The most important finding of the present study was that BDNF intron variant, rs962369 was associated with a significant 3.5-times increase in the risk of single-episode MDD for subjects who were homozygous for the minor allele C. In addition, the variant rs962369 demonstrated an effect on the development of recurrent MDD, most significantly in the log-additive model (1.7-times per C-allele). This evidence concerns the gene BDNF and major depressive disorder.