We choose four nAChR SNPs among many possible nAChR SNPs with a priori evidence for an association with nicotine dependence, with response to nicotine or with smoking cessation. We choose these four based on substantial and repeated a priori evidence of association with nicotine dependence and with abstinence (below). The a priori associations represented by these four nAChR SNPs are the only association signals investigated across the eight RCTs to date.
