While twin and genetic studies demonstrated that risk of developing PTSD conditional on trauma exposure is partly driven by genetic factors9,10, the specific characterization of the genetic architecture of PTSD is just emerging as very large meta-analyses of genome-wide association studies (GWAS) become available. Recent research by our workgroup – the Psychiatric Genomic Consortium for PTSD (PGC-PTSD)11,12 and the VA Million Veteran Program (MVP)13 – contributed to an increased appreciation for the genetic complexity of PTSD as a highly polygenic disorder. Despite sample sizes of over 200,000 individuals, these studies identified at most 16 PTSD risk loci, which were not consistent across datasets, indicating the necessity of still larger sample sizes. In addition, these studies did not examine the X chromosome, which comprises 5% of the human genome, and may be particularly important given sex differences in PTSD prevalence.
