We find a marked increase in phenotypic variance explained by genome-wide polygenic risk scores (PRS) compared to previous publications (sample size weighted mean observed Nagelkerke’s R2 = 0.08 across datasets, liability scale R2=0.04, for p-threshold 0.01; Supplementary Figure 2 and Supplementary Table 2). Among the different datasets, we observed no association between the PRS R2 and: (i) the gender distribution of the BD cases (p=0.51); (ii) the proportion of cases with psychosis (p=0.61); (iii) the proportion with a family history of BD (p=0.82); or (iv) the median age of onset for BD (p=0.64). In our primary genome-wide analysis, we identified 19 loci exceeding genome-wide significance (P< 5×10−8; Table 1).
