We identified only two genome-wide hits for the higher-order p-factor, both of which were in LD with univariate hits for MDD and SCZ (Supplementary Table 26), and have been described in multiple external GWAS of psychiatric traits (Supplementary Table 27). The p-factor was characterized by the highest level of heterogeneity, with 69 loci identified for QSNP (Supplementary Table 28), 49 of which were in LD with hits on the four psychiatric factors from the correlated factors model. Despite few hits for p, its considerable mean χ2 (1.795) may be attributable to the aggregation of heterogeneous signal across factors 1-4 in the hierarchical factor GWAS.
