We estimated the genetic correlations (rg) between these 26 traits. We confirmed prior reports 21,22 that psychiatric disorders were strongly inter-correlated (e.g., high positive correlations for schizophrenia, bipolar disorder, and MDD) and shared little overlap with neurological disorders (Figure S2 and Table S1). Parkinson’s disease was genetically correlated with intracranial volume 18 (rg=0.29, s.e=0.05) and amyotrophic lateral sclerosis (ALS, rg=0.19, s.e=0.08), while ALS was negatively correlated with intelligence (rg=−0.24, s.e=0.06) and hippocampal volume (rg=−0.24, s.e=0.12). These results indicate that there is substantial genetic heterogeneity across traits, which is a necessary (but not sufficient) condition for trait associations with different tissues or cell types.
