Interestingly, this specific susceptibility for the development of despair‐like behavior in Flot1 KO mice under challenge was paralleled by a concomitant alteration in SERT expression and in the activity of serotonergic neurons which could lead to the speculation that altered SERT levels and function may be a distinct feature also of a subgroup of human patients suffering to depression, a hypothesis which remains to be tested in future translational and clinical studies. Here, SLC6A4 is linked to major depressive disorder.