Although twin studies provide strong evidence for involvement of genetic factors in various stages of smoking behavior, identifying these susceptibility genes has been a challenge. During the past few years, a significant numbe of genome-wide association studies (GWAS) have been conducted for various smoking phenotypes, including SI and current smoking (Caporaso et al. 2009; TGC 2010 Thorgeirsson et al. 2010; Vink et al. 2009), age at smoking initiation (Siedlinski et al. 2011), ND (Bierut et al. 2007 Liu et al. 2009; Uhl et al. 2007), smoking quantity (Siedlinski et al. 2011; Berrettini et al. 2008; Caporaso et al 2009; Liu et al. 2009, 2010; TGC 2010; Thorgeirsson et al 2010, 2008), and smoking cessation (Siedlinski et al. 2011 TGC 2010; Uhl et al. 2008, 2010). However, most of these studies focused primarily on samples of European origin. Given the distinct differences in linkage disequilibrium (LD) patterns across ethnic populations (Li and Burmeiste 2009), a GWAS in other ethnic samples is warranted.
