This replication in a third sample provides further support for a role of the putative promoter region of CHRNB3 and early subjective responses to tobacco (Zeiger et al., 2008). Therefore, we conducted functional studies aimed at determining whether different SNPs in this putative promoter region might lead to differences in expression of CHRNB3. Work by others has shown that a 75bp fragment located immediately upstream of the ATG start site is sufficient for neuronal-specific expression of β3 in birds (Hernandez et al., 1995; Roztocil et al., 1998). Our analysis shows a similar stretch of sequences in the same region of the human CHRNB3 gene, which overlaps with known SNP rs41272375 (see Figure 2). Because the SNP rs4950, immediately downstream of rs41272375, was implicated in our previous study and was nominally significant in this study, we generated two pairs of luciferase reporter assay constructs which included rs4950. One pair of constructs extended approximately 3000 bp upstream of the initiation codon of CHRNB3 and included SNPs rs13277254 and rs13277524. Both of these SNPs are among the top five SNPs (rs10958726, rs1955186, rs1955185,
