We selected 58 candidate genes using a comprehensive bioinformatic approach incorporating expert opinion, automated literature searches, and public pathway databases. The candidate gene list includes several neuronal nicotinic acetylcholine receptors (nAchRs) and genes in the dopamine-mediated reward system, including dopamine receptors, dopamine transporter, and enzymes involved in biosynthesis and metabolism. Additional addiction-related secondary messenger pathway genes, and genes hypothesized to play a role in modulating the dopamine pathway owing to upstream signaling (e.g. serotonin pathway) and those with direct physical interaction with dopamine receptors were also included. The complete list of genes is presented in Table 1.
