A common variant in the FTO locus is associated with waist-hip ratio in Indian adolescents

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.

Polymorphisms on rs9939609 FTO and rs17782313 MC4R genes in children and adolescent obesity: A systematic review

The aim of this review was to assess whether the presence of rs9939609 and rs17782313 polymorphisms increase the risk for obesity among children and adolescents. This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist and it was registered in PROSPERO. The search was performed in the PubMed/Medline, The Cochrane Library, and Web of Science databases. The risk of bias of the studies was accessed using the Newcastle-Ottawa scale and JBI Critical Appraisal Checklist for Analytical. The search of the databases retrieved 859 references. Twelve studies were eligible to be included in this systematic review. Five studies founded a positive association between overweight and obesity in children and adolescents with the presence of the rs17783213 and four studies with rs9939609. Three studies did not find an association between overweight and obesity in children and adolescents with the presence of rs17782313 or rs9939609. One found a protective effect for obesity in individuals with risk A allele referring to rs9939609, one found a synergistic effect in relation to the presence of polymorphisms rs17782313 and rs9939609 for obese phenotype, and one observed that the presence together of the rs9939609, rs17782313, and rs12970134 MC4R were significant for the presence of obesity in children and adolescents. The results suggest that depending on the population evaluated and ethnicity, the polymorphisms rs17782313 and rs9939609 could be associated with overweight and obesity in children and adolescents.

The association between FTO rs9939609 gene polymorphism and anthropometric indices in adults

Background

Fat mass and obesity-associated gene (FTO) is the most studied obesity-related gene up to date. We aimed to assess anthropometric indices in carriers of FTO rs9939609 polymorphism with overweight across Iranian population (Shiraz) to find out the associations of this polymorphism with obesity indices.

Methods

This was a cross-sectional study conducted on 198 overweight healthy adults aged 20-45 years old. We assessed the body composition of the participants using bioelectrical impedance analyzer. In addition, we measured the waist circumference (WC) and hip circumference (HC). Waist to hip ratio (WHR) and waist to height ratio (WHtR) were also calculated by equations. The participants’ genotype was determined by ARMS-PCR. Also, data analysis was performed using SPSS software version 20 and R software version 3.6.2.

Results

The mean values of body mass index (BMI) and age of the participants were 26.93 ± 1.13 kg/m² and 33.33 ± 6.35 years old, respectively. Homozygous carriers of A-allele had significantly higher values for BMI (0.60 kg/m², p = 0.026), WHR (0.04 unit, p = 0.003), and WHtR (0.02 unit, p = 0.030) than the homozygous carriers of T-allele. Individuals with AA genotype had greater WC (2.66 cm, p = 0.042, and 4.03 cm, p = 0.002), fat mass (2.24 kg, p = 0.004, and 3.02 kg, p = 0.001), and trunk fat (1.53 kg, p = 0.001, and 2.08 kg, p = 0.001) compared to those with AT and TT genotypes, respectively. Interestingly, after adjustment of the confounders, significant associations were observed among rs9939609 polymorphism and BMI, Wt, WC, trunk fat percentage, WHR, and WHtR.

Conclusions

A-allele of the FTO rs9939609 polymorphism was indicated to be associated with greater general and central obesity in adult population of Shiraz, Iran.

Influence of FTO rs9939609 and Mediterranean diet on body composition and weight loss: a randomized clinical trial

Background

The Mediterranean diet (MeD) plays a key role in the prevention of obesity. Among the genes involved in obesity, the Fat mass and obesity-associated gene (FTO) is one of the most known, but its interaction with MeD remained uncertain so far.

Methods

We carried out a study on a sample of 188 Italian subjects, analyzing their FTO rs9939609 alleles, and the difference in body composition between the baseline and a 4-weeks nutritional intervention. The sample was divided into two groups: the control group of 49 subjects, and the MeD group of 139 subjects.

Results

We found significant relations between MeD and both variation of total body fat (ΔTBFat) (p = 0.00) and gynoid body fat (p = 0.04). ∆TBFat (kg) demonstrated to have a significant relation with the interaction diet-gene (p = 0.04), whereas FTO was associated with the variation of total body water (p = 0.02).

Conclusions

MeD demonstrated to be a good nutritional treatment to reduce the body fat mass, whereas data about FTO remain uncertain. Confirming or rejecting the hypothesis of FTO and its influence on body tissues during nutritional treatments is fundamental to decide whether its effect has to be taken into consideration during both development of dietetic plans and patients monitoring.

Trial Registration ClinicalTrials.gov Id: NCT01890070. Registered 01 July 2013, https://clinicaltrials.gov/ct2/show/NCT01890070

IRX3 is a genetic modifier for birth weight, adolescent obesity and transaminase metabolism

OBJECTIVE

IRX3 expression has been functionally associated in obesity-associated long-distance susceptibility loci, but the effect of the IRX3 genetic variants on human obesity and obesity-related metabolism remains uncertain.

METHODS

To determine the genetic role of IRX3, we conducted a molecular epidemiological analysis using three haplotype tagging single nucleotide polymorphisms (SNPs; rs8053360, rs3751723 and rs12445085) and one nonsynonymous SNP (rs1126960) at the IRX3 locus in 333 junior and senior high school students from a northeast Chinese population.

RESULTS

We identified significant associations between IRX3 SNPs and birth weight, body mass index (BMI), aspartate aminotransferase (AST), alanine aminotransferase (ALT) and AST/ALT ratio. The rs8053360 CC and rs1126960 GG genotypes were associated with increased birth weight and BMI, especially in females. Individuals with the rs12445085 TT genotype had significantly higher levels of AST and ALT, whereas individuals with the rs1126960 GG genotype had a significantly lower AST/ALT ratio than did individuals with other genotypes. However, no significant relationships were found between any of the IRX3 SNPs and metabolic syndrome or diabetes.

CONCLUSIONS

IRX3 genetic variants associate with birth weight, BMI and AST/ALT-related transaminase metabolism, supporting the role of IRX3 as an obesity-associated susceptibility gene.

Parental determinants of metabolic syndrome among adolescent Asian Indians: A cross-sectional analysis of parent-offspring trios

BACKGROUND

The aim of the present study was to investigate the relationship between parental metabolic syndrome (MS) and the risk of MS and associated abnormalities in adolescent offspring.

METHODS

This cross-sectional study was performed on 304 adolescents (12-16 years; 236 children with at least one parent and 124 father-mother-child trios) recruited from four schools representing different socioeconomic strata from Vellore, India. Anthropometric data was collected and blood pressure, blood glucose, and lipids were measured.

RESULTS

The prevalence of MS in adolescent offspring, fathers, and mothers was 3.3%, 52.5%, and 48.7% respectively. The most commonly observed metabolic abnormality among adolescents was lower high-density lipoprotein. Maternal waist circumference (WC) was strongly correlated with adolescent body mass index (P = 0.007), WC (P < 0.001), serum triglycerides (P = 0.02), and systolic (P = 0.005) and diastolic (P = 0.01) blood pressure. Maternal MS status was significantly associated with a greater risk of central obesity (WC odds ratio [OR] 2.02; 95% confidence interval [CI] 1.21-3.17) in offspring. Both parents having MS conferred a significant effect on the child's WC (OR 1.21; 95% CI 1.72-2.07) and increased risk of MS (OR 6.19; 95% CI 1.64-23.26).

CONCLUSIONS

This study highlights the possible heritable parental components that may contribute to the MS phenotype in offspring: MS in adolescent offspring is related to parental MS status, and maternal traits reflect offspring adiposity and metabolic traits more strongly than paternal factors. Therefore, adolescent children of parents with MS should be targets for primordial prevention of cardiometabolic disease.

Association of FTO rs9939609 SNP with Obesity and Obesity- Associated Phenotypes in a North Indian Population

OBJECTIVES

Obesity is a common disorder that has a significant impact on morbidity and mortality. Twin and adoption studies support the genetic influence on variation of obesity, and the estimates of the heritability of body mass index (BMI) is significantly high (30 to 70%). Variants in the fat mass and obesity-associated (FTO) gene have been associated with obesity and obesity-related phenotypes in different populations. The aim of this study was to examine the association of FTO rs9939609 with obesity and related phenotypes in North Indian subjects.  .

METHODS

Gene variants were investigated for association with obesity in 309 obese and 333 non-obese patients. Genotyping of the FTO rs9939609 single nucleotide polymorphism (SNP) was analyzed using Restriction Fragment Length Polymorphism Analysis of PCR-Amplified Fragments. We also measured participants fasting glucose and insulin levels, lipid profile, percentage body fat, fat mass and fat free mass.  .

RESULTS

Waist to hip ratio, systolic blood pressure, diastolic blood pressure, percentage body fat, fat mass, insulin concentration, and homeostasis model assessment index (HOMA-Index) showed a significant difference between the study groups. Significant associations were found for FTO rs9939609 SNP with obesity and obesity-related phenotypes. The significant associations were observed between the rs9939609 SNP and blood pressure, fat mass, insulin, and HOMA-index under a different model.  .

CONCLUSION

This study presents significant association between FTO rs9939609 and obesity defined by BMI and also established the strong association with several measures of obesity in North Indian population.

Associations between a common variant near the MC4R gene and serum triglyceride levels in an obese pediatric cohort

Polymorphisms near the MC4R gene may be related to an increased risk for obesity, but studies of variations in this gene and its relation to cardiometabolic profiles and food intake are scarce and controversial. The aim of this study is to evaluate the influence of the variants rs12970134 and rs17782313 near the MC4R gene in food intake, binge eating (BE) behavior, anthropometric parameters, body composition, metabolic profile, and cardiometabolic risk factors in obese children and adolescents. This is a cross-sectional study that included obese children and adolescents. We evaluated anthropometric, metabolic parameters and cardiometabolic risk factors, including hypertension, impaired fasting glucose, hypertriglyceridemia, and low HDL-cholesterol. BE was assessed through the BE scale, and a 24-h recall was used to evaluate total caloric intake and percentage of macronutrients and types of dietary fat. The MC4R variants rs12970134 and rs17782313 were genotyped using TaqMan assay. To assess the magnitude of risk, a logistic regression adjusted for Z-BMI, age, and gender was performed, adopting the significance level of 0.05. The study included 518 subjects (52.1 % girls, 12.7 ± 2.7 years old, Z-BMI = 3.24 ± 0.57). Carriers of the variant rs17782313 exhibit increased triglyceride levels (108 ± 48 vs. 119 ± 54, p = 0.034) and an increased risk of hypertriglyceridemia (OR 1.985, 95 % CI 1.288-3.057, p = 0.002). There was no association of the SNP rs12970134 with clinical, metabolic, or nutritional parameters. The variant rs12970134 and rs17782313 did not influence food intake or the presence of BE. The variant rs17782313 is associated with an increased risk of hypertriglyceridemia in obese children and adolescents.

Association between rs12970134 Near MC4R and adiposity indexes in a homogenous population of Caucasian schoolchildren

BACKGROUND

To assess whether previously identified obesity-susceptibility loci were associated with overweight/obesity risk in a homogeneous population of Caucasian schoolchildren and whether these associations varied with age.

METHODS

Seven hundred and forty-five schoolchildren (353 boys, mean age: 8.3 ± 1.4 years) underwent anthropometric assessments. A saliva sample was collected for DNA extraction and assessment of 19 single-nucleotide polymorphisms previously associated with obesity.

RESULTS

Only the rs12970134 in the MC4R gene was significantly associated with overweight/obesity risk, with a higher frequency of the AA risk genotype in children with a BMI >85th (8.3%) than in those with a BMI <85th percentile (3.0%), p = 0.001; odds ratio (95% CI) of 1.544 (1.192-1.998), p = 0.001, after adjusting for age, sex and pubertal stage. BMI standard deviation scores (SDS) and waist-to-height ratio (W/Hr) progressively increased across the rs12970134 genotypes (GG vs. AG vs. AA): BMI SDS, p = 0.004; W/Hr, p = 0.009. When dividing the study population into two groups based on the median age of participants (8.3 years), the differences in BMI SDS and W/Hr across the MC4R genotypes persisted only in children older than 8.3 years.

CONCLUSIONS

In a population of Caucasian schoolchildren, the rs12970134 MC4R variant was significantly associated with excess body weight, particularly in children older than 8 years of age.

FTO is necessary for the induction of leptin resistance by high-fat feeding

OBJECTIVE

Loss of function FTO mutations significantly impact body composition in humans and mice, with Fto-deficient mice reported to resist the development of obesity in response to a high-fat diet (HFD). We aimed to further explore the interactions between FTO and HFD and determine if FTO can influence the adverse metabolic consequence of HFD.

METHODS

We studied mice deficient in FTO in two well validated models of leptin resistance (HFD feeding and central palmitate injection) to determine how Fto genotype may influence the action of leptin. Using transcriptomic analysis of hypothalamic tissue to identify relevant pathways affected by the loss of Fto, we combined data from co-immunoprecipitation, yeast 2-hybrid and luciferase reporter assays to identify mechanisms through which FTO can influence the development of leptin resistant states.

RESULTS

Mice deficient in Fto significantly increased their fat mass in response to HFD. Fto (+/-) and Fto (-/-) mice remained sensitive to the anorexigenic effects of leptin, both after exposure to a HFD or after acute central application of palmitate. Genes encoding components of the NFкB signalling pathway were down-regulated in the hypothalami of Fto-deficient mice following a HFD. When this pathway was reactivated in Fto-deficient mice with a single low central dose of TNFα, the mice became less sensitive to the effect of leptin. We identified a transcriptional coactivator of NFкB, TRIP4, as a binding partner of FTO and a molecule that is required for TRIP4 dependent transactivation of NFкB.

CONCLUSIONS

Our study demonstrates that, independent of body weight, Fto influences the metabolic outcomes of a HFD through alteration of hypothalamic NFкB signalling. This supports the notion that pharmacological modulation of FTO activity might have the potential for therapeutic benefit in improving leptin sensitivity, in a manner that is influenced by the nutritional environment.