We believe the present report provides the first molecular genetic evidence of PTSD heritability and extends previous findings about shared genetic effects between PTSD and other disorders.8, 10, 11, 12 These results portend future success in identifying specific PTSD risk loci when viewed in the context of the trajectories of genetic discoveries for other complex genetic disorders16, 42 that yielded significant polygenic results before identification of robust single variant associations. Specifically, examining 20 730 individuals, we found a molecular genetics-based heritability estimate for EA females of 29% that is similar to h2SNP for schizophrenia and is substantially higher than h2SNP in EA males (estimate not distinguishable from zero). We found strong evidence of overlapping genetic risk between PTSD and schizophrenia along with more modest evidence of overlap with bipolar and major depressive disorder. The combination of informative polygenic results and lack of robust single variant analyses (in our data and in the evaluation of previously reported PTSD loci35, 43, 44, 45, 46) strongly suggests the need for better powered analyses.
