CCK and major depressive disorder: We found 24 genes that have been previously associated with depression, including CSF3, IL1R2, IL6, SERPINA3, MT-ND5, MT-ND6, P2RX2, ATP4, NOTCH1, EGFR, TLR4, STAT3, ERBB2, PROC, CARTPT, GRIK2, CACNA1G, GABRD, BCL2, CHDH, NRGN, SERPINF1, CCK and CRHR1.