The obscure role of genetics on weight loss after bariatric surgery

Weight Loss Following Roux-en-Y Gastric Bypass Causally Implicated with Serum Levels of IL-22: A Mendelian Randomization and Phenome-Wide Association Study

OBJECTIVE

Laparoscopic Roux-en-Y gastric bypass (RYGB) modulates the low-grade inflammatory state associated with severe obesity. This study sought to investigate whether weight loss is causally implicated with changes in serum levels of inflammatory molecules.

METHODS

Using the largest genome-wide association study (n = 1,020 individuals), this study curated five genetic variants associated with weight loss following RYGB. Phenome-wide association studies (PheWAS) were performed to identify other phenotypes associated with these variants. Subsequently, two-sample Mendelian randomization was used to study the causal effects of weight loss on the serum levels of 382 inflammatory proteins (measured in 3,033 individuals). This is the first systematic quasi-experimental investigation of weight loss following RYGB and serum markers of inflammation.

RESULTS

The PheWAS analysis revealed that four of the five variants are associated with phenotypes relating to metabolism and inflammation, including insulin response and levels of C-reactive protein. Two-sample Mendelian randomization of the 382 serum inflammatory markers revealed that weight loss following RYGB increases serum levels of interleukin 22 (IL-22) (beta = 0.021, P < 10-3 ; 95% CI: 0.010-0.031). Sensitivity analyses further supported the results and the causal direction.

CONCLUSIONS

Weight loss following RYGB may cause an increase in IL-22 serum levels, suggesting that weight loss directly contributes to immune modulation following bypass. These results demonstrate the utility of genetic studies to disentangling molecular cause and effect following bariatric surgery.

Preoperative considerations for the pediatric patient undergoing metabolic and bariatric surgery

To ensure successful outcomes in pediatric patients with severe obesity who undergo metabolic and bariatric surgery (MBS), a number of pre-operative patient management options should be considered. This manuscript will review the indications and contraindications of MBS and special considerations for youth who might benefit from MBS. The treatment team conducts a thorough pre-operative evaluation, assessing risks and benefits of surgical intervention, and prepares patients and families to be successful with MBS by providing education about the surgical intervention and lifestyle changes that will be necessary. This article reviews the pre-operative considerations for adolescents with severe obesity who are being considered for MBS, based upon recent clinical practice guidelines.