Our current analysis builds on results from a recently published multivariate GWAS of externalizing [17]. We used GenomicSEM [15] to fit a common factor model using summary statistics from seven externalizing-related phenotypes: attention-deficit/hyperactivity disorder (ADHD), problematic alcohol use (ALCP-total), lifetime cannabis use (CANN), age at first sexual intercourse (FSEX), number of sexual partners (NSEX), general risk tolerance (RISK), and lifetime smoking initiation (SMOK). This analysis suggested a single underlying latent genetic factor (EXT), with residual genetic variance on each phenotype. The original paper presented GWAS results for that latent factor EXT. Here, we extended the original model to partition SNP effects on ALCP-total into two pathways: those that are shared among externalizing phenotypes and those that are specific to problematic alcohol use (ALCP-specific) [17].
