Our GWAS analyses of PTSD in AAs did not provide any strong evidence of association. When we compared the results of AAs and EAs, we found that no SNPs ranked among the top 100 most significant overlapped between the two population groups. Further, none of the top 10 most significant SNPs in the GWAS results for EAs were associated with PTSD in AAs at p < .05, and vice versa. We tested the association between the two TLL1 SNPs (rs6812849 and rs7691872) and PTSD in AAs after adjustment for local ancestry but no association was observed, and no association was observed in AAs with local African ancestry larger than 50%. Possible explanations for this observation include population differences in epistasis and in gene expression and regulation.
