Body index mass not associated with DRD4, DAT1, BDNF, and COMT gene polymorphisms in young adults without depression or anxiety disorders

Depressive and anxiety disorders have been associated with body mass index (BMI), since mesolimbic reward circuits, such as dopamine secretion and the expression of dopamine neuronal receptors, have been related to weight in people with mental issues. However, few studies have analyzed polymorphisms of genes of the dopaminergic system in healthy populations. We evaluated association of BMI with four polymorphisms of genes related to the dopaminergic system, DRD4, DAT1, BDNF, and COMT, in young adults without depression or anxiety disorders. Blood samples of 62 subjects were analyzed for polymorphisms of VNTR DRD4 and DAT1 by PCR, and the SNPs of BDNF and COMT genes by Sanger sequencing, as well as their score in the Beck Depression and Beck Anxiety inventories. We also measured the level of physical activity, height (cm), weight (kg), and calculated BMI. Multivariate linear regression was used to analyze associations between BMI and polymorphisms. Allelic frequencies of the four genes in the sample studied were in Hardy-Weinberg equilibrium. BMI was higher in male subjects (p<0.05). Multivariate linear regression did not show an association between the polymorphisms with BMI after adjusting by sex. The BMI of young adults without depression and anxiety disorders was not found to be associated with polymorphisms of the 3rd exon of DRD4, 3'UTR of DAT1 genes, rs6265 BDNF, or rs4680 COMT.