The association of smoking dependence was explored in the lung cancer report by Hung and colleagues [13] who did not detect any association with individual Fagerstrom indices of nicotine addiction or when comparing controls with a heaviness of smoking index (HSI). Another lung cancer report by Amos and colleagues [12] did show weak evidence for association with smoking behavior, while a further report by Thorgeirsson and colleagues[14] showed very strong association with smoking behavior. Association of this locus with nicotine dependence has been reported in two other studies [15],[16]. Thus, it is reasonable to conclude that the variants may affect smoking behavior, at the same time as having a significant effect on COPD and other smoking related diseases such as lung cancer and peripheral arterial disease [12]–[14].
