Association study of childhood obesity with eight genetic variants recently identified by genome-wide association studies

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.

The association between living environmental factors and adolescents' body weight: a cross-sectional study

BACKGROUND

The effect of the living environment on public health has received increasingly scholarly attention. This study aims to explore the relationship between adolescents' body weight and their living environmental factors.

METHODS

This cross-sectional study comprised 1362 middle-school students from Nanjing and 826 from Changzhou in China. We further collected information on living environmental factors based on their home address and ran multivariate logistic regressions to explore potential correlations after considering a range of potential confounding factors.

RESULTS

Approximately 25% (n = 303) of students from Nanjing and 26% (n = 205) of students from Changzhou were excessive body weight. In Nanjing, students' BMI (Body Mass Index) showed a strong negative correlation with the number of sports venues in their neighborhood (Adjusted Odds Ratio (AOR): 0.64, 95%CI: 0.40-0.94) after controlling for other covariates. In Changzhou, we observed a positive correlation between adolescents' body weight and the number of bus stops in their neighbourhood (AOR:1.63, 95%CI:1.11-2.38).

CONCLUSIONS

The living environment factors were independently associated with teenagers' excessive body weight. We hypothesis that the environmental risk factors might be associated with political management, which will consequently affect personal health outcomes. Further research and proactive measures are required to manage those potential risks and attenuate the problem.

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.

Whole Genome Interpretation for a Family of Five

Although best practices have emerged on how to analyse and interpret personal genomes, the utility of whole genome screening remains underdeveloped. A large amount of information can be gathered from various types of analyses via whole genome sequencing including pathogenicity screening, genetic risk scoring, fitness, nutrition, and pharmacogenomic analysis. We recognize different levels of confidence when assessing the validity of genetic markers and apply rigorous standards for evaluation of phenotype associations. We illustrate the application of this approach on a family of five. By applying analyses of whole genomes from different methodological perspectives, we are able to build a more comprehensive picture to assist decision making in preventative healthcare and well-being management. Our interpretation and reporting outputs provide input for a clinician to develop a healthcare plan for the individual, based on genetic and other healthcare data.

The current review of adolescent obesity: the role of genetic factors

Obesity, a complex, multi-factor and heterogeneous condition, is thought to result from the interaction of environmental and genetic factors. Considering the result of adolescence obesity in adulthood, the role of genetic factors comes to the fore. Recently, many genome-wide association studies (GWAS) have been conducted and many loci associated with adiposity have been identified. In adolescents, the strongest association with obesity has been found in single nucleotide polymorphisms (SNP) in the FTO gene. Besides FTO, GWAS showed consistent effects between variants in MC4R, TMEM18, TNNI3K, SEC16B, GNPDA2, POMC and obesity. However, these variants may not have similar effects for all ethnic groups. Although recently genetic factors are considered to contribute to obesity, relatively little is known about the specific loci related to obesity and the mechanisms by which they cause obesity.

Genetic variants in the FAM3C gene are associated with lipid traits in Chinese children

BACKGROUND

Previous studies have related FAM3C gene with childhood bone health, and the regulation of lipid metabolism in hepatocytes. The present case-control study aimed to analyze the association of FAM3C genetic variants with overweight/obesity and lipid traits among Chinese children.

METHODS

Two genetic variants (rs7776725 and rs7793554) within the FAM3C gene were genotyped in 3305 Chinese children aged 6-18 years.

RESULTS

In the whole study population, the T-allele of rs7776725 and A-allele of rs7793554 within the FAM3C gene were associated with 40.2% (95% CI: 11.6-76.1%; P = 0.004) and 29.1% (6.9-56.0%; P = 0.008) increased risk of dyslipidemia, higher triglyceride (P = 0.014 and P = 0.001) and lower HDL-C (P = 0.015 and P = 0.003). In addition, we found that rs7776725 interacted with sex on dyslipidemia (P_{for interaction} = 0.004), and sex-stratified analyses showed that it was significantly associated with dyslipidemia only in girls (P = 8.78 × 10^-5). The variant also showed nominally significant interactions with sex on total cholesterol and LDL-C (P_{for interaction} = 0.012 and 0.008).

CONCLUSION

We found that FAM3C genetic variants were associated with dyslipidemia and lipid traits among Chinese children. In addition, we found significant gene-by-sex interactions. Our findings provided evidence supporting the role of FAM3C gene in regulating lipid metabolism in humans.

IMPACT

FAM3C genetic variants were associated with dyslipidemia and lipid traits among Chinese children. In addition, we found significant gene-by-sex interactions. FAM3C/rs7776725 was associated with dyslipidemia and lipid traits only in girls. Our findings provided evidence supporting the role of FAM3C gene in regulating lipid metabolism in humans.

A Genome-Wide Association Study of Childhood Body Fatness

OBJECTIVE

This study aimed to uncover genetic contributors to adiposity in early life.

METHODS

A genome-wide association study of childhood body fatness in 34,401 individuals within the Nurses' Health Studies and the Health Professionals Follow-up Study was conducted. Data were imputed to the 1000 Genomes Phase 3 version 5 reference panel.

RESULTS

A total of 1,354 single-nucleotide polymorphisms (P < 10^-4 ) were selected for replication in a previously published genome-wide association study of childhood BMI. Nineteen significant genome-wide (P < 5 × 10^-8 ) regions were observed, fourteen of which were previously associated with childhood obesity and five were novel: BNDF (P = 7.58 × 10^-13 ), PRKD1 (P = 1.43 × 10^-10 ), 20p13 (P = 2.05 × 10^-10 ), FHIT (P = 1.77 × 10^-8 ), and LOC101927575 (P = 3.22 × 10^-8 ). The BNDF, FHIT, and PRKD1 regions were previously associated with adult BMI. LOC101927575 and 20p13 regions have not previously been associated with adiposity phenotypes. In a transcriptome-wide analysis, associations for POMC at 2p23.3 (P = 3.36 × 10^-6 ) and with TMEM18 at 2p25.3 (P = 3.53 × 10^-7 ) were observed. Childhood body fatness was genetically correlated with hip (r_g = 0.42, P = 4.44 × 10^-16 ) and waist circumference (r_g = 0.39, P = 5.56 × 10^-16 ), as well as age at menarche (r_g = -0.37, P = 7.96 × 10^-19 ).

CONCLUSIONS

Additional loci that contribute to childhood adiposity were identified, further explicating its genetic architecture.

Causal associations of body mass index and waist-to-hip ratio with cardiometabolic traits among Chinese children: A Mendelian randomization study

BACKGROUND AND AIMS

Body mass index (BMI) and waist-to-hip ratio (WHR) have been reported to be causally associated with cardiometabolic diseases in adults in European populations. However, this causality was less explored in East Asian populations and in children. Our study aimed to explore and compare the causal associations of general obesity (measured by BMI) and central obesity (measured by WHR) with cardiometabolic traits.

METHODS AND RESULTS

We performed a Mendelian randomization (MR) analysis in 2030 unrelated children from two independent case-control studies in Beijing, China. BMI-associated single nucleotide polymorphisms (SNPs) and WHR-SNPs identified by previous genome-wide association studies were used as genetic instruments to examine the casual associations of BMI and WHR with cardiometabolic traits, including glycemic traits, blood lipids, and blood pressure. Each 1-SD increase in BMI and WHR were significantly associated with 0.111 mmol/L and 0.110 mmol/L increase in log-transformed fasting insulin (FINS), 0.049 and 0.060 increase in log-transformed HOMA-β, 0.112 and 0.108 increase in log-transformed HOMA-IR, 0.009 mmol/L and 0.015 mmol/L increase in log-transformed triglyceride, and 15.527 mmHg and 7.277 mmHg increase in systolic blood pressure, respectively (all P < 0.05). The receiver operating characteristic curves showed that WHR had a stronger effect on FINS, HOMA-β, HOMA-IR, and triglyceride than BMI (all P < 0.05).

CONCLUSIONS

Using the MR method, we found that the genetic predisposition to higher BMI or WHR was associated with altered cardiometabolic traits in Chinese children. When compared with general obesity, central obesity might have stronger effects on glycemic traits and blood lipids among children.

A trans-ancestral meta-analysis of genome-wide association studies reveals loci associated with childhood obesity

Although hundreds of genome-wide association studies-implicated loci have been reported for adult obesity-related traits, less is known about the genetics specific for early-onset obesity and with only a few studies conducted in non-European populations to date. Searching for additional genetic variants associated with childhood obesity, we performed a trans-ancestral meta-analysis of 30 studies consisting of up to 13 005 cases (≥95th percentile of body mass index (BMI) achieved 2-18 years old) and 15 599 controls (consistently <50th percentile of BMI) of European, African, North/South American and East Asian ancestry. Suggestive loci were taken forward for replication in a sample of 1888 cases and 4689 controls from seven cohorts of European and North/South American ancestry. In addition to observing 18 previously implicated BMI or obesity loci, for both early and late onset, we uncovered one completely novel locus in this trans-ancestral analysis (nearest gene, METTL15). The variant was nominally associated with only the European subgroup analysis but had a consistent direction of effect in other ethnicities. We then utilized trans-ancestral Bayesian analysis to narrow down the location of the probable causal variant at each genome-wide significant signal. Of all the fine-mapped loci, we were able to narrow down the causative variant at four known loci to fewer than 10 single nucleotide polymorphisms (SNPs) (FAIM2, GNPDA2, MC4R and SEC16B loci). In conclusion, an ethnically diverse setting has enabled us to both identify an additional pediatric obesity locus and further fine-map existing loci.

Interaction between lifestyle behaviors and genetic polymorphism in SCAP gene on blood pressure among Chinese children

BACKGROUNDS

Previous studies had revealed that sterol regulatory element-binding protein (SREBP) cleavage-activating protein (SCAP) rs12487736 polymorphism was associated with blood pressure (BP), but whether rs12487736 could interact with lifestyle behaviors on BP is unknown.

METHODS

A case-control study with 1092 Chinese children was conducted.

RESULTS

We found an interaction between rs12487736 and high calorie foods intake (fried chips/cakes/cookies) on systolic blood pressure (SBP) (P_interaction = 0.027), and rs12487736 was associated with SBP in the subgroup having high calorie foods at least once in the last week (b = 2.19, P = 0.025), but not in the subgroup not having high calorie foods. Also, interaction between protein intake (meat/fish/soy beans/egg) and rs12487736 on diastolic BP (DBP) was identified (P_interaction = 0.049); rs12487736 was associated with DBP in the subgroup consuming protein (meat/fish/soy beans/egg) <twice/day (b = 3.38, P = 0.014), but not in the subgroup ≥twice/day. There is combined effect between rs12487736 and physical activity on DBP. In the subgroup who were inactive (physical activity <1 h/day), rs12487736 was significantly associated with DBP (b = 3.27, P = 0.046), but not in the active group (physical activity ≥1 h/day). Similar combined effect between rs12487736 and soft drink was found.

CONCLUSIONS

Interactions or combined effects between SCAP and lifestyle behaviors on BP support the importance of promoting a healthy lifestyle in the children genetically predisposed to higher BP.

Physical activity attenuates the association between the IRS1 genotype and childhood obesity in Chinese children

BACKGROUND AND AIMS

The insulin receptor substrate 1 (IRS1) rs2943650 was found to be associated with obesity in adults, but the association has not been evaluated in children. The present study aimed to examine whether IRS1 rs2943650 was associated with obesity in Chinese children and investigate the interaction between rs2943650 and physical activity.

METHODS AND RESULTS

IRS1 rs2943650 was genotyped in 3303 Chinese children aged 6-18 years recruited from four independent studies. Logistic regression and linear regression were performed to examine associations. Meta-analyses were conducted to pool the results of the four independent studies. The C-allele carriers of rs2943650 showed a 29% higher risk of obesity than noncarriers (OR (95% CI) = 1.29 (1.05, 1.58), P = 0.02) and a 0.41 kg/m² increase in BMI (β (95% CI) = 0.41 (0.05, 0.78) kg/m², P = 0.02). We also observed significant interactions between rs2943650 and physical activity/sedentary behaviors on obesity (P_{forinteraction}<0.05). Compared with the physically active children (physical activity ≥1 h/d and sedentary behaviors <2 h/d), the risk allele (C) of rs2943650 was significantly associated with a 241% increased risk of obesity among inactive children who participated in physical activity <1 h/d and sedentary behaviors ≥2 h/d (OR (95% CI) = 3.41 (1.45, 8.01), P = 0.005).

CONCLUSIONS

We found that IRS1 rs2943650 was significantly associated with BMI and risk of childhood obesity. Additionally, we also found significant interaction between IRS1 rs2943650 polymorphism and physical activity/sedentary behaviors on childhood obesity. Our study would provide novel insights into the function of the IRS1 gene and the implementation of effective intervention strategies of childhood obesity.

Low Salivary Amylase Gene (AMY1) Copy Number Is Associated with Obesity and Gut Prevotella Abundance in Mexican Children and Adults

Genome-wide association studies (GWAS) have identified copy number variants (CNVs) associated with obesity in chromosomal regions 1p31.1, 10q11.22, 11q11, 16p12.3, and recently 1p21.1, which contains the salivary amylase gene (AMY1). Recent evidence suggests this enzyme may influence gut microbiota composition through carbohydrate (mainly starch) degradation. The role of these CNVs in obesity has been scarcely explored in the Latino population, and thus the aim of our study was to evaluate the association of 1p31.1, 10q11.22, 11q11, 16p12.3 and 1p21.1 CNVs with obesity in 921 Mexican children, to replicate significant associations in 920 Mexican adults, and to analyze the association of AMY1 copy number with gut microbiota in 75 children and 45 adults. Of the five CNVs analyzed, 1q11 CNV was significantly associated with obesity in children, but not in adults. Only AMY1 CNV was significantly associated with obesity in both age groups. Moreover, gut microbiota analyses revealed a positive correlation between AMY1 copy number and Prevotella abundance. This genus has enzymes and gene clusters essential for complex polysaccharide degradation and utilization. To our knowledge, this is the first study to analyze the association of these five CNVs in the Mexican population and to report a correlation between AMY1 CN and gut microbiota in humans.

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.

Birthweight, time-varying adiposity growth and early menarche in girls: A Mendelian randomisation and mediation analysis

OBJECTIVE

To explore the causal effect of time-varying z-BMI growth on early menarche using Mendelian randomisation (MR); to identify critical adiposity predictors of early menarche; to compare the effects of birthweight and time-varying z-BMI growth as mediators of the path from genes to early menarche using mediation analysis.

METHODS

We used data from the Taiwan Children Health Study with 21 obesity-related single-nucleotide polymorphisms (SNPs) to yield genetic (instrumental variable)IVs for adiposity. Children with available data on genotyping, birthweight, adiposity, and menarcheal age were included.

RESULTS

In MR analyses, results based on the time-varying z-BMI growth show more statistical power and capture more information of adiposity growth (p=0.01) than those based on single point z-BMI (p=0.02). Among adiposity measures, critical predictors of early menarche are fat free mass (RR=1.33, 95% CI 1.07-1.65) and waist/height ratio (RR=1.27, 95% CI 1.03-1.56). Other potential predictors of early menarche are sum of skinfold (RR=1.24, 95% CI 1.03-1.48) and total body fat (RR=1.20, 95% CI 1.05-1.38). In both one-mediation and multi-mediation analyses, time-varying z-BMI growth in the prepubertal years plays a crucial mediator in the pathway from the genes to early menarche.

CONCLUSIONS

This study discovered that greater prepubertal adiposity growth is a crucial mediator in the path from genes to early menarche. For girls with genes positively associated with obesity; and/or of lower birthweight, a strategy to prevent childhood adiposity should be implemented in order to avoid early menarche development.

Waist-hip ratio related genetic loci are associated with risk of impaired fasting glucose in Chinese children: a case control study

Background

The meta-analyses of genome-wide association studies identified several waist-hip ratio (WHR) related loci in individuals of European ancestry. Since the pattern of fat distribution and the relationship between fat distribution and glucose metabolism disturbance in Chinese are different from those in Europeans, the present study aimed to explore the individual and cumulative effects of WHR-related loci on glycemic phenotypes in Chinese children.

Methods

A total of 2030 children were recruited from two independent studies. Eleven single nucleotide polymorphisms (SNPs) were selected and genotyped using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). Logistic regression and linear regression model were used to examine the association of 11 SNPs and genetic risk score (GRS) with impaired fasting glucose (IFG) and fasting plasma glucose (FPG), respectively.

Results

Three SNPs (rs6795735, rs984222 and rs1011731) were nominally associated with IFG (all P < 0.05). Each WHR-increasing (C) allele of rs6795735 (ADAMTS9) was associated with a 40.1% increased risk of IFG (OR = 1.401, 95% CI = 1.131–1.735, P = 0.002), which remained significant after Bonferroni correction. We observed no association of both weighted and unweighted GRS with FPG and IFG (all P > 0.05).

Conclusions

We identified individual effects of rs6795735 (ADAMTS9), rs984222 (TBX15-WARS2), and rs1011731 (DNM3-PIGC) on glycemic phenotypes in Chinese children for the first time. The study suggests that genetic predisposition to central obesity is associated with impaired fasting glucose, providing more evidence for the pathogenesis of diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12986-018-0270-2) contains supplementary material, which is available to authorized users.

Overweight and Obesity in Schoolchildren: Hierarchical Analysis of Associated Demographic, Behavioral, and Biological Factors

Studies focused on the mechanisms involved in the development of obesity in children and adolescents have reported associations between this condition and birth weight, sedentary lifestyle, and hereditary conditions. However, few studies have simultaneously evaluated these factors. This cross-sectional study aims to identify demographic, behavioral, and biological factors associated with overweight/obesity in children and adolescents. 381 schoolchildren aged seven to 17 years were included in the study to evaluate the associations between overweight/obesity and biological factors (including family history of obesity, birth weight, and the fat mass and obesity-associated (FTO) rs9939609 polymorphism), demographic variables (including gender and age), and behavioral variables (including physical activity and/or sports participation). The results of this study showed that there was a lower prevalence of obesity in schoolchildren aged 11-17 years (PR: 0.89; p=0.004). Obesity was more prevalent in children whose father (PR: 1.24; p < 0.001) and maternal grandmother (PR: 1.16; p=0.019) were obese. Higher prevalence rates of obesity were also identified in schoolchildren who were overweight at birth (PR: 1.18; p=0.002) and carriers of the obesity risk genotype (PR: 1.13; p=0.016). Biological factors, such as family history of obesity, overweight at birth, and the presence of the fat mass and obesity-associated rs9939609 polymorphism were associated with the prevalence of obesity in children and adolescents.

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

Background

Recent studies indicated that eating behaviors are under genetic influence, and the melanocortin 4 receptor (MC4R) gene polymorphisms can affect the total energy intake and the consumption of fat, protein and carbohydrates. Our study aims at investigating the association of the MC4R polymorphism with appetite and food intake among Chinese children.

Methods

A family-based association study was conducted among 151 Chinese trios whose offsprings were overweight/obese children aged 9–15 years. The rs12970134 near MC4R was genotyped, and the Children Eating Behavior Questionnaire (CEBQ) and a self-designed questionnaire measuring food intake were performed. The FBAT and PBAT software packages were used.

Results

The family-based association analysis showed that there was a significant association between rs12970134 and obesity (Z = 2.449, P = 0.014). After adjusting for age, gender and standardized BMI, rs12970134 was significantly associated with food responsiveness (FR) among children (β'_b = 0.077, P_b = 0.028), and with satiety responsiveness (SR) in trios (P = -0.026). The polymorphism was associated with beverage intake (β'_b = 0.331, P_b = 0.00016 in children; P = 0.043 in trios), but not significantly associated with vegetable, fruit or meat intake (P>0.050). We further found a significant mediation effect among the rs12970134, FR and beverage intake (b = 0.177, P = 0.047).

Conclusions

Our study is the first to report that rs12970134 near MC4R was associated with appetite and beverage intake, and food responsiveness could mediate the effect of rs12970134 on beverage intake in overweight and obese Chinese children population. Further studies are needed to uncover the genetic basis for eating behaviors, which could lead to develop and implement effective interventional strategies early in life.

Association Study of Three Gene Polymorphisms Recently Identified by a Genome-Wide Association Study with Obesity-Related Phenotypes in Chinese Children

OBJECTIVE

This study aimed to examine associations of three single-nucleotide polymorphisms (SNPs) with obesity-related phenotypes in Chinese children. These SNPs were identified by a recent genome-wide association (GWA) study among European children. Given that varied genetic backgrounds across different ethnicity may result in different association, it is necessary to study these associations in a different ethnic population.

METHODS

A total of 3,922 children, including 2,191 normal-weight, 873 overweight and 858 obese children, from three independent studies were included in the study. Logistic and linear regressions were performed, and meta-analyses were conducted to assess the associations between the SNPs and obesity-related phenotypes.

RESULTS

The pooled odds ratios of the A-allele of rs564343 in PACS1 for obesity and severe obesity were 1.180 (p = 0.03) and 1.312 (p = 0.004), respectively. We also found that rs564343 was nominally associated with BMI, BMI standard deviation score (BMI-SDS), waist circumference, and waist-to-height ratio (p < 0.05).

CONCLUSIONS

We showed for the first time that the rs564343 in PACS1 was associated with risk of severe obesity in a non-European population. This SNP was also found to be associated with common obesity and various obesity-related phenotypes in Chinese children, which had not been reported in the original study. The results demonstrated the value of conducting genetic researches in populations with different ethnicity.

Physical activity and sedentary behavior can modulate the effect of the PNPLA3 variant on childhood NAFLD: a case-control study in a Chinese population

Background

The patatin like phospholipase containing domain 3 gene (PNPLA3) rs738409 C > G polymorphism, one of the most important gene polymorphisms involved in hepatic steatosis, has been reported to interact with different nutrients and dietary patterns on Non-Alcoholic Fatty Liver Disease (NAFLD), but no studies have focused on its interaction with physical activity or sedentary behavior. Therefore, this study aims at determining whether physical activity or sedentary behavior could modulate the effect of the PNPLA3 variant on childhood NAFLD.

Methods

A case-control study was conducted including 1027 Chinese children aged 7–18 years old (162 children with NAFLD and 865 children without). The anthropometric measurements, liver ultrasound examination, questionnaires and genotyping of the PNPLA3 rs738409 polymorphism were performed.

Results

Stratified analyses showed that the proportions of NAFLD increased with the G-allele number only in children who did not have enough physical activity (physical activity < 1 h/d) (OR 3.05, 95% CI 1.82–5.12, P < 0.001), and in children with a sedentary lifestyle (sedentary behavior ≥ 2 h/d) (OR 3.41, 95% CI 1.88–6.18, P < 0.001). Significant interactions on childhood NAFLD were found between the G-allele number in the PNPLA3 rs738409 polymorphism and behaviors, including physical activity (P = 0.001), sedentary behavior (P = 0.010) and the combination of physical activity and sedentary behavior (P < 0.001).

Conclusion

This is the first study to report the interaction between the PNPLA3 rs738409 polymorphism and physical activity or sedentary behavior on NAFLD, providing new clues on the function of the PNPLA3 gene, which will also be useful for future risk assessment and personalized treatment of NAFLD.

Electronic supplementary material

The online version of this article (doi:10.1186/s12881-016-0352-9) contains supplementary material, which is available to authorized users.

HIF3A DNA Methylation Is Associated with Childhood Obesity and ALT

Gene polymorphisms associated so far with body mass index (BMI) can explain only 1.18–1.45% of observed variation in BMI. Recent studies suggest that epigenetic modifications, especially DNA methylation, could contribute to explain part of the missing heritability, and two epigenetic genome-wide analysis studies (EWAS) have reported that Hypoxia Inducible Factor 3 Alpha Subunit (HIF3A) methylation was associated with BMI or BMI change. We therefore assessed whether the HIF3A methylation is associated with obesity and other obesity-related phenotypes in Chinese children. The subjects included 110 severe obese cases aged 7–17y and 110 normal-weight controls matched by age and gender for measurement of blood DNA methylation levels at the HIF3A gene locus using the Sequenom’s MassARRAY system. We observed significantly higher methylation levels in obese children than in controls at positions 46801642 and 46801699 in HIF3A gene (P<0.05), and found positive associations between methylation and alanine aminotransferase (ALT) levels adjusted by gender, age and BMI at the position 46801699 (r = 0.226, P = 0.007). These results suggest that HIF3A DNA methylation is associated with childhood obesity, and has a BMI-independent association with ALT. The results provide evidence for identifying epigenetic factors of elivated ALT and may be useful for risk assessment and personalized medicine of liver diseases such as non-alcoholic fatty liver disease (NAFLD).