cross validation, all samples from the same individual were always in the same fold, and that no fold differed in size by more than 5% from any other fold. Similar to protein weights, mRNA weights were estimated using all models to train weights and the most predictive model was used. Next, FUSION combined the genetic effect of depression (i.e., depression GWAS Z-score) with the mRNA or protein expression weights by calculating the linear sum of Zscorre × weight for the independent SNPs at the locus to perform a PWAS or TWAS16.
