a risk locus (Berrettini et al., 2008; Thorgeirsson et al., 2008; Caporaso et al., 2009; Liu et al., 2009; Vink et al., 2009; Tobacco and Genetics Consortium 2010; Liu et al., 2010; Thorgeirsson 2010). Our meta-analysis of linkage scans of smoking behavior identified a genome-wide significant linkage for the maximum number of cigarettes smoked in a 24-hour period in a region (20q13.12-q13.32) harboring CHRNA4 (Han et al., 2010). This motivated us to evaluate the association of CHRNA4 with smoking behavior in two independent samples.
