Nicotine addiction has profound clinical and public health consequences because it is associated with reduced ability to cease tobacco use [1],[2], and tobacco use is the leading cause of preventable morbidity and mortality in developed countries [3]. Meta-analysis of numerous twin studies shows that both genes and environment play an important role in smoking-related behaviors [4]. Nicotine is the primary agent in tobacco smoke that leads to addiction, and while progress has been made in finding genes that contribute to nicotine addiction in humans [5]–[9], there is a great need for additional progress.
