We next investigated the polygenic load for depression in the recurrent and single-episode case groups, using a multivariate polygenic risk score (mvPRS) approach15 and the depression GWAS meta-analysis14,25 without iPSYCH samples for training. This analysis showed significant association of single-episode (β=0.36, SE=0.0081, P<10−7) and recurrent depression (β=0.43, SE=0.014, P<10−7) case groups with PRS for depression (DEP-PRS), but with a significantly larger effect size for recurrent than for single-episode depression (P=4.8 x 10−6, Supplementary Figure S16-1A and Supplementary Table S16A). This observed increased polygenic load among recurrent cases reinforces previous observations11,12,73,74.
