Because the discovery stage effectively exhausted large study cohorts available for replication, we performed a series of preregistered quasi-replication analyses (Supplementary Tables 11–12). As quasi-replication analyses of the 579 SNPs (Supplementary Information section 4), a three-step method tested their association with two independent, GWAS meta-analyses on externalizing phenotypes: (1) alcohol use disorder (rg with EXT = 0.52; N = 202,004), and (2) antisocial behavior (rg with EXT = 0.69; N = 32,574). We had preregistered to hold out antisocial behavior from the externalizing GWAS to enable quasi-replication with a central externalizing trait that was not included in the model. First, we tested whether the 579 SNPs (or an LD proxy for missing SNPs, r2 > 0.8) showed sign concordance, i.e., the same direction of effect between EXT and alcohol use disorder or antisocial behavior: 75.4% of SNPs showed sign concordance with alcohol use disorder (two-sided test P = 6.84×10−36) and 66.9% with antisocial behavior (two-sided test P = 1.39×10−15) (Extended Data Fig. 3). For the second and third tests, we generated empirical null distributions for the two phenotypes by randomly
