Several GWAS have consistently identified a region on chromosome 15q24 associated with smoking intensity or lung cancer (51–55). Candidate gene studies have also confirmed the association between variation mapped to the gene cluster (CHRNA5, CHRNA3 and CHRNB4) at 15q24 and different smoking behaviors (34, 56–59). We are not aware of any individual genomewide linkage scan which has reported genomewide suggestive or significant linkage in the region of 15q24. Our primary 30 cM width GSMA did not detect any signal in 15q24, but we did find PSR=0.058 at bin 15.2 (15q21.1–q25.1) which covered the region 15q24 in the 30 cM shifted GSMA of smoking behavior in the European descent populations. The evidence for linkage obtained from the current GSMA thus fails to provide linkage support for the region 15q24 that apparently harbors ND susceptibility genes. The fact that we did not find any stronger evidence for linkage in this region might imply that the genetic effect is small and the current GSMA does not have sufficient power to achieve significant evidence for linkage in this region or that the heterogeneity among
