Obesity Susceptibility Genes Research Articles

Methylation Patterns of Diabetes and Obesity Susceptibility Genes in Gestational Diabetes Mellitus: A Cross-Sectional Analysis from Karachi, Pakistan.

Background: Women with gestational diabetes mellitus (GDM) and their offspring have an increased risk of adverse perinatal and long-term health outcomes, which may be attributable to epigenetic modification of diabetes and obesity susceptibility genes. We aimed to investigate the methylation patterns of eight genes in GDM and normoglycemic (NG) mothers, and their respective offspring. Methods: This cross-sectional study, conducted at Aga Khan University from August 2019 to December 2022, recruited pregnant women in the first trimester of gestation from the outpatient obstetrics clinic. Participants were classified as NG or GDM based on the Society of Obstetricians and Gynecologists Pakistan. Venous blood samples were collected from mothers and cord blood from neonates. Peripheral blood mononuclear cells were used for DNA extraction and methylation analysis using methylation-specific PCR. Maternal and neonatal clinical data were recorded. Statistical analysis was performed using R, including binary logistic regression to assess the association between various gene methylation levels and GDM. Results: The study found that GDM mothers had significantly higher fasting blood glucose, 2-hr OGTT, and serum carboxymethyl lysine (CML) levels compared to NG mothers, but no significant differences in neonatal birth weight or serum CML levels. Chemerin methylation was significantly lower in GDM mothers and their babies, while NAMPT, MTNR1B, FNDC5, FAT4, and FTO methylation levels were higher in GDM offspring compared to NG offspring. GDM mothers also had higher methylation levels of brain-derived neurotrophic factor gene (BDNF). Multivariable binary logistic regression identified methylation levels of maternal BDNF and neonatal MTNR1B to be independently associated with GDM. Conclusions: Our study shows a trend of epigenetic modifications in both GDM mothers and their offspring in various genes related to metabolism and inflammation, suggesting an intergenerational transmission of increased risk of developing metabolic disorders. These findings emphasize the need for high throughput studies, early screening, tight glucose control during pregnancy, and postnatal follow-up to mitigate long-term health risks.

Aging reveals a sex-dependent susceptibility of sarcospan-deficient mice to cardiometabolic disease.

Numerous genes including sarcospan (SSPN) have been designated as obesity-susceptibility genes by human genome-wide association studies. Variants in the SSPN locus have been linked with sex-dependent obesity-associated traits; however, this association has not been investigated in vivo. To delineate the role SSPN plays in regulating metabolism with potential to impact cardiac function, we subjected young and aged global SSPN-deficient (SSPN-/-) male and female mice to obesogenic conditions (60% fat diet). We hypothesized that loss of SSPN combined with metabolic stress would increase susceptibility of mice to cardiometabolic disease. Baseline and end-point assessments of several anthropometric parameters were performed including weight, glucose tolerance, and fat distribution of mice fed control (CD) and high-fat (HFD) diet. Doppler echocardiography was used to monitor cardiac function. White adipose and cardiac tissues were assessed for inflammation by histological, gene expression, and cytokine analysis. Overall, SSPN deficiency protected both sexes and ages from diet-induced obesity, with a greater effect in females. SSPN-/- HFD mice gained less weight than wild-type (WT) cohorts, while SSPN-/- CD groups increased weight. Furthermore, aged SSPN-/- mice developed glucose intolerance regardless of diet. Echocardiography showed preserved systolic function for all groups; however, aged SSPN-/- males exhibited significant increases in left ventricular mass (CD) and signs of diastolic dysfunction (HFD). Cytokine analysis revealed significantly increased IL-1α and IL-17Α in white adipose tissue from young SSPN-/- male mice, which may be protective from diet-induced obesity. Overall, these studies suggest that several sex-dependent mechanisms influence the role SSPN plays in metabolic responses that become evident with age.NEW & NOTEWORTHY Young and aged sarcospan (SSPN)-deficient mice were examined to assess the role of SSPN in obesity and cardiometabolic disease. Both sexes displayed a "leaner" phenotype in response to high-fat diet (HFD). Notably, several sex differences were identified in aged SSPN-deficient mice: 1) females developed glucose intolerance (control and HFD) and 2) males exhibited increased left ventricular mass (control) and diastolic dysfunction (HFD). Therefore, we conclude that SSPN exerts a sex-dependent influence on obesity-associated diseases.

Association of LEP rs2167270 and LEPR rs1137100 genetic variants with obesity in the Jordanian population cohort

Background Previous Genome Wide Association Studies (GWAS) of obesity susceptibility genes in different populations have confirmed the association of some variants with obesity, body mass index (BMI), and some related metabolic traits. To our knowledge, the current study is the first to investigate the genetic basis of obesity in the Jordanian population. The aim of our study is to investigate the occurrence and frequency of obesity-related genes in Jordanian individuals and any possible relationship between SNP genetic markers and phenotypic characteristics of studied individuals. Methods A total of 150 Jordanian unrelated adults, including 83 obese, 26 overweight, and 41 normal-weight subjects, were genotyped using the high resolution melt analysis (HRMA) and tested for the association of single nucleotide polymorphisms (SNPs), rs2167270 in LEP gene and rs1137100 in LEPR gene, with obesity risk, obesity/overweight risk, BMI, weight, height, total cholesterol, HDL-cholesterol, LDL-cholesterol, triglycerides, and blood level glucose. Results A significant association between obesity risk and the rs2167270 mutation in LEP gene was observed under a dominant model (odds ratio (OR) = 2.5147, 95% CI =1.0629 to 5.9494, p = 0.0358). A marginal (not significant) association between BMI and the rs2167270 mutation in LEP gene (p = 0.075), was also detected. Moreover, an association between rs2167270 mutation in LEP gene and glucose blood level was observed (p = 0.038). Total cholesterol and LDL-cholesterol also presented a weak association with the rs1137100 mutation in LEPR gene, with p = 0.071 and p = 0.078, respectively. Additionally, no significant association between LDL-cholesterol and the rs2167270 mutation in LEP gene was observed (p = 0.091). By contrast, there was no association between weight or height and the SNPs mutation evaluated in this study (p > 0.05). Conclusions These results suggest that some SNPs in some obesity-related genes may contribute to obesity risk and its related anthropometric and metabolic traits in Jordanian population. To confirm these results, further studies on a larger Jordanian cohort should be carried out.

Association study of obesity susceptibility gene polymorphisms in relation to 5 tunisian families

Association study of obesity susceptibility gene polymorphisms in relation to 5 tunisian families

Emerging Role and Mechanism of the FTO Gene in Cardiovascular Diseases.

The fat mass and obesity-associated (FTO) gene was the first obesity-susceptibility gene identified through a genome-wide association study (GWAS). A growing number of studies have suggested that genetic variants of FTO are strongly associated with the risk of cardiovascular diseases, including hypertension and acute coronary syndrome. In addition, FTO was also the first N6-methyladenosine (m6A) demethylase, suggesting the reversible nature of m6A modification. m6A is dynamically deposited, removed, and recognized by m6A methylases, demethylases, and m6A binding proteins, respectively. By catalyzing m6A demethylation on mRNA, FTO may participate in various biological processes by modulating RNA function. Recent studies demonstrated that FTO plays a pivotal role in the initiation and progression of cardiovascular diseases such as myocardial fibrosis, heart failure, and atherosclerosis and may hold promise as a potential therapeutic target for treating or preventing a variety of cardiovascular diseases. Here, we review the association between FTO genetic variants and cardiovascular disease risk, summarize the role of FTO as an m6A demethylase in cardiovascular disorders, and discuss future research directions and possible clinical implications.

Fine Mapping of the MAP2K5 Region Identified rs7175517 as a Causal Variant Related to BMI in China and the United Kingdom Populations.

Background: Genome-wide association studies (GWASs) have consistently identified MAP2K5 as an obesity susceptibility gene. To deepen our understanding of the potential causal genetic variants of this region, a fine-mapping study of MAP2K5 was conducted. Methods and Results: SNPs rs7175517 (G > A) and rs4776970 (T > A) were identified as the leading SNPs associated with BMI in both Chinese and the United Kingdom populations. Second, colocalization of GWAS and expression quantitative trait loci (eQTL) analyses and bioinformatic analyses indicated that rs7175517 is the functionally leading variant in the MAP2K5 gene region. Dual-luciferase assays indicated that the G allele of rs7175517 reduced the mRNA expression of MAP2K5 in HEK293T cells. The possible mechanism was that the G allele interacted with more RNA repressors from nuclei extracts, which was evidenced by electrophoretic mobility shift assays (EMSAs). Furthermore, the pathway enrichment analyses of the products from DNA pull-down and protein mass spectrometry demonstrated that the G allele of rs7175517 might interact with RNA catabolic or splicing transcription factors, which consequentially increased adiposity deposition. Conclusion: SNP rs7175517 of the MAP2K5 gene was the putative causal variant associated with BMI. More precisely designed in vitro or animal experiments are warranted to further delineate the function of MAP2K5 in adipogenesis.

The rs45454496 (E1813K) variant in the adiposity gene ANK2 doesn't associate with obesity in Southern European subjects

Recently ANK2, encoding ankyrin-B (AnkB), has been proposed as an obesity susceptibility gene. AnKB negatively regulates the expression of glucose transporter 4 (GLUT4) in adipocytes, and it has been hypothesized that functional alterations of AnkB may determine the persistence of GLUT4 on the cell surface, increasing glucose transport in adipocytes. Adipose tissue-specific AnkB-KO mice develop obesity and progressive pancreatic islet dysfunction with age or high-fat diet. AnkB-deficient adipocytes exhibit increased lipid accumulation associated with increased glucose uptake and impaired endocytosis of GLUT4. Functional alterations have been observed in ANK2 gene in European Americans and African Americans and have been proposed as candidates to contribute to obesity susceptibility in humans.Considering that variants of ANK2 gene were previously observed in subjects of American and African American ethnicity, and that these variants were never studied in association with obesity, we performed a genetic association analysis with obesity in a cohort of Southern European subjects.For this study 1900 Italian subjects with body mass index (BMI) between 16 and 91 were selected.All subjects underwent clinical examination, anthropometric measurements and routine laboratory tests. The SNPs rs45454496 (E1813K) and rs35530544 (L1622I) have been studied in DNAs by Eco TM Real-Time PCR System by Illumina.Among the 1900 subjects we identified 15 (frequency 0.7%) heterozygous subjects for the rs45454496 variant and no homozygous subject. The observed frequency in our population is more than double that observed in other populations of European origin (0.7% vs 0.3%, p = 0.3).We then analysed the association between this polymorphism and clinical and biochemical characteristics. Carriers of the mutation showed no significantly differences compared to wild-type subjects in any of the parameters examined. Population stratification by BMI showed a random distribution of the rs45454496 variant according to weight. Also, population stratification based on glycaemic alterations showed no association of the rs45454496 variant with categories of glucose metabolism. Finally, we analysed the study cohort for the rs35530544, but we did not observe any subject carrying the variant in an initial sample of 840 patients.In conclusion, we observed that the rs45454496 (E1813K) variant of ANK2 gene, although showing a higher frequency in our Southern European population (0.7%) than the frequencies reported in other populations of European origin, in the analysed sample does not seem to have effects on clinical and metabolic alterations.

890-P: CDK5 Regulatory Subunit-Associated Protein 1-Like 1 Promotes Adipocyte Proliferation through Transcriptional Activation of NEK8 in T2DM and Obesity

Background: Adipogenesis is a complex biological process and the main cause of obesity. CDK5 Regulatory Subunit-Associated Protein 1-like 1 (CDKAL1) serves as a susceptibility gene for obesity and type 2 diabetes (T2DM). However, whether CDKAL1 plays any functional role in adipocyte proliferation had not been well investigated. Methods: CDKAL1 expression was manipulated using a specific shRNA or the CDKAL1-full length expressing recombinant plasmids. MTT assay was performed to determine 3T3-L1 cell growth with either overexpression or downregulation of CDKAL1. Interaction between CDKAL1 and never-in-mitosis A-related kinase 8 (NEK8) in HEK293T and 3T3-L1 cells was examined using Co-immunoprecipitation (Co-IP) and Confocal immunofluorescence staining. Western blot assay was performed to determine the protein expression of NEK8 and CDKAL1. Dual-luciferase reporter assay was used to detect the transcriptional regulation of CDKAL1 on NEK8. The in vivo role of CDKAL1 and NEK8 was explored in an in vivo mouse model of T2DM. Results: In the present study, we found that overexpression of CDKAL1 promoted adipocyte proliferation of 3T3-L1 cells, whereas knockdown of CDKAL1 delayed 3T3-L1 proliferation. Mechanically, CDKAL1 interacted with NEK8 and transcriptionally activated its expression in adipocytes. Moreover, elevated levels of CDKAL1 and NEK8 were observed in patients with T2DM compared to the healthy subjects. Implantation of 3T3-L1 cells with CDKAL1 overexpression increased blood glucose in dietetic mice. Conclusions: Collectively, these findings suggest that CDKAL1 functions as a positive regulator of adipocyte proliferation, providing novel experimental evidences into the link between CDKAL1 and T2DM and obesity. Disclosure Y. Chen: None. Funding Chinese Postdoctoral Science Foundation (2019M651218); Natural Science Foundation of Jilin Province (20190201031JC)

Relationship of FTO gene variations with NAFLD risk in Chinese men.

BackgroundFat mass and obesity-associated (FTO) gene is an obesity susceptibility gene and its relationship with the nonalcoholic fatty liver disease (NAFLD) remains unclear. This study aims to investigate the relationships of FTO gene variations with NAFLD risk in a Chinese male population.MethodsA 1:2 matched case–control study was performed on 275 cases of NAFLD and 550 controls matched for age. Nine of the FTO gene single nucleotide polymorphisms (SNPs) were genotyped.ResultsLogistic regression analysis found that FTO rs1477196 was significantly associated with the susceptibility to NAFLD in recessive genetic models [unadjusted odds ratio (OR) = 2.52, 95% confidence interval (CI): 1.22–5.19, P = 0.012] and the relativity weakened after further adjustment for body mass index (BMI), uric acid, metabolic syndrome, smoking, and drinking (adjusted OR = 2.18, 95% CI: 0.96–4.99, P = 0.06). In the obese group, the AA + AG genotypes of rs1121980 and rs9940128 were associated with a decreased risk of NAFLD, when compared with the GG genotype, respectively (rs1121980: adjusted OR = 0.62, 95% CI = 0.39–0.99, P = 0.044; rs9940128: adjusted OR = 0.61, 95% CI = 0.38–0.97, P = 0.038). Furthermore, rs1477196 was associated with the severity of NAFLD (OR = 2.95, 95% CI = 1.09–7.94, P = 0.034).ConclusionsOur results demonstrated that the FTO gene was related to the presence and severity of NAFLD in a Chinese male population, and the relationships of the tested SNPs with NAFLD are most probably mediated by BMI.

The association of dietary and plasma fatty acid composition with FTO gene expression in human visceral and subcutaneous adipose tissues.

The human obesity susceptibility gene, FTO, associates with body mass and obesity in humans through regulation of energy expenditure and intake. We aimed to determine how fatty acids in plasma and in diet associate with FTO gene expression in subcutaneous and visceral adipose tissues. In this study, 97 participants aged ≥ 18years were selected from patients admitted to the hospital for abdominal surgeries. Habitual dietary intake of participants was collected using a valid and reliable food frequency questionnaire (FFQ), from which the intake of fatty acids was quantified. Plasma fatty acids were assessed by gas-liquid chromatography. The mRNA expression of the FTO gene in visceral and subcutaneous adipose tissues obtained by biopsy was measured by Real-Time Quantitative Reverse Transcription PCR. Standardized β-coefficients were calculated by multivariable linear regression. After adjusting for age, homeostasis model insulin resistance index (HOMA-IR), and body mass index, total fatty acid intake was significantly associated with FTO gene expression in visceral (STZβ = 0.208, P = 0.037) and subcutaneous (STZβ = 0.236, P = 0.020) adipose tissues. Dietary intake of monounsaturated fatty acid (MUFA) and polyunsaturated fatty acids (PUFA) had positive significant associations with the expression of FTO in visceral (STZβ = 0.227, P = 0.023; STZβ = 0.346, P < 0.001, respectively) and subcutaneous (STZβ = 0.227, P = 0.026; STZβ = 0.274, P = 0.006, respectively) adipose tissues. There were no associations between plasma fatty acids and FTO mRNA expression in either subcutaneous or visceral adipose tissues. The weak association of dietary total fatty acids, MUFA, and PUFA with FTO gene expression in both adipose tissues may highlight the importance of dietary fatty acids composition along with total fat intake in relation to FTO gene expression.

The Obesity-Susceptibility Gene TMEM18 Promotes Adipogenesis through Activation of PPARG

TMEM18 is the strongest candidate for childhood obesity identified from GWASs, yet as for most GWAS-derived obesity-susceptibility genes, the functional mechanism remains elusive. We here investigate the relevance of TMEM18 for adipose tissue development and obesity. We demonstrate that adipocyte TMEM18 expression is downregulated in children with obesity. Functionally, downregulation of TMEM18 impairs adipocyte formation in zebrafish and in human preadipocytes, indicating that TMEM18 is important for adipocyte differentiation invivo and invitro. On the molecular level, TMEM18 activates PPARG, particularly upregulating PPARG1 promoter activity, and this activation is repressed by inflammatory stimuli. The relationship between TMEM18 and PPARG1 is also evident in adipocytes of children and is clinically associated with obesity and adipocyte hypertrophy, inflammation, and insulin resistance. Our findings indicate a role of TMEM18 as an upstream regulator of PPARG signaling driving healthy adipogenesis, which is dysregulated with adipose tissue dysfunction and obesity.

The expression of genes in top obesity-associated loci is enriched in insula and substantia nigra brain regions involved in addiction and reward.

Genome-wide association studies (GWAS) have identified more than 250 loci associated with body mass index (BMI) and obesity. However, post-GWAS functional genomic investigations have been inadequate for understanding how these genetic loci physiologically impact disease development. We performed a PCR-free expression assay targeting genes located nearby the GWAS-identified SNPs associated with BMI/obesity in a large panel of human tissues. Furthermore, we analyzed several genetic risk scores (GRS) summing GWAS-identified alleles associated with increased BMI in 4,236 individuals. We found that the expression of BMI/obesity susceptibility genes is strongly enriched in the brain, especially in the insula (p = 4.7×10-9) and substantia nigra (p = 6.8×10-7), which are two brain regions involved in addiction and reward. Inversely, we found that top obesity/BMI-associated loci, including FTO, showed the strongest gene expression enrichment in the two brain regions. Our data suggest for the first time that the susceptibility genes for common obesity may have an effect on eating addiction and reward behaviors through their high expression in substantia nigra and insula, i.e. a different pattern from monogenic obesity genes that act in the hypothalamus and cause hyperphagia. Further epidemiological studies with relevant food behavior phenotypes are necessary to confirm these findings.

The Effect Of FTO rs9969309 Polymorphism On Body Composition in Chinese adults

The FTO (fat mass and obesity associated) gene, the first common obesity susceptibility gene in a Caucasian population, was reported by GWAS (genome-wide association studies) in 2007. PURPOSE: The aim of this study was to explore the effect of genotypes of FTO rs9969309 polymorphism on body composition related traits in Chinese adults. METHODS: Forty-three Chinese adults aged from 19 to 55 years old (32 males and 11 females) were recruited from Shenzhen University and a running club of local community. The subjects participated in physical activity at least three times per week with thirty minutes each session. Body composition related traits, including body weight (BW), hip circumference (HC), abdomen circumference (AC), waist-hip ratio (WHR), percentage of body fat (PBF), fat mass (FM), fat free mass (FFM) and body mass index (BMI), were analyzed by bioelectrical impedance analyzer (BH-380 in Beijing Acemeway Company). The genotypes of FTO rs9939609 were analyzed by the Beijing Genomics Institute. One-way ANOVA was used to compare between genotypes and body composition related data. RESULTS: There were three genotypes (TT, AT and AA) in rs9939609 polymorphism, in which 24 individuals with TT genotype, 16 individuals with AT genotype and 3 individuals with AA genotype. The body composition related traits, including HC, AC, BMI and FM, were significantly lower in TT genotypes than those in AA genotypes (p=0.017, p=0.004, p=0.002, p=0.006, respectively), and were significantly lower in TT genotypes than those in AT genotypes (p=0.025, p=0.023, p=0.010, p=0.041, respectively). Also, there was a significant difference only between TT and AA genotypes in WHR (p=0.015). No significant differences were found in the three genotypes with BW, PBF and FFM. CONCLUSION: The results indicate differences in several body composition parameters regarding the FTO rs9969309 polymorphism in a small sample of Chinese adults.

111The cardiometabolic consequences of obesity susceptibility gene variants in severe obesity

111The cardiometabolic consequences of obesity susceptibility gene variants in severe obesity

FTO rs9939609 Gene Polymorphism and Obesity: Lack of Association in Kidney Transplantation

The fat mass and obesity-associated (FTO) gene is one of the most important obesity susceptibility genes. Some FTO gene polymorphisms have been associated with obesity, diabetes, and hypertension, all conditions for which, after transplant, there is increased susceptibility, due to effects of immunosuppressive regimens. To evaluate whether FTO could be a candidate for targeted preventive intervention in the transplant setting, we investigated whether the common genetic variation, FTO rs9939609T>A, could affect weight gain and risk of cardiovascular complications in kidney transplantation. MethodsIn 198 kidney transplant recipients, FTO rs9939609 was investigated in association with body mass index (BMI)/obesity and with other clinical markers of posttransplant risk, then monitored up to 5 years after transplantation. Genotyping was performed using an allelic discrimination method on a real-time polymerase chain (PCR) system. Associations were analyzed using the chi-square test; differences between genotypes were examined with analysis of variance or Kruskal-Wallis test; tests for repeated measures and a general linear model analysis controlling for age and gender were also utilized. ResultsAllele and genotype frequencies of FTO rs9939609 in recipients (T/T, 29.8%; T/A, 49.0%; A/A, 21.2%; A, 45.7%; T, 54.3%) reflect those present in healthy Caucasian populations. In the face of pre-/posttransplant differences in total cholesterol, triglycerides, or fasting glucose, results did not show significant changes in these factors among genotypes either before or after transplantation. ConclusionThis study highlights a lack of association of FTO rs9939609T>A genotypes and posttransplant weight gain, plasma lipids, and fasting blood glucose in kidney transplantation.

Association of melatonin receptor 1 B gene (rs10830963 and rs9192552) polymorphısm with adolescent obesity and related comorbidities in Turkey.

ObjectiveTo examine the role of rs10830963 and rs8192552 polymorphisms in melatonin receptor 1 B (MTNR1B) gene on the development of obesity and related comorbidities among adolescents in South-Eastern Turkey.MethodsThe present study included 200 unrelated adolescents (100 obese, 100 normal weight). The rs8192552 and rs10830963 polymorphisms in the MTNR1B gene were genotyped using a PCR SNaPshot assay.ResultsNo statistically significant association was observed between MTNR1B gene rs8192552/rs10830963 polymorphisms and adolescent obesity. In adolescents with an rs8192552 E allele, homeostasis model assessment for insulin resistance (IR) level was lower and IR was less common. In morbidly obese adolescents with an rs8192552 E allele, total cholesterol level was lower. In obese adolescents with metabolic syndrome, plasma fasting glucose level was higher in rs10830963G allele carriers. In obese girls, body weight was lower in those with a rs10830963 C allele, whereas in obese boys, body weight and waist circumference were higher in those with a rs10830963 C allele.ConclusionsThe MTNR1B gene was not confirmed as an obesity susceptibility gene in adolescents. However, an association between the MTNR1B gene and IR/hypercholesterolemia/metabolic syndrome was observed in obese adolescents. A sex-specific effect on obesity was also identified.

Detecting epistasis within chromatin regulatory circuitry reveals CAND2 as a novel susceptibility gene for obesity.

Genome-wide association studies have identified many susceptibility loci for obesity. However, missing heritability problem is still challenging and ignorance of genetic interactions is believed to be an important cause. Current methods for detecting interactions usually do not consider regulatory elements in non-coding regions. Interaction analyses within chromatin regulatory circuitry may identify new susceptibility loci. We developed a pipeline named interaction analyses within chromatin regulatory circuitry (IACRC), to identify genetic interactions impacting body mass index (BMI). Potential interacting SNP pairs were obtained based on Hi-C datasets, PreSTIGE (Predicting Specific Tissue Interactions of Genes and Enhancers) algorithm, and super enhancer regions. SNP × SNP analyses were next performed in three GWAS datasets, including 2286 unrelated Caucasians from Kansas City, 3062 healthy Caucasians from the Gene Environment Association Studies initiative, and 3164 Hispanic subjects from the Women's Health Initiative. A total of 16,643,227 SNP × SNP analyses were performed. Meta-analyses showed that two SNP pairs, rs6808450-rs9813534 (combined P = 2.39 × 10-9) and rs6808450-rs3773306 (combined P = 2.89 × 10-9) were associated with BMI after multiple testing corrections. Single-SNP analyses did not detect significant association signals for these three SNPs. In obesity relevant cells, rs6808450 is located in intergenic enhancers, while rs9813534 and rs3773306 are located in the region of strong transcription regions of CAND2 and RPL32, respectively. The expression of CAND2 was significantly downregulated after the differentiation of human Simpson-Golabi-Behmel syndrome (SGBS) preadipocyte cells (P = 0.0241). Functional validation in the International Mouse Phenotyping Consortium database showed that CAND2 was associated with increased lean body mass and decreased total body fat amount. Detecting epistasis within chromatin regulatory circuitry identified CAND2 as a novel obesity susceptibility gene. We hope IACRC could facilitate the interaction analyses for complex diseases and offer new insights into solving the missing heritability problem.

Obesity: Nutrition and Genetics—A Short Narrative Review

Obesity has become a major global health challenge and it is a risk factor for the development of several comorbid conditions. Additionally, obesity has considerable economic consequences. Obesity is a multifactorial condition that arises from independent influences of genetic and social-environmental factors on food intake and physical activity. It has been difficult to establish clear associations between weight status and the intake of single foods or food groups. In most people, the predisposition to obesity has a polygenic basis, which means that obesity will develop if an individual has several polygenic variants that increase body weight. The FTO gene was the first GWAS-identified obesity-susceptibility gene and since then other polygenic variants that are associated with BMI and dietary intake have also been identified. However, this is still an active area of research as more polygenetic variants await discovery.

Inactivation of SPAK kinase reduces body weight gain in mice fed a high-fat diet by improving energy expenditure and insulin sensitivity.

The STE20/SPS1-related proline-alanine-rich protein kinase (SPAK) controls the activity of the electroneutral cation-chloride cotransporters (SLC12 family) and thus physiological processes such as modulation of cell volume, intracellular chloride concentration [Cl-]i, and transepithelial salt transport. Modulation of SPAK kinase activity may have an impact on hypertension and obesity, as STK39, the gene encoding SPAK, has been suggested as a hypertension and obesity susceptibility gene. In fact, the absence of SPAK activity in mice in which the activating threonine in the T loop was substituted by alanine (SPAK-KI mice) is associated with decreased blood pressure; however its consequences in metabolism have not been explored. Here, we fed wild-type and homozygous SPAK-KI mice a high-fat diet for 17 wk to evaluate weight gain, circulating substrates and hormones, energy expenditure, glucose tolerance, and insulin sensitivity. SPAK-KI mice exhibit resistance to HFD-induced obesity and hepatic steatosis associated with increased energy expenditure, higher thermogenic activity in brown adipose tissue, increased mitochondrial activity in skeletal muscle, and reduced white adipose tissue hypertrophy mediated by augmented whole body insulin sensitivity and glucose tolerance. Our data reveal a previously unrecognized role for the SPAK kinase in the regulation of energy balance, thermogenesis, and insulin sensitivity, suggesting that this kinase could be a new drug target for the treatment of obesity and the metabolic syndrome.

Association of obesity susceptibility gene variants with metabolic syndrome in women

Aim. The aim of the study was a replicative analysis of the association of polymorphic variants of genes associated with obesity revealed by results of wide-genomic studies (GWAS) with the development of a cluster of metabolic syndrome risk parameters in women of Bashkir and Tatar ethnicity. The polymorphic markers of the following genes were analyzed: SEC16B, FADS1, KCTD15, MAF, MAP2K5, NEGR1, BDNF, TMEM18.&#x0D; Materials and methods. The study involved 243 women with metabolic syndrome and 298 women without the metabolic syndrome. Amplification of DNA fragments was performed using real-time PCR and TaqMan technique.&#x0D; Results. We found the association the metabolic syndrome with genetic markers of genes MAF and TMEM18 from Tatar. Protective informative marker of the metabolic syndrome among Tatar and Bashkir was the TT haplotype TMEM18 gene (rs2860323 and rs6548238) (р=0.005 and р=0.001, respectively). We identified the association marker rs2241423 MAP2K5 gene with the level of waist circumference (p=0.003) and with the level of cholesterol (p=0.014), the marker rs11084753 KCTD15 gene with glucose levels after exercise (p=0.002), the level of triglycerides (p=0.003) and HDL (p=0.0008) among Tatar women. We identified the association rs2241423 MAP2K5 gene marker to glycated hemoglobin level (p=0.002) and a marker gene rs174550 FADS1 with triglyceride levels (p=0.02) among Bashkir women.&#x0D; Conclusion. It can be assumed that the polymorphic variants FADS1, KCTD15, MAF, MAP2K5, TMEM18 genes are an important part of the genetic structure of predisposition to metabolic syndrome and/or to a cluster of clinical and biochemical indicators of the risk of metabolic syndrome.