Although smoking initiation and nicotine dependence are related, the genetics of nicotine dependence are of primary interest because of its public health ramifications: nicotine dependence predicts difficulty with cessation and carries most of the morbidity associated with smoking. Specifically, the quantity of cigarettes smoked in a lifetime is associated with lung disease and heart disease, and smoking cessation is a positive prognostic factor for both. Individuals with nicotine dependence account for 13% of the general population but consume 58% of the cigarettes smoked in the United States.2 Thus, understanding the genetics of nicotine dependence can lead to targeted treatments and may ultimately decrease tobacco-associated morbidity and mortality.
