Tobacco smoking is one of the most costly health issues facing the world today. According to the World Health Organization, billions of dollars were spent in smoking related health care and in the US alone, 440,000 deaths were attributed to smoking related disorders in 2002 [MMWR, [2004]]. While smoking is a complex behavior in which many environmental factors are involved, genetic-epidemiology studies in the last decade have provided compelling evidence that genetic factors play a significant etiologic role [True et al., [1997]; Lerman et al., [1999]; Sullivan and Kendler, [1999]; Li et al., [2003]; Munafo et al., [2004]]. Genome wide linkage scans [Bergen et al., [1999]; Duggirala et al., [1999]; Straub et al., [1999]; Bierut et al., [2004]; Vink et al., [2004]; Li et al., [2006]; Swan et al., [2006]] and association studies [Ishikawa et al., [1999]; Bierut et al., [2000]; Caporaso et al., [2001]; Sullivan et al., [2001]; Feng et al., [2004]; Ling et al., [2004]; Li et al., [2007]; Nussbaum et al., [2008]] have identified linkage regions and candidate genes for tobacco smoking and nicotine dependence.
