Our top gene associated with lifetime cannabis use was NCAM1, a known candidate for nicotine dependence.45 The role of NCAM1 is to regulate pituitary growth hormone secretion as a membrane-bound glycoprotein that mediates cell–cell contact by hemophilic interactions.46NCAM1 is part of the NCAM1–TTC12–ANKK1–DRD2 (NTAD) gene cluster, which is related to neurogenesis and dopaminergic neurotransmission. This evidence concerns the gene GH1 and nicotine dependence.