A multianalytical approach to evaluate the association of 55 SNPs in 28 genes with obesity risk in North Indian adults

Association of common genetic variants with body mass index in Russian population

BACKGROUND

Overweight is the scourge of modern society and a major risk factor for many diseases. For this reason, understanding the genetic component predisposing to high body mass index (BMI) seems to be an important task along with preventive measures aimed at improving eating behavior and increasing physical activity.

METHODS

We analyzed genetic data of a European cohort (n = 21,080, 47.25% women, East Slavs ancestry >80%) for 5 frequently found genes in the context of association with obesity: IPX3 (rs3751723), MC4R (rs17782313), TMEM18 (rs6548238), PPARG (rs1801282) and FTO (rs9939609).

RESULTS

Our study revealed significant associations of FTO (rs9939609) (β = 0.37 (kg/m²)/allele, p = <2 × 10^-16), MC4R (rs17782313) (β = 0.28 (kg/m²)/allele, p = 5.79 × 10^-9), TMEM18 (rs6548238) (β = 0.29 (kg/m²)/allele, p = 2.43 × 10^-8) with BMI and risk of obesity.

CONCLUSIONS

The results confirm the contribution of FTO, M4CR, and TMEM18 genes to the mechanism of body weight regulation and control.

Impact of Genetic Risk Score and Dietary Protein Intake on Vitamin D Status in Young Adults from Brazil

Given the relationship between vitamin D deficiency (VDD) and adverse outcomes of metabolic diseases, we investigated the interplay of dietary and genetic components on vitamin D levels and metabolic traits in young adults from Brazil. Genetic analysis, dietary intake, and anthropometric and biochemical measurements were performed in 187 healthy young adults (19−24 years). Genetic risk scores (GRS) from six genetic variants associated with vitamin D (vitamin D-GRS) and 10 genetic variants associated with metabolic disease (metabolic-GRS) were constructed. High vitamin D-GRS showed a significant association with low 25(OH)D concentrations (p = 0.001) and high metabolic-GRS showed a significant association with high fasting insulin concentrations (p = 0.045). A significant interaction was found between vitamin D-GRS and total protein intake (g/day) (adjusted for non-animal protein) on 25(OH)D (pinteraction = 0.006), where individuals consuming a high protein diet (≥73 g/d) and carrying >4 risk alleles for VDD had significantly lower 25(OH)D (p = 0.002) compared to individuals carrying ≤4 risk alleles. Even though our study did not support a link between metabolic-GRS and vitamin D status, our study has demonstrated a novel interaction, where participants with high vitamin D-GRS and consuming ≥73 g of protein/day had significantly lower 25(OH)D levels. Further research is necessary to evaluate the role of animal protein consumption on VDD in Brazilians.

Association of FTO, ABCA1, ADRB3, and PPARG variants with obesity, type 2 diabetes, and metabolic syndrome in a Northwest Mexican adult population

AIM

To identify associations among allelic variants of the genes FTO, ABCA1, ADRB3, and PPARG with anthropometric and biochemical traits, metabolic diseases (obesity, T2D or metabolic syndrome) in an adult population from Northwest Mexico.

METHODS

Blood samples were collected from 846 subjects including 266 normal weight subjects, 285 with obesity, and 295 with T2D. Of the 846 persons in the study, 365 presented metabolic syndrome diagnostic criteria. Anthropometric and biochemical traits were recorded and 4 single nucleotide polymorphisms (SNPs): FTO rs9939609 A-allele, ABCA1 rs9282541 A-allele, ADRB3 rs4994 G-allele, and PPARG rs1801282 G-allele were genotyped by real-time PCR.

RESULTS

FTO rs9939609 A-allele was significantly associated with obesity (p: 8.3 × 10^-4), and metabolic syndrome (p: 0.001), but no individual SNPs were significantly associated with T2D. Finally, the cumulative risk of the four SNPs was significantly associated with obesity (p: 1.95 × 10^-4).

CONCLUSION

Associations in FTO, ABCA, ADRB3, and PPARG SNPs presented in this study with obesity and metabolic syndrome could represent a risk for developing metabolic diseases in Northwest Mexican adult subjects.

The association between polymorphisms near TMEM18 and the risk of obesity: a meta-analysis

BACKGROUND

Many studies have proposed that the pathogenesis of obesity has a genetic basis, with an important risk factor being the presence of polymorphisms in the region of the TMEM18 gene, which plays a significant role in feeding behaviour; however, subsequent studies among different ethnic populations and age groups have shown inconsistent results. Therefore, this present meta-analysis examines the relationship between TMEM18 polymorphisms with the risk of obesity with regard to age group and ethnic population.

METHODS

A literature database search was conducted for available relevant studies investigating the association between obesity risk and the presence of rs6548238, rs4854344, rs11127485, rs2867125 and rs7561317 polymorphisms in TMEM18. Pooled odds ratio (OR) and 95% confidence intervals (95% CI) were calculated by either a fixed-effects model or random effect model based on a heterogeneity test. The meta-analysis of rs6548238 and its surrogates examined the relationships between 53 395 obesity cases and 123 972 healthy controls from 27 studies and published data from the POPULOUS collection (Poland).

RESULTS

A significant association is observed between rs6548238 (and surrogate) and obesity risk, with OR = 1.25 (95% CI: 1.08-1.45). Regarding population type, a significant association was revealed among groups of Europeans with OR = 1.32 (1.10-1.59) and Mexicans with OR = 1.39 (1.13-1.73). However, a lack of statistical significance was noticed in groups in Asia with OR = 1.11 (95% CI: 0.86-1.42). Regarding age, a significant association was observed among children with OR = 1.28 (95% CI: 1.18-1.39) but not in adults OR = 1.21 (95% CI: 0.92-1.58).

CONCLUSIONS

The polymorphisms near TMEM18 appear to play a role in the development of obesity. Our findings indicate that differences exist between ethnic populations and age groups, supporting those of a previous study showing the various effects of genetic factors on age and ethnic groups.

FTO and IRX3 Genes are Not Promising Markers for Obesity in Labrador Retriever Dogs

Obesity is a serious problem in numerous dog breeds, but knowledge of its hereditary background is scarce. On the contrary, numerous DNA polymorphisms associated with human obesity have been identified, with the strongest effect being demonstrated for FTO gene. We used targeted next-generation sequencing (tNGS) to search for polymorphisms in the region harboring FTO and IRX3 in 32 Labrador dogs. Moreover, we investigated the selected regions of FTO and IRX3, orthologous to the human regions associated with obesity, in 165 Labradors. For all dogs, the following information was available: age, sex, gonadal status, body weight, and body conformation score (BCS). The use of tNGS revealed 12,217 polymorphisms, but none of these obtained significance when lean and obese dogs were compared. Study of two SNPs in the 5’-flanking region of FTO in 165 dogs – creating two upstream reading frames (uORFs) – also showed no association with body weight and BCS but suggested the need for improvement in FTO annotation. No polymorphism was found in the 5’UTR of IRX3. Additionally, no differences of CpG islands methylation status between lean and obese dogs were found. Our study suggests that FTO and IRX3 are not useful markers of obesity in Labrador dogs.

The role of the genetic variants IRX3 rs3751723 and FTO rs9939609 in the obesity phenotypes of children and adolescents

OBJECTIVE

We investigated the association of IRX3 SNP rs3751723 with anthropometric characteristics related to adiposity and potential relationships with FTO SNP rs9939609 in a population of Brazilian children and adolescents.

METHODS

A total of 871 children and adolescents between 7 and 17 years of age were recruited. Adiposity measurements and biochemical parameters were assessed. The variants were genotyped by real-time PCR. Analysis of multiple linear regression, multiple logistic regression, and generalised multifactor dimensionality reduction (GMDR) adjusted for sex, age and ethnicity were applied to test the polymorphisms association with obesity-related phenotypes and the interaction between them.

RESULTS

The analyses showed that IRX3 was associated with obesity and fat percentage (BF%). An association of FTO rs9939609 with body mass index (BMI) Z-Score and with waist circumference (WC) was detected. The odds ratios (OR) showed that IRX3 rs3751723 was associated with risk of obesity in additive model (p=0.017), recessive model (p=0.016) and with high BF% in all models. FTO rs9939609 was associated with risk of obesity in additive model (p=0.031), recessive (p=0.033) and with altered WC in all models. GMDR-based predictive models for the risk of obesity, altered WC and high BF% adjusted by age, ethnicity and sex suggested no interaction of the two loci.

CONCLUSIONS

The genetic variants rs3751723 and rs9939609 have an influence on the characteristics of adiposity; however, the effects of IRX3 and FTO investigated polymorphisms are independent in relation to adiposity parameters.

Genetic risk score based on fat mass and obesity-associated, transmembrane protein 18 and fibronectin type III domain containing 5 polymorphisms is associated with anthropometric characteristics in South Brazilian children and adolescents

The prevalence of childhood obesity has increased worldwide. Although it is considered a polygenic inheritance disease, little is known about its susceptibility when the additive effect is considered. The aim of this study is to investigate whether the genetic risk score (GRS) based on previously associated obesity polymorphisms (SNP) rs9939609 (fat mass and obesity-associated (FTO)), rs6548238 (transmembrane protein 18 (TMEM18)) and rs16835198 (fibronectin type III domain containing 5 (FNDC5)) could serve as a predictor for anthropometric characteristics in a sample of Brazilian children and adolescents. This is a cross-sectional study with 1471 children and adolescents aged 6–17 years. BMI, waist circumference (WC) and percentage of body fat and metabolic parameters were verified. In all, three SNP were genotyped by TaqMan™ allelic discrimination. The metabolic and anthropometric parameters were compared between the genotypes, and the unweighted and weighted GRS (GRS and wGRS, respectively) were created to test the additive effect of these genetic polymorphisms on anthropometric parameters. The prevalence of overweight plus obesity was 41 %. Significant associations were identified forFTOrs9939609,TMEM18rs6548238 andFNDC5rs16835198 and for GRS and wGRS with anthropometric phenotypes. The higher score of wGRS was associated with obesity (OR: 2·65, 95 % CI 1·40, 5·04,P=0·003) and with greater WC (OR: 2·91, 95 % CI 1·57, 5·40,P=0·001). Our results suggest that these genetic variants contribute to obesity susceptibility in children and adolescents and reinforce the idea that the additive effect may be useful to elucidate the genetic component of obesity.