Nevertheless, none of the examined SNPs were found to be associated with depression in colorectal cancer patients, including the deletion SNP of 5-HTTLPR, rs6295 in serotonin 1a receptor (HTR1a), rs6265 in BDNF, rs1360780 in FKBP5 and rs4680 in COMT. This evidence concerns the gene BDNF and major depressive disorder.