In humans, the C(-1019)G 5-HT1A promoter polymorphism leading to 5-HT1A receptor overexpression is proposed to represent a risk factor for depression (Lemonde et al., 2003; Strobel et al., 2003; Rothe et al., 2004; reviewed in Albert and Francois, 2010) and response to antidepressant drugs (reviewed in Albert, 2012). This evidence concerns the gene HTR1A and depressive disorder.