After standardized and uniform quality control, additive logistic regression analyses were performed on individual disorders (Online Methods). 6,786,993 SNPs were common across all datasets and were retained for further study. Using the summary statistics of these SNPs, we first estimated pairwise genetic correlations among the eight disorders using linkage disequilibrium (LD) score regression analyses (Bulik-Sullivan et al., 2015) (Online Methods; Fig. 1a; Table S2.1). The results were broadly concordant with previous estimates (Brainstorm Consortium, 2018; Cross-Disorder Group of the Psychiatric Genomics Consoritum, 2013). The genetic correlation was highest between SCZ and BIP (rg = 0.70 ±0.02), followed by OCD and AN (rg = 0.50 ±0.12). Interestingly, based on genome-wide genetic correlations, MD was closely correlated with ASD (rg=0.45 ±0.04) and ADHD (rg=0.44 ±0.03), two childhood-onset disorders. Despite variation in magnitude, significant genetic correlations were apparent for most pairs of disorders, suggesting a complex, higher-order genetic structure underlying psychopathology (Fig. 1b).
