BDNF and major depressive disorder: However, cigarette smoking, illicit substance use, diabetes mellitus, symptoms of depression, or putative genetic markers for BDNF (rs6265 [Val66MET], rs1519480) and CRP (rs3093080, rs3093066, rs3093062, rs3093059, rs3093058, and rs3091244) were not associated significantly with 8-oxodG.