GABRA4 and substance abuse: PC2 was enriched for mood, substance abuse, and psychosis disorders along its negative thalamic axis (dorsal-to-ventral), with genes for gamma-aminobutyric acid (GABRA4/GABRA5), corticotropin releasing hormone (CRH), opioid receptors (OPRM1), and glutamate metabotropic receptors (GRM7) being implicated across disorders (Supplementary Data 12; the positive axis of PC2 did not show any significant enrichment).