Next, we compared spatio-temporal gene-expression patterns for the 109 pleiotropic risk loci and the 37 disorder-specific loci using post-mortem brain data. On average, disorder-specific and pleiotropic risk loci showed a similar level of gene expression in both prenatal and postnatal development after multiple testing correction (t-test p > 0.025 ×10−2; Fig. S4). During prenatal development, non-pleiotropic loci (mainly SCZ-associated) showed peak expression in the first trimester, after which expression rapidly decreased, while pleiotropic genes associated with only 2 disorders (“pleiotropy=2”; 60 loci) and those associated with more than 2 (“pleiotropy>2”, 49 loci) showed peak expression around the second trimester (Fig. 5b). After birth, all three groups showed gradually increasing gene expression until adulthood. Expression levels were associated with the degree of pleiotropy, with the pleiotropy>2 group showing higher gene expression than either the pleiotropy=2 group (t-test p < 2.10×10−4) or non-pleiotropic risk loci (t-test p < 2.2×10−16).
