The relationships between disorders were expressed as SNP-based coheritabilities (Fig. 1). The rg SNP value was high between schizophrenia and bipolar disorder at 0.68 (0.04 standard error (s.e.)), moderate between schizophrenia and major depressive disorder at 0.43 (0.06 s.e.), bipolar disorder and major depressive disorder at 0.47 (0.06 s.e.), and ADHD and major depressive disorder at 0.32 (0.07 s.e.), low between schizophrenia and ASD at 0.16 (0.06 s.e.) and non-significant for other pairs of disorders (Supplementary Table 1). The rg SNP value for correlation is expected to be equal to the rg value from family studies only if genetic correlation is the same across the allelic frequency spectrum and if the linkage disequilibrium (LD) between genotyped and causal variants is similar for both disorders. The sample size for ASD was the smallest but still could detect correlations of >|0.18| different from zero in bivariate analyses with all other disorders.
