Although our study was sufficiently powered to detect small to moderate genetic effects, we could not resolve the ambiguity of pharmacogenetic findings for BDNF. Several clinical and preclinical studies have assigned a major impact of BDNF in the pathophysiology of depression and its recovery mechanisms, while pharmacogenetic and case-control studies on BDNF polymorphisms have produced conflicting results [19], [22]–[24], [41], [47], [50]–[56]. This evidence concerns the gene BDNF and major depressive disorder.