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

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.

Genetic risk score based on obesity-related genes and progression in weight loss after bariatric surgery: a 60-month follow-up study

BACKGROUND

Obesity is a polygenic multifactorial disease. Recent genome-wide association studies have identified several common loci associated with obesity-related phenotypes. Bariatric surgery (BS) is the most effective long-term treatment for patients with severe obesity. The huge variability in BS outcomes between patients suggests a moderating effect of several factors, including the genetic architecture of the patients.

OBJECTIVE

To examine the role of a genetic risk score (GRS) based on 7 polymorphisms in 5 obesity-candidate genes (FTO, MC4R, SIRT1, LEP, and LEPR) on weight loss after BS.

SETTING

University hospital in Spain.

METHODS

We evaluated a cohort of 104 patients with severe obesity submitted to BS (Roux-en-Y gastric bypass or sleeve gastrectomy) followed up for >60 months (lost to follow-up, 19.23%). A GRS was calculated for each patient, considering the number of carried risk alleles for the analyzed genes. During the postoperative period, the percentage of excess weight loss total weight loss and changes in body mass index were evaluated. Generalized estimating equation models were used for the prospective analysis of the variation of these variables in relation to the GRS.

RESULTS

The longitudinal model showed a significant effect of the GRS on the percentage of excess weight loss (P = 1.5 × 10-5), percentage of total weight loss (P = 3.1 × 10-8), and change in body mass index (P = 7.8 × 10-16) over time. Individuals with a low GRS seemed to experience better outcomes at 24 and 60 months after surgery than those with a higher GRS.

CONCLUSION

The use of the GRS in considering the polygenic nature of obesity seems to be a useful tool to better understand the outcome of patients with obesity after BS.

The melanocortin-4 receptor pathway and the emergence of precision medicine in obesity management

Over the past few decades, there has been a global surge in the prevalence of obesity, rendering it a globally recognized epidemic. Contrary to simply being a medical condition, obesity is an intricate disease with a multifactorial aetiology. Understanding the precise cause of obesity remains a challenge; nevertheless, there seems to be a complex interplay among biological, psychosocial and behavioural factors. Studies on the genetic factors of obesity have revealed several pathways in the brain that play a crucial role in food intake regulation. The best characterized pathway, thus far, is the leptin-melanocortin pathway, from which disruptions are responsible for the majority of monogenic obesity disorders. The effectiveness of conservative lifestyle interventions in addressing monogenic obesity has been limited. Therefore, it is crucial to complement the management strategy with pharmacological and surgical options. Emphasis has been placed on developing drugs aimed at replacing the absent signals, with the goal of restoring the pathway. In both monogenic and polygenic forms of obesity, outcomes differ across various interventions, likely due to the multifaceted nature of the disease. This underscores the need to explore alternative therapeutic strategies that can mitigate this heterogeneity. Precision medicine can be regarded as a powerful tool that can address this concern, as it values the understanding of the underlying abnormality triggering the disease and provides a tailored treatment accordingly. This would assist in optimizing outcomes of the current therapeutic approaches and even aid in the development of novel treatments capable of more effectively managing the global obesity epidemic.

Decreased Weight Loss Following Bariatric Surgery in Patients with Type 2 Diabetes

BACKGROUND

Bariatric surgery represents the most effective treatment for achieving significant and sustained weight loss. We aimed to assess whether presence of type 2 diabetes (T2D) at baseline, and T2D remission following bariatric surgery affect the weight loss outcome.

METHODS

Data of 312 consecutive morbidly obese subjects who underwent bariatric surgery were analysed. Patients underwent either RYGB (77%), or sleeve gastrectomy (23%), and their body weight was followed-up for 1, 2, 3, 4, and 5 years at regular ambulatory visits (N = 269, 312, 210, 151, 105, at each year, respectively). T2D remission was assessed according to the ADA criteria.

RESULTS

In the whole dataset, 92 patients were affected by T2D. Patients with T2D were older than patients without T2D (52 ± 9 vs 45 ± 11 years, p < 0.0001), but there were no differences in baseline BMI, sex, and type of intervention received. We found that presence of T2D at baseline was associated with smaller weight loss at 1, 2, 3, 4, and 5 years following bariatric surgery (δ BMI at 2 years: - 13.7 [7.7] vs - 16.4 [7.3] kg/m²; at 5 years - 12.9 [8.8] vs - 16.3 [8.7] kg/m² in patients with T2D vs patients without T2D respectively, all p < 0.05). When dividing the patients with T2D in remitters and non-remitters, non-remitters had significantly smaller weight loss compared to remitters (δ BMI at 2 years: - 11.8 [6.3] vs - 15.4 [7.8] kg/m²; at 5 years: - 8.0 [7.1] vs - 15.0 [7.2] kg/m², non-remitters vs remitters respectively, all p < 0.05).

CONCLUSIONS

T2D is independently associated to smaller weight loss following bariatric surgery, especially in subjects not achieving diabetes remission. • Patients with T2D achieve smaller weight loss following bariatric surgery • When dividing the T2D patients in remitters and non-remitters, non-remitters achieve significantly smaller weight loss compared to remitters.

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 Clinical-Genetic Score for Predicting Weight Loss after Bariatric Surgery: The OBEGEN Study

Around 30% of the patients that undergo bariatric surgery (BS) do not reach an appropriate weight loss. The OBEGEN study aimed to assess the added value of genetic testing to clinical variables in predicting weight loss after BS. A multicenter, retrospective, longitudinal, and observational study including 416 patients who underwent BS was conducted (Clinical.Trials.gov- NCT02405949). 50 single nucleotide polymorphisms (SNPs) from 39 genes were examined. Receiver Operating Characteristic (ROC) curve analysis were used to calculate sensitivity and specificity. Satisfactory response to BS was defined as at nadir excess weight loss >50%. A good predictive model of response [area under ROC of 0.845 (95% CI 0.805–0.880), p < 0.001; sensitivity 90.1%, specificity 65.5%] was obtained by combining three clinical variables (age, type of surgery, presence diabetes) and nine SNPs located in ADIPOQ, MC4R, IL6, PPARG, INSIG2, CNR1, ELOVL6, PLIN1 and BDNF genes. This predictive model showed a significant higher area under ROC than the clinical score (p = 0.0186). The OBEGEN study shows the key role of combining clinical variables with genetic testing to increase the predictability of the weight loss response after BS. This finding will permit us to implement a personalized medicine which will be associated with a more cost-effective clinical practice.

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.

Baseline Presence of NAFLD Predicts Weight Loss after Gastric Bypass Surgery for Morbid Obesity

Background. Bariatric surgery is a widely used treatment for morbid obesity. Prediction of postoperative weight loss currently relies on prediction models, which mostly overestimate patients’ weight loss. Data about the influence of Non-alcoholic fatty liver disease (NAFLD) on early postoperative weight loss are scarce. Methods. This prospective, single-center cohort study included 143 patients receiving laparoscopic gastric bypass surgery (One Anastomosis-Mini Gastric Bypass (OAGB-MGB) or Roux-en-Y Gastric Bypass (RYGB)). Liver biopsies were acquired at surgery. NAFLD activity score (NAS) assigned patients to “No NAFLD”, “NAFL” or “NASH”. Follow up data were collected at 3, 6 and 12 months. Results. In total, 49.7% of patients had NASH, while 41.3% had NAFL. Compared with the No NAFLD group, NAFL and NASH showed higher body-mass-index (BMI) at follow-up (6 months: 31.0 kg/m² vs. 36.8 kg/m² and 36.1 kg/m², 12 months: 27.0 kg/m² vs. 34.4 and 32.8 kg/m²) and lower percentage of total body weight loss (%TBWL): (6 months: 27.1% vs. 23.3% and 24.4%; 12 months: 38.5% vs. 30.1 and 32.6%). Linear regression of NAS points significantly predicts percentage of excessive weight loss (%EWL) after 6 months (Cologne-weight-loss-prediction-score). Conclusions. Histopathological presence of NAFLD might lead to inferior postoperative weight reduction after gastric bypass surgery. The mechanisms underlying this observation should be further studied.