These results are especially interesting in light of recent publications that report association between variation in CHRNA5-CHRNA3-CHRNB4 and smoking quantity [12] and nicotine dependence [13] and thus provide evidence of replication of the initial association discovered in [6]. Furthermore, the same or correlated variants also show association with lung cancer [13-15]. In these new papers, the reported association was either at rs16969968 (when genotyped), or at rs8034191, rs1317286, or rs1051730, all of which have very high r2 with rs16969968 (0.966, 1.0 and 0.90 respectively in HapMap CEU) and all of which we studied here. Our analysis studied cocaine rather than nicotine dependence, so the conclusions here may not directly translate to smoking or lung cancer. However it is intriguing to note that in our cocaine dependence analysis, rs8034191 is ruled out (heterogeneity p-value 0.048), rs1317286 has a heterogeneity p-value of 0.06, and rs1051730, while not ruled out (heterogeneity p-value 0.20), has an odds ratio of 0.91 in the AA sample versus 0.66 in the EA sample. Applying this cross-population approach to an African American sample of nicotine dependent (or lung
