We assembled a list of 486 genes biologically relevant for addiction mainly through an expert nomination process (http://grants.nih.gov/grants/guide/notice-files/NOT-DA-07-010.html). Most of these were identified based on involvement in neurobiological pathways relevant to substance abuse and were in part vetted by addiction neurobiologists (see Acknowledgments). These included genes involved in biosynthesis, metabolism, transport, receptor binding, and intracellular signaling. Common biochemical pathways and systems included the serotonergic, noradrenergic, dopaminergic, GABA-ergic, glutamatergic, opioid, alcohol metabolizing and nicotinic systems. In addition, genes involved in the metabolism of FDA-approved medications for substance abuse were also included (e.g., cytochrome p450 genes); genes involved in the medications' pharmacodynamic effects were selected as part of the pathway-based approach. 34 of these genes were added to the initial results of the nomination process because they used for recent custom panel of SNPs for alcoholism and other addiction related traits [16], and 96 of these genes were added from a recent study of addiction [17].
