FOXP2 and nicotine dependence: For cannabis use disorder, 2 genes were significantly associated including, PDE4B (P = 2.09 × 10−6) and FOXP2 (P = 9.30 × 10−7, Supplementary Table 3), and one gene for nicotine dependence—ARHGAP22 (P = 2.42 × 10−6, Supplementary Table 4).