Genes such as PRKACA in module a was enriched in integration of energy metabolism, morphine addiction and glutamatergic synapse pathways; in module b, genes such as CCL20, FPR2 and GNA11 were related to GPCR ligand binding, GPCR downstream signaling and Gastrin-CREB signaling pathway via PKC and MAPK pathways; in module c, the gene NFYB was highly associated with RNA binding-related pathways; while in module d, the gene HDAC10 was significantly enriched in two pathways, alcoholism and chromatin modifying enzymes (Table 3) . Here, CCL20 is linked to alcohol drinking.