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

Investigation of associations of European, African, Amerindian genomic ancestries and MC4R, FTO, FAIM2, BDNF loci with obesity-related traits in Rio de Janeiro, Brazil

A complex web of causation is involved in adiposity, including environmental, social and genetic factors. We aimed to investigate associations between genetic factors such as ancestry and single nucleotide polymorphisms, and obesity-related traits in a sampled Brazilian population. A sample of 501 unrelated adults participating in 2013 at the longitudinal Pró-Saúde Study (EPS) in Rio de Janeiro, Brazil was selected. We analysed 46 AIM-InDels (insertion/deletion) as genetic ancestry markers and four single nucleotide polymorphisms located in the genes MC4R (rs17782313), FTO (rs9939609), FAIM2 (rs7138803) and BDNF (rs4074134), previously described as associated with obesity. The selected obesity-related markers were anthropometric parameters such as body mass index, waist circumference and waist-to-hip ratio, and body composition measurements namely body fat percentage, android fat mass and gynoid fat mass. The sample showed greater European ancestry (57.20%), followed by African (28.80%) and lastly Amerindian (14%). Our results suggest that the rs4074134 (BDNF) CC genotype was directly associated with gynoid fat mass, whereas body fat percentage, android fat mass and the anthropometric parameters seem not to be associated with neither ancestry nor the four polymorphisms in this population sample, most likely due to a stronger role of social, behavioural and environmental determinants.

Association between olfactory pathway gene variants and obesity in Chinese Han population: A case-control study based on genetic score

BACKGROUND

Our previous bivariate genome-wide association study in dizygotic twins suggested that the olfactory transduction pathway genes were associated with obesity in Northern Han Chinese adults. In this study, we attempted to verify the associations of the olfactory transduction pathway genes score with obesity in population with the same genetic background, and to estimate the interaction between gene variants and potential environment factors.

METHODS

A case-control study was conducted in Qingdao, China in 2019-2021, which enrolled 301 obesity cases and 307 controls. Based on the candidate gene selection method, 29 single nucleotide polymorphisms (SNPs) in 7 olfactory pathway genes were selected. Genomic deoxyribonucleic acid (DNA) was isolated and purified from the peripheral blood leukocytes by using DNA extraction kits and was genotyped by the MassArray system. The weighted genetic score of each gene was calculated to analyze the effect of whole gene. The effect of gene scores on obesity and the gene-environment interaction were estimated by logistic regression.

RESULTS

After adjusting for age, sex, smoking, alcohol drinking, physical activity, we observed positive associations of OR4D1 (OR = 1.531, 95% CI = 1.083-2.164, P = 0.016) and OR52K1 (OR = 1.437, 95% CI = 1.055-1.957, P = 0.022) gene scores with obesity, as well as negative associations of OR2L8 (OR = 0.708, 95% CI = 0.504-0.995, P = 0.046) and CALML3 (OR = 0.601, 95% CI = 0.410-0.881, P = 0.009) gene scores with obesity. Significant multiplicative model interaction between OR4D1 and smoking (P_interaction = 0.041) as well as CALML3 and smoking (P_interaction = 0.026) on obesity were identified. Stratified analysis showed that in smokers, OR4D1 gene score was positively associated with obesity (OR = 2.673, 95% CI = 1.348-5.299, P = 0.005) and CALML3 gene score was negatively correlated with obesity (OR = 0.252, 95% CI = 0.103-0.618, P = 0.003). The relationships were not statistically significant in non-smokers (OR4D1: OR = 1.216, 95% CI = 0.806-1.836, P = 0.351; CALML3: OR = 0.764, 95% CI = 0.492-1.188, P = 0.232).

CONCLUSIONS

Genetic variations in the olfactory pathway were associated with obesity in Northern Han Chinese adults. Smoking modified the effect of OR4D1 and CALML3 gene variants on obesity.

The association between FTO rs9939609 polymorphism and serum lipid profile in adult women

BACKGROUND

FTO gene is considered to play an important role in many metabolic diseases. Evidence from studies indicated the possible association between the FTO rs9939609 polymorphisms with serum lipid profile. Therefore, this study aimed to investigate the association of FTO rs9939609 polymorphism with lipid profile in Iranian women.

METHODS

This cross-sectional study was carried out on 380 adult women. Information about age, height, weight, BMI, physical activity, and dietary intake were collected. The serum levels of Low Density Lipoprotein (LDL), High Density Lipoprotein (HDL), Triglyceride (TG), and total cholesterol were measured. The FTO gene was genotyped for rs9939609 polymorphism. The participants were divided into two groups of TT and AT/AA considering dominant model of FTO rs9939609 polymorphism.

RESULTS

General characteristics of the participants with different FTO genotypes were not significantly different. The lower levels of HDL were observed in AT/AA genotypes compared to the TT wild type genotype of FTO rs9939609 polymorphism (P = 0.004). Adjustments of age, BMI, and physical activity did not change the results.

CONCLUSIONS

However, the significant association between FTO genotype and the HDL level was disappeared after further adjustments for dietary intake. Further studies are warranted to identify the underlying mechanisms of the possible association between FTO gene and serum lipid profile.

FTO gene polymorphism and longitudinal changes in nutritional/obesity status in children and adolescents: Schoolchildren's health cohort study

The fat mass and obesity-associated gene (FTO) has been extensively reported in the literature related to nutritional status, but there has been limited description of the genetic contribution to obesity risk during childhood and adolescence, especially in Latin Americans. This study aims to associate the rs9939609 polymorphism, of the FTO gene, with changes in nutritional status in Brazilian schoolchildren followed for 3 years. A longitudinal study was conducted with 355 schoolchildren, aged 7-15 years in 2011/2012 and subsequently re-evaluated in 2014/2015. Nutritional (obesity) status was classified by identifying those exceeding recommended thresholds for waist circumference (WC), waist-to-height ratio (WHtR), body mass index (BMI), and body fat percentage (BF%). The rs9939609 polymorphism was genotyped by a real-time polymerase chain reaction. Relative risk (RR with 95% confidence interval) of obesity status by FTO gene polymorphism was calculated by Poisson regression. The risk group was determined for genotypes with the allele A polymorphism, and regression models were adjusted for age, sex, height, ethnicity, and geographical location. Considering the longitudinal changes in status over the 3-year follow-up, the RR of developing a WC exceeding the threshold recommended (WC >75^th age and sex-standardized percentile), or remaining with this condition, was higher in children with AT/AA genotype. For WC, the RR was 1.66 (1.07; 2.58) in crude analysis and 1.17 (1.01; 1.35) following adjustment for age (years), gender, ethnicity, and geographical location. The comparative risk of abdominal obesity, assessed by WHtR (not recommended threshold ≥0.50), was 53% and 8%, respectively, higher in AT/AA compared to TT genotype.Conclusion: This is one of the first longitudinal investigations to show a significant association between the A allele of the rs9939609 polymorphism and individuals with higher than recommended WC and WHtR measures in Brazilian children and adolescents. What is known: • The FTO has an effect on increases in body mass index (BMI) among children and adolescents. • It established the association between FTO and overweight/obesity in Caucasians. What is new: • The presence of the risk allele of rs9939609 (FTO gene) polymorphism is associated with increased abdominal fat in Brazilian schoolchildren. • Was detected an association between FTO gene polymorphism (rs9939609) with WC in follow-up cohort and changes in WC and WHtR follow-up over 3 years, during childhood and adolescence growth.

Association and interaction of the FTO rs1421085 with overweight/obesity in a sample of Pakistani individuals

PURPOSE

Genetic variants determine the predisposition of an individual to obesity in a given environment. The present study was conducted to seek an association of the FTO variant rs1421085 with overweight/obesity and related traits in 612 Pakistani subjects in a case-control manner (overweight/obese = 306 and non-obese = 306). Moreover, interaction effects of the rs1421085 and overweight/obesity on multiple metabolic traits were also investigated, which were never explored before in Pakistani as well as in any other population.

MATERIALS AND METHODS

Anthropometric traits were measured by standard procedures, while metabolic parameters were determined by biochemical assays. Genotyping of the rs1421085 was carried out by TaqMan allelic discrimination assay. The data were analysed using SPSS software version 19.

RESULTS

The study revealed a significant association of the rs1421085 with overweight/obese phenotype with respect to over-dominant model indicated by h-index. The CT genotype of the rs1421085 was observed to increase the risk of being overweight/obese by 1.583 times (95% CI 1.147-2.185, p = 0.005). The CT genotype was also found to be associated with higher values of all anthropometric variables (except height and waist-to-hip ratio). Moreover, the interaction between the CT genotype of the rs1421085 and overweight/obesity was found to influence several metabolic parameters (raised blood pressure, product of triglyceride and glucose index, triglyceride levels, LDL-C, VLDL-C, coronary risk index, atherogenic index, and triglyceride-to-HDL-C ratio).

CONCLUSION

In conclusion, the rs1421085 was found to be associated with overweight/obesity and related anthropometric traits independent of age and gender in Pakistani population. Moreover, this variant was found to influence various metabolic traits in the presence of overweight/obesity.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

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.

Genetic variants in the fat mass and obesity-associated (FTO) gene confer risk for extreme obesity and modulate adiposity in a Brazilian population

Obesity is a major public health problem worldwide. It has a complex etiology, influenced by environmental and genetic factors. FTO has been recognized as an important genetic factor for obesity development. This study evaluated the contribution of FTO polymorphisms (rs9939609 and rs17817449) for extreme obesity in terms of the period of obesity onset, anthropometric, and biochemical parameters. The haplotype and the combined effects of FTO risk alleles on obesity susceptibility were evaluated. We investigated 169 normal-weight subjects (body mass index, BMI: 22.8 [21.0; 24.0] kg/m²) and 123 extremely obese individuals (BMI: 47.6 [44.1; 53.1] kg/m²). Genotyping was performed by real time PCR. Our results showed a strong association between FTO variants and extreme obesity. Carriers of the AT haplotype had an increased risk for extreme obesity. Gene scores suggested that the risk of developing extreme obesity was increased 1.37-fold per risk allele added. Both polymorphisms also influenced BMI and body weight. Additionally, rs17817449 influenced triglyceride levels. No effect of FTO variants on the period of obesity onset was found. In conclusion, the FTO polymorphisms showed a strong association with development of extreme phenotype of obesity and adiposity modulation in a Brazilian population.

The FTO genetic variants are associated with dietary intake and body mass index amongst Emirati population

BACKGROUND

The risk of obesity is determined by complex interactions between genetic and environmental factors. Little research to date has investigated the interaction between gene and food intake. The aim of the current study is to explore the potential effect of fat mass and obesity-associated protein gene (FTO) rs9939609 and rs9930506 single nucleotide polymorphism (SNP) on the pattern of food intake in the Emirati population.

METHODS

Adult healthy Emirati subjects with Body mass index (BMI) of 16-40 kg/m2 were included in the study. Genotyping for FTO rs9939609(A>T) and rs9930506(A>G) was performed using DNA from saliva samples. Subjects were categorized according to the WHO classification by calculating the BMI to compare different classes. Dietary intake was assessed by a sixty-one-item FFQ that estimated food and beverage intakes over the past year. The daily energy, macronutrient, and micronutrient consumption were computed.

RESULTS

We included 169 subjects in the final analysis (mean age 30.49± 9.1years, 57.4% females). The mean BMI of the study population was 26.19 kg/m2. Both SNPs were in Hardy Weinberg Equilibrium. The rs9939609 AA genotype was significantly associated with higher BMI (p = 0.004); the effect was significant in females (p = 0.028), but not in males (p = 0.184). Carbohydrate intake was significantly higher in AA subjects with a trend of lower fat intake compared to other genotypes. The odds ratio for the AA was 3.78 in the fourth quartile and 2.67 for the A/T in the second quartile of total carbohydrate intake, considering the first quartile as a reference (95% CI = 1.017-14.1 and 1.03-6.88, respectively). Fat intake was significantly lower in the FTO rs9930506 GG subjects. The presence of FTO rs9930506 GG genotype decreased the fat intake in subjects with FTO rs9939609 AA (p = 0.037).

CONCLUSIONS

The results of this study highlight the interaction of the FTO risk alleles on the food intake in Emirati subjects. The FTO rs9939609 AA subjects had higher carbohydrate and lower fat intake. The latter was accentuated in presence of rs9930506 GG genotype.

The association of the fat mass and obesity-associated gene (FTO) rs9939609 polymorphism and the severe obesity in a Brazilian population

Background: Obesity occurs due to the interaction between the genetic background and environmental factors, including an increased food intake and a sedentary lifestyle. Nowadays, it is clear that there is a specific circuit, called leptin-melanocortin pathway, which stimulates and suppresses food intake and energy expenditure. Therefore, the aim of this study was to evaluate the influence of genetic variants related to appetite regulation and energy expenditure on severe obesity susceptibility and metabolic phenotypes in a Brazilian cohort. Material and methods: A total of 490 participants were selected (298 severely obese subjects and 192 normal-weight individuals). Genomic DNA was extracted and polymorphisms in protein related to agouti (AGRP; rs5030980), ghrelin (GHRL; rs696217), neuropeptide Y (NPY; rs535870237), melanocortin 4 receptor (MC4R; rs17782313), brain-derived neurotrophic factor (BDNF; rs4074134) and fat mass and obesity-associated (FTO; rs9939609) genes were genotyped using TaqMan® probes. Demographic, anthropometric, biochemical and blood pressure parameters were obtained from the participants. Results: Our results showed that FTO rs9939609 was associated with severe obesity susceptibility. This polymorphism was also related to body weight, body mass index (BMI), waist to weight ratio (WWR) and inverted BMI. Individuals carrying the mutant allele (A) showed higher levels of BMI as well as lower values of WWR and inverted BMI. Conclusion: This study showed that FTO rs9939609 polymorphism plays a significant role in predisposing severe obesity in a Brazilian population.

Identification of genetic basis of obesity and mechanistic link of genes and lipids in Pakistani population

We aimed to identify the genetic causes of common forms of obesity in the Pakistani people and find out the mechanistic link by observing the relationship of genes and serum lipid traits. Four hundred and seventy-five subjects were genotyped for two mutations in (leptin:N103K and proopiomelanocortin:R236G) and ten common variants in different genes. Serum lipids were also measured. The prevalence of mutations was very low (one heterozygous subject each for both mutations), but fairly high minor/risk allele frequency (M/RAF) was observed for all SNPs. MAF of G2548A was 42.8% in obese and 30.1% in controls (P=5.7 × 10⁻⁵), it showed association with weight, body mass index (BMI), waist circumference (WC), high density lipoprotein cholesterol (HDL-c) and leptin, Gln223Arg had MAF 32% in obese and 18.7% in controls (P=5.4 × 10⁻⁶), it showed association with fasting plasma glucose (FPG) and all lipid traits, Ala54Thr had MAF 42.4% in obese and 33.1% (P=0.002), it showed association with none of the tested parameters. rs9939609 MAF was 26.6%, and showed association with none of the tested parameters. rs1802295 (P=0.002); rs7178572 (P=0.007); rs2028299 (P=0.04); rs4812829 (P=0.02) showed significant while rs3923113 and rs16861329 did not show a significant association (P=0.20 and P=0.3, respectively) with obesity. Major genetic contribution to common forms of obesity in Pakistan is from low/modest effect size common variants that act additively to affect body weight quantitatively and mechanism may involve modulating serum lipids.

Use of a gene score of multiple low-modest effect size variants can predict the risk of obesity better than the individual SNPs

BACKGROUND

Obesity is a complex disorder, the development of which is modulated by a multitude of environmental, behavioral and genetic factors. The common forms of obesity are polygenic in nature which means that many variants in the same or different genes act synergistically and affect the body weight quantitatively. The aim of the current study was to use information from many common variants previously identified to affect body weight to construct a gene score and observe whether it improves the associations observed. The SNPs selected were G2548A in leptin (LEP) gene, Gln223Arg in leptin receptor (LEPR) gene, Ala54Thr in fatty acid binding protein 2 (FABP2) gene, rs1121980 in fat mass and obesity associated (FTO) gene, rs3923113 in Growth Factor Receptor Bound Protein 14 (GRB14), rs16861329 in Beta-galactoside alpha-2,6-sialyltransferase 1 (ST6GAL1), rs1802295 in Vacuolar protein sorting-associated protein 26A (VPS26A), rs7178572 in high mobility group 20A (HMG20A), rs2028299 in adaptor-related protein complex 3 (AP3S2), and rs4812829 in Hepatocyte Nuclear Factor 4 Alpha (HNF4A).

METHODS

A total of 475 subjects were genotyped for the selected SNPs in different genes using different genotyping techniques. The study subjects' age, weight, height, BMI, waist and hip circumference, serum total cholesterol, triglycerides, LDL and HDL were measured. A summation term, genetic risk score (GRS), was calculated using SPSS.

RESULTS

The results showed a significantly higher mean gene score in obese cases than in non-obese controls (9.1 ± 2.26 vs 8.35 ± 2.07, p = 2 × 10- 4). Among the traits tested for association, gene score appeared to significantly affect BMI, waist circumference, and all lipid traits.

CONCLUSION

In conclusion, the use of gene score is a better way to calculate the overall genetic risk from common variants rather than individual risk variants.

Effect of selected polymorphisms of genes lep, MTHFR and FTO to BMI level and gender-specificity

The aim of this study is to investigate the effect of selected polymorphisms LEP (G2548A), MTHFR (C677T) and FTO (rs1121980) on body mass index in humans. In the study participated 79 people from Slovakia with some genetic relatedness. Genomic DNA was isolated from the buccal swabs using a commercial kit Qiagen DNA Mini Kit (Qiagen). The detection of SNP polymorphisms in human genes LEP, MTHFR and FTO was performed using molecular genetics methods such as PCR-RFLP and ARMS. The most common genotypes in all 3 polymorphism were found in heterozygous form (for LEP AG = 0.5190, for MTHFR CT = 0.519, for FTO CT =0.4051). The LEP gene had increased frequency of G allele (0.5506), the MTHFR gene T allele (0.6646) and FTO gene T allele (0.50635). The least frequent genotype in LEP was AA (0.1899), in MTHFR was TT (0.0759), in FTO it was CC (0.2911). According to the results we can assume that the genotypes AA (LEP G2548A), CC (FTO rs1121980) and TT (MTHFR C677T) in case of women have a protective effect on the prevalence of obesity, based on BMI, compared to the other genotypes and this polymorphism is gender-specific. Added anthropometric measurements, blood test and extension of the group in the future evaluation could increase the statistical relevance in relation to obesity and gender-specificity.

Copy Number Variations in Candidate Genes and Intergenic Regions Affect Body Mass Index and Abdominal Obesity in Mexican Children

Introduction. Increase in body weight is a gradual process that usually begins in childhood and in adolescence as a result of multiple interactions among environmental and genetic factors. This study aimed to analyze the relationship between copy number variants (CNVs) in five genes and four intergenic regions with obesity in Mexican children. Methods. We studied 1423 children aged 6–12 years. Anthropometric measurements and blood levels of biochemical parameters were obtained. Identification of CNVs was performed by real-time PCR. The effect of CNVs on obesity or body composition was assessed using regression models adjusted for age, gender, and family history of obesity. Results. Gains in copy numbers of LEPR and NEGR1 were associated with decreased body mass index (BMI), waist circumference (WC), and risk of abdominal obesity, whereas gain in ARHGEF4 and CPXCR1 and the intergenic regions 12q15c, 15q21.1a, and 22q11.21d and losses in INS were associated with increased BMI and WC. Conclusion. Our results indicate a possible contribution of CNVs in LEPR, NEGR1, ARHGEF4, and CPXCR1 and the intergenic regions 12q15c, 15q21.1a, and 22q11.21d to the development of obesity, particularly abdominal obesity in Mexican children.

rs3751812, a common variant in fat mass and obesity-associated (FTO) gene, is associated with serum high- and low-density lipoprotein cholesterol in Pakistani individuals

OBJECTIVES

The aim of the present study was to investigate the effect of a common variant of the fat mass and obesity associated (FTO) gene, rs3751812 in obese Pakistani individuals, compare this effect with nonobese controls of the same ethnicity, and then correlate it with serum lipid profile and anthropometric parameters.

METHODS

We genotyped 475 samples using TaqMan allelic discrimination assay. Serum total cholesterol, triacylglycerols, and high- (HDL-C) and low-density lipoprotein cholesterol (LDL-C) concentrations were measured. Statistical analysis was done by SPSS version 22 and the results were analyzed for any significant associations.

RESULTS

Results demonstrated that the variant is significantly associated with obesity in Pakistan. The study found, for the first time, that the variant has a significant effect on lowering HDL-C and increasing LDL-C. Among anthropometric measures, the variant showed significant association with body mass index and weight.

CONCLUSION

The study concludes that the FTO variant is consistently associated with obesity in the Pakistani population and its association with anthropometric and lipid parameters show that it may mediate its role by altering fat deposition and disturbing serum lipid profile. However, future studies with larger sample size are needed to validate the results of the present study.