Considering that (1) the participants in most of these studies were primarily European Americans or of European origin, with the exception of two studies on African Americans [18], [28], and (2) there are distinct differences in linkage disequilibrium (LD) patterns across different ethnic populations [12], it is of tremendous interest to determine whether variants in this gene cluster play any role in the etiologies of smoking behavioral phenotypes in other ethnic groups. Thus, the major objective of this study was to test for such genetic effects in a large population-based Korean sample.
