Contribution of 5-HTTLPR and BDNF gene variants to obesity risk

Background: 5-Hydroxytryptamine (5-HT, serotonin) plays an important role in the central nervous control of energy balance and is involved in several biological processes including mood, appetite, sleep, libido, memory, and body weight regulation. Brain-derived neurotrophic factor (BDNF) is also currently recognized as an important participant in the regulation of food intake. The aim of this study was to evaluate whether the 5-HTTLPR S/L and BDNF Val66Met gene variants are associated with obesity in a sample of adults of Croatian origin. Materials and methods: 462 individuals were investigated including 301 obese (BMI ≥ 30 kg/m2) and 161 lean (BMI < 25 kg/m2) (mean age ± SD was 49 ± 8 years). Genotyping of triallelic structure of 5-HTTLPR (LA, LG, S) and of BDNF Val66Met polymorphisms was performed using the RealTime based allele specific PCR methods. Results: In the whole group we found no associations between 5-HTTLPR S/L and BDNF Val66Met polymorphisms and obesity. When we compared male and female samples, we observed statistically significant differences in the distribution of 5-HTTLPR genotypes: 5-HTTLPR LALA genotype was more frequent in the group of lean women comparing to the group of lean men (41% and 28% respectively, P = 0.022). The 5-HTTLPR S and BDNF Met allele carriers have higher risk to develop obesity (OR 2.07) than non carriers (P = 0.038). Discussion: Our findings indicate that 5-HTTLPR polymorphism may be linked with obesity in adult female population, reinforcing the role of the serotonin transporter as a risk factor for the obesity phenotype. SERTPR and BDNF gene interactions could additionally predispose to obesity risk.