Influence of G308A polymorphism of tumor necrosis factor alpha gene on insulin resistance in obese patients after weight loss

Background and objective: An accumulating body of evidence shows that modest weight loss (5%) through dietary changes and exercices is an effective means for managing obesity-associated disorders. As far as we kow, nobody has described the dietary response in insulin resistance and adipocytokines, analyzing the G308A variant of the tumor necrosis factor alpha (TNF-alpha) gene. The aim of our study was to investigate the influence of G308A polymorphism in the TNF-alpha gene on insulin resistance and weight loss secondary to a hypocaloric diet in obese patients. Patients and method: A population of 69 obese -body mass index (BMI) > 30 kg/m(2)- non diabetic outpatients was analyzed in a prospective way. Before and after 3 months of life style modification program, tetrapolar electrical bioimpedance, blood pressure, a serial assessment of nutritional intake with 3 days written food records and biochemical analysis were performed. The lifestyle modification program consisted of a hypocaloric diet 1,520 kcal. Results: Sixty-nine patients completed the follow-up during 3 months, with a weight loss (standard deviation) of 2.96 (3.4) kg (3.3%). Fifty two patients (13 males and 39 females) (75.3%) had the genotype G308/G308 (wild group) with an average age of 44.9 (16.8) years, and 17 patients (5 males and 12 females) (24.7%) had the genotype G308/A308 (mutant group) with an average age of 48.3 (15.2) years, without statistical differences. In mutant type group, BMI, body weight and waist circumference decreased. Mutant type group had higher basal and after treatment weight than wild group. Conclusions: Weight loss is associated with different changes depending of TNF-alpha genotype. Carries of G308G variant of TNF-alpha gene have a better metabolic response than A308 obeses.