Cigarette smoking is the most preventable cause of morbidity and death, resulting in more than 438,000 deaths in the United States in 2000 and approximately $193 billion in health-related economic losses (Mokdad and others 2004). Over the past four decades, cigarette smoking has caused an estimated 12 million deaths, including 4.1 million from cancers, 5.5 million from cardiovascular diseases, 2.1 million from respiratory diseases, and 94,000 infant deaths attributable to maternal smoking during pregnancy (www.cdc.gov/nccdphp/publications/aag/osh.htm.). Although cigarette smoke contains many noxious compounds, including carbon monoxide, acetaldehyde, and tobacco-specific nitrosamines, it is nicotine dependence (ND) that maintains the continued use of tobacco (Stolerman and Jarvis 1995; USDHHS 2000; WHO 2002). Twin and family studies reveal that genetics contributes significantly to ND, with an estimated mean heritability of 0.56 in adult smokers (Li and others 2003).
