Since cigarette use involves both motivational and reward systems that develop through interactions between genes and the environment, studies of the joint effects of multiple genetic mutations across different environments could be useful in understanding the range of genetic susceptibility to environmental risk factors influencing cigarette use and its health consequences (4). GxE studies have been useful in determining whether genetic effects are more or less important under particular environmental conditions (5). For example, restricting the availability of tobacco has been found to reduce the effect of genes influencing whether individuals initiate and maintain smoking behaviors. Alternatively, under environments where there are fewer restrictions, the importance of the role of genes is expected to increase since individuals are able to express the full range of phenotypes (6), inclusive of nicotine dependence and tobacco-related health conditions such as heart disease and cancer. Quitting cigarette use can effectively reduce the risk of these tobacco-related outcomes for each individual smoker, while also substantially reducing excess health-care utilization and improved labor supply on a larger scale (4). However, to improve strategies for disease prevention and intervention efforts focused on smoking cessation, a better understanding of genetic, social environment, and individual determinants of risk contributing
