BDNF and major depressive disorder: Although the sample size in our study was much smaller than those in recent meta-analyses of G×E interactions of SLC6A4[9], [10], [11], our results supported the negative trend for an association of the effect of 5-HTTLPR in SLC6A4. Although the most recent meta-analysis of BDNF[8] showed a significant association of the effect of the G×E interaction on the depression state, as shown in an individual report of FKBP5[28], our data could not support these findings.