Our analysis of the ancestry-related allele ΔF of common variants indicated that African ancestry is the most divergent group, in agreement with the current knowledge about genetics of human demographic history [38,39]. Conversely, the admixed-American group showed lower allele ΔFs than the other ancestry groups. It is highly likely that this is due to the complex admixture of African, Amerindian and European ancestries present in these populations [29]. When considering the observed ancestry-related differences in common variants in both GWAS-relevant genes and their interactive partners, we detected a number of variants with noteworthy allele ΔFs which are also potentially involved in regulatory mechanisms, suggesting their role in the diverse outcomes observed in drug dependence GWAS-among human populations. Regarding the rare variants analysis, we observed that there are differences among ancestry groups for the occurrence of regulatory rare variants. These differences are significant when we considered the entire genome, but, when we focused on specific gene regions, they are not statistically significant. The result observed, considering genomic differences, is in accordance with recent evidence that has indicated differences in the stratification
