Although many previous studies have demonstrated significant associations with SNPs that map to the chromosome 15 nicotinic receptor cluster (CHRNA5/CHRNA3/CHRNB4), we found no GWS results for this region (Table S2 in Supplement 1). The most significant p value that we observed for this gene cluster was 6.78 × 10−7 for rs11633958, which is intronic at CHRNA5. We observed p values of <10−5 at each of the three loci. Both the Yale-Penn and the SAGE samples contributed to these findings, and the EA contribution was in most cases greater than the AA contribution.
