Numerous genome-wide studies and meta-analyses conducted in multiple ethnic groups have identified genes thought to be responsible for smoking related measures and behaviors, including smoking quantity (cigarettes smoked per day: CPD) and the Fagerström Test for Nicotine Dependence (FTND) (Bierut et al., 2007; Berrettini et al., 2008; Vink et al., 2009; TAG 2010; Thorgeirsson et al., 2010; Liu et al., 2010; Li et al., 2006; Li et al., 2008; David et al., 2012; Chen et al., 2012; Rice et al., 2012). In addition, targeted association studies have identified the CHRNA5-A3-B4 gene cluster as being associated with nicotine dependence in various ethnic populations (Saccone et al., 2007, 2009, 2009b; Li et al., 2010, 2010b). The missense polymorphism rs16969968:G>A in CHRNA5 is thought to confer risk for heavy smoking in people of European ancestry as it encodes an amino acid change (D398N) that leads to hypo-functionality of (α4β2)2α5 nAChRs (Bierut et al, 2008; Kuryatov et al., 2011; Tammimäki et al, 2012). However, rs16969968:G>A has a low minor allele frequency (MAF) in populations other than those of European descent (Bierut et al., 2008)
