Finally, we took several steps to validate the MVP-EXT factor. First, we ran the genetic correlation between MVP-EXT and EXT1.0, which was strong (rG = 0.87, 95% CI = 0.83, 0.91). Second, we compared the genetic correlations of MVP-EXT and EXT1.0 with 93 external traits. The correlation of rG effect size estimates was very strong (r = 0.96, 95% CI = 0.93, 0.97). Third, we tested the association between the MVP-EXT PGS and a matched latent factor of externalizing in COGA and Add Health. The PGS was associated with externalizing in each cohort, as well as on overall effect (Beta META = 0.20, 95% CI = 0.18, 0.22). Taken together, these results suggest that the MVP-EXT factor largely recapitulated the model from EXT1.0 (full results from GWAS and post-GWAS biological characterization presented in the supplementary information and Supplemental Tables 2–8).
