Gene-environment interactions, including interactions with age-at-onset of smoking, have been the focus of several recent candidate gene analyses (Weiss et al. 2008; Chen et al. 2009; Schmid et al. 2009) However, we are unaware of multi-gene analyses of gene-environment interactions for smoking; i.e., analyses in which many polymorphisms are tested in interactive models with putative environmental moderators. Such exploratory approaches may prove to be fruitful for both enhancing our understanding of the etiology of nicotine dependence, as well as for gene discovery and validation (Kraft et al. 2007).
