The Waist-Hip Ratio is a Mediator Between Serum Levels of Brain-Derived Neurotrophic Factor and Its Val66Met Polymorphism in Adolescents.

Aim: To explore anthropometric, metabolic and dietary factors associated with and their interplays with the Val66Met polymorphism at brain-derived neurotrophic factor (BDNF) gene (Bdnf) on serum BDNF levels in adolescents. Methods: Serum BDNF levels were quantified using an enzyme-linked immunosorbent assay in 644 high school students (278 males/366 females). A polymerase chain reaction and restriction fragment length polymorphism assay were utilized for Bdnf Val66Met genotyping followed by verification using DNA sequencing. Serum levels of metabolic characteristics were assayed by routine methods. The intake of macro and micronutrients was collected by a three-day food record. Results: Serum BDNF levels were found to be significantly different in the subjects with different genotypes of Bdnf Val66Met (Val/Val homozygotes, 60.05 ± 28.07 ng/mL vs Val/Met heterozygotes, 56.37 ± 29.34 ng/mL vs Met/Met homozygotes, 51.32 ± 24.54 ng/mL, p = 0.022). Among the 36 tested variables, waist-hip ratio (WHR) (ß = -0.163, p < 0.001), iodine intake (ß = 0.132, p = 0.001), heart rate (ß = 0.108, p = 0.005), high-density lipoprotein cholesterol (HDL-C) (ß = 0.098, p = 0.011) and dietary fiber intake (ß = 0.082, p = 0.084) were the predictor of serum BDNF levels, while SBP (ß = 0.097, p = 0.013) and WHR (ß = 0.091, p = 0.021) were related with Bdnf Val66Met. Moreover, WHR was observed to play a partial mediating role in the relationship between Bdnf Val66Met and serum BDNF levels (95% CI [-1.161, -0.087]) and contribute 13.05% of its total effect on serum BDNF levels. Conclusion: There are interplays between WHR and Bdnf Val66Met on serum BDNF levels, which may be among the explanations for the previous heterogeneous reports and provide novel insights into the regulation of serum BDNF levels.