Lerman et al. (2004) reported that the G allele carriers were more likely to quit smoking successfully using nicotine replacement therapy. Furthermore Zhang et al. (2006) found in 688 Caucasian smokers and nonsmokers that three OPRM1 SNPs (rs9479757, rs2075572, and rs10485057) were highly significant for tobacco smoking initiation (p = 0.0002), and marginal for nicotine dependence (p = 0.05). Recently Verhagen et al. (2012) published a meta-analysis about smoking initiation, nicotine dependence and smoking cessation. This evidence concerns the gene OPRM1 and nicotine dependence.