PIK3CD and alcohol dependence: The top five upregulated KEGG pathways are protein digestion and absorption, PI3K-Akt signaling pathway, focal adhesion, ECM–receptor interaction, and Ras signaling pathway, whereas the top five downregulated KEGG pathways are neuroactive ligand–receptor interaction, alcoholism, cytokine–cytokine receptor interaction, tryptophan metabolism, and cell adhesion molecules (Figure 4B).