PCDH9 and major depressive disorder: Based on human studies, 12 unique genes residing in MDD-associated loci overlapped with genes differentially methylated upon exposure to cannabis [44,47,48], with 9 of them (ESRRG, CACNA1C, GPC5, FAM189A1, MAD1L1, ADARB2, RERE, PCDH9, and RBFOX1) also identified as overlapping with MDD genes in animal studies of exposure to CBD or THC [41,42,43].