current sample size of over 20 000 was still a limiting factor in single variant analyses. The strong evidence of shared genetic effects between PTSD and SCZ is worth further investigation and consistent with data from birth cohort studies that have found early childhood factors such as low IQ57, 58 and psychotic symptoms59 to be risk factors for both syndromes, but not for MDD or BIP. More variable evidence suggests that larger samples are needed to precisely resolve genetic overlap for BIP and MDD. Finally, the distribution of individuals of different ancestries in this analysis illuminated analytical and interpretational disparities for individuals of all ancestries as compared with EA individuals, and highlights the need for large genetic studies in non-European populations. Data from the largest genetic examination of PTSD to date demonstrate significant heritability for the development of PTSD, suggest at least partial genetic mediation of comorbidities, and outline important areas for future progress in understanding the genomic architecture of PTSD.
