of life when smoking initiation occurs in 80–90% of the cases(30, 55). We have also shown that rs1051730[A] is associated with increased risk of smoking persistence. CHRNA3-rs1051730 is located in a region of high linkage disequilibrium. In this regard, genotype at rs1051730 is highly correlated (r2=0.9 in Caucasians) with genotype at a non-synonymous (aspartic acid [D] to asparagine [N]; rs16969968) SNP mapping in CHRNA5. The asparagine allele at rs16969968 has been shown to moderate nicotine response both in vitro(14) and in vivo(9). Of note, the asparagine allele is on the same haplotype-background of 1051730[A] and might therefore be the ‘risk’ variant in this region.
