Most of the selected genes of this pathway from the current GWAS pathway analyses, including, CHRNA5–CHRNA3–CHRNB432, GABBR133, GABBR233, GRM734, GRM835, GRIN2A35, and CHRND36 are significantly associated with nicotine dependence and smoking behavior, as well as known smoking-related diseases such as lung cancer. The gene discussed is CHRNA5; the disease is nicotine dependence.