A recent project that illustrates the “Pharmaco-omics” research strategy that has proved to be so powerful in our studies of SSRI response in patients suffering from MDD is our 2016 “Molecular Psychiatry” (Gupta et al, 12:1717-1725, 2016) study which reported that, of the panel of LCECA platform plasma metabolites that we assayed at three time points for 300 MDD patients being treated with SSRIs, it was plasma serotonin that was most highly associated with virtually all of the clinical symptom-related outcomes and—furthermore—when we performed a GWAS for level of plasma serotonin as the phenotype, we identified two novel genes, TSPAN5 and ERICH3, that were genome-wide significant, both of which are highly expressed in the brain and which we could link functionally to serotonin biosynthesis in neuronally-derived cells. Finally, the ERICH3 SNPs from the GWAS were replicated in two other studies of SSRI response in MDD. These were striking and potentially significant examples of the power of joining multiple “omics” techniques—particularly against a background of the general lack of success of genomic techniques alone when applied to psychiatric illness.