The analyses were also carried out in the four samples separately to check for heterogeneity in the results across studies. None of the polygenic personality scores were significantly associated with MDD in the MDD2000+ study with the proportion of explained variance always below 0.1%. This is in contrast to the analyses of the GAIN-MDD sample in which polygenic N scores based were significantly higher in MDD cases than in controls, explaining between 0.2 and 0.4% of the variance (P-values <0.005) (see Supplementary Figure 1a). Moreover, polygenic C scores, based on the sets of SNPs with P-values <0.3 and <0.5, were lower in MDD cases explaining 0.2 and 0.3% of the variance (P-values <0.05). Thus, the significant results for MDD are mostly driven by the GAIN-MDD study.
