The genes involved in immune and inflammatory responses that were among the top 10 downregulated and upregulated genes related to responsiveness to SSRI treatment consisted of BTNL8, CLC, CTSW, FCRL6, GNAQ, HLA-DPB1, IGKC, KIR2DS1, NOD2, USP41, VNN1, and XCL1. The BTNL8, HSPH1, IGKC, KATNBL1, LYVE1, MIR15A, PTCH2, and SCARNA17 genes were also found to be differently expressed between MDD patients and controls. This evidence concerns the gene MIR15A and major depressive disorder.