represent true positive observations, we have focused on gene variants that are also identified in other comparisons between individuals who are dependent on other substances vs controls. This strategy may reduce the novelty of the list of genes reported here, though these findings do provide novel information concerning the possible roles of variants in these genes in vulnerability to nicotine dependence as opposed to dependence on other substances. We can compare current data to very recent reports that identify SNPs whose allelic frequencies differ between dependent vs nondependent smokers [51,52]. Three hundred thirty-one and 623 of the SNPs that distinguish nicotine dependent vs control individuals and 16 and 25 of the SNPs that distinguish successful vs unsuccessful quitters lie within 10 and 100 kb of one of these candidate genes. These SNPs thus provide modest additional support to findings reported at the ADRBK2, AVPR1A, BDNF, CCK, CHRNA10, CHRNA2, CHRNA4, CHRNA5, CHRNA6, CHRNA7, CHRNB2, CHRNG, CLCA1, CLTCL1, CNR1, CTNNA3, DBH, DDC, DRD1, DRD3, FBXL17, FMO1, FMO4, FTO, GABBR2, GABRA4, GABRB2, HTR1A, HTR5A, KCNJ6, NPY, NRXN1, OPRD1, OPRK1, PDYN, PENK, PIP5K2A, POMC, SLC6A3, SLC6A4, TRPC7 and VPS13A loci [51,52].
