Influence of FTO variants on obesity, inflammation and cardiovascular disease risk biomarkers in Spanish children: a case-control multicentre study

Genetic Variants in the Fat Mass and Obesity-Associated Gene and Risk of Obesity/Overweight in Children and Adolescents: A Systematic Review and Meta-Analysis

OBJECTIVE

The variations in the single-nucleotide polymorphisms (SNPs) of the fat mass and obesity (FTO)-associated gene have been linked to being overweight or obese in children. In this research a thorough examination was performed to elucidate the connection between various FTO gene SNPs and overweight or obesity in children and adolescents.

METHOD

We searched PubMed, Google scholar, Web of Science and Scopus until January 2024 to find studies that investigate the association between different SNPs of FTO gene and the risk of overweight/obesity in children and adolescents. After filtering the relevant studies, meta-analysis was used to quantify the association of FTO gene SNPs within different genetic inheritance models.

RESULTS

We have identified 32 eligible studies with 14,930 obese/overweight cases and 24,765 healthy controls. Our recessive model showed a significant association with rs9939609 (OR: 1.56, 95% CI: 1.20; 2.02, p < 0.01) and rs1421085 (OR: 1.77, 95% CI: 1.14; 2.75, p < 0.01). Besides, in the homozygote model, rs1421085 showed the highest association (OR: 2.32, 95% CI: 1.38; 3.89, p < 0.01) with the risk of obesity in a population of children and adolescents. Moreover, there are other SNPs of FTO genes, such as rs9921255, rs9928094 and rs9930333, which showed a positive association with obesity and overweight. However, their effects were evaluated in very few numbers of studies.

CONCLUSION

In this study, we have found that the FTO rs9939609 and rs1421085 are associated to an increased risk of obesity among children and adolescents. Besides, the findings of this study further reaffirmed the established link between rs9939609 and obesity in children and adolescents.

N6-methyladenosine modification in ischemic stroke: Functions, regulation, and therapeutic potential

N6-methyladenosine (m6A) modification is the most frequently occurring internal modification in eukaryotic RNAs. By modulating various aspects of the RNA life cycle, it has been implicated in a wide range of pathological and physiological processes associated with human diseases. Ischemic stroke is a major cause of death and disability worldwide with few treatment options and a narrow therapeutic window, and accumulating evidence has indicated the involvement of m6A modifications in the development and progression of this type of stroke. In this review, which provides insights for the prevention and clinical treatment of stroke, we present an overview of the roles played by m6A modification in ischemic stroke from three main perspectives: (1) the association of m6A modification with established risk factors for stroke, including hypertension, diabetes mellitus, hyperlipidemia, obesity, and heart disease; (2) the roles of m6A modification regulators and their functional regulation in the pathophysiological injury mechanisms of stroke, namely oxidative stress, mitochondrial dysfunction, endothelial dysfunction, neuroinflammation, and cell death processes; and (3) the diagnostic and therapeutic potential of m6A regulators in the treatment of stroke.

Interaction of common variants of FTO gene and Dietary Inflammatory Index on obesity measures: Tehran Lipid and Glucose Study

Background

This study aimed to examine the interaction of Dietary Inflammatory Index (DII) and fat mass and obesity-associated gene (FTO) single-nucleotide polymorphisms (SNPs) on change in obesity measures.

Methods

A total of 4480 participants from the Tehran Lipid and Glucose Study were selected. DII was calculated using a Food Frequency Questionnaire. The FTO SNPs rs8050136, rs14211085 and rs1121980 were selected. Changes in obesity measures were calculated.

Results

In individuals with risk allele of FTO SNP rs8050136, greater adherence to DII was associated with increased odds of higher waist circumference (WC) (OR, Q1-Q4: 1, 0.87, 0.88, 0.94; P trend=0.01), but deceased odds of waist to hip ratio (WHR) (OR, Q1-Q4: 1, 0.85, 0.76, 0.70; P trend=0.01). Moreover, higher score of DII was significantly related to elevated odds of having high Visceral Adiposity Index (VAI) in individuals with wild-type genotype of FTO SNPs. For changes in WC, a significant interaction was identified between FTO rs1421085 and DII; the second quartile of DII was associated with increased odds of having a high WC in carriers of wild variant (TT genotype) of rs1421085 (OR 1.43; 95% CI 1.04 to 1.97), but not in individuals with risk allele of this SNP (TC CC). Although there are significant relationships between SNPs or genetic risk score and change in WHR or VAI, but there is no significant interaction between FTO SNPs and DII regarding change in body mass index, WHR and VAI.

Conclusions

There may be an interactive effect between DII and the FTO rs1421085 genotypes on change in WC.

RNA modification: mechanisms and therapeutic targets

RNA modifications are dynamic and reversible chemical modifications on substrate RNA that are regulated by specific modifying enzymes. They play important roles in the regulation of many biological processes in various diseases, such as the development of cancer and other diseases. With the help of advanced sequencing technologies, the role of RNA modifications has caught increasing attention in human diseases in scientific research. In this review, we briefly summarized the basic mechanisms of several common RNA modifications, including m6A, m5C, m1A, m7G, Ψ, A-to-I editing and ac4C. Importantly, we discussed their potential functions in human diseases, including cancer, neurological disorders, cardiovascular diseases, metabolic diseases, genetic and developmental diseases, as well as immune disorders. Through the "writing-erasing-reading" mechanisms, RNA modifications regulate the stability, translation, and localization of pivotal disease-related mRNAs to manipulate disease development. Moreover, we also highlighted in this review all currently available RNA-modifier-targeting small molecular inhibitors or activators, most of which are designed against m6A-related enzymes, such as METTL3, FTO and ALKBH5. This review provides clues for potential clinical therapy as well as future study directions in the RNA modification field. More in-depth studies on RNA modifications, their roles in human diseases and further development of their inhibitors or activators are needed for a thorough understanding of epitranscriptomics as well as diagnosis, treatment, and prognosis of human diseases.

Polymorphisms of Fat Mass and Obesity-Associated Gene in the Pathogenesis of Child and Adolescent Metabolic Syndrome

Childhood metabolic syndrome (MetS) is prevalent around the world and is associated with a high likelihood of suffering from severe diseases such as cardiovascular disease later in adulthood. MetS is associated with genetic susceptibility that involves gene polymorphisms. The fat mass and obesity-associated gene (FTO) encodes an RNA N6-methyladenosine demethylase that regulates RNA stability and molecular functions. Human FTO contains genetic variants that significantly contribute to the early onset of MetS in children and adolescents. Emerging evidence has also uncovered that FTO polymorphisms in intron 1, such as rs9939609 and rs9930506 polymorphisms, are significantly associated with the development of MetS in children and adolescents. Mechanistic studies reported that FTO polymorphisms lead to aberrant expressions of FTO and the adjacent genes that promote adipogenesis and appetite and reduce steatolysis, satiety, and energy expenditure in the carriers. The present review highlights the recent observations on the key FTO polymorphisms that are associated with child and adolescent MetS with an exploration of the molecular mechanisms underlying the development of increased waist circumference, hypertension, and hyperlipidemia in child and adolescent MetS.

The association between variant rs9939609 in the FTO gene with free leptin index and the risk of obesity in the Indonesian children population

Background

Several studies have reported that fat mass and obesity-associated gene (FTO), especially the rs9939609 polymorphism, are associated with obesity and high leptin levels. The free leptin index (FLI) is known to be accurate in determining the function of leptin. The aim of this study was to determine the association between the rs9939609 variant in the FTO gene and FLI and the risk of obesity among children living in Medan, Indonesia.

Methods

This case–control study included 212 children aged 6–12 years who were genotyped for variants of the rs9939609 FTO gene. The case group consisted of children with obesity who were < 6 years old, and the control group had a normal body mass index and came from the Bataknese or Chinese ethnicities. Anthropometric measurements were performed. Serum leptin and soluble leptin receptor (sOB-R) levels were measured. Odds ratio and 95% confidence intervals were calculated to determine the risk of having obesity associated with the risk allele.

Results

In this study, there was no significant association between leptin, soluble leptin receptor, or free leptin index and the rs9939609 FTO gene; however, the risk allele (A) of FTO rs9939609 had a significant association with obesity in Chinese ethnicity subjects (p < 0.05). The AA/AT genotype had an increased risk of FLI 5.889 times compared to the TT genotype. Multivariate analysis showed that the rs9939609 polymorphism in the FTO gene played a role in obesity through the FLI.

Conclusion

It was concluded that the rs9939609 polymorphism played a significant role in obesity through FLI. Further studies are still needed.

Targeted metabolomics suggests a probable role of the FTO gene in the kynurenine pathway in prediabetes

Background

Genome-wide association studies have identified the alpha-ketoglutarate dependent dioxygenase gene (FTO) as the first susceptibility gene of obesity. In the present study, we utilized targeted metabolomics in an attempt to further elucidate mechanisms underlying the action of the FTO gene.

Methods

This study was part of a health survey of employees of the Electricity Generating Authority of Thailand (n = 79, 10 female and 69 male). Targeted metabolomics was performed by liquid chromatography-mass spectrometry using Biocrates AbsoluteIDQ-p180 kit. Genotyping of FTO rs9939609 was performed by real-time PCR (TaqMan™ MGB probes).

Results

Using OPLS-DA variable importance in projection (VIP), tryptophan was found to be among the metabolites with the 10 highest VIP scores. Pearson's correlation analysis showed that kynurenine and tryptophan were positively correlated only in subjects with the rs9939609 A allele (n = 32, r = 0.56, p < 0.001) and the correlation coefficients were significantly higher in subjects having the A allele than in those without the A allele (p < 0.05). Moreover, the kynurenine/tryptophan ratio was significantly associated with the presence of the A allele, independently of body mass index and sex.

Conclusions

The FTO gene is likely to influences the conversion of tryptophan to kynurenine.

Genetic variation in satiety signaling and hypothalamic inflammation: merging fields for the study of obesity

Although obesity has been a longstanding health crisis, the genetic architecture of the disease remains poorly understood. Genome-wide association studies have identified many genomic loci associated with obesity, with genes being enriched in the brain, particularly in the hypothalamus. This points to the role of the central nervous system (CNS) in predisposition to obesity, and we emphasize here several key genes along the satiety signaling pathway involved in genetic susceptibility. Interest has also risen regarding the chronic, low-grade obesity-associated inflammation, with a growing concern toward inflammation in the hypothalamus as a precursor to obesity. Recent studies have found that genetic variation in inflammatory genes play a role in obesity susceptibility, and we highlight here several key genes. Despite the interest in the genetic variants of these pathways individually, there is a lack of research that investigates the relationship between the two. Understanding the interplay between genetic variation in obesity genes enriched in the CNS and inflammation genes will advance our understanding of obesity etiology and heterogeneity, improve genetic risk prediction analyses, and highlight new drug targets for the treatment of obesity. Additionally, this increased knowledge will assist in physician's ability to develop personalized nutrition and medication strategies for combating the obesity epidemic. Though it often seems to present universally, obesity is a highly individual disease, and there remains a need in the field to develop methods to treat at the individual level.

Novel methylation mark and essential hypertension

Background

Essential hypertension (EH) is an important risk factor for various cardiovascular, cerebral and renal disorders. It is a multi-factorial trait which occurs through complex interplay between genetic, epigenetic, and environmental factors. Even after advancement of technology and deciphering the involvement of multiple signalling pathways in blood pressure regulation, it still remains as a huge global concern.

Main body of the abstract

Genome-wide association studies (GWAS) have revealed EH-associated genetic variants but these solely cannot explain the variability in blood pressure indicating the involvement of additional factors. The etiopathogenesis of hypertension has now advanced to the level of epigenomics where aberrant DNA methylation is the most defined epigenetic mechanism to be involved in gene regulation. Though role of DNA methylation in cancer and other mechanisms is deeply studied but this mechanism is in infancy in relation to hypertension. Generally, 5-methylcytosine (5mC) levels are being targeted at both individual gene and global level to find association with the disease. But recently, with advanced sequencing techniques another methylation mark, N6-methyladenine (6mA) was found and studied in humans which was earlier considered to be absent in case of eukaryotes. Relation of aberrant 6mA levels with cancer and stem cell fate has drawn attention to target 6mA levels with hypertension too.

Conclusion

Recent studies targeting hypertension has suggested 6mA levels as novel marker and its demethylase, ALKBH1 as probable therapeutic target to prevent hypertension through epigenetic programming. This review compiles different methylation studies and suggests targeting of both 5mC and 6mA levels to cover role of methylation in hypertension in broader scenario.

FTO Suppresses STAT3 Activation and Modulates Proinflammatory Interferon-Stimulated Gene Expression

Signaling initiated by type I interferon (IFN) results in the induction of hundreds of IFN-stimulated genes (ISGs). The type I IFN response is important for antiviral restriction, but aberrant activation of this response can lead to inflammation and autoimmunity. Regulation of this response is incompletely understood. We previously reported that the mRNA modification m⁶A and its deposition enzymes, METTL3 and METTL14 (METTL3/14), promote the type I IFN response by directly modifying the mRNA of a subset of ISGs to enhance their translation. Here, we determined the role of the RNA demethylase fat mass and obesity-associated protein (FTO) in the type I IFN response. FTO, which can remove either m⁶A or cap-adjacent m⁶Am RNA modifications, has previously been associated with obesity and body mass index, type 2 diabetes, cardiovascular disease, and inflammation. We found that FTO suppresses the transcription of a distinct set of ISGs, including many known pro-inflammatory genes, and that this regulation requires its catalytic activity but is not through the actions of FTO on m⁶Am. Interestingly, depletion of FTO led to activation of the transcription factor STAT3, whose role in the type I IFN response is not well understood. This activation of STAT3 increased the expression of a subset of ISGs. Importantly, this increased ISG induction resulting from FTO depletion was partially ablated by depletion of STAT3. Together, these results reveal that FTO negatively regulates STAT3-mediated signaling that induces proinflammatory ISGs during the IFN response, highlighting an important role for FTO in suppression of inflammatory genes.

Evidence from a meta-analysis for association of MC4R rs17782313 and FTO rs9939609 polymorphisms with susceptibility to obesity in children

BACKGROUND AND AIM

The aim of this study was to evaluate the association of MC4R rs17782313 and FTO rs9939609 polymorphisms with childhood obesity.

METHODS

A universal search was performed up to May 2021.

RESULTS

A total of 31 studies including 13 studies with 9565 cases and 11956 controls on MC4R rs17782313 and 18 studies with 4789 cases and 15918 controls on FTO rs9939609 were selected.

CONCLUSIONS

Pooled data showed that FTO rs9930506 and MC4R rs17782313 polymorphisms were significantly associated with obesity in children. Stratified analyses revealed that these genetic variants were associated with childhood obesity in Caucasian and Asian children.

Association of Diet, Physical Activity Guidelines and Cardiometabolic Risk Markers in Children

The aim was to identify different dietary and physical activity (PA) patterns in 5- to 14-year-old children with a high prevalence of overweight and obesity using cluster analysis based on their adherence to the Spanish Society of Community Nutrition dietary guidelines and levels of PA, and to determine their associations with age, sex, body composition, and cardiometabolic risk markers. In 549 children, hierarchical cluster analysis was used to identify subgroups with similar adherence to dietary recommendations and level of PA. Three clusters were identified: Cluster 1, with the lowest level of vigorous PA and adherence to dietary recommendations; Cluster 2, with the lowest levels of moderate and vigorous PA and the highest adherence to dietary recommendations; and Cluster 3, with the highest level of PA, especially vigorous PA and a medium level adherence to dietary recommendations. Cluster 3 had lower total body fat and higher lean body mass percentages than Cluster 2. Cluster 2 had lower high-density lipoprotein cholesterol and higher low-density lipoprotein cholesterol levels than Cluster 1. The results from our study suggest that it is important to consider adherence to PA recommendations together with adherence to dietary guidelines to understand patterns of obesogenic habits in pediatric populations with high prevalence of overweight and obesity.

Relationship of FTO gene variations with NAFLD risk in Chinese men

Background

Fat mass and obesity-associated (FTO) gene is an obesity susceptibility gene and its relationship with the nonalcoholic fatty liver disease (NAFLD) remains unclear. This study aims to investigate the relationships of FTO gene variations with NAFLD risk in a Chinese male population.

Methods

A 1:2 matched case–control study was performed on 275 cases of NAFLD and 550 controls matched for age. Nine of the FTO gene single nucleotide polymorphisms (SNPs) were genotyped.

Results

Logistic regression analysis found that FTO rs1477196 was significantly associated with the susceptibility to NAFLD in recessive genetic models [unadjusted odds ratio (OR) = 2.52, 95% confidence interval (CI): 1.22–5.19, P = 0.012] and the relativity weakened after further adjustment for body mass index (BMI), uric acid, metabolic syndrome, smoking, and drinking (adjusted OR = 2.18, 95% CI: 0.96–4.99, P = 0.06). In the obese group, the AA + AG genotypes of rs1121980 and rs9940128 were associated with a decreased risk of NAFLD, when compared with the GG genotype, respectively (rs1121980: adjusted OR = 0.62, 95% CI = 0.39–0.99, P = 0.044; rs9940128: adjusted OR = 0.61, 95% CI = 0.38–0.97, P = 0.038). Furthermore, rs1477196 was associated with the severity of NAFLD (OR = 2.95, 95% CI = 1.09–7.94, P = 0.034).

Conclusions

Our results demonstrated that the FTO gene was related to the presence and severity of NAFLD in a Chinese male population, and the relationships of the tested SNPs with NAFLD are most probably mediated by BMI.

Adiponectin is Increased in Pediatric Patients With Autoimmune Hepatitis Independent of Body Weight

OBJECTIVE

A high prevalence of obesity is reported in children and adolescents with autoimmune hepatitis (AIH). Adipokines participate in inflammatory processes. The objective of this study was to examine the relationship between excess weight and systemic inflammation, adipokines, and ghrelin in adolescents with AIH.

METHOD

This case-controlled study included 27 adolescents with AIH (13 with excess weight and 14 with normal weight) and a control group. Excess weight was defined by a body mass index/age Z score >+1 standard deviation. Adipokines (adiponectin, leptin, tumor necrosis factor alpha, interleukin 6 [IL-6], and IL-10) and ghrelin were measured with Luminex technology.

RESULTS

Adiponectin (μg/mL) was higher (P < 0.001) in AIH adolescents with and without excess weight (median: 35.0 and 42.1, respectively) than in normal-weight (17.5) and excess-weight (17.0) controls. Leptin was higher (P < 0.001) in excess-weight AIH patients (18.0 ng/mL) and controls (19.8 ng/mL) than in normal-weight AIH (7.7 ng/mL) and control (7.0 ng/mL) adolescents. IL-6 levels were higher in excess-weight (3.8 pg/mL) and normal-weight (3.8 pg/mL) AIH patients than in excess-weight (1.1 pg/mL) and normal-weight (0.5 pg/mL) controls. IL-10 levels were higher (5.2 pg/mL) in normal-weight AIH patients than in excess-weight (1.8 pg/mL) and normal-weight (2.1 pg/mL) controls. Ferritin levels were lower in patients with AIH than in controls.

CONCLUSIONS

Independent of body weight, AIH patients had higher levels of adipokines, especially adiponectin and IL-6. Leptin levels were associated with body weight and were not influenced by AIH. IL-10 levels were associated with lean tissue in AIH.

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.

Age-Period-Cohort Analysis of Abdominal Obesity in Iranian Children and Adolescents: The CASPIAN Study

BACKGROUND

The assessment of the trend of changes in the prevalence of abdominal obesity can provide useful health information.

OBJECTIVES

This study aimed to conduct an age-period-cohort (APC) analysis to provide the trend of the prevalence of abdominal obesity in the Iranian pediatric population through the three temporal dimensions of age, period, and cohort.

METHODS

Data were gathered from a total number of 53,962 Iranian children and adolescents aged 5 to 19 years through four surveys of a national surveillance program (the CASPIAN study) conducted in 2003, 2007, 2011, and 2015. Abdominal obesity was defined as a waist-to-height ratio of ≥ 0.5. The APC analysis was performed using the "apc_ie"command in STATA software.

RESULTS

A significant correlation existed between age, period, and cohort effects and the prevalence of abdominal obesity in children and adolescents. With increasing age, regardless of considerable fluctuations, the prevalence of abdominal obesity followed an overall increasing trend in both genders. The age effect coefficient increased from -2.1 in the age group of 5 - 9 years to 1.1 in the age group of 10 - 14 years and then decreased to 1.0 in the age group of 15 - 19 years among boys; figures followed an increasing trend in girls from -2.2 to 0.8 and 1.5, respectively. As for the period effect, in both boys and girls, the prevalence of abdominal obesity followed an increasing trend when coming from the earlier periods to the recent ones (from -4.6 to 4.0 in boys and from -4.1 to 2.4 in girls). Likewise, this prevalence increased from earlier birth cohorts to the recent ones in both genders.

CONCLUSIONS

The prevalence of abdominal obesity is increasing among Iranian children and adolescents and this rising trend is affected by age, period, and birth cohort effects. The findings of this study emphasize the necessity of implementing comprehensive interventions for tackling the epidemic of childhood obesity.

Genetic variation of FTO: rs1421085 T>C, rs8057044 G>A, rs9939609 T>A, and copy number (CNV) in Mexican Mayan school-aged children with obesity/overweight and with normal weight

OBJECTIVES

Genetic variation of the fat mass and obesity associated gene (FTO) has been identified as a risk factor for obesity and obesity traits. Distribution of FTO single nutleotide polymorphisms (SNPs) rs1421085T>C, rs9939609T>A, rs8057044G>A and copy number variation (CNV) was evaluated in association with childhood obesity or overweight status in children with Mayan ethnicity.

METHODS

We included 318 school-aged children with obesity or overweight status (body mass index [BMI]: >85th percentile) and 303 children with normal weight (BMI: 15th-85th percentile). Genotyping was performed using real-time polymerase chain reaction (RT-PCR) with TaqMan probes. The cross-sectional study was carried out using univariate and multivariate logistic regression models adjusted for gender.

RESULTS

FTO-SNP rs1421085 showed significant differences between children with obesity and children with normal weight for the heterozygous genotype (P = 0.003) and for allele frequencies (P = 0.023). Adjusting by gender, significant differences were found in frequencies of the hetezygous genotype of SNPs rs9939609 (P = 0.023) and rs1421085 (P = 0.003) as well as in allele frequencies (P = 0.042 and P = 0.013, respectively) between girls with obesity and girls without obesity. In contrast, SNP rs8057044 was significantly different only between heterozygous overweight versus normal weight boys (P = 0.035) and for the allele frequency of rs8057044 (P = 0.021). The mean relative CNV was significantly higher in male overweight children than in boys with normal weight (P = 0.000).

CONCLUSIONS

The FTO SNP rs1421085 is a genetic factor associated with obesity in Mayan school-aged children. FTO SNPs rs1421085 and rs9939609 affect genetic susceptibility for obesity only in girls, whereas, SNP rs8057044 and CNV are associated with overweight status only in boys.

The FTO rs9939609 polymorphism and obesity risk in teens: Evidence-based meta-analysis

OBJECTIVE

This meta-analysis aims evaluate the association of the polymorphism rs9939609 of FTO with the risk of obesity among children and adolescents, based on the assessment of four genetic models: codominant, dominant, recessive alleles model.

METHODS

Case-control studies, published between the years 2011-2015, were selected from tree available databases (PubMed, Scopus and Web of Science) and were analysed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. Thirteen studies were included totalling 15,613 participants, divided into 7311 cases and 8302 controls.

RESULTS

The FTO rs9939609 polymorphism was significantly associated with increased risk of obesity in children and adolescents for homozygous genotypes AA and heterozygous AT (TT vs. AT+AA: OR=0.723, 95% CI 0.629 to 0.832; p<0.0001).

CONCLUSION

This meta-analysis shows that the FTO rs9939609 polymorphism in the gene is a risk factor for obesity in children and adolescents with the presence of the A allele, both homozygous genotype AA situation, as heterozygous AT.

Influence of FTO rs9939609 polymorphism on appetite, ghrelin, leptin, IL6, TNFα levels, and food intake of women with morbid obesity

BACKGROUND

The fat mass and obesity-related (FTO) gene has a strong relationship with obesity, extreme obesity and inflammatory state, and may also be associated with food intake regulation.

OBJECTIVE

The aim of the present study was to evaluate the influence of the rs9939609 single-nucleotide polymorphism of the FTO gene on appetite, ghrelin, leptin, interleukin 6 (IL6), tumor necrosis factor α (TNFα) levels and food intake of morbidly obese women.

MATERIALS AND METHODS

The study comprised 70 women, aged between 20 and 48 years, from Rio de Janeiro, Brazil. The participants were selected according to the body mass index between 40 and 60 kg/m². Anthropometric and biochemical data were measured during fasting. Hormones and inflammatory data were measured before and after the participants ate an isocaloric meal. Dietary records were calculated and analyzed using a nutritional assessment program. Visual analog scales were used for behaviors of the sensations of appetite and food preferences. The FTO rs9939609 variant was genotyped using real-time polymerase chain reaction.

RESULTS

Participants with the AA genotype had lower values of ghrelin and IL6 and higher values of leptin than those with TT and TA in the postprandial period. Comparing the plasma concentrations of ghrelin, insulin, IL6 and TNFα intragenotypes, it was observed that those with TT had decreased leptin and increased IL6 at the postprandial period. Subjects with TA showed increased postprandial IL6, and those with AA had decreased postprandial ghrelin. There was no difference in TNFα intra- and intergenotypes. The postprandial sensations of hunger were lower in AA than those with TT. There were differences between genotypes regarding ingested grams of protein by weight, cholesterol, B3, B5, B6 and B12 vitamins, and selenium potassium and sodium minerals.

CONCLUSION

These findings suggest that genetics may exert an influence on physiologic factors and might alter eating behavior.

Analysis of SNPs of MC4R, GNB3 and FTO gene polymorphism in obese Saudi subjects

Background

The goal of this study was to analyze the association between the FTO rs17817449 (G>T), G protein beta3 subunit (GNB3) C825T and Melanocortin 4 receptor (MC4R) A822G single nucleotide polymorphism (SNP) with obesity in Saudi subjects.

Methods

The subjects were divided into 2 groups according to BMI: Obese (BMI> 29.9) and non- obese control (BMI<24.9). Genotyping of the target genes were determined by polymerase chain reaction (PCR) followed by restriction fragment length polymorphism analysis (RFLP).

Results

We demonstrated the association of the FTO genotype TT with increased weight, BMI and leptin levels in both males and females. However, there was no association of genotype TT with fasting blood glucose, triglycerides and cholesterol levels. Regarding GNB3 rs5443 polymorphism, the likelihood of obesity was linked to the TT genotype which was also associated with increased leptin levels. On the other hand, the SNP of MC4R A822G did not exhibit any significant association with obesity among studied subjects and showed only the presence of homozygous AA genotype.

Conclusion

The polymorphism of FTO gene rs17817449 and GNB3 gene rs5443 (C825T) may be a genetic determinant of obesity in Saudi population whereas impact of MC4R Asn274Ser change could not be detected.

Age-Period-Cohort Analysis of Obesity and Overweight in Iranian Children and Adolescents

BACKGROUND

To date, few studies looked upon obesity and overweight in children and adolescents through the 3 different temporal dimensions of age, period, and cohort. The current study aimed at evaluating the trends of these health issues among children under 19 years old using the age-period-cohort (APC) analysis.

METHODS

Data gathered through 5 cross sectional studies including 2 national health surveillance (1990 - 91 and 1999), and 3 CASPIAN surveys (2003, 2009, and 2011). Subjects were classified by their body mass index (BMI) into 3 groups of normal (BMI < 85th percentile), overweight-obese (85th percentile < BMI < 95th percentile), and obese (95th percentile < BMI). Intrinsic estimator method was used to analyze the effects of age, period, and birth cohort on obesity and overweight among the subjects.

RESULTS

A total of 80,698 children and adolescents under 19 years old, including 40,419 (50.09%) males and 40,279 (49.91%) females, were evaluated. The prevalence of obesity decreased progressively by age in males and females with minor discrepancies. It increased from 1990 to 2009 in both genders, but from that point on remained quite constant in males and dropped significantly in females. The prevalence of obesity was steady in earlier birth cohorts, but increased significantly after the birth cohorts from 1986 to 1990.

CONCLUSIONS

Environmental factors and social stresses during neonatal and infantile periods (birth cohort effect) along with other variables influencing the children later in their lives (period effect) affect the prevalence of overweight and obesity substantially. Moreover, a decrease in the prevalence of obesity and overweight was observed by age increase (age effect).

Leptin Receptor Gene Variant rs11804091 Is Associated with BMI and Insulin Resistance in Spanish Female Obese Children: A Case-Control Study

Leptin is an endocrine hormone that has a critical role in body weight homoeostasis and mediates its effects via the leptin receptor (LEPR). Common polymorphisms in the genes coding leptin receptors have been associated with metabolic abnormalities. We assessed the association of 28 LEPR polymorphisms with body mass index (BMI) and their relationship with obesity-related phenotypes, inflammation and cardiovascular disease risk biomarkers. A multicentre case-control study was conducted in 522 children (286 with obesity and 236 with normal-BMI). All anthropometric, metabolic factors and biomarkers were higher in children with obesity except apolipoprotein (Apo)-AI, cholesterol, high-density lipoprotein cholesterol (HDL-c), and adiponectin, which were lower in the obesity group; and glucose, low-density lipoprotein cholesterol (LDL-c), and matrix metalloproteinase-9 that did not differ between groups. We identified the associations between rs11208659, rs11804091, rs10157275, rs9436303 and rs1627238, and BMI in the whole population, as well as the association of rs11804091, rs10157275, and rs1327118 with BMI in the female group, although only the rs11804091 remained associated after Bonferroni correction (p = 0.038). This single nucleotide polymorphisms (SNP) was also associated with insulin (p = 0.004), homeostasis model assessment for insulin resistance (HOMA-IR) (p = 0.006), quantitative insulin sensitivity check index (QUICKI) (p = 0.005) and adiponectin (p = 0.046) after adjusting for age, Tanner stage and BMI. Our results show a sex-specific association between the rs11804091 and obesity suggesting an influence of this SNP on insulin resistance.

Pathophysiology of hypertension in obese children: a systematic review

Hypertension is increasingly common in overweight and obese children. The mechanisms behind the development of hypertension in obesity are complex, and evidence is limited. In order to effectively treat obese children for hypertension, it is important to have a deeper understanding of the pathophysiology of hypertension in obese children. The present review summarizes the main factors associated with hypertension in obese children and discusses their potential role in its pathophysiology. Systematic searches were conducted in PubMed and EMBASE for articles published up to October 2014. In total, 60 relevant studies were included. The methodological quality of the included studies ranged from weak to strong. Several factors important in the development of hypertension in obese children have been suggested, including endocrine determinants, such as corticosteroids and adipokines, sympathetic nervous system activity, disturbed sodium homeostasis, as well as oxidative stress, inflammation and endothelial dysfunction. Understanding the pathophysiology of hypertension in overweight and obese children is important and could have implications for its screening and treatment. Based on solely cross-sectional observational studies, it is impossible to infer causality. Longitudinal studies of high methodological quality are needed to gain more insight into the complex mechanisms behind the development of hypertension in obese children.

Differences in body mass index according to fat mass- and obesity-associated (FTO) genotype in Mexican patients with bipolar disorder

OBJECTIVES

The prevalence of obesity has dramatically increased in many countries and it is particularly high in patients with bipolar disorder (BD). A region in the first intron of the fat mass- and obesity-associated (FTO) gene, encompassing markers rs9939973, rs8050136, and rs9939609, has been consistently associated with obesity and body mass index (BMI) in different populations. We sought to determine whether FTO is associated with BMI and/or obesity in patients with BD.

METHODS

The sample included 129 Mexican Mestizo patients with bipolar I or bipolar II disorder. After obtaining informed consent, participants were evaluated with the Structured Clinical Interview for DSM-IV Axis I Disorders and weight, height, and body measurements were recorded. DNA was extracted from a 5-mL blood sample and real-time polymerase chain reaction was performed. The results were analyzed with Haploview v4.2 and SPSS v21.

RESULTS

Differences in mean BMI were explained by rs8050136 and rs9939609 genotypes, especially by comparing non-carriers and carriers of two copies of the risk allele (Tukey's p ≤ 0.019), with a mean difference in BMI as high as 7.81 kg/m(2) . Differences in BMI were also explained by the interaction of the genotype (rs8050136 and/or rs9939609), the use of second-generation antipsychotics, and the use of mood stabilizers (p ≤ 0.41). Obesity was also associated with these two markers when patients with and without obesity were compared.

CONCLUSIONS

In patients with BD, differences in BMI may be affected by the presence of FTO risk alleles, especially in homozygous individuals for these variants. Besides evaluating the possible metabolic effects of certain antipsychotics or mood stabilizers, it is important to evaluate the role of other factors such as FTO risk alleles.

Familial aggregation and childhood blood pressure

There is growing concern about elevated blood pressure (BP) in children. The evidence for familial aggregation of childhood BP is substantial. Twin studies have shown that a large part of the familial aggregation of childhood BP is due to genes. The first part of this review provides the latest progress in gene finding for childhood BP, focusing on the combined effects of multiple loci identified from the genome-wide association studies on adult BP. We further review the evidence on the contribution of the genetic components of other family risk factors to the familial aggregation of childhood BP including obesity, birth weight, sleep quality, sodium intake, parental smoking, and socioeconomic status. At the end, we emphasize the promise of using genomic-relatedness-matrix restricted maximum likelihood (GREML) analysis, a method that uses genome-wide data from unrelated individuals, in answering a number of unsolved questions in the familial aggregation of childhood BP.

Early screening of FTO and MC4R variants in newborns of Greek origin

BACKGROUND

Variants of fat mass and obesity associated gene (FTO) and melanocortin-4 receptor gene (MC4R) are related to obesity, overweight and type 2 diabetes.

OBJECTIVES

To examine the presence of FTO and MC4R variants in Greek newborns.

SUBJECTS AND METHODS

A total 1530 newborns of Greek origin were subjected to genetic testing for rs9939609 (FTO) and for rs17782313 (MC4R) variants using dried blood spot (DBS) analysis.

RESULTS

Some 20.2% of newborns carried none of the tested variants. FTO homozygotes and FTO heterozygotes correspond to 18.0% and 45.9% of neonates, respectively. MC4R homozygotes and MC4R heterozygotes were identified in 6.7% and 36.3% of neonates, respectively. Of the infants, 2.2% carried both variants in homozygosity, whereas heterozygotes for both variants correspond to 16.7% of the tested neonates.

CONCLUSION

The results indicate high prevalence of homozygosity and heterozygosity for tested variants. Early screening via DBS may be beneficial in order to adopt a healthy lifestyle.

FTO gene: association to weight regain after lifestyle intervention in overweight children

OBJECTIVE

Polymorphisms in intron 1 of the 'fat mass and obesity-associated' (FTO) gene are associated with weight status. We hypothesized that the risk allele at a polymorphism in intron 1 of FTO is associated with weight regain after end of lifestyle intervention.

METHODS

We longitudinally analyzed the changes of weight status as BMI-SDS in 346 unrelated overweight children (mean age 10.6 ± 2.6 years, 45% male, mean BMI-SDS 2.39 ± 0.49) both at the end of a 1-year lifestyle intervention and 1 year after the end of this intervention. We genotyped the obesity risk SNP rs9939609 at FTO by ARMS-PCR.

RESULTS

The children reduced their BMI-SDS (-0.29 ± 0.33; p < 0.001) during intervention and increased their BMI-SDS between the end of intervention and 1 year later (+0.10 ± 0.41; p < 0.001). The obesity risk allele at FTO SNP rs9939609 was not associated with BMI-SDS reduction during the lifestyle intervention (p = 0.622), but with weight regain 1 year after end of the intervention in multiple linear regression analyses adjusted for age, sex, pubertal stage, and baseline BMI-SDS (Bonferroni corrected p = 0.002).

CONCLUSIONS

The obesity risk allele at a polymorphism in intron 1 of FTO was associated with weight regain 1 year after a 1-year lifestyle intervention.

Epigenetics: an accessible mechanism through which to track and respond to an obesogenic environment

Obesity and its consequences impact everyone. Obesity occurs because of an interaction between an obesogenic environment and genetics. In order to confront obesity, we must understand the contribution of each of these components. Environmental influences on obesity include our extrinsic environment, such as food deserts, as well as our intrinsic environment, like perinatal exposures. Epigenetics provides a biological mechanism to reveal the accumulation of extrinsic and intrinsic environmental exposures from fetal life to adulthood. Human and animal studies demonstrate changes in epigenetic modifications which are associated with an obesogenic environment. Furthermore, evidence exists in humans and animal models that suggest environmental epigenetics may serve as a biomarker or a target for intervention. To successfully target obesity, we must intervene on an environmental as well as genetic level. Combating food deserts for example will help to change the extrinsic environment, while targeting epigenetic modification remains a goal for changing our biology.

Association of FTO polymorphisms with obesity and metabolic parameters in Han Chinese adolescents

Background

Previous studies have suggested that fat mass-and obesity-associated (FTO) gene is associated with body mass index (BMI) and the risk of obesity. This study aims to assess the association of five FTO polymorphisms (rs9939609, rs8050136, rs1558902, rs3751812 and rs6499640) with obesity and relative parameters in Han Chinese adolescents.

Methods

We examined a total of 401 adolescents, 223 normal weights (58.7% boys, 41.3% girls), 178 overweight (60.1% boys, 39.9% girls), aging from 14 to 18-years-old, recruited randomly from public schools in the central region of Wuxi, a southern city of China. DNA samples were genotyped for the five polymorphisms by Sequenom Plex MassARRAY. Association of the FTO polymorphisms with BMI, serum fasting plasm glucose (FPG), fasting insulin (FIns), triglyceride (TG) and cholesterol (TC) were investigated.

Results

1) Serum FPG, FIns, TG and TC were statistically significant higher than that in normal control group. 2) We found that BMI was higher in the rs9939609 TA+AA, rs8050136 AC+AA, rs1558902 TA+AA and rs3751812 GT+TT genotypes than in wild TT genotypes (rs9939609: P = 0.038; rs1558902: P = 0.038;), CC genotypes(rs8050136: P = 0.024) and GG genotypes (rs3751812: P = 0.024), which were not significant on adjusting for multiple testing. 3) In case-control studies, five polymorphisms were not significantly associated with overweight (p>0.05), haplotype analyses showed non-haplotype is significantly associated with a higher risk of being overweight (p>0.05). 4) There existed no significant statistical difference about FPG, FIns, TG and TC in genotype model for any SNP.

Conclusions

Our study has conducted a genetic association study of the FTO polymorphisms with BMI, serum fasting plasm glucose (FPG), fasting insulin (FIns), triglyceride (TG) and cholesterol (TC). Our study found BMI of subjects with A allele of FTO rs9939609 is higher than that with T allele. Further studies on other polymorphisms from FTO and increasing the sample size are needed.