Twin, adoption, clinical trial, and case-control studies suggested that there is strong evidence of the influence of genetic variants in nicotine-dependence etiology and treatment, where genetic variants' contributions were evaluated at more than 50% [1, 32], conveying the possibility that CYP2A6 polymorphism information analysis may strengthen nicotine dependence treatment. This evidence concerns the gene CYP2A6 and nicotine dependence.