Substance-specific genetic signals fell primarily into three broad categories: drug-specific metabolism (e.g., ADH1B for PAU), drug receptors (e.g., CHRNA5 for PTU, OPRM1 for OUD), and general neurotransmitter mechanisms (e.g., CACNA1A for CUD). Surprisingly, even after accounting for the addiction-rf, dopaminergic genes (DBH and PDE1C in particular) were implicated in substance-specific effects for tobacco (PTU). On the other hand, CUD-specific genes did not include well-studied receptor targets (e.g., CNR1) or metabolic mechanisms (e.g., Cytochrome P450 genes).
