ESR1, FTO, and UCP2 genes interact with bariatric surgery affecting weight loss and glycemic control in severely obese patients

Characterising the genetic architecture of changes in adiposity during adulthood using electronic health records

Obesity is a heritable disease, characterised by excess adiposity that is measured by body mass index (BMI). While over 1,000 genetic loci are associated with BMI, less is known about the genetic contribution to adiposity trajectories over adulthood. We derive adiposity-change phenotypes from 24.5 million primary-care health records in over 740,000 individuals in the UK Biobank, Million Veteran Program USA, and Estonian Biobank, to discover and validate the genetic architecture of adiposity trajectories. Using multiple BMI measurements over time increases power to identify genetic factors affecting baseline BMI by 14%. In the largest reported genome-wide study of adiposity-change in adulthood, we identify novel associations with BMI-change at six independent loci, including rs429358 (APOE missense variant). The SNP-based heritability of BMI-change (1.98%) is 9-fold lower than that of BMI. The modest genetic correlation between BMI-change and BMI (45.2%) indicates that genetic studies of longitudinal trajectories could uncover novel biology of quantitative traits in adulthood.

Use of polygenic risk scores to assess weight loss after bariatric surgery: a 5-year follow-up study

BACKGROUND

Bariatric surgery (BS) is currently the most effective long-term treatment of severe obesity. However, the interindividual variability observed in surgical outcomes suggests a moderating effect of several factors, including individual genetic background. This study aimed to investigate the contribution of the genetic architecture of body mass index (BMI) to the variability in weight loss outcomes after BS.

METHODS

A total of 106 patients with severe obesity who underwent Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy were followed up for 5 years. Changes in BMI (BMIchange) and percentage of total weight loss (%TWL) were evaluated during the postoperative period. Polygenic risk scores (PRSs), including 50 genetic variants, were calculated for each participant to determine their genetic risk of high BMI based on a previous genome-wide association study. Generalized estimating equation models were used to study the role of the individual's polygenic score and other factors on BMIchange and %TWL in the long term after surgery.

RESULTS

This study found an effect of the polygenic score on %TWL and BMIchange, in which patients with lower scores had better outcomes after surgery than those with higher scores. Furthermore, when analyzing only patients who underwent RYGB, the results were replicated, showing greater weight loss after surgery for patients with lower polygenic scores.

DISCUSSION

Our results indicate that genetic background assessed with PRSs, along with other individual factors, such as biological sex, age, and preoperative BMI, has an effect on BS outcomes and could represent a useful tool for estimating surgical outcomes in advance.

Interaction Effects of FTO and MC4R Polymorphisms on Total Body Weight Loss, Post-Surgery Weight, and Post-Body Mass Index after Bariatric Surgery

Bariatric surgery (BS) is considered the most effective intervention for patients with severe obesity and is used to maintain long-term weight loss and glycemic control. The aim of this study was to analyze the effects of genotypes and haplotypes of the fat mass and obesity-associated (FTO) and melanocortin 4 receptor (MC4R) genes on total body weight loss (TBWL), post-surgery weight, and post-BMI after bariatric surgery. We retrospectively selected 101 patients from Bajio High Specialty Regional Hospital, León Guanajuato, México, who underwent Roux-en-Y gastric bypass (RYGB) to determine their body mass index (BMI), blood pressure, biochemical characteristics, and comorbidities. Post-surgery, patients were referred for registered anthropometry and blood pressure. Glucose, lipid and hepatic profiles, and insulin, leptin, and ghrelin levels were measured, and rs9939609, rs9930506, and rs1421085 FTO and rs17782313 MC4R polymorphisms were genotyped. Six (4-8) years after BS, post-surgery weight was greater in carriers of the rs9939609 and rs1421085 risk genotypes. TBWL was lower for the rs9930506 and rs1421085 risk genotypes. Insulin and HOMA-IR were greater in patients with the three FTO polymorphisms. There were significant interaction effects of the rs9930506 and rs1421085 FTO risk genotypes on weight and BMI in response to BS. No association was found with the MC4R polymorphism. The genotypes and haplotypes of the FTO gene influence post-surgery weight, TBWL, insulin levels, and HOMA-IR.

Genetic variants associated with weight loss and metabolic outcomes after bariatric surgery: A systematic review

The extent to which genetic variations contribute to interindividual differences in weight loss and metabolic outcomes after bariatric surgery is unknown. Identifying genetic variants that impact surgery outcomes may contribute to clinical decision making. This review evaluates current evidence addressing the association of genetic variants with weight loss and changes in metabolic parameters after bariatric surgery. A search was conducted using Medline, Embase, Scopus, Web of Science, and Cochrane Library. Fifty-two eligible studies were identified. Single nucleotide polymorphisms (SNPs) at ADIPOQ (rs226729, rs1501299, rs3774261, and rs17300539) showed a positive association with postoperative change in measures of glucose homeostasis and lipid profiles (n = 4), but not with weight loss after surgery (n = 6). SNPs at FTO (rs11075986, rs16952482, rs8050136, rs9939609, rs9930506, and rs16945088) (n = 10) and MC4R (rs11152213, rs476828, rs2229616, rs9947255, rs17773430, rs5282087, and rs17782313) (n = 9) were inconsistently associated with weight loss and metabolic improvement. Four studies examining the UCP2 SNP rs660339 reported associations with postsurgical weight loss. In summary, there is limited evidence supporting a role for specific genetic variants in surgical outcomes after bariatric surgery. Most studies have adopted a candidate gene approach, limiting the scope for discovery, suggesting that the absence of compelling evidence is not evidence of absence.

The genetic architecture of changes in adiposity during adulthood

Obesity is a heritable disease, characterised by excess adiposity that is measured by body mass index (BMI). While over 1,000 genetic loci are associated with BMI, less is known about the genetic contribution to adiposity trajectories over adulthood. We derive adiposity-change phenotypes from 1.5 million primary-care health records in over 177,000 individuals in UK Biobank to study the genetic architecture of weight-change. Using multiple BMI measurements over time increases power to identify genetic factors affecting baseline BMI. In the largest reported genome-wide study of adiposity-change in adulthood, we identify novel associations with BMI-change at six independent loci, including rs429358 (a missense variant in APOE). The SNP-based heritability of BMI-change (1.98%) is 9-fold lower than that of BMI, and higher in women than in men. The modest genetic correlation between BMI-change and BMI (45.2%) indicates that genetic studies of longitudinal trajectories could uncover novel biology driving quantitative trait values in adulthood.

A single FTO gene variant rs9939609 is associated with weight change and insulin resistance improvement in response to a robotic sleeve gastrectomy in individuals with severe obesity

BACKGROUND

Genetic mechanisms have been involved in the weight response secondary to bariatric surgery.

OBJECTIVE

The aim of our study was to evaluate the effects of the rs9939609 genetic variant on weight loss and metabolic parameters after sleeve gastrectomy.

SETTING

Tertiary hospital.

METHODS

A total of 95 participants were enrolled. Co-morbidities, biochemical evaluation, and anthropometric parameters were registered before and after 3-, 6-, and 12-month follow-up. Genotype of the rs9939609 fat mass and obesity-associated (FTO) gene was evaluated.

RESULTS

We grouped the participants into 2 groups: carriers of A allele (TA+AA, 69.5%) and noncarriers of A allele (TT, 30.5%). We detected a statistically significant reduction of blood pressure, biochemical, and anthropometric parameters at 3 times during follow-up. After 6 months, changes of some parameters were greater in non-A allele carriers: weight (-39.6 + 4.0 kg versus -24.6 + 2.8 kg; P = .02), waist circumference (-21.1 + 2.1 cm versus -16.2 + 1.8 cm; P = .04), insulin (-12.3 + .9 mUI/L versus -8.9.1 + .2 mUI/L; P = .02), and homeostasis model assessment of insulin resistance (-3.1 + .1 units versus -2.3 + .1 units; P = .02 ). After 12 months, changes of the aforementioned parameters remained greater in non-A allele carriers. The percentage of participants with diabetes diminished earlier in the non-A allele carriers than A allele carriers at 6-month follow-up. The percentage of participants with diabetes at the end of the study was lower in non-A allele carriers (3.4% versus 12.1%; P = .02).

CONCLUSIONS

Our data suggest that non-A allele carriers of the genetic variant (rs9939609) of the FTO gene showed a better improvement of anthropometric and insulin levels in non-A allele carriers after a robotic sleeve gastrectomy. Both improvements are associated with a lower percentage of participants with diabetes at 12 months.

Haplotype of ESR1 and PPARD Genes Is Associated with Higher Anthropometric Changes in Han Chinese Obesity by Adjusting Dietary Factors-An 18-Month Follow-Up

The obesity genetic effect may play a major role in obesogenic environment. A combined case-control and an 18-month follow-up were carried out, including a total of 311 controls and 118 obese cases. All participants were aged in the range of 20-55 y/o. The body mass index (BMI) of obese cases and normal controls was in the range of 27.0-34.9 and 18.5-23.9 kg/m², respectively. The rs712221 on Estrogen receptor1 (ESR1) and rs2016520 on Peroxisome proliferator-activated receptor delta (PPARD) showed significant associations with obesity. The TT (odds ratio (OR): 2.42; 95% confidence interval (CI): 1.46-4.01) and TT/TC (OR: 2.80; 95% CI: 1.14-6.85) genotypes on rs712221 and rs2016520 had significantly higher obesity risks, respectively. Moreover, the synergic effect of these two risk SNPs (2-RGH) exhibited an almost geometrical increase in obesity risk (OR: 7.00; 95% CI: 2.23-21.99). Obese individuals with 2-RGH had apparently higher changes in BMI increase, body weight gain and dietary fiber intake but a lower total energy intake within the 18-month follow-up.

Lack of Association Between 11 Gene Polymorphisms on Weight Loss One Year After Roux-en-Y Gastric Bypass Surgery in Women

BACKGROUND

Although effective, the impact of bariatric surgery on weight loss is variable, and little is known about the influence of single nucleotide polymorphisms (SNPs). This study investigated the association of eleven SNPs related to obesity with weight loss one year after Roux-Y gastric bypass (RYGB) surgery in female patients.

METHODS

This prospective study included 351 women with obesity. The genotypes for eleven SNPs (GHRL - rs26802; GHSR - rs572169; LEP - rs7799039; LEPR - rs1137101; 5HT2C - rs3813929; UCP2 - rs659366; UCP3 - rs1800849; SH2B1 - rs7498665; TAS1R2 - rs35874116; TAS1R2 - rs9701796; FTO - rs9939609) were determined using real-time polymerase chain reaction (PCR) and TaqMan assays. Anthropometric measurements were performed before and one year after RYGB surgery. To evaluate the factors that influenced the proportion of weight loss 1 year after surgery, beta regression analysis was used. The models were estimated using the SAS software GLIMMIX procedure. The level of significance adopted for the statistical tests was 5%.

RESULTS

The average percentage of total body weight loss in one year was 64.4 ± 5.8% and the median was 65.0%. In assessing the proportion of weight loss in one year after surgery, using univariate analysis (beta regression), no single nucleotide polymorphisms (SNPs) influenced weight loss. And in the multiple analysis, with stepwise process of variable selection, no variable was significant to compose the multiple model.

CONCLUSION

The 11 SNPs investigated did not influence weight loss one year after RYGB surgery in female patients. This result indicates that individual behaviors and other factors might better contribute to the magnitude of loss weight loss in a short period after bariatric surgery. This article is protected by copyright. All rights reserved.

The joint effect of PPARG upstream genetic variation in association with long-term persistent obesity: Tehran cardio-metabolic genetic study (TCGS)

PURPOSE

This study is the first study that aims to assess the association between SNPs located at the PPARG gene with long term persistent obesity. In this cohort association study, all adult individuals who had at least three consecutive phases of BMI (at least nine years) in Tehran genetic Cardio-metabolic Study (TCGS) were included.

METHODS

Individuals who always had 30 ≤ BMI < 35 and individuals who always had 20 < BMI ≤ 25 were assigned to the long-term persistent obese group and persistent normal weight group, respectively. Other individuals were excluded from the study. We used four gamete rules to make SNP sets from correlated nearby SNPs and kernel machine regression to analyze the association between SNP sets and persistent obesity or normal weight.

RESULTS

The normal group consisted of 1547 individuals with the mean age of 40 years, and the obese group consisted of 1676 individuals with mean age of 48 years. Two groups had a significant difference between all measured clinical characteristics at entry time. The kernel machine result shows that nine correlated SNPs located upstream of PPARG have a significant joint effect on persistence obesity.

CONCLUSION

This is the first study on the association between PPARG variants with persistent obesity. Three of the nine associated markers were reported in previous GWAS studies to be associated with related diseases. For the studied markers in the PPARG gene, the Iranian allele frequency was near the American and European populations.

LEVEL III

Case-control analytic study.

A Systematic Review of Genetic Correlates of Weight Loss After Bariatric Surgery

This systematic review synthesized research evaluating the relationship between genetic predictors and weight loss after bariatric surgery. Fifty-seven studies were identified that examined single genes or genetic risk scores. Uncoupling protein (UCP) rs660339 was associated with excess weight loss after surgery in 4 of 6 studies. The most commonly assessed genes were fat mass and obesity-associated (FTO) gene (n = 10) and melanocortin-4 receptor (MC4R) (n = 14). Both were inconsistently related to weight loss. Genetic risk scores predicted weight loss in 6 of 7 studies. This evidence suggests the potential of using genetic variants and genetic risk scores to predict the amount of weight loss anticipated after bariatric surgery and identify patients who may be at risk for suboptimal weight reduction.

-866G/A and Ins/Del polymorphisms in UCP2 gene are associated with reduced short-term weight loss in patients who underwent Roux-en-Y gastric bypass

BACKGROUND

Uncoupling protein 2 (UCP2) plays an important role in energy expenditure regulation. Previous studies have associated the common -866G/A (rs659366) and Ins/Del polymorphisms in the UCP2 gene with metabolic and obesity-related phenotypes. However, it is still unclear whether these polymorphisms influence weight loss after bariatric surgery.

OBJECTIVES

To investigate whether UCP2 -866G/A and Ins/Del polymorphisms are associated with weight loss outcomes after bariatric surgery.

SETTING

Longitudinal study in a university hospital.

METHODS

We retrospectively evaluated 186 patients who underwent Roux-en-Y gastric bypass (RYGB) surgery for clinical and laboratory characteristics in the preoperative period, 6, 12, and 18 months after RYGB. The -866G/A (rs659366) polymorphism was genotyped using real-time PCR, while the Ins/Del polymorphism was genotyped by direct separation of PCR products in 2.5% agarose gels.

RESULTS

Patients with the -866A/A genotype showed higher body mass index (BMI) after 6, 12, and 18 months of surgery and excess body weight after 6 and 12 months compared with G/G patients. They also showed lower excess weight loss (EWL%) after 6 and 12 months of surgery. Ins allele carriers (Ins/Ins + Ins/Del) had lower delta (Δ) BMI 12 months after surgery compared with Del/Del patients. Accordingly, patients carrying haplotypes with ≥2 risk alleles of these polymorphisms had higher BMI and excess weight and lower EWL% during follow-up.

CONCLUSION

UCP2 -866A/A genotype is associated with higher BMI and excess weight and lower EWL% during an 18-month follow-up of patients who underwent RYGB, while the Ins allele seems to be associated with lower ΔBMI 12 months after surgery. Further studies are needed to confirm the associations of the -866G/A and Ins/Del polymorphisms with weight loss after bariatric surgery.

Identification of Key Pathways and Genes in Obesity Using Bioinformatics Analysis and Molecular Docking Studies

Obesity is an excess accumulation of body fat. Its progression rate has remained high in recent years. Therefore, the aim of this study was to diagnose important differentially expressed genes (DEGs) associated in its development, which may be used as novel biomarkers or potential therapeutic targets for obesity. The gene expression profile of E-MTAB-6728 was downloaded from the database. After screening DEGs in each ArrayExpress dataset, we further used the robust rank aggregation method to diagnose 876 significant DEGs including 438 up regulated and 438 down regulated genes. Functional enrichment analysis was performed. These DEGs were shown to be significantly enriched in different obesity related pathways and GO functions. Then protein-protein interaction network, target genes - miRNA regulatory network and target genes - TF regulatory network were constructed and analyzed. The module analysis was performed based on the whole PPI network. We finally filtered out STAT3, CORO1C, SERPINH1, MVP, ITGB5, PCM1, SIRT1, EEF1G, PTEN and RPS2 hub genes. Hub genes were validated by ICH analysis, receiver operating curve (ROC) analysis and RT-PCR. Finally a molecular docking study was performed to find small drug molecules. The robust DEGs linked with the development of obesity were screened through the expression profile, and integrated bioinformatics analysis was conducted. Our study provides reliable molecular biomarkers for screening and diagnosis, prognosis as well as novel therapeutic targets for obesity.

Obesity and genetics

Genetics is now known to play a substantial role in the predisposition to obesity and may contribute up to 70% risk for the disease. Over a hundred genes and gene variants related to excess weight have been discovered. Yet, genetic obesity risk does not always translate into actual obesity development, suggesting complex interactions between genetic, behavioral, and environmental influences and resulting epigenetic changes. Rare but serious forms of monogenic obesity typically appear in early childhood. Polygenic obesity is most common and demonstrates strong interplay between genes and the obesogenic environment. This review provides an overview of genetic causes of obesity, potential mechanisms of epigenetic changes, and environmental influences that should diminish obesity bias and offer hope for more effective obesity prevention and intervention strategies.

LSG vs MGB-OAGB-3 Year Follow-up Data: a Randomised Control Trial

AIM

The objective of this study is to compare 3-year follow-up results of one anastomosis gastric bypass (MGB-OAGB) and laparoscopic sleeve gastrectomy (LSG) in terms of weight loss, complications, resolution of comorbidities and quality of life.

MATERIALS AND METHODS

A prospective randomised study of results between 100 LSG patients and 101 MGB-OAGB patients was done from 2012 to 2015. The results were compared regarding operative outcomes, percentage of excess weight loss (%EWL), complications, resolution of comorbidities and quality of life (BAROS score) at 3 years follow-up.

RESULTS

Follow-up was achieved in 93 MGB-OAGB vs 92 LSG patients for 3-year period. The average %EWL for MGB-OAGB vs LSG was 66.48 vs 61.15% at the end of 3 years respectively, which was statistically insignificant. Diabetes remission was seen in 89.13% of MGB-OAGB patients and 81.82% of LSG patients. Remission of hypertension was seen in 74% of MGB-OAGB patients and 72.22% of LSG patients. Bariatric analysis reporting and outcome system (BAROS) with comorbidity in LSG patients and MGB-OAGB patients was 6.03 and 6.96 respectively, whereas in patients without comorbidity, BAROS score was 3.86 in LSG group and 4.34 in MGB-OAGB group.

CONCLUSIONS

In our study, at 36 months follow up, there was no significant difference between LSG and MGB-OAGB in %EWL and remission of HTN. Type 2 diabetes mellitus (T2DM) remission rates were higher after MGB-OAGB as compared to LSG but the difference was statistically insignificant. MGB-OAGB patients with comorbidities have a better quality of life and BAROS score compared to LSG patients.

FABP2, LEPR223, LEP656, and FTO Polymorphisms: Effect on Weight Loss 2 Years After Bariatric Surgery

PURPOSE

Differences in weight loss outcomes after bariatric surgery may be related to individual preoperative characteristics. The aim of this study was to evaluate the potential effect of fatty acid binding protein-2 (rs1799883), leptin receptor (LEP223, rs1137101 and LEP656, rs1805094), and fat mass and obesity-related (rs9939609) genotypes on weight loss 2 years after bariatric surgery in Brazilian patients.

MATERIALS AND METHODS

Prospective observational study involving 105 patients (lost to follow-up, 25.7%). In the preoperative period, patients were clinically evaluated and a fasting blood sample for genetic analysis (by real-time DNA amplification technique) was collected. From the patient's medical records, follow-up weight loss (3, 6, 12, 24 months) was obtained. Percentage of excess weight loss (%EWL) was examined by pairwise comparison across the polymorphisms.

RESULTS

At baseline, the mean weight was 127.5 (23.3) kg and age 43.1 (10.9) years old. The %EWL was significant over time (p < 0.01). Only the LEP223 genotype showed association (p < 0.01). Up to 6 months after surgery, no differences were observed. At 12 months, a significant difference (p = 0.03) between AA (n = 19) and GG (n = 34) groups was observed, with 76.5% EWL versus 52.0%, respectively. This difference remained at 24 months. Other genotypes did not present any significant association.

CONCLUSIONS

There is a different evolution of weight loss in carriers of the LEP223 after bariatric surgery. The AA genotype seems to be associated with a higher weight loss. However, this pattern was evident only at 12 months after surgery.

Diagnosis of obesity and use of obesity biomarkers in science and clinical medicine

The global epidemic of obesity is a major public health problem today. Obesity increases the risk of many chronic diseases, such as type 2 diabetes, coronary heart disease, and certain types of cancer, and is associated with lower life expectancy. The body mass index (BMI), which is currently used to classify obesity, is only an imperfect measure of abnormal or excessive body fat accumulation. Studies have shown that waist circumference as a measure of fat distribution may improve disease prediction. More elaborate techniques such as magnetic resonance imaging are increasingly available to assess body fat distribution, but these measures are not readily available in routine clinical practice, and health-relevant cut-offs not yet been established. The measurement of biomarkers that reflect the underlying biological mechanisms for the increased disease risk may be an alternative approach to characterize the relevant obesity phenotype. The insulin/insulin-like growth factor (IGF) axis and chronic low-grade inflammation have been identified as major pathways. In addition, specific adipokines such as leptin, adiponectin and resistin have been related to obesity-associated health outcomes. This biomarker research, which is currently further developed with the application of high throughput methods, gives important insights in obesity-related disease etiology and pathophysiological pathways and may be used to better characterize obese persons at high risk of disease development and target disease-causing biomarkers in personalized prevention strategies.

Weight loss and metabolic improvements in obese patients undergoing gastric banding and gastric banded plication: A comparison

OBJECTIVES

Obesity is a pandemic health problem. Bariatric surgery is the only efficient method for long-term effective weight loss in subjects with severe obesity. Laparoscopic adjustable gastric banding (LAGB) has been widely applied for weight loss. However, a novel technique called laparoscopic adjustable gastric banded plication (LAGBP) has been proposed as an alternative to LAGB. Surgeons generally consider LAGBP to have a relative advantage on weight loss than that derived from LAGB. This initial study applied various biostatistical models and considered a relative longer observation period to compare the effects of LAGB and LAGBP.

METHODS

A total of 340 obese patients (290 who underwent LAGB and 50 who underwent LAGBP) with a body mass index of ≥35 kg/m² and ages 20 to 55 y were recruited from the Division of General Surgery, Taipei Medical University Hospital in Taipei, Taiwan and observed for 24 to 36 mo postoperatively.

RESULTS

Both surgical procedures resulted in significant weight loss, amelioration of poor glucose metabolism, and decreased serum triacylglycerol levels. However, the trend analysis showed no significant differences between the postoperative effects of LAGB and LAGBP (P for trend = 0.21 for body mass index reduction, 0.13 for total body fat percentage reduction, 0.25-0.29 for glucose metabolism amelioration, and 0.10-0.29 for blood pressure improvement). Improvements in serum total cholesterol and high-density lipoprotein cholesterol levels were observed after LAGB only and LAGBP only, respectively, at 24 mo postoperatively. The Framingham Coronary Heart Disease Risk score also showed significant decrease for patients who underwent LAGB and LAGBP.

CONCLUSIONS

Both LAGB and LAGBP demonstrated comparable efficacy in reducing body weight and improving metabolic parameters in a 24 to 36 mo follow-up period. LABG showed the ability to reduce systolic blood pressure and LAGBP exhibited triacylglycerol-lowering effects. A longer observational period is needed in future studies.

From genetics and epigenetics to the future of precision treatment for obesity

Obesity has become a major global health problem, epitomized by excess accumulation of body fat resulting from an imbalance between energy intake and expenditure. The treatments for obesity range from modified nutrition and additional physical activity, to drugs or surgery. But the curative effect of each method seems to vary between individuals. With progress in the genetics and epigenetics of obesity, personalization of the clinical management of obesity may be at our doorstep. This review presents an overview of our current understanding of the genetics and epigenetics of obesity and how these findings influence responses to treatments. As bariatric surgery is the most effective long-term treatment for morbid obesity, we pay special attention to the association between genetic factors and clinical outcomes of bariatric surgery. Finally, we discuss the prospects for precision obesity treatment.

The importance of gene-environment interactions in human obesity

The worldwide obesity epidemic has been mainly attributed to lifestyle changes. However, who becomes obese in an obesity-prone environment is largely determined by genetic factors. In the last 20 years, important progress has been made in the elucidation of the genetic architecture of obesity. In parallel with successful gene identifications, the number of gene-environment interaction (GEI) studies has grown rapidly. This paper reviews the growing body of evidence supporting gene-environment interactions in the field of obesity. Heritability, monogenic and polygenic obesity studies provide converging evidence that obesity-predisposing genes interact with a variety of environmental, lifestyle and treatment exposures. However, some skepticism remains regarding the validity of these studies based on several issues, which include statistical modelling, confounding, low replication rate, underpowered analyses, biological assumptions and measurement precision. What follows in this review includes (1) an introduction to the study of GEI, (2) the evidence of GEI in the field of obesity, (3) an outline of the biological mechanisms that may explain these interaction effects, (4) methodological challenges associated with GEI studies and potential solutions, and (5) future directions of GEI research. Thus far, this growing body of evidence has provided a deeper understanding of GEI influencing obesity and may have tremendous applications in the emerging field of personalized medicine and individualized lifestyle recommendations.

Genetics of Bariatric Surgery Outcomes

Outcomes after bariatric surgery can vary widely and seem to have a significant genetic component. Only a small number of candidate gene and genome-wide association studies have analyzed bariatric surgery outcomes. The role of bile acids in mediating the beneficial effects of bariatric surgery implicate genes regulated by the farnesoid X receptor transcription factor.

The Role of FTO and Vitamin D for the Weight Loss Effect of Roux-en-Y Gastric Bypass Surgery in Obese Patients

BACKGROUND

A recent study in children demonstrated that the rs9939609 single-nucleotide polymorphism in the fat mass and obesity (FTO) gene influences prospective weight gain, however, only in those who were vitamin D-deficient. If this might also be the case for Roux-en-Y gastric bypass (RYGB), surgery-induced weight loss is however unknown. The objective of this study is to examine if the magnitude of RYGB surgery-induced weight loss after 2 years depends on patients' FTO rs9939609 genotype (i.e., TT, AT, and AA) and presurgery vitamin D status (<50 nmol/L equals deficiency).

METHODS

Before and at 24 months after RYGB surgery, BMI was measured in 210 obese patients (mean BMI 45 kg/m(2), 72 % females). Serum 25-hydroxyvitamin D3 levels were also repeatedly measured. Following surgery, vitamin D was supplemented. Possible weight loss differences between genotypes were tested with multiple linear regressions.

RESULTS

The per-allele effect of each FTO A-allele on excessive BMI loss (EBMIL) was 3 % (P = 0.02). When split by baseline status, the EBMIL of vitamin D-deficient patients carrying AA exceeded that of vitamin D-deficient patients carrying TT by ~14 % (P = 0.03). No such genotypic differences were found in patients without presurgery vitamin D deficiency. Post-surgery serum levels of vitamin D did not differ between groups.

CONCLUSIONS

Our data suggest that presurgery vitamin D levels influence the size of genotype effects of FTO rs9939609 on RYGB surgery-induced weight loss in obese patients.

Vitamin D status and supplementation before and after bariatric surgery: a comprehensive literature review

BACKGROUND

Bariatric surgery is the most effective long-term weight loss method. The most common procedures are Roux-en-Y gastric bypass (RYGB) and vertical sleeve gastrectomy (VSG). Bariatric patients are at high risk of vitamin D deficiency (VDD) and insufficiency (VDI), which are associated with skeletal and nonskeletal ailments. There is no consensus regarding the optimal treatment for VDD/VDI in bariatric patients.

OBJECTIVES

To critically examine the literature on vitamin D status (serum 25[OH]D concentrations) pre- and postbariatric surgery as well as supplementation regimens currently used.

METHODS

We searched PubMed, Embase, and Cochrane from inception to May 2015 for articles relating to vitamin D, RYGB, and VSG. Of 208 citations retrieved, 30 were included.

RESULTS

Preoperative VDD (<20 ng/mL) ranged from 13% to 90%, while VDI (<30 ng/mL) was found in up to 98%. Prevalence remained similar postoperatively and was highest after RYGB. Most studies found dosages<800 IU daily insufficient postbariatric surgery. Other studies examined the effectiveness of dosages between 1000 and 5000 IU daily, reaching similar conclusions. Several studies suggested using 50,000 IU weekly plus a daily dose. No studies reported optimization.

CONCLUSIONS

It is widely accepted that serum 25(OH)D concentrations above 30 ng/mL are optimal; however, current postbariatric vitamin D supplementation fails to raise 25(OH)D above that level universally. This review highlights both the great need and the lack of consensus on the optimal supplementation regimen (dosage and frequency) for pre- and postbariatric patients. Future studies should investigate multiple regimens and attempt to identify methods for personalizing these regimens if found necessary.

NIH working group report-using genomic information to guide weight management: From universal to precision treatment

OBJECTIVE

Precision medicine utilizes genomic and other data to optimize and personalize treatment. Although more than 2,500 genetic tests are currently available, largely for extreme and/or rare phenotypes, the question remains whether this approach can be used for the treatment of common, complex conditions like obesity, inflammation, and insulin resistance, which underlie a host of metabolic diseases.

METHODS

This review, developed from a Trans-NIH Conference titled "Genes, Behaviors, and Response to Weight Loss Interventions," provides an overview of the state of genetic and genomic research in the area of weight change and identifies key areas for future research.

RESULTS

Although many loci have been identified that are associated with cross-sectional measures of obesity/body size, relatively little is known regarding the genes/loci that influence dynamic measures of weight change over time. Although successful short-term weight loss has been achieved using many different strategies, sustainable weight loss has proven elusive for many, and there are important gaps in our understanding of energy balance regulation.

CONCLUSIONS

Elucidating the molecular basis of variability in weight change has the potential to improve treatment outcomes and inform innovative approaches that can simultaneously take into account information from genomic and other sources in devising individualized treatment plans.

Effect of ethnicity on weight loss after bariatric surgery

BACKGROUND

Previous studies have reported better weight loss after bariatric surgery among non-Hispanic whites (NHW) versus non-Hispanic blacks (NHB) and Hispanics. The majority of these studies took place in areas where NHW are the majority. This study aimed to compare post-surgery weight outcomes by ethnicity in a geographic area where Hispanics are the majority.

METHODS

A retrospective medical chart review of 3268 patients (1561 Hispanic, 660 NHB, and 1047 NHW) who underwent Roux-en-Y gastric bypass (RYGB) or Adjustable Gastric Band (AGB) placement from 2002 to 2012 were analyzed. Percentages of excess weight loss (EWL) and body mass index (BMI) changes at 6, 12, and 24 months post-surgery were compared by ethnic group.

RESULTS

At 6 months, EWL was significantly different by ethnicity (52.7 ± 15.9 Hispanics, 49.7 ± 15.7 NHW, 43.0 ± 17.3 NHB, P < 0.001). These differences remained at 1 year (66.0 ± 20.3 Hispanics, 64.0 ± 20.3 NHW, 54.1 ± 21.3 NHB, P < 0.001) and 2 years (68.6 ± 24.1 Hispanics, 69.5 ± 21.2 NHW, 57.6 ± 25.4 NHB, P < 0.001). Ethnic group changes in BMI were similar to EWL changes. Analysis stratified by gender, type of surgery, and BMI category (<40, 40-49.99, ≥50 kg/m(2)) showed lower EWL in NHB than Hispanics and NHW. NHW had higher EWL than Hispanics only when they underwent AGB and had a BMI >40 kg/m(2).

CONCLUSIONS

Up to 2 years after RYGB, mean EWL and BMI reduction patterns are similar among NHW and Hispanics and significantly better than NHB. These patterns were comparable but not as pronounced among patients with AGB surgery. Our findings suggest that social factors may contribute to successful weight loss after bariatric surgery.

Comparative physiogenomic analyses of weight loss in response to 2 modes of bariatric surgery: demonstration with candidate neuropsychiatric and cardiometabolic genes

BACKGROUND

Surgical weight loss response is variable, with suboptimal outcomes in some patients. We hypothesized that genetic biomarkers may be related to weight change.

METHODS

We tested 330 single nucleotide polymorphisms (SNPs) in genes relevant to metabolic regulation in 161 patients whose decrease in body mass index (BMI), 1 year after laparoscopic adjustable gastric banding (LAGB) or Roux-en-Y gastric bypass (RYGB), was small (lowest quartile response) or large (highest quartile response). LAGB patients whose BMI decreased≤4.7 or≥10.2 units comprised groups I (n = 43) and II (n = 40), respectively. RYGB patients whose BMI decreased≤13.6 or≥19.8 units comprised groups III (n = 39) and IV (n = 39), respectively. Within each surgery, SNPs with large differences in reference allele frequency (z score>2, corresponding to values displaced 2 standard deviations [SD] from the mean for all SNPs) in low versus high quartiles, were identified. We compared reference allele frequencies, within surgical procedure, using the χ(2) test (using Bonferroni correction for multiple testing).

RESULTS

The mean percent excess weight losses (±SD) corresponding to groups I, II, III, and IV were: 16 (±12), 64 (±30), 55 (±16), and 75 (±17), respectively. SNPs with z score>2 were identified in genes involved in LAGB response, lipid metabolic regulation (APOE, rs439401; APOC4, rs2288911), neural processes (DRD3, rs167771; HTR3 B, rs3758987), and xeno- or endobiotic metabolism (CYP3 A4, rs12333983); and for RYGB response, in lipid transport (SCARB1, rs10846744), folate metabolism (MTHFR, rs2066470), regulation of glycolysis in immune cells (HIF1 A, rs1951795), vitamin K cycling (VKORC1, rs2359612), and xeno- or endobiotic metabolism (CYP3 A4, rs2242480). For LAGB response, APOE SNP frequencies were significantly different.

CONCLUSIONS

With further validation, information derived from patient DNA may be useful to predict surgical weight loss outcomes and guide selection of surgical approach.

Inhibitory effects of high stability fucoxanthin on palmitic acid-induced lipid accumulation in human adipose-derived stem cells through modulation of long non-coding RNA

Obesity is a serious worldwide disease, which is growing in epidemic proportions. Adipose-derived stem cells (ADSCs) are characterized as a source of mesenchymal stem cells that have acted as a potential application for regeneration. Recently, seaweeds rich in flavonoids and polysaccharides have been supposed to show the ability to modulate risk factors for obesity and related diseases. In the present study, we investigated the anti-obesity properties of high stability fucoxanthin (HS-Fx) derived from brown seaweeds on the adipogenesis of ADSCs upon treatment with palmitic acid (PA). First, we showed the differentiation capability of ADSCs from morbid obesity patients to transform into different cell types. Second, we found that the co-treatment of ADSCs with HS-Fx and PA showed no significant cytotoxicity against ADSCs, but PA induced the elevation of reactive oxygen species (ROS) and lipid droplet accumulation was abolished. Thirdly, the PA-mediated down-regulation of lipid metabolism genes was reversed by the treatment of HS-Fx. By long non-coding RNAs (lncRNAs) screening, we found that PA-induced increases in the targeted lncRNAs were also decreased upon treatment with HS-Fx. On Silencing, these lncRNAs corresponded to the decrease in the lipid droplet accumulation of ADSCs induced by PA. ADSCs from obese patients would be direct and meaningful model cells to investigate the development of obesity-related diseases and their treatments, rather than cell lines from other species. HS-Fx showed anti-obesity capability through modulating the elevation of ROS, down-regulation of lipid metabolism genes induced by PA, and upstream signaling, which might be critically resulted from the expression of lncRNAs.

Efficacy of Laparoscopic Mini Gastric Bypass for Obesity and Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

Background. Controversies on the utility of laparoscopic mini gastric bypass (LMGB) in weight loss and type 2 diabetes mellitus (T2DM) control still exist. Methods. We conducted a comprehensive literature search of PubMed, EMBASE, and Cochrane Library. Review Manager was used to perform the meta-analysis and the weighted mean difference (WMD) and/or odds ratio with 95% confidence interval (95% CI) were used to evaluate the overall size effect. Results. The literature search identified 16 studies for systematic review and 15 articles for meta-analysis. Compared with LAGB, LSG, and LRYGB, LMGB showed significant weight loss [WMD, −6.58 (95% CI, −9.37, −3.79), P < 0.01 (LAGB); 2.86 (95% CI, 1.40, 5.83), P = 0.004 (LSG); 10.33 (95% CI, 4.30, 16.36), P < 0.01 (LRYGB)] and comparable/higher T2DM remission results [86.2% versus 55.6%, P = 0.06 (LAGB); 89.1% versus 76.3%, P = 0.004 (LAGB); 93.4% versus 77.6%, P = 0.006 (LAGB)]; LMGB also had shorter learning curve and less operation time than LRYGB [WMD, −35.2 (95% CI, −46.94, −23.46)]. Conclusions. LMGB appeared to be effective in weight loss and T2DM remission and noninferior to other bariatric surgeries. However, clinical utility of LMGB needs to be further validated by future prospective randomized controlled trials.

The effect of rs9939609 FTO gene polymorphism on weight loss after laparoscopic sleeve gastrectomy

PURPOSE

Remarkable differences in weight loss have been observed in obese patients undergoing laparoscopic sleeve gastrectomy (LSG). These high variations might be partly explained by genetic factors. The rs9939609 fat mass and obesity-associated gene (FTO) polymorphism has been implicated in the susceptibility of obesity. We aimed to explore the effects of the rs9939609 FTO gene polymorphism on weight loss among severely obese patients applying for LSG.

MATERIALS AND METHODS

All individuals were analyzed for the FTO rs9939609 gene polymorphism. A total of 74 morbid obese patients (20 male, 54 female) were operated. Body weight and body mass index (BMI) were measured at before LSG and after surgery at the sixth month.

RESULTS

Twenty-eight patients (37.8%) had genotype TT (wild-type allel), 36 patients (48.6%) had genotype TA, and 10 patients (13.5%) had genotype AA. In both wild-type group and mutant group, BMI and weight levels decreased at the sixth month after surgery. Percent of excess weight loss (EWL) at 6 months of follow-up was similar in both groups. There were no differences between the mutant and wild-type groups percent of EWL at the sixth month after applying LSG.

CONCLUSION

Our data showed that the rs9939609 FTO gene polymorphism is not a useful genetic test prior to LSG to help clinicians predicting the weight loss for severely obese patients in short-term follow-up.

Five-year outcome of bariatric surgery in a patient with melanocortin-4 receptor mutation

Monogenic obesity is characterized by mutations in genes involved in the central regulation of food intake. Melanocortin-4 receptor (MC4R) mutations are the most frequent monogenic cause of severe early onset human obesity. Although bariatric surgery is the most effective therapy for idiopathic morbid obesity in adults, little is known about its effectiveness in patients with monogenic obesity syndromes. We report 5-year outcome of gastric bypass surgery in a young man with severe super-obesity associated with MC4R mutation. A 22-year-old man with a weight of 221.6 kg and body mass index of 76.7 kg m(-2) associated with a heterozygous MC4R mutation was referred to our centre for bariatric surgery. He underwent Roux-en-Y gastric bypass (RYGB) surgery and achieved weight loss of 76% of excess weight over a follow-up period of 58 months. Heterozygous MC4R mutations have been associated with dominantly inherited obesity in various ethnic groups, and non-surgical interventions are rarely effective in the long term. One previous report of bariatric surgery in a patient with complete MC4R deficiency reported poor weight loss after gastric banding. We speculate that patients with MC4R mutations achieve superior weight loss outcomes from procedures such as RYGB that produce neurohormonal changes rather than gastric restriction alone due to beneficial effects on appetite and satiety regulation.

Efficacy and safety of laparoscopic mini gastric bypass. A systematic review

BACKGROUND

Laparoscopic mini-gastric bypass (LMGB) is a relatively new bariatric procedure; published studies are accumulating in various settings. The objective of this study was to summarize the available evidence about the efficacy and safety of LMGB.

METHODS

A systematic search in the literature was performed , and PubMed and reference lists were scrutinized (end-of-search date: July 15, 2013). For the assessment of the eligible articles, the Newcastle-Ottawa quality assessment scale was used.

RESULTS

Ten eligible studies were included in this study, reporting data on 4,899 patients. According to all included studies, LMGB induced substantial weight and body mass index reduction, as well as substantial excess weight loss. Moreover, resolution or improvement in all major associated medical illnesses and improvement in overall Gastrointestinal Quality of Life Index score were recorded. Major bleeding and anastomotic ulcer were the most commonly reported complications. Readmission rate ranged from 0%- 11%, whereas the rate of revision operations ranged from .3%- 6%. The latter were conducted due to a variety of medical reasons such as inadequate or excessive weight loss, malnutrition, and upper gastrointestinal bleeding. Finally, the mortality rate ranged between 0% and .5% among primary LMGB procedures.

CONCLUSION

LMGB represents an effective bariatric procedure; its safety and minimal postoperative morbidity seem remarkable. Randomized comparative studies seem mandatory for the further evaluation of LMGB.

Bariatric surgery: the challenges with candidate selection, individualizing treatment and clinical outcomes

Obesity is recognized as a global health crisis. Bariatric surgery offers a treatment that can reduce weight, induce remission of obesity-related diseases, and improve the quality of life. In this article, we outline the different options in bariatric surgery and summarize the recommendations for selecting and assessing potential candidates before proceeding to surgery. We present current data on post-surgical outcomes and evaluate the psychosocial and economic effects of bariatric surgery. Finally, we evaluate the complication rates and present recommendations for post-operative care.

ESR1 gene and insulin resistance remission are associated with serum uric acid decline for severely obese patients undergoing bariatric surgery

BACKGROUND

Hyperuricemia is associated with obesity. Few studies have reported the effects of different types of bariatric surgery on uric acid metabolism. The aim of our study was to determine the relationships between serum uric acid reduction and estrogen receptor-α (ESR1) gene polymorphism, as well as the type of bariatric surgery received. The potential physiological pathways involved in postsurgery serum uric acid reduction were also discussed.

METHODS

A total of 508 severely obese Han Chinese patients, aged 20 to 50 years, with a body mass index (BMI)≥35 kg/m(2) were selected. Patients received either laparoscopic adjustable gastric banding (LAGB; n = 164) or laparoscopic mini-gastric bypass (LMGB; n = 344). A 12-month follow-up was performed to explore the effects of the type of bariatric surgery and ESR1 polymorphism on serum uric acid reduction.

RESULTS

The rs712221 polymorphism of ESR1 affects serum uric acid reduction after bariatric surgery. The LMGB group exhibited a greater reduction in serum uric acid level compared with the LAGB counterpart after adjusting for sex, age, and metabolic confounders (-2.3 ± 2.1 mg/dL versus-1.2 ± 1.1 mg/dL; P = .002). Patients with the rs712221 genotype exhibited better glycemic control and a greater serum uric acid reduction at 12 months after surgery. The effects of the rs712221 polymorphism in LMGB patients resulted in the greatest serum uric acid reduction (-2.7 ± 1.4 mg/dL).

CONCLUSIONS

For severely obese Han Chinese patients, bariatric surgery appears to reduce serum uric acid levels, potentially mediated by synergic effects of surgery type, BMI reduction, rs712221 locus, insulin sensitivity, and changed dietary factors via an unknown mechanism.