Rs12970134 near MC4R is associated with appetite and beverage intake in overweight and obese children: A family-based association study in Chinese population

Exploring the interplay of genetic variants and environmental factors in childhood obesity: A systematic review and meta-analysis

Dynamic interactions between genetic predispositions and environmental exposures significantly shape the escalating prevalence of childhood obesity. This systematic review synthesizes observational and clinical trial evidence on the gene-environment interplays influencing childhood obesity, highlighting the role of genetic variants and environmental moderators such as dietary habits, physical activity, sleep durations, parental behaviors, socioeconomic status, ethnicity, gender, as well as lifestyle interventions. We conducted an exhaustive search across 5 databases (Medline, PubMed, EMBASE, Web of Science, and Cochrane Library), adhering to PRISMA guidelines. We ultimately included 147 studies that investigated these interplays in diverse populations. Specifically, 83 studies focused on gene-diet interplays, 23 on gene-physical activity, 5 on sedentary behavior, 3 on screen time, 7 on sleep duration, 10 on parental behavior, 4 on socioeconomic status, 16 on gender, 8 on age, 7 on ethnicity, and 13 on the effects of lifestyle interventions. Notably, we meta-analyzed energy expenditure and macronutrient consumption, including carbohydrates, proteins, and fats, as well as the proportion of energy supplied by each nutrient between carriers and noncarriers of the FTO effect allele, revealing that carriers consumed a higher proportion of fat calories, with no other significant differences noted. This review demonstrates that genetic risk variants, particularly in FTO (e.g., rs9939609) and MC4R (e.g., rs17782313), amplify the adverse effects of obesogenic behaviors, offering insights into the intricate pathophysiology of childhood obesity and suggesting the potential for personalized interventions based on genetic profiles.

Genetic variants in the MC4R gene and risk of obesity/overweight: A systematic review and meta-analysis

AIM

Obesity is a significant health issue worldwide, progressing due to genetic factors and lifestyle. Melanocortin 4 receptor (MC4R) gene polymorphisms have been identified as a cause of overweight and obesity risk. The aim of this study was a comprehensive assessment of MC4R polymorphism effects on overweight/obesity risk.

METHODS

All retrieved literature from PubMed, Web of Science and Scopus according to PRISMA guidelines up to June 2022 was reviewed. Inclusion criteria are restricted to English-language, human case-control/cohort studies with genotype distributions of MC4R polymorphisms and their association with obesity and overweight in any geographic regions and age. The heterogeneity using the I-squared statistic (I2), the Q-test and Prediction Interval (PI) and publication bias using Begg's and Egger's tests were examined, and the pooled odds ratios in different genetic models were estimated using a random effect model. Subgroup analysis was performed by the geographic regions and age groups. Risk of bias for individual studies was not assessed. The review is limited by restricted racial diversity and exclusion of environmental factors, incomplete data and limited access to certain articles. This work received no specific funding, and the review was not prospectively registered.

RESULTS

In our study, 39 eligible studies with 43 697 overweight and obese cases and 52 272 normal weights were included. In mixed-age populations, rs17700633, rs17782313, rs11872992, rs12970134, rs2229616 and rs571312 were evaluated. The remarkable association was seen by rs17782313 and rs12970134 in the Homozygous model (OR = 1.73; 95% CI: 1.51, 1.98 and 1.74; 95% CI: 1.29; 2.35, respectively). In addition, rs17782313 and rs12970134 were found to be more strongly linked to overweight and obesity in Asian and European population groups, as determined by a subgroup analysis of the geographic regions.

CONCLUSION

The present study confirms the high association of rs17782313 and rs12970134 with obesity and overweight in all age groups and geographic regions. However, further functional studies and high-population research on other MC4R SNPs must validate their role.

Genetic associations with neural reward responsivity to food cues in children

Objective

To test associations of candidate obesity-related single nucleotide polymorphisms (SNPs) and obesity polygenic risk scores (PRS) with neural reward reactivity to food cues.

Methods

After consuming a pre-load meal, 9-12-year-old children completed a functional magnetic resonance imaging (fMRI) paradigm with exposure to food and non-food commercials. Genetic exposures included FTO rs9939609, MC4R rs571312, and a pediatric-specific obesity PRS. A targeted region-of-interest (ROI) analysis for 7 bilateral reward regions and a whole-brain analysis were conducted. Independent associations between each genetic factor and reward responsivity to food cues in each ROI were evaluated using linear models.

Results

Analyses included 151 children (M = 10.9 years). Each FTO rs9939609 obesity risk allele was related to a higher food-cue-related response in the right lateral hypothalamus after controlling for covariates including the current BMI Z-score (p < 0.01), however, the association did not remain significant after applying the multiple testing correction. MC4R rs571312 and the PRS were not related to heightened food-cue-related reward responsivity in any examined regions. The whole-brain analysis did not identify additional regions of food-cue-related response related to the examined genetic factors.

Conclusion

Children genetically at risk for obesity, as indicated by the FTO genotype, may be predisposed to higher food-cue-related reward responsivity in the lateral hypothalamus in the sated state, which, in turn, could contribute to overconsumption.

Clinical trial registration

https://clinicaltrials.gov/study/NCT03766191, identifier NCT03766191.

Understanding risk and causal mechanisms for developing obesity in infants and young children: A National Institutes of Health workshop

Obesity in children remains a major public health problem, with the current prevalence in youth ages 2-19 years estimated to be 19.7%. Despite progress in identifying risk factors, current models do not accurately predict development of obesity in early childhood. There is also substantial individual variability in response to a given intervention that is not well understood. On April 29-30, 2021, the National Institutes of Health convened a virtual workshop on "Understanding Risk and Causal Mechanisms for Developing Obesity in Infants and Young Children." The workshop brought together scientists from diverse disciplines to discuss (1) what is known regarding epidemiology and underlying biological and behavioral mechanisms for rapid weight gain and development of obesity and (2) what new approaches can improve risk prediction and gain novel insights into causes of obesity in early life. Participants identified gaps and opportunities for future research to advance understanding of risk and underlying mechanisms for development of obesity in early life. It was emphasized that future studies will require multi-disciplinary efforts across basic, behavioral, and clinical sciences. An exposome framework is needed to elucidate how behavioral, biological, and environmental risk factors interact. Use of novel statistical methods may provide greater insights into causal mechanisms.

Melanocortin-4 receptor and proopiomelanocortin: Candidate genes for obesity in domestic shorthair cats

Obesity is an escalating global health problem affecting both humans and companion animals. In cats it is associated with increased mortality and multiple diseases, including diabetes mellitus. Two genes coding for proteins known to play a critical role in energy homeostasis across species are the proopiomelanocortin (POMC) gene and the melanocortin-4 receptor (MC4R) gene. A missense variant in the coding sequence of the feline MC4R (MC4R:c.92C>T) has been reported to be associated with diabetes and overweight in domestic shorthair cats, and while variants in the POMC gene are known to cause obesity in humans and dogs, variants in POMC and their association with feline obesity and diabetes mellitus have not been investigated to date. The current study aimed to assess the association between the previously described MC4R variant and body condition score (BCS), as well as body fat content (%BF) in 89 non-diabetic domestic shorthair cats. Furthermore, we investigated the feline POMC gene as a potential candidate gene for obesity. Our results indicate that the MC4R:c.92C>T polymorphism is not associated with BCS or %BF in non-diabetic domestic shorthair cats. The mutation analysis of all POMC exons identified two missense variants, with a variant in exon 1 (c.28G>C; p.G10R) predicted to be damaging. The variant was subsequently assessed in all 89 cats, and cats heterozygous for the variant had a significantly increased body condition score (p = 0.03) compared with cats homozygous for the wild-type allele. Results from our study provide additional evidence that the previously described variant in MC4R is not associated with obesity in domestic shorthair cats. More importantly, we have identified a novel variant in the POMC gene, which might play a role in increased body condition score and body fat content in domestic shorthair cats.

An Association between Diet and MC4R Genetic Polymorphism, in Relation to Obesity and Metabolic Parameters-A Cross Sectional Population-Based Study

The melanocortin-4 receptor (MC4R) gene harbours one of the strongest susceptibility loci for obesity and obesity-related metabolic consequences. We analysed whether dietary factors may attenuate the associations between MC4R genotypes and obesity and metabolic parameters. In 819 participants genotyped for common MC4R polymorphisms (rs17782313, rs12970134, rs633265, and rs135034), the anthropometric measurements, body fat content and distribution (visceral and subcutaneous adipose tissue, VAT and SAT, respectively), and blood glucose, insulin, total-, LDL-, HDL-cholesterol, triglycerides concentrations, and daily macronutrient intake were assessed. ANOVA or Kruskal–Wallis tests were used, and multivariate linear regression models were developed. We observed that the CC genotype carriers (rs17782313) presented higher VAT, VAT/SAT ratio, fasting blood glucose and triglyceride concentrations when they were stratified to the upper quantiles of protein intake. An increase in energy derived from proteins was associated with higher BMI (Est. 5.74, R² = 0.12), body fat content (Est. 8.44, R² = 0.82), VAT (Est. 32.59, R² = 0.06), and VAT/SAT ratio (Est. 0.96, R² = 0.05). The AA genotype carriers (rs12970134) presented higher BMI, body fat, SAT and VAT, fasting blood glucose, triglycerides and total cholesterol concentrations. An increase in energy derived from proteins by AA carriers was associated with higher VAT (Est.19.95, R² = 0.06) and VAT/SAT ratio (Est. 0.64, R² = 0.05). Our findings suggest that associations of the common MC4R SNPs with obesity and its metabolic complications may be dependent on the daily dietary intake, which may open new areas for developing personalised diets for preventing and treating obesity and obesity-related comorbidities.

Effects of exercise and diet intervention on appetite-regulating hormones associated with miRNAs in obese children

AIMS

This study investigated the effects of exercise and diet intervention on appetite-regulating hormones and subjective appetite changes in obese children and examined expressions of specific key microRNAs (miRNA, miR).

METHODS

16 obese children were included in a training program consisting of exercise and diet intervention for 6 weeks. Before and after the intervention, fasting blood was collected to determine appetite-regulating hormones (leptin, ghrelin, and orexin) and miRNA (miR-103a-3p and miR-200a-3p) levels; eating behavior of the children was reported using the Children Eating Behavior Questionnaire (CEBQ).

RESULTS

The level of orexin was significantly decreased (P < 0.05), while ghrelin was significantly enhanced (P < 0.05) after 6 weeks. The scores of food responsiveness (FR) and enjoyment of food (EF) of the CEBQ were significantly decreased (P < 0.05) after intervention. The changes of leptin and that of SR were significantly correlated (r = - 0.455, P < 0.05), and the correlation between the alterations of orexin and that of EF was moderate with significance (r = 0.625, P < 0.05). miR-103a-3p expression was not statistically changed, while miR-200a-3p was significantly inhibited after 6-week intervention (P < 0.05). The correlation between relative changes of miR-103a-3p and that of leptin and orexin were both with significant difference (r = 0.413, P < 0.05; r = 0.409, P < 0.05), whereas the alterations of miR-200a-3p were not correlative with hormones or appetite sensation.

CONCLUSION

Exercise combined with diet intervention for 6 weeks was effective in regulating appetite sensations and hormones in obese children, and miR-103a-3p and miR-200a-3p might provide a foundation for target biomarkers of appetite trait in modulating the energy balance control by exercise and dietary intervention.

LEVEL OF EVIDENCE

Level III, case-control analytic study.

TRIAL REGISTRATION

The trial was registered in ClinicalTrials.gov (NCT03762629).

Association between rs1421085 and rs9939609 Polymorphisms of Fat Mass and Obesity-Associated Gene with High-Density Lipoprotein Cholesterol and Triglyceride in Obese Turkish Children and Adolescents

Several studies have shown that rs9939609 and rs1421085 in fat mass and obesity-associated ( FTO ) gene rs17782313 and rs12970134 in melanocortin-4 receptor ( MC4R ) gene influence obesity. In the present study, we aimed to determine association between rs9939609, rs1421085, rs17782313, and rs12970134 polymorphism, and their relation with body mass index (BMI), glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR) and lipid values in obese children. We included 100 newly diagnosed obese children and 100 healthy children. The rs1421085 (CC/CT) ( p  = 0.019) and rs9939609 (AA/AT) ( p  = 0.002) polymorphism regions were higher in the obese group. Additionally, we found that both the rs1421085 (CC/CT) and rs9939609 (AA/AT) polymorphism associated with high-density lipoprotein cholesterol ( p  = 0.011 and p  = 0.003) and triglycerides ( p  = 0.01 and p  = 0.004) level, respectively. Further, the rs9939609 and rs1421085 variants of FTO gene associated with HDL-cholesterol and triglycerides levels in obese children; however, updated studies with a large sample size are required to establish strong links with genetic variants and risk factors in childhood obesity.

The interaction between dietary Non-Enzymatic Antioxidant Capacity (NEAC) with variants of Melanocortin-4 receptor (MC4R) 18q21.23-rs17782313 locus on hypothalamic hormones and cardio-metabolic risk factors in obese individuals from Iran

Background: In the current study, we aimed to evaluate the interaction between dietary Non-Enzymatic Antioxidant Capacity (NEAC) and rs17782313 polymorphism on hypothalamic hormones and cardio-metabolic risk factors. Methods: A total of 287 subjects (aged 20-50 years, 147 males and 140 females) enrolled in the cross-sectional study. Dietary NEAC was assessed using databases of NEAC measurements compiled from outcomes for three different analyses: oxygen radical absorbance capacity (ORAC), ferric reducing-antioxidant power (FRAP), and total radical-trapping antioxidant parameter (TRAP) and genotyping for the near MC4R rs17782313 was carried out by Polymerase chain reaction-restriction fragments length polymorphism (PCR-RFLP) method. Results: The significant interactions were found between adherence to the dietary NEAC and MC4R rs17782313 in relation to high-density lipoprotein-cholesterol (HDL-C), glucose, α-melanocyte stimulating hormone (α-MSH), insulin and quantitative insulin sensitivity check index (QUICKI) (P _Interaction = 0.03, 0.01, 0.04, 0.04 and 0.04, respectively). In homozygous subjects for the minor allele, the serum insulin level and QUICKI in participants with the highest adherence to TRAP were significantly higher than those with the lowest adherence (p < 0.001). There was a significant inverse association between high ORAC score and risk of metabolic syndrome even after adjusting for potential confounders (OR: 0.33; 95%CI:0.13-0.81) and also a significant inverse association between high NEAC (ORAC, FRAP and TRAP assays) score and high triglyceride (TG) level was found in obese adults. Conclusion: In conclusion, our study found for the first time that the NEAC significantly interacts with the rs17782313 genotypes to influence several metabolic risk factors in obesity.

The interaction between dietary patterns and melanocortin-4 receptor polymorphisms in relation to obesity phenotypes

INTRODUCTION

Data shows that interactions between dietary factors and genetic variants can modulate the association of polymorphisms such as the Melanocortin-4 receptor (MC4R) gene with obesity. Considering the limited data available on this topic we aimed to investigate interactions between dietary patterns (DPs) and MC4R polymorphisms in relation to obesity phenotypes.

METHODS

This cohort study was performed in the framework of Tehran Lipid and Glucose Study; for eligible participants in this study (n=3850), the median follow-up was 4 years. DPs were determined using factor analysis. The genotypes of polymorphisms (17782313rs and 12970134rs) were identified and their interaction with DPs were assessed in relation to incidence of obesity phenotypes including central obesity, general obesity and visceral adiposity dysfunction.

RESULTS

The mean age of participants (62.5% females) were 37.0±13.7 years. Two main DPs (healthy and unhealthy) were extracted. C-allele carriers of rs17782313 in higher quartiles of the healthy DP score had a significant decrease in the incidence of general obesity, compared to those who had the TT genotype (HR=0.61, 95% CI=0.42-0.89, P interaction=0.01). For rs12970134 A-allele carriers, subjects in the second compared to the first quartile of the healthy DP score, had a significant decrease in the incidence of general obesity (HR=0.68, 95% CI=0.46-0.99). There were no significant interaction between DPs and MC4R variants in relation to other obesity phenotypes.

CONCLUSION

Our results indicate that the healthy DP could interact with rs17782313 in relation to incidence of general obesity.

Genes and Eating Preferences, Their Roles in Personalized Nutrition

At present, personalized diets, which take into account consumer genetic characteristics, are growing popular. Nutrigenetics studies the effect of gene variations on metabolism and nutrigenomics, which branches off further and investigates how nutrients and food compounds affect genes. This work deals with the mutations affecting the assimilation of metabolites, contributing to nutrigenetic studies. We searched for the genes responsible for eating preferences which allow for the tailoring of personalized diets. Presently, genetic nutrition is growing in demand, as it contributes to the prevention and/or rehabilitation of non-communicable diseases, both monogenic and polygenic. In this work, we showed single-nucleotide polymorphisms in genes-missense mutations that change the functions of coded proteins, resulting in a particular eating preferences or a disease. We studied the genes influencing food preferences-particularly those responsible for fats and carbohydrates absorption, food intolerance, metabolism of vitamins, taste sensations, oxidation of xenobiotics, eating preferences and food addiction. As a result, 34 genes were identified that affect eating preferences. Significant shortcomings were found in the methods/programs for developing personalized diets that are used today, and the weaknesses were revealed in the development of nutrigenetics (inconsistency of data on SNP genes, ignoring population genetics data, difficult information to understand consumer, etc.). Taking into account all the shortcomings, an approximate model was proposed in the review for selecting an appropriate personalized diet. In the future, it is planned to develop the proposed model for the compilation of individual diets.

The MC4R genetic variants are associated with lower visceral fat accumulation and higher postprandial relative increase in carbohydrate utilization in humans

Purpose

The interactions between lifestyle and genetic factors play an important role in obesity development. Mutations in melanocortin-4-receptor (MC4R) gene are one of the most common cause of monogenic obesity, however, the functional effects of polymorphic variants near MC4R gene in general populations remain uncertain. The aim of our study was to analyze whether the common single nucleotide polymorphisms (SNPs) of MC4R gene influence the food preferences, physical activity, body fat content and distribution, as well as fasting and postprandial energy expenditure and substrates utilization.

Methods

We genotyped previously identified MC4R SNPs: rs17782313, rs633265, rs1350341, rs12970134 in 927 subjects, who underwent anthropometric, total body fat content, visceral (VAT) and subcutaneous adipose tissue (SAT) measurements, and daily physical activity and dietary intake analysis. In randomly selected 47 subjects the energy expenditure, carbohydrate and lipid utilizations were evaluated in fasting state and after high-carbohydrate and control meals intake.

Results

We found the significant associations between studied SNPs of MC4R gene and VAT and VAT/SAT ratio. Moreover, the GG genotype carriers of rs1350341, who had the lowest VAT accumulation (p = 0.012), presented higher relative increase in postprandial carbohydrate utilization (p = 0.013, p = 0.024).

Conclusions

We have observed that common SNPs of the MC4R gene influence the body fat content and distribution, as well as relative increase in postprandial carbohydrate utilization. We believe that our study may help to understand better the impact of MC4R gene on obesity development, and to help to provide personalized prevention/treatment strategies to fight against obesity and its metabolic consequences.

Hypothalamic Integration of the Endocrine Signaling Related to Food Intake

Hypothalamic integration of gastrointestinal and adipose tissue-derived hormones serves as a key element of neuroendocrine control of food intake. Leptin, adiponectin, oleoylethanolamide, cholecystokinin, and ghrelin, to name a few, are in a constant "cross talk" with the feeding-related brain circuits that encompass hypothalamic populations synthesizing anorexigens (melanocortins, CART, oxytocin) and orexigens (Agouti-related protein, neuropeptide Y, orexins). While this integrated neuroendocrine circuit successfully ensures that enough energy is acquired, it does not seem to be equally efficient in preventing excessive energy intake, especially in the obesogenic environment in which highly caloric and palatable food is constantly available. The current review presents an overview of intricate mechanisms underlying hypothalamic integration of energy balance-related peripheral endocrine input. We discuss vulnerabilities and maladaptive neuroregulatory processes, including changes in hypothalamic neuronal plasticity that propel overeating despite negative consequences.