GABBR2 and major depressive disorder: Of specific interest, and consistent with current hypotheses for the molecular pathology of MDD, was the inclusion of brain-derived neurotrophic factor (BDNF) and other factors implicated in development and maintenance of cell circuits (Ephrin receptors EPHA3 and EPHA 5; Netrin G1 (NTNG1); SLITRK3 and SLITRK5), of GABA-related genes (GABBR2, GABRA4 and CALB1), glutamate receptors (GRM1 and GRM7) and other signaling neuropeptides previously implicated in mechanisms of psychiatric disorders [reelin (RLN) and gastrin-releasing peptide (GRP)] (Table 2).