In this study, we performed GWAS analyses of PTSD in 1578 EAs (300 PTSD cases) and 2766 AAs (444 PTSD cases). In the primary analyses in EAs, we observed genome-wide significant evidence of association to that trait for one SNP located on chromosome 7p12, rs406001. Two other SNPs in the same region, rs382903 and rs450378, were the second and fourth most significant SNPs. The region showing the second strongest evidence of association was the first intron of TLL1 where three SNPs, rs6812849, rs7691872 and rs1503292, ranked in the top 10 results. When GWAS analyses were restricted to subjects with trauma exposure, despite the exclusion of nearly one third of the subjects, the results were very similar. Chromosome 7p12 and the first intron of TLL1 remained the top two most significant genomic regions. Based on the GWAS results, we genotyped six SNPs in an independent sample of nearly 2000 EAs using TaqMan genotyping or GoldenGate custom array. Two SNPs located in the first intron of TLL1 were significantly associated with PTSD with p values 6.3×10−6 and 2.3×10−4. Combining the GWAS and
