was evaluated using receiver operating characteristic (ROC) analyses. All analyses were performed with SAS (v. 9.2, SAS Institute, Inc., Cary, NC) and R (v. 3.0.1, R Project for Statistical Computing). Finally, the total variance in liability to MDD (subtypes) explained by the joint effect of all SNPs (SNP-heritability, h2SNP) was estimated using genomic-relationship-matrix restricted maximum likelihood (GREML) analyses(41) implemented in GCTAv.1.24.1(21). H2SNP is estimated in a linear mixed model in which the measure of genetic similarity (based on the GRM) is included as a random effect to predict the phenotype. All analyses were corrected for year of birth, gender and three ancestry-informative principal components(32) to take possible population stratification into account. Significance level was set at p<0.05, two-tailed.
