Beyond finding DNMT3B and (as expected) CHRNA5-CHRNA3-CHRNB4, our GWAS meta-analysis resulted in P<5×10−7 for two other loci previously implicated in smoking, CHRNA4 on chromosome 20q1323, 24 and dopamine β-hydroxylase (DBH) on chromosome 9q34.17, 24 Our prior nicotine dependence GWAS meta-analysis of EUR studies identified the CHRNA4 splice site SNP rs2773500.23 Rare CHRNA4 variants have also been found to associate with nicotine dependence.67, 68 Our study supported common CHRNA4 SNP associations among EUR samples, but no association was detected for these SNPs among AA studies (Table 1).
