Serotonin transporter gene promoter polymorphism is associated with body mass index and obesity in non-elderly stroke patients

Background: The serotonergic system is involved in the complex behavioral and physiological process in maintaining energy balance. Genetic factors regulating serotonergic function may have links with the development of obesity. Aim: To investigate whether the 5-HTTLPR polymorphism of the serotonin transporter gene is associated with body mass index (BMI) and obesity in stroke patients. Subjects and methods: The study included 376 patients (65.3±11.3 yr; male, 61.7%) with stroke. Associations between the 5-HTTLPR and BMI and obesity (BMI>-25 kg/m2) were examined in all subjects. In order to test age-dependent effects of the genetic variant, the association was also examined in the non-elderly subgroup (<65 yr) and the elderly subgroup (>-65 yr) respectively. Results: For non-elderly subjects, the SS genotype was independently associated with increased BMI level (β=1.84, p=0.037) and obesity (odds ratio 4.17, 95% CI 1.25–14.0, p=0.021) when the LL genotype was used as the reference. The association was not found for all patients or in the elderly subgroup. The LS genotype was not different from the LL genotype in BMI level or risk of obesity, either for all subjects or with regard to the non-elderly and elderly subgroups. Conclusions: The SS genotype of 5-HTTLPR is an independent determinant of increased BMI level and obesity in non-elderly stroke patients but not in elderly patients. An age-dependent modification for the effect of the 5-HTTLPR on development of obesity is considered.