localization of the tagged protein to the nucleus. The level of FTO–HA protein achieved in transfected cells was tightly regulated, and experiments with selective inhibitors revealed that FTO–HA is rapidly degraded via the ubiquitin/proteasome pathway. The nuclear localization was not altered by proteasome inhibitors, although following treatment with PYR-41, an inhibitor of ubiquitination, some of the protein adopted a perinuclear localization. Unexpectedly, modestly increased expression of FTO–HA selectively enhanced the first phase of insulin secretion when INS-1 monolayers or pseudoislets were stimulated with 20 mM glucose, whereas the second phase remained unchanged. The mechanism responsible for the potentiation of glucose-induced insulin secretion is unclear; however, further experiments revealed that it did not involve an increase in insulin biosynthesis or any changes in STAT3 (signal transducer and activator of transcription 3) expression. Taken together, these results suggest that the FTO protein may play a hitherto unrecognized role in the control of first-phase insulin secretion in pancreatic β-cells.