Genetic Risk Score Does Not Predict the Outcome of Obesity Surgery

Abdominal Obesity Genetic Variants Predict Waist Circumference Regain After Weight Loss

Although many individuals are able to achieve weight loss, maintaining this loss over time is challenging. We aimed to study whether genetic predisposition to general or abdominal obesity predicts weight regain after weight loss. We examined the associations between genetic risk scores for higher BMI and higher waist-to-hip ratio adjusted for BMI (WHRadjBMI) with changes in weight and waist circumference up to 3 years after a 1-year weight loss program in participants (n = 822 women, n = 593 men) from the Look AHEAD (Action for Health in Diabetes) study who had lost ≥3% of their initial weight. Genetic predisposition to higher BMI or WHRadjBMI was not associated with weight regain after weight loss. However, the WHRadjBMI genetic score did predict an increase in waist circumference independent of weight change. To conclude, a genetic predisposition to higher WHRadjBMI predicts an increase in abdominal obesity after weight loss, whereas genetic predisposition to higher BMI is not predictive of weight regain. These results suggest that genetic effects on abdominal obesity may be more pronounced than those on general obesity during weight regain.

ARTICLE HIGHLIGHTS

Nearly all individuals who intentionally lose weight experience weight regain. Individuals with a higher genetic risk for abdominal adiposity experience increased regain in waist circumference after weight loss. Genetic predisposition to higher BMI does not predict weight regain after weight loss.

Combined Effect of Genetic Variants on Long-Term Weight Response after Bariatric Surgery

The pathophysiology of body weight control involves complex interactions between hormonal, environmental, behavioral and genetic factors. The purpose of this study was to analyze the association between single nucleotide polymorphisms (SNPs) of 13 genes encoding gastrointestinal peptides, their receptors or the proteins involved in their expression, with long-term weight response in a cohort of 375 patients undergoing bariatric surgery (BS). To evaluate weight response, we combined several variables to define specific response phenotypes six years after surgery. The study protocol was registered in ISRCTN (ID80961259). The analysis of the selected SNPs was performed via allelic discrimination using Taqman^® probes (Applied Biosystems, Foster City, CA, USA). The genotype association study was performed using the SNPstat program, with comparisons adjusted for sex, age, initial body mass index, type 2 diabetes, hypertension diagnosis and the type of surgery. We identified eight genetic variants associated with the weight response to BS, independently of the presurgery patient profile and the type of surgical technique, from which we calculated the unweighted risk score (RS) for each phenotype. The highest scoring category in each RS was significantly associated with lower weight loss (p = 0.0001) and greater weight regain (p = 0.0012) at the end of the 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.

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.

Genetic markers of abdominal obesity and weight loss after gastric bypass surgery

Background

Weight loss after bariatric surgery varies widely between individuals, partly due to genetic differences. In addition, genetic determinants of abdominal obesity have been shown to attenuate weight loss after dietary intervention with special attention paid to the rs1358980-T risk allele in the VEGFA locus. Here we aimed to test if updated genetic risk scores (GRSs) for adiposity measures and the rs1358980-T risk allele are linked with weight loss following gastric bypass surgery.

Methods

Five hundred seventy six patients with morbid obesity underwent Roux-en-Y gastric bypass. A GRS for BMI and a GRS for waist-hip-ratio adjusted for BMI (proxy for abdominal obesity), respectively, were constructed. All patients were genotyped for the rs1358980-T risk allele. Associations between the genetic determinants and weight loss after bariatric surgery were evaluated.

Results

The GRS for BMI was not associated with weight loss (β = -2.0 kg/100 risk alleles, 95% CI -7.5 to 3.3, p = 0.45). Even though the GRS for abdominal obesity was associated with an attenuated weight loss response adjusted for age, sex and center (β = -14.6 kg/100 risk alleles, 95% CI -25.4 to -3.8, p = 0.008), it was not significantly associated with weight loss after adjustment for baseline BMI (β = -7.9 kg/100 risk alleles, 95% CI -17.5 to 1.6, p = 0.11). Similarly, the rs1358980-T risk allele was not significantly associated with weight loss (β = -0.8 kg/risk allele, 95% CI -2.2 to 0.6, p = 0.25).

Discussion

GRSs for adiposity derived from large meta-analyses and the rs1358980-T risk allele in the VEGFA locus did not predict weight loss after gastric bypass surgery. The association between a GRS for abdominal obesity and the response to bariatric surgery may be dependent on the association between the GRS and baseline BMI.

A Genetic Risk Score for the Estimation of Weight Loss After Bariatric Surgery

BACKGROUND

Sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB) are the most frequent bariatric surgery procedures worldwide. In this prospective study, we examined the association of a genetic risk score (GRS) with loss of excess weight after bariatric surgery.

METHODS

A total of forty-seven morbidly obese Greek patients who underwent SG (81%) or RYGB were recruited, followed up for 2 years and genotyped. Weight loss after surgery was reported as the percentage of excess weight that was lost (%EWL) at 12 and 24 months after surgery. A GRS was constructed based on previously BMI- and WHR-related single nucleotide polymorphisms (SNPs) that were found significantly correlated with weight loss after bariatric surgery in our population. The level of post-surgery %EWL after 12 and 24 months was estimated through two multiple linear regression models that considered the effects of relevant genetic risk variants.

RESULTS

The first proposed model suggested that the predictor variables of GRS, age, and BMI had a significant effect on %EWL12m. GRS was significantly associated with %EWL12m, indicating a 4.618% decrease of %EWL12m per score unit. The second model indicated a positive correlation between %EWL24m and %EWL12m, suggesting that while post-surgery weight loss increased during the first 12 months, an increase was expected in the next 12 months as well. GRS was also significantly associated with %EWL24m, indicating approximately 3% decrease of %EWL24m per score unit.

CONCLUSION

GRS can be used in the future together with other preoperative parameters in order to predict the outcome of bariatric surgery.

Genetic Determinants of Weight Loss After Bariatric Surgery

BACKGROUND

The weight loss after bariatric surgery shows considerable individual variation. Twin studies of response to dietary interventions and studies of bariatric surgery patients suggest that genetic differences may play a role. This study aimed to examine the effect of three genetic risk scores on the inter-individual variation in excess body mass index loss (EBMIL) after Roux-en-Y gastric bypass. Furthermore, we searched among known adiposity-related single nucleotide polymorphisms (SNPs) for genetic determinants of the inter-individual variation in EBMIL.

METHODS

Patients with morbid obesity underwent Roux-en-Y gastric bypass and were genotyped (n = 577). Two genetic risk scores for weight loss after bariatric surgery and a genetic risk score for body mass index were calculated. Associations between the genetic risk scores and EBMIL were evaluated. Lasso regression was performed on 126 SNPs known to be associated with adiposity.

RESULTS

The average EBMIL was 76.9% (range 21.7-149.2%). EBMIL was 81.1% (SD 20.6) and 73.9% (SD 21.7) in the high and low tertile groups of a genetic risk score for weight loss. Patients with a low genetic risk score for body mass index (in the lowest 5% percentile) had an EBMIL of 68.8% (SD 20.6, p = 0.018). Thirteen adiposity-related SNPs were identified to associate with EBMIL through lasso regression.

DISCUSSION

A genetic risk score was associated with EBMIL after bariatric surgery, but may not yet be applicable to clinical practice. Patients genetically predisposed to low body mass index had lower weight loss after bariatric surgery.

Meta-Analysis of Differential miRNA Expression after Bariatric Surgery

Bariatric surgery is an efficient treatment for weight loss in obese patients and for resolving obesity comorbidities. However, the mechanisms behind these outcomes are unclear. Recent studies have indicated significant alterations in the transcriptome after surgery, specifically in the differential expression of microRNAs. In order to summarize the recent findings, we conducted a systematic summary of studies comparing microRNA expression levels before and after surgery. We identified 17 animal model and human studies from four databases (Ovid, Scopus, Web of Science, and PubMed) to be enrolled in this meta-analysis. From these studies, we identified 14 miRNAs which had the same direction of modulation of their expression after surgery in at least two studies (downregulated: hsa-miR-93-5p, hsa-miR-106b-5p, hsa-let-7b-5p, hsa-let-7i-5p, hsa-miR-16-5p, hsa-miR-19b-3p, hsa-miR-92a-3p, hsa-miR-222-3p, hsa-miR-142-3p, hsa-miR-140-5p, hsa-miR-155-5p, rno-miR-320-3p; upregulated: hsa-miR-7-5p, hsa-miR-320c). Pathway analysis for these miRNAs was done using database resources (DIANA-TarBase and KEGG pathway database) and their predicted target genes were discussed in relation with obesity and its comorbidities. Discrepancies in study design, such as miRNA source, bariatric surgery type, time of observation after surgery, and miRNA profiling methods, were also discussed.

Polygenic risk score for predicting weight loss after bariatric surgery

BACKGROUND

The extent of weight loss among patients undergoing bariatric surgery is highly variable. Herein, we tested the contribution of genetic background to such interindividual variability after biliopancreatic diversion with duodenal switch.

METHODS

Percentage of excess body weight loss (%EBWL) was monitored in 865 patients over a period of 48 months after bariatric surgery, and two polygenic risk scores were constructed with 186 and 11 (PRS186 and PRS11) single nucleotide polymorphisms previously associated with body mass index (BMI).

RESULTS

The accuracy of the %EBWL logistic prediction model - including initial BMI, age, sex, and surgery modality, and assessed as the area under the receiver operating characteristics (ROC) curve adjusted for optimism (AUCadj = 0.867) - significantly increased after the inclusion of PRS186 (ΔAUCadj = 0.021; 95% CI of the difference [95% CIdiff] = 0.005-0.038) but not PRS11 (ΔAUCadj= 0.008; 95% CIdiff= -0.003-0.019). The overall fit of the longitudinal linear mixed model for %EBWL showed a significant increase after addition of PRS186 (-2 log-likelihood = 12.3; P = 0.002) and PRS11 (-2 log-likelihood = 9.9; P = 0.007). A significant interaction with postsurgery time was found for PRS186 (β = -0.003; P = 0.008) and PRS11 (β = -0.008; P = 0.03). The inclusion of PRS186 and PRS11 in the model improved the cost-effectiveness of bariatric surgery by reducing the percentage of false negatives from 20.4% to 10.9% and 10.2%, respectively.

CONCLUSION

These results revealed that genetic background has a significant impact on weight loss after biliopancreatic diversion with duodenal switch. Likewise, the improvement in weight loss prediction after addition of polygenic risk scores is cost-effective, suggesting that genetic testing could potentially be used in the presurgical assessment of patients with severe obesity.

FUNDING

Heart and Stroke Foundation of Canada (G-17-0016627) and Canada Research Chair in Genomics Applied to Nutrition and Metabolic Health (no. 950-231-580).

A Genetic Risk Score Is Associated with Weight Loss Following Roux-en Y Gastric Bypass Surgery

Background

Currently, Roux-en Y gastric bypass (RYGB) is the most efficient therapy for severe obesity. Weight loss after surgery is, however, highly variable and genetically influenced. Genome-wide association studies have identified several single nucleotide polymorphisms (SNP) associated with body mass index (BMI) and waist-hip ratio (WHR). We aimed to identify two genetic risk scores (GRS) composed of weighted BMI and WHR-associated SNPs to estimate their impact on excess BMI loss (EBMIL) after RYGB surgery.

Methods

Two hundred and thirty-eight obese patients (BMI 45.1 ± 6.2 kg/m², 74 % women), who underwent RYGB, were genotyped for 35 BMI and WHR-associated SNPs and were followed up after 2 years. SNPs with high impact on post-surgical weight loss were filtered out using a random forest model. The filtered SNPs were combined into a GRS and analyzed in a linear regression model.

Results

An up to 11 % lower EBMIL with higher risk score was estimated for two GRS models (P = 0.026 resp. P = 0.021) composed of seven BMI-associated SNPs (closest genes: MC4R, TMEM160, PTBP2, NUDT3, TFAP2B, ZNF608, MAP2K5, GNPDA2, and MTCH2) and of three WHR-associated SNPs (closest genes: HOXC13, LYPLAL1, and DNM3-PIGC). Patients within the lowest GRS quartile had higher EBMIL compared to patients within the other three quartiles in both models.

Conclusions

We identified two GRSs composed of BMI and WHR-associated SNPs with significant impact on weight loss after RYGB surgery using random forest analysis as a SNP selection tool. The GRS may be useful to pre-surgically evaluate the risks for patients undergoing RYGB surgery.

Electronic supplementary material

The online version of this article (doi:10.1007/s11695-016-2072-9) contains supplementary material, which is available to authorized users.

Effect of RET c.2307T>G Polymorphism on the Outcomes of Posterior Sagittal Neurectomy for Hirschsprung Disease Procedure in Indonesian Population

We investigated the effect of RET c.2307T>G polymorphism on the outcomes of posterior sagittal neurectomy for Hirschsprung disease (PSNHD) procedure in Indonesia. Hirschsprung disease (HSCR) is a neurocristopathy characterized by absence of enteric ganglia along variable lengths of the intestine in neonates. The RET c.2307T>G polymorphism has been shown to be associated with HSCR. Many surgical techniques with some advantage and disadvantage were established for HSCR. We have conducted PSNHD in short-segment HSCR patients.Thirty-one nonsyndromic HSCR patients underwent PSNHD. The polymorphism was determined using PCR-RFLP in genomic DNA. The rate of enterocolitis and constipation outcomes following PSNHD were 6 (19%) and 4 (13%) patients, respectively. The RET c.2307T>G polymorphism did not influence either enterocolitis or constipation outcome following PSNHD at P value of 0.07 (OR = 0.28; 95% CI = 0.08-1.05) and 0.67 (OR = 0.58; 95% CI = 0.12-2.76), respectively. Our study suggested that RET c.2307T>G polymorphism may not affect outcomes of PSNHD procedure in Indonesia. Furthermore, a multicenter study with a larger sample size is necessary to clarify this result.

rs4771122 Predicts Multiple Measures of Long-Term Weight Loss After Bariatric Surgery

We examined the association of 34 single nucleotide polymorphisms with weight loss up to 9.5 years after Roux-en-Y surgery. Participants were enrollees in the NUgene biobank with stored DNA and linked electronic health records. Ninety-five self-identified white participants underwent surgery and had follow-up weights obtained between 1 and 9.5 years after surgery. SNP rs4771122 was the variant most significantly associated with long-term weight loss after surgery in a repeated linear mixed model (p = .004) of long-term weight loss. In this model, each additional copy of the minor allele was associated with nearly 5 % greater percentage weight loss. This same SNP was also nominally significantly (p < .05) associated with weight loss trajectories, weight loss nadir, and weight loss 2 years after surgery.

Influence of excess weight loss and weight regain on biochemical indicators during a 4-year follow-up after Roux-en-Y gastric bypass

BACKGROUND

Bariatric surgery produces a substantial weight loss and improves the comorbidities associated with obesity such as diabetes mellitus and dyslipidemia, although inability to lose weight or weight regain has been estimated to occur in 20 % of cases. The objective of the present study was to assess the influence of weight variations on biochemical indicators during a 4-year period after bariatric surgery.

METHODS

A 4-year retrospective longitudinal study was conducted on 138 patients with grade III obesity submitted to Roux-en-Y gastric bypass, with the assessment of anthropometric measurements and biochemical indicators. The patients were divided into two groups according to percent excess weight loss (%EWL): %EWL > 50 % and %EWL < 50 %, and into two groups according to weight regain: <10 % and >10 %. The Student t test for independent samples was used to assess the differences in biochemical indicators between groups (p ≤ 0.05).

RESULTS

Four years after surgery, there was a weight loss of 49.4 ± 21.8 kg and %EWL of 61 ± 21.2 %, with 73.2 % (n = 101) of the patients showing %EWL of 50 % or more. Significant weight regain occurred in 24.6 % of the sample. There was a difference in weight, BMI, total cholesterol, LDL-cholesterol, triglycerides, and albumin between patients with different %EWL. No difference in biochemical indicators was observed between subjects with and without regain.

CONCLUSION

Four years after surgery, greater %EWL was associated with a better lipid profile. In addition, weight regain did not change the biochemical indicators of this patient series.

Five-year results after laparoscopic sleeve gastrectomy: a prospective study

BACKGROUND

Whilst the early to mid-term efficacy of laparoscopic sleeve gastrectomy (SG) is well established, there is comparatively less detailing of long-term efficacy. The objectives of this study were to evaluate the long-term outcomes of patients undergoing SG at the authors' institution.

METHODS

All patients undergoing SG during the past 5 or more years were eligible. Outcomes included baseline demographic data, preoperative characteristics, percentage excess weight loss (%EWL), co-morbidity improvement and resolution, serum hemoglobin A(1c) (HbA(1c)), serum lipid profile, and the Bariatric Analysis Reporting Outcome System (BAROS) questionnaire. A subset analysis was also performed with patients stratified in to super obese (body mass index ≥ 50 kg/m(2)).

RESULTS

There were 96 patients who underwent surgery between March 2007 and July 2008. Of these, 10 declined to participate, 28 were unable to be contacted, and 3 were deceased; therefore, 55 patients were included in the analysis. The mean yearly %EWL to postoperative year 5 was 56% (year 1), 55% (year 2), 46% (year 3), 43% (year 4), and 40% (year 5). Combined improvement and resolution rates at 5 years were 79%, 61%, and 73% for type 2 diabetes, hypertension, and obstructive sleep apnea, respectively. The HbA(1c) was significantly reduced at long-term follow-up. The mean BAROS score was 3.13 (95% CI: 2.4, 3.9). Weight loss outcomes were less favorable in super obese patients.

CONCLUSION

Weight loss outcomes at 5 year follow-up were modest after SG though improvement in co-morbidity status was maintained.