The details for how GWAS traits were selected are presented in detail in the original EXT analysis [17]. Briefly, we included GWAS of externalizing traits if studies had 50,000 or more participants, included relevant covariates (e.g., sex, age, ancestral principal components), were successfully genotyped genome-wide (individual genotyping rate: >95%), passed the standard quality controls, and were limited to unrelated individuals or used techniques to correct for relatedness. We standardized input summary statistics for each of the externalizing phenotypes and filtered to a set of common SNPs across each of the GWAS for a total of 6,132,068 common SNPs (MAF > 0.5%). Next, we performed association tests across all available SNPs, where EXT and ALCP-specific were sequentially regressed onto each SNP. All analyses were limited to samples of European ancestries. See Supplementary Note 2 for detailed information.
