GAD2 and major depressive disorder: Using the FCG mice to dissect the respective contributions of sex-related factors, we then show that genetic sex (i.e., X/Y-chromosome factors), independent of gonadal sex or circulating testosterorone, influences expression of these same genes in pro-anxiety/depression directions (lower expression in XY) (Figure 5), suggesting a mouse/human conserved mechanism of SST, GAD67, and GAD65 trans-regulation by X/Y-encoded genes.