Influence of the BDNF Val66Met polymorphism on weight loss after bariatric surgery: a 24-month follow-up.

ABSTRACT: Background Bariatric surgery is currently the most effective long-term treatment for severe obesity. However, interindividual variation in surgery outcome has been observed, and research suggest a moderating effect of several factors including baseline co-morbidities (e.g. type 2 diabetes (T2D) and genetic factors. No data are currently available on the interaction between T2D and variants in BDNF and its effect on weight loss after surgery. Objective To examine the role of the BDNF Val66Met polymorphism (rs6265), and the influence of T2D, and their interaction on weight loss after bariatric surgery in a cohort of patients with severe obesity. Setting University Hospital in Spain. Methods We evaluated a cohort of 158 patients with obesity submitted to bariatric surgery (Roux-en-Y Gastric Bypass or Sleeve Gastrectomy) followed-up over 24 months (t24m: loss to follow-up: 0%). During the post-operative period, percentage of excess body mass index loss (%EBMIL), percentage of excess weight loss (%EWL) and total weight loss (%TWL) were evaluated. Results Longitudinal analyses showed a suggestive effect of BDNF genotype on the %EWL (P = 0.056) and indicated that individuals carrying the Met allele may experience a better outcome after bariatric surgery than those with the Val/Val genotype. We found a negative effect of a T2D diagnosis at baseline on %EBMIL (P = 0.004). Additionally, we found an interaction between BDNF genotype and T2D on %EWL and %EBMIL (P = 0.027 and P = 0.0004, respectively), whereby individuals with the Met allele without T2D at t0 displayed a greater %EWL and more %EBMIL at t12m and t24m than their counterparts with T2D or patients with the Val/Val genotype with or without T2D. Conclusion Our data showed an association between the Met variant, and greater weight loss after bariatric surgery in patients without T2D. The presence of T2D seems to counteract this positive effect.