Several genes contain SNPs whose allelic frequencies distinguish nicotine dependent from control individuals. We have focused on the 30 genes for which the differences between dependent and control individuals enhance the convergence of results previously obtained from four other abuser vs control whole genome association studies. The identification of allelic associations within so many genes that encode cell adhesion and extracellular matrix molecules support important roles for neuronal connectivities and memory-like functions in individual differences in vulnerabilities to addictions [32]. Data for each of these 30 genes provides new information about vulnerability to nicotine dependence. However, the approach that we use here does bias against genes that may contribute to vulnerability to nicotine alone. Failure to be included on this list should not be taken to exclude involvement in nicotine dependence of genes, such as those that encode nicotine metabolizing enzymes, that have been associated with nicotine dependence in previous studies [33].
