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

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. To investigate whether UCP2 −866G/A and Ins/Del polymorphisms are associated with weight loss outcomes after bariatric surgery. Longitudinal study in a university hospital. 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. 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. 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. •Carriers of -866A/A genotype maintained higher BMI at 6, 12 and 18 months after RYGB compared to G/G patients.•In -866A/A carriers, excess weight was higher while EWL% was lower at 6 and 12 months after RYGB compared to G/G carriers.•Ins allele of Ins/Del polymorphism seems to be associated with lower BMI change 12 months after RYGB surgery.