By comparing heavy smokers and never smokers, we identified five novel regions of association with smoking behaviour and confirmed four previously reported loci (15q25, 7p14, DBH, and BDNF; table 2; appendix pp 32–37).17–19 The novel signals included rs4466874, in an intron of NCAM1 (chromosome 11), and rs10193706, an intergenic SNP on chromosome 2 downstream of TEX41 and upstream of PABPC1P2 (table 2; appendix pp 110–112). Uncorrelated (r2<0·0001 with rs4466874) SNPs in TTC12 and ANKK1, near to NCAM1, have also previously shown association with nicotine dependence (appendix pp 74–75).44 A proxy of rs10193706 on chromosome 2 (rs953246, r2=0·48) is a trans eQTL for NCAM1 on chromosome 11 in brain tissue (appendix pp 76–77). Another proxy of rs10193706 on chromosome 2 (rs12622738, r2=0·86) is a trans eQTL in the substantia nigra for WDR61 on chromosome 15, 300 kb from the established 15q25 smoking locus (appendix pp 76–77).
