The PPI analysis for the 15 overlapping genes between ADHD and HNC (including ACD, ADORA2A, CRP, CYP2D6, DCT, DYRK1A, FER, IGF-1, IL-6, MYC, NF1, NGF, NLRP3, NR4A2, and PER3) produced a network with 15 nodes and 87 edges (see Figure 3a). Here, CYP2D6 is linked to attention deficit-hyperactivity disorder.