Our identification of some SNP markers whose allelic frequencies distinguish controls from addicts of different ethnicities supports “common disease/common allele” genetic architecture for significant portions of addiction vulnerability [48] based on relatively old allelic variants. The good fits between results from ethnically-matched samples from the current data and dbGAP samples also support the idea that many addiction vulnerability variants are likely to display substantial differences from one human population to another (Drgon et al, in preparation). In our current data, the same phase is not detected for many of the SNP associations noted in samples of different racial/ethnic backgrounds. Although we believe that this is a likely consequence of the differences in detailed linkage disequilibrium between the SNP markers and the actual pathogenic allelic variants at many of these chromosomal loci, some of these phase differences are also likely to reflect results that co-occur in the two independent samples by chance.
