Variations in the FTO gene are associated with severe obesity in the Japanese

Comparison of the risk of obesity in the FTO rs9939609 genotype in a multiethnic group in Asia systematic review and meta-analysis

Aim

This study aims to examine the comparative risk of obesity in the FTO rs9939609 genotype in multiethnic groups in Asia, considering that obesity has become a global disease.

Data synthesis

Data searches were carried out in several electronic databases: PubMed, Scopus, Google Scholar, ScienceDirect, ClinicalTrials.gov and NCBI. The search involved a combination of keywords related to genetics and obesity risk. Pooled Odds Ratio (POR) with 95% CI was calculated based on the pooled data. Review Manager (RevMan) 5.4.1 were used to analyze the data.

Results

From 18 studies, the results of the dominant genetic model AA vs. TT showed POR 95%Cl = 1.95 (1.36-2.80); p < 0.00001, in AA vs. TA genetic recessive model, POR 95%Cl =1.31 (1.07-1.60); p = 0.002, then the final model of TA vs. TT codominance genetic model obtained POR 95%Cl = 1.52 (1.04-2.23); p < 0.00001. The overall risk of bias was low.

Conclusion

From this research, it was found that there was a comparison of the genotype that had a higher risk of obesity, namely the AA genotype in multiethnic groups in Asia.

Systematic review registration

https://www.crd.york.ac.uk/prospero/display_record.php?RecordID=546434.

Single nucleotide polymorphisms (SNPs) that are associated with obesity and type 2 diabetes among Asians: a systematic review and meta-analysis

Single nucleotide polymorphisms (SNPs) could increase the susceptibility of individuals to develop obesity and type 2 diabetes (T2DM). Obesity and T2DM are closely related pathophysiologically, thus similar SNPs could mediate both these diseases, but this is rarely reported. Furthermore, limited studies have been performed to summarize SNP data in the Asian population compared to the Western population. In this study, we aimed to summarize SNPs that are associated with the development of obesity and T2DM among Asian populations. We searched six literature databases and Review Manager (RevMan) was used for meta-analysis. The pooled odds ratios (ORs) and 95% CIs were calculated with a random effects model for the heterogeneity among studies. The pooled analysis showed that rs9939609 (FTO gene) and rs17782313 and rs571312 (MC4R gene) are associated with obesity with an odd ratio (OR) of 1.37, 1.36 and 1.29 respectively. For T2DM, five SNPs, rs7903146 and rs12255372 (TCF7L2 gene), rs13266634 and rs11558471 (SLC30A8 gene) and rs2283228 (KCNQ1 gene) have also shown strong associations with T2DM at OR of 1.64, 1.61, 1.22, 1.29 and 1.60 respectively. This data could be used to develop a gene screening panel for assessing obesity and T2DM susceptibility.

Investigation of genetic markers associated to type 2 diabetes mellitus in Santarém-Pará

Genetic, epigenetic and environmental factors play an important role in the genesis of Type 2 Diabetes Mellitus (T2D). In the genetic context, one of the strategies used to investigate possible associations with diabetes is the search for Single Nucleotide Polymorphisms (SNPs), involving the comparison of alelle frequencies, the phenotypic variations and other relevant factors, such as environmental influences and lifestyle choices, Thus, the aim of this study was to find the relationship of risk variants for T2D in SNPs (rs4994) in the ADRB3 gene; (rs1799854) in the ABCC8 gene; (rs7901695 and rs12255372) in the TCF7L2 gene; and (rs8050136) in the FTO gene in a sample of the population of the municipality of Santarém (PA), Brazilian Amazon, in the northern region of Brazil. ABCC8 (rs1799854 C>T) showed a statistically significant association with T2D. Each chosen gene and SNP has been previously implicated in T2D risk according to existing scientific literature, owing to their roles in glucose regulation and body fat.

Unexpected identification of obesity-associated mutations in LEP and MC4R genes in patients with anorexia nervosa

Mutations leading to a reduced or loss of function in genes of the leptin-melanocortin system confer a risk for monogenic forms of obesity. Yet, gain of function variants in the melanocortin-4-receptor (MC4R) gene predispose to a lower BMI. In individuals with reduced body weight, we thus expected mutations leading to an enhanced function in the respective genes, like leptin (LEP) and MC4R. Therefore, we have Sanger sequenced the coding regions of LEP and MC4R in 462 female patients with anorexia nervosa (AN), and 445 healthy-lean controls. In total, we have observed four and eight variants in LEP and MC4R, respectively. Previous studies showed different functional in vitro effects for the detected frameshift and non-synonymous variants: (1) LEP: reduced/loss of function (p.Val94Met), (2) MC4R: gain of function (p.Val103Ile, p.Ile251Leu), reduced or loss of function (p.Thr112Met, p.Ser127Leu, p.Leu211fsX) and without functional in vitro data (p.Val50Leut). In LEP, the variant p.Val94Met was detected in one patient with AN. For MC4R variants, one patient with AN carried the frameshift variant p.Leu211fsX. One patient with AN was heterozygous for two variants at the MC4R (p.Val103Ile and p.Ser127Leu). All other functionally relevant variants were detected in similar frequencies in patients with AN and lean individuals.

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.

Differential Association of FTO Gene variants and Haplotypes with the Susceptibility to Polycystic Ovary Syndrome According To Obesity in Women with PCOS

We explored the relation between FTO single gene variants (rs1861868, rs9939973, rs1421085, rs1121980, rs17817449, rs8050136, rs9939609, rs9930506, and rs8044769) and polycystic ovary syndrome (PCOS), in particular, according to the obesity status. This retrospective population-based case-control study involved women with PCOS (583) and 713 eumenorrheic control women; genotyping was done by real-time PCR. Significantly higher minor allele frequency (MAF) of rs9939973, rs17817449, rs9939609, and rs9930506 and lower MAF of rs1121980 were seen in PCOS cases. Lower risk of PCOS was associated with rs1121980 and rs8050136 heterozygous and minor allele-homozygous genotypes, while an elevated risk of PCOS was seen with minor allele-homozygous rs9939973, rs17817449, and r9939609 heterozygous and genotypes and minor allele-homozygous rs9930506 and rs8044769 genotype. While none of the tested FTO SNPs variants was associated with PCOS in normal body weight/lean subjects, rs9939973, rs9939609, and rs9930506 were negatively associated with PCOS in overweight subjects. In comparison, rs1861868 was negatively, while rs8044769 was positively associated with PCOS in obese subjects. Haplotype analysis identified haplotypes GACCTCTAT, AACCTCTAT, AACCTATAT and AGTTGCAGC, and GACCTCTAC to be positively associated with PCOS, while haplotypes GGTTGAAGC, GACCTATAT, GGTTGCAGC, and GATCTATAT were negatively associated with PCOS. Apart from GGTTGAAGC, these haplotypes remained associated with altered risk of PCOS after adjusting for covariates. In addition to rs17817449, rs9939609, rs9930506, and rs1121980, this study is the first to demonstrate association of rs9939973 and rs8044769 with altered risk of PCOS and the first to confirm the BMI dependency on the association of FTO variants with PCOS. This underscores the role of FTO gene variants as predisposing factors of PCOS.

Minor alleles in the FTO SNPs contributed to the increased risk of obesity among Korean adults: meta-analysis from nationwide big data-based studies

BACKGROUND/OBJECTIVES

Many studies have revealed an association between fat mass and the obesity-related gene (FTO) and obesity. On the other hand, no meta-analysis was conducted with data from only Koreans. Therefore, this study performed a meta-analysis using Korean data to provide evidence for the association between FTO single nucleotide polymorphisms (SNPs) and the risk of obesity among Korean adults.

SUBJECT/METHODS

Meta-analysis was finally conducted with data extracted from seven datasets of four studies performed on Korean adults after the screening passed. Five kinds of FTO SNPs (rs9939609, rs7193144, rs9940128, rs8050136, and rs9926289) were included, and the relationship between FTO SNPs and body mass index (BMI) was investigated using linear regression with an additive model adjusted for covariants, such as age, sex, and area.

RESULTS

The minor alleles of FTO SNPs were associated with increased BMI (odds ratio [OR], 1.31; 95% confidence interval [CI], 1.21-1.42). In sub-group analysis, FTO rs9939609 T>A was significantly associated with BMI (OR, 1.23; 95% CI, 1.06-1.42). The other FTO SNPs together were significantly associated with BMI (OR, 1.37; 95% CI, 1.25-1.49). The publication bias was not observed based on Egger's test.

CONCLUSIONS

This meta-analysis showed that minor alleles in the FTO SNPs were significantly associated with an increased BMI among Korean adults. This meta-analysis is the first to demonstrate that minor alleles in the FTO SNPs contribute significantly to the increased risk of obesity among Korean adults using data from a Korean population.

FTO Common Obesity SNPs Interact with Actionable Environmental Factors: Physical Activity, Sugar-Sweetened Beverages and Wine Consumption

Genetic background is estimated to play >50% in common obesity etiology. FTO single nucleotide polymorphisms (SNPs) are strongly associated with BMI, typically in European cohorts. We investigated the interaction of common FTO SNPs with actionable environmental factors, namely physical activity, sugar-sweetened beverages (SSB) and wine consumption, and verified FTO common SNPs predisposition to obesity in the Israeli population. Adults’ (>18 years old, n = 1720) FTO common SNPs data and lifestyle and nutrition habits questionnaires were analyzed using binary logistic regression models, adjusted for confounding variables (age, sex) assuming dominant, recessive and additive genetic models. Eighteen FTO SNPs were associated with significant increased obesity risk and interacted with physical activity (p < 0.001), wine consumption (p < 0.014) and SSB consumption (p < 0.01). Inactive rs9939609 risk-allele carriers had significantly higher obesity risk compared to their active counterparts (OR = 2.54, 95% CI 1.91−3.39 and OR = 3.77, 95% CI 2.47−5.75; p < 0.001 with 3.1 and 3.5 BMI increment for heterozygotes and homozygotes, respectively). SSB consumption (≥1 serving/day) significantly raised obesity risk and wine consumption (1−3 drinks/weekly) significantly lowered obesity risk for rs9939609 risk-allele carriers (OR = 1.54, 95% CI 1.05−2.27; p = 0.028 and OR = 0.61, 95% CI 0.47−0.79; p < 0.001, respectively). Our findings demonstrate that actionable lifestyle factors modify the common FTO obesity risk in predisposed carriers, and they have personal and public health implications.

Association between fat mass and obesity-related variant and osteoarthritis risk: Integrated meta-analysis with bioinformatics

Objective

The association of fat mass and obesity-related (FTO) gene with osteoarthritis (OA) risk has been investigated in multiple genome-wide association studies but showed inconsistent results. Our study aimed to assess FTO expression in different OA sequencing datasets and to meta-analyze whether FTO polymorphism was associated with the risk of osteoarthritis.

Method

Gene expression profiles were obtained from ArrayExpress, Gene Expression Omnibus (GEO), and BioProject databases. Three electronic databases including PubMed and EMBASE were systematically retrieved to identify articles exploring the association between FTO polymorphisms and OA risk published before September 2022. Summary odds ratios (ORs) and corresponding 95% confidence intervals (95% CIs) were calculated to perform the result. Stata software was utilized to conduct analyses on predetermined ethnicity and gender subgroups and sensitivity.

Results

FTO gene was differentially expressed in the datasets from the UK. This systematic review and meta-analysis encompasses eight studies that revealed a significant association between FTO polymorphisms and OA risk [OR 1.07, 95% CI (1.03, 1.11), P < 0.001] in the overall population. In subgroup analysis, a marked association was observed in European Caucasian [OR 1.08, 95% CI (1.04–1.12), P < 0.001] and North American Caucasian with the Asian subgroups [OR 0.98, 95% CI (0.83–1. 6), P = 0.83] as an exception. Among the studies, four of them demonstrated attenuation in their OA risk after body mass index (BMI) adjustment in Caucasian populations.

Conclusion

FTO significant differential expression was associated with the increased risk of OA in Caucasian populations. Nevertheless, the causality between FTO polymorphisms and OA risk remains largely elusive. Hence, further studies with larger sample size are necessary to validate whether FTO gene polymorphism contributes to OA susceptibility.

Fat mass and obesity-associated gene (FTO) hypermethylation induced by decabromodiphenyl ethane causing cardiac dysfunction via glucolipid metabolism disorder

Decabromodiphenyl ethane (DBDPE) is a major alternative to BDE-209 owing to its lower toxicity. However, the mass production and increased consumption of DBDPE in recent years have raised concerns related to its adverse health effects. However, the effect and mechanism of DBDPE on cardiotoxicity have rarely been studied. In the present study, we investigated the impacts of DBDPE on the cardiovascular system in male SD rats and then explored the underlying mechanisms to explain the cardiotoxicity of DBDPE using AC16 cells. Under in vivo conditions, male rats were administered with an oral dosage of DBDPE at 0, 5, 50, and 500 mg/kg/day for 28 days, respectively. Histopathological analysis demonstrated that DBDPE induced cardiomyocyte injury and fibrosis, and ultrastructural observation revealed that DBDPE could induce mitochondria damage and dissolution. DBDPE could thus decrease the level of MYH6 and increase the level of SERCA2, which are the two key proteins involved in the maintenance of homeostasis during myocardial contractile and diastolic processes. Furthermore, DBDPE could increase the serum levels of glucose and low-density lipoprotein but decrease the content of high-density lipoprotein. In addition, DBDPE could activate the PI3K/AKT/GLUT2 and PPARγ/RXRα signaling pathways in AC16 cells. In addition, DBDPE decreased the UCP2 level and ATP synthesis in mitochondria both under in vitro and in vivo conditions, consequently leading to apoptosis via the Cytochrome C/Caspase-9/Caspase-3 pathway. Bisulfite sequencing PCR (BSP) identified the hypermethylation status of fat mass and obesity-associated gene (FTO). 5-aza exerted the opposite effects on the PI3K/AKT/GLUT2, PPARγ/RXRα, and Cytochrome C/Caspase-9/Caspase-3 signaling pathways induced by DBDPE in AC16 cells. In addition, the DBDPE-treated altered levels of UCP2, ATP, and apoptosis were also found to be significantly reversed by 5-aza in AC16 cells. These results suggested that FTO hypermethylation played a regulative role in the pathological process of DBDPE-induced glycolipid metabolism disorder, thereby contributing to the dysfunction of myocardial contraction and relaxation through cardiomyocytes fibrosis and apoptosis via the mitochondrial-mediated apoptotic pathway resulting from mitochondrial dysfunction.

Pathophysiological Role of Genetic Factors Associated With Gestational Diabetes Mellitus

Gestational Diabetes Mellitus (GDM) is a highly prevalent maternal pathology characterized by maternal glucose intolerance during pregnancy that is, associated with severe complications for both mother and offspring. Several risk factors have been related to GDM; one of the most important among them is genetic predisposition. Numerous single nucleotide polymorphisms (SNPs) in genes that act at different levels on various tissues, could cause changes in the expression levels and activity of proteins, which result in glucose and insulin metabolism dysfunction. In this review, we describe various SNPs; which according to literature, increase the risk of developing GDM. These SNPs include: (1) those associated with transcription factors that regulate insulin production and excretion, such as rs7903146 (TCF7L2) and rs5015480 (HHEX); (2) others that cause a decrease in protective hormones against insulin resistance such as rs2241766 (ADIPOQ) and rs6257 (SHBG); (3) SNPs that cause modifications in membrane proteins, generating dysfunction in insulin signaling or cell transport in the case of rs5443 (GNB3) and rs2237892 (KCNQ1); (4) those associated with enzymes such as rs225014 (DIO2) and rs9939609 (FTO) which cause an impaired metabolism, resulting in an insulin resistance state; and (5) other polymorphisms, those are associated with growth factors such as rs2146323 (VEGFA) and rs755622 (MIF) which could cause changes in the expression levels of these proteins, producing endothelial dysfunction and an increase of pro-inflammatory cytokines, characteristic on GDM. While the pathophysiological mechanism is unclear, this review describes various potential effects of these polymorphisms on the predisposition to develop GDM.

FTO m6A Demethylase in Obesity and Cancer: Implications and Underlying Molecular Mechanisms

Fat mass and obesity-associated protein (FTO) is the first reported RNA N6-methyladenosine (m6A) demethylase in eukaryotic cells. m6A is considered as the most abundant mRNA internal modification, which modulates several cellular processes including alternative splicing, stability, and expression. Genome-wide association studies (GWAS) identified single-nucleotide polymorphisms (SNPs) within FTO to be associated with obesity, as well as cancer including endometrial cancer, breast cancer, pancreatic cancer, and melanoma. Since the initial classification of FTO as an m6A demethylase, various studies started to unravel a connection between FTO’s demethylase activity and the susceptibility to obesity on the molecular level. FTO was found to facilitate adipogenesis, by regulating adipogenic pathways and inducing pre-adipocyte differentiation. FTO has also been investigated in tumorigenesis, where emerging studies suggest m6A and FTO levels are dysregulated in various cancers, including acute myeloid leukemia (AML), glioblastoma, cervical squamous cell carcinoma (CSCC), breast cancer, and melanoma. Here we review the molecular bases of m6A in tumorigenesis and adipogenesis while highlighting the controversial role of FTO in obesity. We provide recent findings confirming FTO’s causative link to obesity and discuss novel approaches using RNA demethylase inhibitors as targeted oncotherapies. Our review aims to confirm m6A demethylation as a risk factor in obesity and provoke new research in FTO and human disorders.

Association of FTO gene variants rs9939609 and rs1421085 with polycystic ovary syndrome

Background

Polycystic ovary syndrome (PCOS) is among the most common complex genetic endocrinopathy, and its etiology and pathophysiology remain controversial. FTO is a large highly polymorphic gene and was coined as the first locus associated with adiposity. The association of the intronic variant FTO rs9939609 or FTO rs1421085 with PCOS has been controversial and unclear, mainly due to ethnic differences among populations. The present study aims to investigate the association of FTO rs9939609 or FTO rs1421085 polymorphisms with PCOS in Saudi Arabian women.

Results

A total of 98 PCOS patients and 99 healthy females were included in this study. PCR and genotyping (TaqMan®SNP Genotyping Assay) were employed. For FTO rs9939609, the genotype TA and the recessive model (TA + AA) in PCOS patients were significantly different compared with control subjects (p = 0.008 and p = 0.007, respectively). The allele frequency of the FTO rs9939609 gene variant was associated significantly (p = 0.027) with PCOS, suggesting that the A allele is a risk factor for PCOS susceptibility. However, for the FTO rs1421085 variant, the genotype and allele distributions did not differ significantly between PCOS patients and controls (p > 0.05).

Conclusions

This is the first report to study the association of FTO rs9939609 and FTO rs1421085 with PCOS in Saudi women. Results suggest that the FTO rs9939609 gene variant could be a genetic predisposing factor for PCOS Saudi women.

Association of FTO rs1421085 single nucleotide polymorphism with fat and fatty acid intake in Indonesian adults

Objective

Recent studies showed that genetic polymorphisms in the fat mass and obesity-associated gene (FTO) were associated with obesity and dietary intake. In this study of 71 adults in Jakarta, Indonesia, we investigated FTO rs1421085 association with body mass index (BMI), macronutrient intake, and fatty acid intake. The association was evaluated using linear regression analyses assuming co-dominant, dominant, recessive, over-dominant, and additive genetic models.

Results

Only individuals with the CC genotype had a considerably higher BMI (p < 0.001), which indicates a recessive genetic trait, but the incidence for this genotype is low (68 TT + TC vs. 3 CC). Individuals with the minor C allele had an estimated increase of fat intake by 3.45–4.06% across various genetic models (dominant: p < 0.010, over-dominant: p < 0.030, additive: p < 0.010). Subjects with TC/CC genotypes had increased dietary monounsaturated fatty acid (MUFA; 1.14%, p = 0.046) and saturated fatty acid (SAFA; 2.06%, p = 0.023) intakes, compared to those with the TT genotype. In conclusion, our study provided evidence for the association between FTO rs1421085 risk allele with higher BMI and individual preferences for consuming more fat, MUFA, and SAFA. This study highlights the important role of FTO gene in food preference, and its influence on body weight.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05823-1.

Relationship between the FTO Genotype and Early Chronic Kidney Disease in Type 2 Diabetes: The Mediating Role of Central Obesity, Hypertension, and High Albuminuria

INTRODUCTION

Single nucleotide polymorphisms (SNP) in the fat mass and obesity-associated (FTO) gene have been associated with type 2 diabetes (T2D) and its complications. The aim of the present research was to investigate which and how (directly or indirectly) clinical and metabolic variables mediate the association between fat mass and the FTO gene and early chronic kidney disease (CKD) in individuals with T2D.

METHODS

This cross-sectional study was conducted in a sample of 236 participants with T2D (53.4% women, mean age 60 ± 10 years). DNA samples were genotyped for the rs7204609 polymorphism (C/T) in the FTO gene. Clinical, anthropometric, and metabolic data were collected. Path analysis was used to evaluate the associations.

RESULTS

Of the sample, 78 individuals with T2D had CKD (33%). Presence of the risk allele (C) was higher among participants with CKD (21.8 vs. 10.8%; p = 0.023). This polymorphism was positively associated with higher waist circumference, which in turn was associated with higher glycated hemoglobin and higher blood pressure. A higher blood-pressure level was associated with higher urinary albumin excretion (UAE) and as expected, higher UAE was associated with CKD. Path analysis showed an indirect relationship between the FTO gene and early CKD, mediated by waist circumference, blood-pressure levels, and UAE.

CONCLUSIONS

These findings suggest that the C allele may contribute to genetic susceptibility to CKD in individuals with T2D through the presence of central obesity, hypertension, and high albuminuria.

Context-Dependent Roles of RNA Modifications in Stress Responses and Diseases

RNA modifications are diverse post-transcriptional modifications that regulate RNA metabolism and gene expression. RNA modifications, and the writers, erasers, and readers that catalyze these modifications, serve as important signaling machineries in cellular stress responses and disease pathogenesis. In response to stress, RNA modifications are mobilized to activate or inhibit the signaling pathways that combat stresses, including oxidative stress, hypoxia, therapeutic stress, metabolic stress, heat shock, DNA damage, and ER stress. The role of RNA modifications in response to these cellular stressors is context- and cell-type-dependent. Due to their pervasive roles in cell biology, RNA modifications have been implicated in the pathogenesis of different diseases, including cancer, neurologic and developmental disorders and diseases, and metabolic diseases. In this review, we aim to summarize the roles of RNA modifications in molecular and cellular stress responses and diseases.

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.

Genetics of Obesity in East Asians

Obesity has become a public health problem worldwide. Compared with Europe, people in Asia tend to suffer from type 2 diabetes with a lower body mass index (BMI). Genome-wide association studies (GWASs) have identified over 750 loci associated with obesity. Although the majority of GWAS results were conducted in individuals of European ancestry, a recent GWAS in individuals of Asian ancestry has made a significant contribution to the identification of obesity susceptibility loci. Indeed, owing to the multifactorial character of obesity with a strong environmental component, the revealed loci may have distinct contributions in different ancestral genetic backgrounds and in different environments as presented through diet and exercise among other factors. Uncovering novel, yet unrevealed genes in non-European ancestries may further contribute to explaining the missing heritability for BMI. In this review, we aimed to summarize recent advances in obesity genetics in individuals of Asian ancestry. We therefore compared proposed mechanisms underlying susceptibility loci for obesity associated with individuals of European and Asian ancestries and discussed whether known genetic variants might explain ethnic differences in obesity risk. We further acknowledged that GWAS implemented in individuals of Asian ancestries have not only validated the potential role of previously specified obesity susceptibility loci but also exposed novel ones, which have been missed in the initial genetic studies in individuals of European ancestries. Thus, multi-ethnic studies have a great potential not only to contribute to a better understanding of the complex etiology of human obesity but also potentially of ethnic differences in the prevalence of obesity, which may ultimately pave new avenues in more targeted and personalized obesity treatments.

The interaction between FTO rs9939609 and physical activity is associated with a 2-fold reduction in the risk of obesity in Korean population

OBJECTIVE

FTO (fat mass and obesity-associated) gene is a well-known genetic risk factor for obesity. We investigated whether physical activity modulates the effect of FTO rs9939609 on obesity in Korean population.

METHODS

The study analyzed the correlation between physical activity and obesity in 8840 individuals representing the Korea Association Resource (KARE). The association between obesity-related traits and single-nucleotide polymorphisms (SNPs) was assessed using linear regression models. Physical activity was defined as 3 hours or more of daily intense activity.

RESULTS

Participants carrying rs9939609 (AT+AA) genotypes showed higher BMI compared with those carrying the wild-type (TT) homozygote. The highest significant association was observed between obesity-related traits (ß = .334, P value = 1.76 × 10^-6 ). FTO rs9939609 (AT+AA) increased the risk of obesity (OR = 1.42, CI [1.13-1.79]), which was correlated with BMI correlations. However, active exercise by subjects carrying the same genotype reduced the risk of obesity by nearly 2-fold (OR = 0.62, CI [0.25-0.84]). In contrast, TT genotype was not statistically significant in reducing the risk of obesity in the active exercise group.

CONCLUSIONS

Our results support a previous finding correlating FTO and obesity-related traits and suggest that the interaction with genetic variation and physical activity is an important risk factor for obesity.

A Comprehensive Genome-Wide and Phenome-Wide Examination of BMI and Obesity in a Northern Nevadan Cohort

The aggregation of Electronic Health Records (EHR) and personalized genetics leads to powerful discoveries relevant to population health. Here we perform genome-wide association studies (GWAS) and accompanying phenome-wide association studies (PheWAS) to validate phenotype-genotype associations of BMI, and to a greater extent, severe Class 2 obesity, using comprehensive diagnostic and clinical data from the EHR database of our cohort. Three GWASs of 500,000 variants on the Illumina platform of 6,645 Healthy Nevada participants identified several published and novel variants that affect BMI and obesity. Each GWAS was followed with two independent PheWASs to examine associations between extensive phenotypes (incidence of diagnoses, condition, or disease), significant SNPs, BMI, and incidence of extreme obesity. The first GWAS examines associations with BMI in a cohort with no type 2 diabetics, focusing exclusively on BMI. The second GWAS examines associations with BMI in a cohort that includes type 2 diabetics. In the second GWAS, type 2 diabetes is a comorbidity, and thus becomes a covariate in the statistical model. The intersection of significant variants of these two studies is surprising. The third GWAS is a case vs. control study, with cases defined as extremely obese (Class 2 or 3 obesity), and controls defined as participants with BMI between 18.5 and 25. This last GWAS identifies strong associations with extreme obesity, including established variants in the FTO and NEGR1 genes, as well as loci not yet linked to obesity. The PheWASs validate published associations between BMI and extreme obesity and incidence of specific diagnoses and conditions, yet also highlight novel links. This study emphasizes the importance of our extensive longitudinal EHR database to validate known associations and identify putative novel links with BMI and obesity.

Obesity in the Balinese is associated with FTO rs9939609 and rs1421085 single nucleotide polymorphisms

Obesity prevalence is increasing worldwide, including in the Bali Province, Indonesia, a popular tourism destination area. The common single nucleotide polymorphisms (SNPs) rs9939609 and rs1421085 of the fat mass and obesity-associated (FTO) gene have been repeatedly reported as one of the important obesity genetic risk factors. We have examined the associations of FTO rs9939609 and rs1421085 SNPs with obesity in the 612 unrelated Balinese subjects living in urban and rural areas. Linear and logistic regression analyses with adjustment for age and gender were employed to investigate the association between FTO genotypes, haplotypes and obesity parameters. We found that the FTO SNPs genotypes increased BMI by 1.25 kg/m² (p = 0.012) for rs9939609 AA and 1.12 kg/m² (p = 0.022) for rs1421085 CC, particularly in females and in rural population. Subjects carrying these genotypes also showed a tendency to maintain high BMI, regardless of their age. Our result showed that the FTO rs9939609 and rs1421085 risk alleles were associated with increased BMI and obesity in the Balinese.

Genome-wide association study of morbid obesity in Han Chinese

BACKGROUND

As obesity is becoming pandemic, morbid obesity (MO), an extreme type of obesity, is an emerging issue worldwide. It is imperative to understand the factors responsible for huge weight gain in certain populations in the modern society. Very few genome-wide association studies (GWAS) have been conducted on MO patients. This study is the first MO-GWAS study in the Han-Chinese population in Asia.

METHODS

We conducted a two-stage GWAS with 1110 MO bariatric patients (body mass index [BMI] ≥ 35 kg/m2) from Min-Sheng General Hospital, Taiwan. The first stage involved 575 patients, and 1729 sex- and age-matched controls from the Taiwan Han Chinese Cell and Genome Bank. In the second stage, another 535 patients from the same hospital were genotyped for 52 single nucleotide polymorphisms (SNPs) discovered in the first stage, and 9145 matched controls from Taiwan Biobank were matched for confirmation analysis.

RESULTS

The results of the joint analysis for the second stage revealed six top ranking SNPs, including rs8050136 (p-value = 7.80 × 10- 10), rs9939609 (p-value = 1.32 × 10- 9), rs1421085 (p-value = 1.54 × 10- 8), rs9941349 (p-value = 9.05 × 10- 8), rs1121980 (p-value = 7.27 × 10- 7), and rs9937354 (p-value = 6.65 × 10- 7), which were all located in FTO gene. Significant associations were also observed between MO and RBFOX1, RP11-638 L3.1, TMTC1, CBLN4, CSMD3, and ERBB4, respectively, using the Bonferroni correction criteria for 52 SNPs (p < 9.6 × 10- 4).

CONCLUSION

The most significantly associated locus of MO in the Han-Chinese population was the well-known FTO gene. These SNPs located in intron 1, may include the leptin receptor modulator. Other significant loci, showing weak associations with MO, also suggested the potential mechanism underlying the disorders with eating behaviors or brain/neural development.

Association of Obesity-Related Genetic Variants (FTO and MC4R) with Breast Cancer Risk: A Population-Based Case-Control Study in Iran

Background:

Heterogeneous breast cancer is the most common cause of cancer-related mortality. Obesity defined by BMI is a known major risk factor for breast cancer.

Objectives:

The purpose of this study was to explore the role of obesity related-polymorphisms rs9939609 Fat Mass and Obesity-associated (FTO) and rs17782313 MC4R in breast cancer development.

Materials and Methods:

Matched peripheral blood serum was obtained from 64 breast cancer patients and 83 normal controls. Height and weight were measured to calculate BMI. All were genotyped for the SNPs rs9939609 and rs17782313 using a Tetra-primer ARMS-PCR method. For statistical analysis, the chi-square test and SPSS software were used.

Results:

In subgroup analyses defined by BMI, FTO rs9939609 genotypes (TT/AA/AT) were significantly associated with the risk of breast cancer only in non-obese subjects (p < 0.005). TT genotypes of MC4R rs17782313 in non-obese and genotypes TT/CC in the overweight group were also statistically associated with breast cancer (p &lt; 0.005). No significant associations between any variants and breast cancer risk were seen in obese subjects.

Conclusion:

Based on the absence of an association between obesity-related SNPs and breast cancer in obese subjects, it is proposed that weight gain in Iranian women will help prevent breast cancer risk. The result help for preparing and designing a safe and versatile recombinant drug in future.

Assessment of FTO Gene Polymorphism and its Association with Type 2 Diabetes Mellitus in North Indian Populations

FTO gene polymorphism related to type 2 diabetes and obesity was studied in this north Indian population. This study was done, due to a continuous increase in the risk of obesity and type 2 diabetes in north Indian population, because of lifestyle and genetic variations. Clinically diagnosed subjects of type 2 diabetes mellitus (as per ADA criteria) were taken as cases and age and sex matched subjects without any associated illness were taken as controls. Obesity was estimated by calculating waist circumference and BMI in the study cases and controls. For genetic variation, DNA was isolated with Quaigen kit method and isolated DNA was amplified with PCR. Amplified DNA was resolved in 1% agarose gel electrophoresis. The Hardy-Weinberg equilibrium, OR, CI and P value were calculated using standard protocols. FTO gene polymorphism (SNP 9940128) was found to be significantly correlated with type 2 diabetes mellitus and obesity. The AG genotype frequency was observed to be higher (13.09%) with (P < 0.0001) in the cases as compared to controls. Logistic regression analysis was conducted for AG and GG genotypes with respect to AA. In this novel study genetic co-relation was observed between FTO gene polymorphisms and type 2 diabetes and obesity in the north Indian population.

FTO gene polymorphisms and obesity risk in Chinese population: a meta-analysis

BACKGROUND

There is tremendous increase in obesity worldwide. Many factors including diet, life style, genetic, and epigenetic changes contribute to obesity. The fat mass and obesity-associated (FTO) gene polymorphisms are strongly associated with obesity. It has been reported that FTO single-nucleotide polymorphisms (SNPs) are associated with obesity in European populations; however, it was controversial in Chinese population. The present meta-analysis study was designed to investigate the association between FTO polymorphisms and obesity risk in Chinese population.

METHODS

The investigators searched studies using the following databases: PubMed, web of science, and Cochrane Central Register of Controlled Trials. A random-effects model was used to calculate the pooled odds ratios (ORs). The heterogeneity among the studies was measured by I² value. Subgroup analysis was used to find out the potential factors influencing the heterogeneity.

RESULTS

A total of 18 articles including 26 studies were included in the present meta-analysis. Overall, the FTO SNPs were significantly associated with obesity in Chinese population (OR 1.30; 95% CI 1.19-1.42; P < 0.001) under per-allele comparison. The subgroup analysis also showed strong association between four FTO SNPs (rs9939609, rs6499640, rs8050136, and rs1558902) and obesity risk. Furthermore, subgroup analysis stratified by children/adolescent and adult groups showed same trend.

CONCLUSION

The present meta-analysis indicated that FTO SNPs are associated with obesity risk in both children/adolescents and adults in Chinese population.

Physical Activity Might Reduce the Adverse Impacts of the FTO Gene Variant rs3751812 on the Body Mass Index of Adults in Taiwan

The fat mass and obesity-associated (FTO) gene is a significant genetic contributor to polygenic obesity. We investigated whether physical activity (PA) modulates the effect of FTO rs3751812 on body mass index (BMI) among Taiwanese adults. Analytic samples included 10,853 Taiwan biobank participants. Association of the single-nucleotide polymorphism (SNP) with BMI was assessed using linear regression models. Physical activity was defined as any kind of exercise lasting 30 min each session, at least three times a week. Participants with heterozygous (TG) and homozygous (TT) genotypes had higher BMI compared to those with wild-type (GG) genotypes. The β value was 0.381(p < 0.0001) for TG individuals and 0.684 (p = 0.0204) for TT individuals. There was a significant dose-response effect among carriers of different risk alleles (p trend <0.0001). Active individuals had lower BMI than their inactive counterparts (β = -0.389, p < 0.0001). Among the active individuals, significant associations were found only with the TG genotype (β = 0.360, p = 0.0032). Inactive individuals with TG and TT genotypes had increased levels of BMI compared to those with GG genotypes: Their β values were 0.381 (p = 0.0021) and 0.950 (p = 0.0188), respectively. There was an interaction between the three genotypes, physical inactivity, and BMI (p trend  = 0.0002). Our data indicated that increased BMI owing to genetic susceptibility by FTO rs3751812 may be reduced by physical activity.

Common Polymorphisms Linked to Obesity and Cardiovascular Disease in Europeans and Asians are Associated with Type 2 Diabetes in Mexican Mestizos

Background and objectives: Type 2 diabetes (T2D) is a major problem of public health in Mexico. We investigated the influence of five polymorphisms, previously associated with obesity and cardiovascular disease in Europeans and Asians, on T2D in Mexican Mestizos. Materials and Methods: A total of 1358 subjects from 30 to 85 years old were genotyped for five loci: CXCL12 rs501120; CDNK2A/B rs1333049; HNF-1α rs2259816; FTO rs9939609; and LEP rs7799039. We used logistic regressions to test the effect of each locus on T2D in two case⁻control groups with obesity and without obesity. Also, linear regression models on glucose and glycated hemoglobin (HbA1c) were carried out on the whole sample, adjusted by age, gender, and body mass index. Results: The CXCL12 rs501120 C allele (OR = 1.96, p = 0.02), the FTO rs9939609 A allele (OR = 2.20, p = 0.04) and the LEP rs7799039 A allele (OR = 0.6, p = 0.03) were significantly associated with T2D in obesity case⁻control group. No significant association was found in the non-obesity case⁻control group. The linear regression model showed that CDNK2A/B rs1333049 C allele (β = 0.4, p = 0.03) and FTO rs9939609 A allele (β = 0.5, p = 0.03), were significantly associated with HbA1c, but no association was found among the loci with the glucose levels. Conclusions: Polymorphisms previously linked with obesity and cardiovascular events were also associated with T2D and high levels of HbA1c. Furthermore, we must point at the fact that this is the first report where polymorphisms CXCL12 rs501120 and LEP rs7799039 are associated with T2D in subjects with obesity.

Intron-specific Single Nucleotide Polymorphisms of Fat Mass and Obesity- Associated Gene in Obese and Overweight Individuals of the Indian Adult Population- A Pilot Study

BACKGROUND

The Fat mass and obesity-associated gene (FTO) and its involvement in weight gain and obesity is well-known. However, no reports have been published on the Indian population regarding the relationship between single nucleotide polymorphisms (SNPs) in its intronic region and obesity. The aim of this pilot study was to evaluate the frequency and association of SNPs in intron-1 of the FTO gene in obese and overweight Indian adults.

METHODS

This study group consisted of 80 adults, aged 23.5 ± 8.9 yr, with a mean BMI of 28.8 ± 6.2 kg/m2. Genomic DNA was isolated, exons1-3 & intron1 of FTO were amplified using polymerase chain reaction and sequenced by ABI sequencing detection system. The reported SNPs rs1420185, rs8050136, rs1121980 and rs55872725 were checked for their presence or absence in this group of the adult Indian population.

RESULTS

No mutations were found in the exonic sequence of FTO, however, the association of rs1420185, rs8050136, rs1121980 and rs55872725 SNPs was identified in this population. The genotypic frequency at FTO rs8050136 was 32.2% for C>A, at rs55872725 it was 45.7% for C>T, at rs1420185 it was 27.1% for T>C and at rs1121980 it was 30.5% for G>A. All four SNPs in combination were observed in 6 participants (10.2%), all of whom were found to be either obese or overweight.

CONCLUSION

These findings indicate that Indians with these SNPs are most likely to be at increased risk of obesity.

Novel positioning from obesity to cancer: FTO, an m6A RNA demethylase, regulates tumour progression

PURPOSE

The fat mass- and obesity-associated (FTO) gene on chromosome 16q12.2 shows an intimate association with obesity and body mass index. Recently, research into the FTO gene and its expression product has attracted widespread interest due to the identification of FTO as an N6-methyladenosine (m6A) demethylase. FTO primarily regulates the m6A levels of downstream targets via their 3' untranslated regions. FTO not only plays a critical role in obesity-related diseases but also is involved in the occurrence, development and prognosis of many types of cancer, such as acute myeloid leukaemia, glioblastoma and breast cancer. Currently, studies indicate that FTO is a crucial component of m6A modification, it regulates cancer stem cell function, and promotes the growth, self-renewal and metastasis of cancer cells. In this review, we summarized and analysed the data regarding the structural features and biological functions of FTO as well as its association with different cancers and possible molecular mechanisms.

METHODS

We systematically reviewed the related literatures regarding FTO and its demethylation activity in many pathologic and physiological processes, especially in cancer-related diseases based on PubMed databases in this article.

RESULTS

Mounting evidence indicated that FTO plays a critical role in occurrence, progression and treatment of various cancers, even acting as a cancer oncogene in acute myeloid leukaemia, research on which is no longer restricted to metabolic diseases such as obesity and diabetes.

CONCLUSION

Considering FTO's critical role in many diseases, FTO may become a new promising target for the diagnosis and treatment of various diseases in the near future, especially for specific types of cancers, such as acute myeloid leukaemia, glioblastoma and breast cancer.

The Fat Mass- and Obesity-Associated (FTO) Gene to Obesity: Lessons from Mouse Models

OBJECTIVE

Genetic variants at the fat mass- and obesity-associated (FTO) locus are strongly associated with obesity-related traits by regulating neighboring genes. Nevertheless, it is possible that FTO protein is directly involved in mechanisms regulating body composition and adiposity. Here, the in vivo biological functions of FTO in the risk for obesity were studied by reviewing murine models.

METHODS

The effects of the locus-specific manipulations of the murine Fto gene on metabolic-related phenotypes in genetically modified mouse models were reviewed and summarized into the following three categories: growth and body composition, eating behaviors, and metabolic homeostasis.

RESULTS

The mouse models showed different phenotypes depending on target tissues and methods for gene manipulation. Mice harboring deletions or point mutations at the Fto locus had high metabolic rates, while FTO-overexpressing mice showed dyslipidemia. Both deletion and overexpression of the Fto gene led to abnormal eating behaviors. Intriguingly, several phenotypes were differently expressed depending on developmental timing of the genetic manipulations. For instance, a germ line deletion decreased total body fat mass, while the deletion in adult mice increased it.

CONCLUSIONS

The results highlight that FTO is critical not only for body composition but also normal development, and its function might differ depending on the stage of development.

The FTO rs9939609 "A" allele is associated with impaired fasting glucose and insulin resistance in Emirati population

BACKGROUND

Fat mass and obesity-associated protein gene variants have shown diverse influence on body weight and metabolism across different populations. Overweight, obesity and metabolic syndrome are multifactorial major health problems in the UAE and worldwide. Insulin resistance represents the link between overweight and development of metabolic syndrome and type 2 diabetes mellitus. We investigated two (FTO) variants in Emirati population, in relation to insulin resistance and different parameters of metabolic syndrome.

METHODS

We recruited 259 Emiratis through the UAE National Diabetes and Lifestyle Project. Ethical approval was obtained. Besides basic data collection, venous blood samples were collected. Fasting blood glucose, Lipid profile, and insulin levels were measured. Genotyping for (FTO) rs9939609 (A>T) and rs9930506 (G>A) were performed using real time-PCR. Insulin resistance were identified using HOMA2-IR calculation; with a cut-off point of 1.4 for female and 1.18 for male subjects.

RESULTS

The study included 259 Emiratis (age range 30-53 years, mean 41.76 years, 54.4% females), 24.5% are diabetic and 30.8% are hypertensive, with body mass index of 28.4 ± 5.9 and 28.7 ± 5.7 kg/m² in female and male subjects, respectively. Homozygous A of rs9939609 showed significantly higher fasting glucose compared to other genotypes (p = 0.04) with a trend of higher insulin level and HOMA-2IR. The A/A diabetic patients (n = 13) showed significantly higher insulin levels compared to other genotypes. G allele of rs9930506 showed a trend of higher fasting glucose and HOMA-2IR, but lower insulin level and HbA1c. No association of genotypes was detected with other components of metabolic syndrome.

CONCLUSION

There is an association of FTO rs9939609 A/A genotype and impaired fasting glucose and insulin resistance. Homozygous A genotype diabetic patients may be more vulnerable to blood glucose fluctuation. Focused genotyping can help the health care providers to identify high risk groups of both normal population and diabetic patients to intervene accordingly.

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.

Association of fat mass and obesity-associated and retinitis pigmentosa guanosine triphosphatase (GTPase) regulator-interacting protein-1 like polymorphisms with body mass index in Chinese women

Body mass index (BMI) is the most commonly used quantitative measure of adiposity. It is a kind of complex genetic diseases which are caused by multiple susceptibility genes. The first intron of fat mass and obesity-associated (FTO) has been widely discovered to be associated with BMI. Retinitis pigmentosa GTPase regulator-interacting protein-1 like (RPGRIP1L) is located in the upstream region of FTO and has been proved to be linked with obesity through functional tests. We carried out a genetic association analysis to figure out the role of the FTO gene and the RPGRIP1L gene in BMI. A quantitative traits study with 6,102 Chinese female samples, adjusted for age, was performed during our project. Among the twelve SNPs, rs1421085, rs1558902, rs17817449, rs8050136, rs9939609, rs7202296, rs56137030, rs9930506 and rs12149832 in the FTO gene were significantly associated with BMI after Bonferroni correction. Meanwhile, rs9934800 in the RPGRIP1L gene showed significance with BMI before Bonferroni correction, but this association was eliminated after Bonferroni correction. Our results suggested that genetic variants in the FTO gene were strongly associated with BMI in Chinese women, which may serve as targets of pharmaceutical research and development concerning BMI. Meanwhile, we didn't found the significant association between RPGRIP1L and BMI in Chinese women.

Japanese GWAS identifies variants for bust-size, dysmenorrhea, and menstrual fever that are eQTLs for relevant protein-coding or long non-coding RNAs

Traits related to primary and secondary sexual characteristics greatly impact females during puberty and day-to-day adult life. Therefore, we performed a GWAS analysis of 11,348 Japanese female volunteers and 22 gynecology-related phenotypic variables, and identified significant associations for bust-size, menstrual pain (dysmenorrhea) severity, and menstrual fever. Bust-size analysis identified significant association signals in CCDC170-ESR1 (rs6557160; P = 1.7 × 10-16) and KCNU1-ZNF703 (rs146992477; P = 6.2 × 10-9) and found that one-third of known European-ancestry associations were also present in Japanese. eQTL data points to CCDC170 and ZNF703 as those signals' functional targets. For menstrual fever, we identified a novel association in OPRM1 (rs17181171; P = 2.0 × 10-8), for which top variants were eQTLs in multiple tissues. A known dysmenorrhea signal near NGF replicated in our data (rs12030576; P = 1.1 × 10-19) and was associated with RP4-663N10.1 expression, a putative lncRNA enhancer of NGF, while a novel dysmenorrhea signal in the IL1 locus (rs80111889; P = 1.9 × 10-16) contained SNPs previously associated with endometriosis, and GWAS SNPs were most significantly associated with IL1A expression. By combining regional imputation with colocalization analysis of GWAS/eQTL signals along with integrated annotation with epigenomic data, this study further refines the sets of candidate causal variants and target genes for these known and novel gynecology-related trait loci.

FTO promotes SREBP1c maturation and enhances CIDEC transcription during lipid accumulation in HepG2 cells

The fat mass and obesity-associated (FTO) gene is tightly related to body weight and fat mass, and plays a pivotal role in regulating lipid accumulation in hepatocytes. However, the mechanisms underlying its function are poorly understood. Sterol regulatory element binding protein-1c (SREBP1c) is a transcription factor that regulates lipogenesis. Cell death-inducing DFFA (DNA fragmentation factor-α)-like effector c (CIDEC) plays a crucial role in lipid droplets (LDs) size controlling and lipid accumulation. In this report, we first observed that FTO overexpression in HepG2 cells resulted in an increase of lipogenesis and up-regulation of SREBP1c and CIDEC, two key regulatory factors in lipogenesis. In contrast, FTO knockdown in HepG2 cells resulted in a decrease of lipogenesis and down-regulation of SREBP1c and CIDEC expression. Moreover, SREBP1c knockdown resulted in a decrease of lipogenesis in HepG2 cells with FTO overexpression. In addition, FTO demethylation defect mutant presented less transcription of the key genes, and less nuclear translocation and maturation of SREBP1c. Further investigation demonstrated that overexpression of SREBP1c in HepG2 cells also promoted high CIDEC expression. Luciferase reporter assays showed that SREBP1c significantly stimulated CIDEC gene promoter activity. Finally, CIDEC knockdown reduced SREBP1c-induced lipogenesis. In conclusion, our studies suggest that FTO increased the lipid accumulation in hepatocytes by increasing nuclear translocation of SREBP1c and SREBP1c maturation, thus improving the transcriptional activity of LD-associated protein CIDEC. Our studies may provide new mechanistic insight into nonalcoholic fatty liver disease (NAFLD) mediated by FTO.

A haplotype of three SNPs in FTO had a strong association with body composition and BMI in Iranian male adolescents

Background

Single-nucleotide polymorphisms (SNPs), which are located in the first intron of the FTO gene, are reported to be associated with body weight and the body mass index (BMI). However, their effects on anthropometric measurements in adolescents are poorly understood.

Objective

This study aimed to investigate the association of three adjacent polymorphisms (rs9930506, rs9930501, & rs9932754) in the FTO gene with anthropometric indices in Iranian adolescent males.

Design

The participants comprised a total of 237 adolescent males who were recruited randomly from two high schools in Tehran, Iran. The DNA samples were genotyped for the FTO gene polymorphisms by DNA sequencing. BMI, body fat percentage (BF%), and body muscle percentage (BM%) were determined using a validated bioelectrical impedance analysis scale. The association of the FTO polymorphisms with weight, height, BMI, BF%, and BM% was investigated.

Results

A haplotype of rs9930506, rs9930501, and rs9932754 (GGT) in the first intron of the FTO with complete linkage disequilibrium (LD) was found to be significantly associated with higher weight (OR = 1.32), BMI (OR = 5.36) and BF% (OR = 1.46), and lower BM% (OR = 3.59) (all P<0.001). None of the students with GGC genotypes were underweight, while all of the students with AAT genotypes had high muscle mass.

Conclusions

A haplotype in the first intron of the FTO gene had a strong association with obesity indices in Iranian adolescent males. The FTO gene polymorphisms might have greater effects on anthropometric indices than what was previously imagined. Moreover, we suggested that the FTO gene exerted their effects on anthropometric measurements through haplotypes (and not single SNPs).

Association of the FTO fat mass and obesity-associated gene rs9939609 polymorphism with rewarding value of food and eating behavior in Chilean children

OBJECTIVES

The aim of this study was to assess the association between the single-nucleotide polymorphism rs9939609 in the FTO gene and homeostatic/non-homeostatic eating behavior patterns in Chilean children.

METHODS

A cross-sectional study was conducted in 258 children (44% female; 8-14 y of age). Anthropometric measurements (weight, height, Z-score of height, body mass index, and waist circumference) were performed. Eating behavior was assessed using the Eating in Absence of Hunger Questionnaire; the Child Eating Behavior Questionnaire; the Three Factor Eating Questionnaire, and the Food Reinforcement Value Questionnaire. Genotype of rs9939609 was determined by a Taqman assay. Association of rs9939609 with eating behavior was assessed using non-parametric tests.

RESULTS

Allelic frequencies of rs9939609 were estimated as 77% for the A allele and 23% for the T allele. We found that normal-weight girl A carriers had higher scores of Satiety Responsiveness and Slowness on the Eating subscale. Normal-weight boy A carriers showed significantly higher scores on the Negative Affect and lower scores of the Desire to Drink subscale. In overweight children, A carriers showed higher scores on the Food Responsiveness, Emotional Overeating, Enjoyment of Food, and Food Choice subscales and lower scores on the Satiety- Responsiveness and Slowness in Eating subscales. In obese children, we found higher scores on the Cognitive Restrained subscale and lower Food Choice.

CONCLUSION

The rs9939609 A allele of the FTO gene is associated with eating behavior traits and may predispose to obesity.

Familial aggregation and linkage analysis with covariates for metabolic syndrome risk factors

BACKGROUND

Mechanisms of metabolic syndrome (MetS) causation are complex, genetic and environmental factors are important factors for the pathogenesis of MetS In this study, we aimed to evaluate familial and genetic influences on metabolic syndrome risk factor and also assess association between FTO (rs1558902 and rs7202116) and CETP(rs1864163) genes' single nucleotide polymorphisms (SNP) with low HDL_C in the Tehran Lipid and Glucose Study (TLGS).

MATERIALS AND METHODS

The design was a cross-sectional study of 1776 members of 227 randomly-ascertained families. Selected families contained at least one affected metabolic syndrome and at least two members of the family had suffered a loss of HDL_C according to ATP III criteria. In this study, after confirming the familial aggregation with intra-trait correlation coefficients (ICC) of Metabolic syndrome (MetS) and the quantitative lipid traits, the genetic linkage analysis of HDL_C was performed using conditional logistic method with adjusted sex and age.

RESULTS

The results of the aggregation analysis revealed a higher correlation between siblings than between parent-offspring pairs representing the role of genetic factors in MetS. In addition, the conditional logistic model with covariates showed that the linkage results between HDL_C and three marker, rs1558902, rs7202116 and rs1864163 were significant.

CONCLUSIONS

In summary, a high risk of MetS was found in siblings confirming the genetic influences of metabolic syndrome risk factor. Moreover, the power to detect linkage increases in the one parameter conditional logistic model regarding the use of age and sex as covariates.

FTO genotype, dietary protein intake, and body weight in a multiethnic population of young adults: a cross-sectional study

BACKGROUND

Variation in the fat mass and obesity-associated gene (FTO) has been associated with susceptibility to obesity, but the association appears to be modified by diet. We investigated whether dietary protein intake modifies the association between FTO variant rs1558902 and body mass index (BMI) and waist circumference in young adults (n = 1491) from the cross-sectional Toronto Nutrigenomics and Health Study.

RESULTS

Lifestyle, genetic, anthropometric, and biochemical data were collected and diet was assessed using a Toronto-modified Willett Food Frequency Questionnaire. General linear models stratified by ethnicity and adjusted for age, sex, and total energy intake were used to examine the association between FTO genotypes and measures of body weight, and whether protein intake modified any of the associations. East Asians who were homozygous for the rs1558902 risk allele (A) had a greater BMI (p = 0.004) and waist circumference (p = 0.03) than T allele carriers. This association was not observed in individuals of Caucasian or South Asian ancestry. Among East Asians, a significant FTO-protein interaction was observed for BMI (p = 0.01) and waist circumference (p = 0.007). Those with low protein intake (≤ 18% total energy intake) who were homozygous for the rs1558902 risk allele (A) had significantly higher BMI (p <  0.0001) and waist circumference (p = 0.0006) compared to carriers of the T allele. These associations were absent in the high protein intake group (> 18% total energy intake). Compared to Caucasians and South Asians, East Asians consumed a significantly higher ratio of animal-to-plant protein (p <  0.05).

CONCLUSIONS

These findings suggest that high dietary protein intake may protect against the effects of risk variants in the FTO gene on BMI and waist circumference.

Effect of Obesity-Linked FTO rs9939609 Variant on Physical Activity and Dietary Patterns in Physically Active Men and Women

Single nucleotide polymorphisms (SNPs) in the fat mass and obesity-associated (FTO) locus are associated with obesity, but lifestyle factors may modulate the obesity risk related to FTO. This study examined the physical activity and dietary patterns of 528 physically active white men and women (mean (SD): 34.9 (9.5) years, 26.6 (4.3) kg·m^-2) carrying different risk variants of FTO SNP rs9939609. Sex, age, and anthropometric measurements (stature, body mass, and waist circumference) were self-reported using an online questionnaire, and body mass index and waist-to-height ratio were calculated. Physical activity and eating behaviour were assessed using the International Physical Activity Questionnaire (IPAQ) and Three-Factor Eating Questionnaire (TFEQ), respectively. Body mass, body mass index (BMI), waist circumference, and waist-to-height ratio were not significantly different between individuals expressing different FTO rs9939609 risk variants (all P ≥ 0.66). The cohort was physically active (4516 (3043) total MET min·week^-1), although homozygous risk allele carriers (AA) displayed higher TFEQ cognitive restraint compared with nonrisk allele carriers (TT) (ES = 0.33 and P=0.03). In conclusion, obesity-related parameters were not different in physically active individuals expressing different risk variants of FTO rs9939609, although homozygous risk allele carriers exhibited higher cognitive restraint.

Association between FTO gene polymorphisms and type 2 diabetes mellitus, serum levels of apelin and androgen hormones among Iranian obese women

BACKGROUND AND AIMS

Recent studies show that FTO single nucleotide polymorphisms (SNPs) are associated with obesity and type 2 diabetes mellitus (T2DM). On the other hand, many animal models and clinical studies have demonstrated that apelin, an adipocytokine, is related to the obesity and T2DM. Additionally, obese women are at risk of Hyperandrogenemia. So, the aim of this study was to investigate the relationship between FTO variants (rs763967273, rs759031579, rs141115189, rs9926289, rs76804286 and rs9939609) with T2DM, serum apelin and androgenic hormones in Iranian obese women.

SUBJECTS AND METHODS

197 obese women (123 women with T2DM and 74 women as healthy control) were participated in this study. Anthropometrical and biochemical characteristics were measured. Serum apelin and androgen hormones levels were determined in 66 subjects consisting of 33 cases and 33 controls. PCR were carried out and subsequently, the PCR production was genotyped by Sanger sequencing assay.

RESULTS

Our observations showed that all SNPs are related to T2DM. The rs9926289 FTO variant had a strong association with serum apelin and dehydroepiandrosterone-sulfate levels (P=0.04 and P=0.03, respectively) among SNPs. In addition, apelin and androgenic hormones were correlated with T2DM. Two polymorphisms including rs9939609 and rs9926289 had a strong Linkage disequilibrium (r²=1).

CONCLUSION

FTO variants not only were associated with T2DM, but also some variants had a strong association with apelin and androgenic hormones profile.

The (FTO) gene polymorphism is associated with metabolic syndrome risk in Egyptian females: a case- control study

Background

Variations within fat mass and obesity associated (FTO) gene had crosstalk with obesity risk in European and some Asian populations. This study was designed to investigate FTO rs9939609 association with metabolic syndrome (MetS) as well as biochemical parameters as plasma glucose, serum triacylglycerol (TAG), total cholesterol (TC) and transaminases enzymes in Arab female population from Egypt.

Methods

In order to achieve that, FTO gene rs9939609 (A < T) was genotyped using TaqMan SNP Genotyping Assay in a total of 197 females which were enrolled in this study. Fasting levels of serum insulin, lipid profile and plasma glucose, in addition to liver transaminases were measured. The association between the genotype distribution and MetS risk was evaluated using Chi-square and logistic regression tests in a case-control design under different genetic models.

Results

The association of genotype distribution with MetS was significant (χ2 = 8.6/P = 0.014) with an increased odds ratio under dominant model (OR = 1.97, P = 0.029 and 95%C.I = 1.07–3.6) and recessive model (OR = 2.95, P = 0.017 and 95%C.I = 1.22–7.22). Moreover, (AA) subjects showed significant lower HDL-C levels (P = 0.009) when compared to (TT) ones. In addition, interestingly subjects with (AA) genotype have significantly higher ALT levels (P = 0.02) that remained significant after correction of major confounders as body mass index and serum triacylglycerols but not after conservative Bonferroni adjustment.

Conclusions

The present study shows for first time that FTO gene rs9939609 is genetic risk factor for metabolic syndrome in Egyptian population which may help in understanding the biology of this complex syndrome and highlighted that this association may be through HDL-C component. The association of this genetic polymorphism with ALT levels needs to be studied in other populations with larger sample size.

Genetic association of FTO/IRX region with obesity and overweight in the Polish population

Background/Objectives

Genome-wide association studies (GWAS) have identified many loci associated with body mass index (BMI) in many different populations. Variants in the FTO locus are reported to be one of the strongest genetic predictors of obesity. Recent publications pointed also to a topologically associated domain (TAD) which is identified as a novel region affecting BMI. The TAD area encompasses the IRXB cluster (IRX3, IRX5, IRX6), FTO and RPGRIP1L genes.

Subjects/Methods

In this study, we investigated the relationship between variation of the FTO and IRX genes and obesity in Poles. We presented a case—control association analysis (normal versus overweight and/or obesity group) of Polish adult individuals (N = 5418). We determined whether or not the chromosomal region 16:53 500 000–55 500 000 contains polymorphic variants which are correlated with BMI in Polish population, including sex and age stratified analysis.

Results

The obtained results showed that the problem of weight-height abnormalities differently affects populations of Polish women and men (χ² = 187.1; p<0.0001). From 353 SNPs enrolled to this study, 86 were statistically significant (highest χ² = 15.72; p = 7.35E-05 observed for rs1558902). Linkage disequilibrium (LD) analysis revealed 61 blocks in the tested region of chromosome 16, with 24 SNPs located within the same block (block 8) of approximately 40 kb, in almost complete LD (|D’|>0.98, r²>0.80). We confirmed presence of the genetic susceptibility loci located in intron 1 of the FTO gene, which were correlated with BMI in our study group. For the first time, our analyses revealed strong association of FTO intronic variants (block 8) with overweight in group of men only. We have also identified association of the IRX region with overweight and/or obesity in Polish individuals.

Conclusion

Our study demonstrated how tested SNPs make differential contributions to obesity and overweight risk. We revealed sex dependent differences in the distribution of tested loci which are associated with BMI in the population of Poles.