Our results of depression-like behavior in KIV mice of both genders are in contrast to the previous studies showing unchanged depression-like behavior or female-specific depression-like behavior under stress in BDNF-coding region deficient mice (BDNF +/- and conditional knockouts, 56, 57, 58, 59, 60 reviews in Duman and Monteggia13 and Groves61). This evidence concerns the gene BDNF and major depressive disorder.