One limitation of the current state of the PGC AD data is that it is modest in sample size, and thus, sex-stratified analyses of AD are under-powered and models cannot converge. Thus, the present study was not able to fully examine sex differences in the shared risk between PTSD and AD. As larger samples become available, this will be an important area of investigation. We note that a recently published study of the largest AUD data to date with a sample over 200,000 (from the Million Veteran Program; Kranzler et al., 2019) was able to separately estimate sex-specific heritability in EA samples. However, even in this larger sample, while a nominally higher SNP-based heritability estimate was found for females than males, the authors stated that potential hypotheses for this difference (e.g., substantially smaller sample size and greater standard error, higher liability-threshold and burden or risk variants in females) could not be explicitly tested due to the still lower statistical power in the female sample, as the sample was predominately male (93%). Present study analyses did include sex-stratified PTSD subsamples, supported
