We also found that many differentially expressed miRNAs and mRNAs identified in Set 1 brain tissue samples by RNA-seq were not confirmed in Set 2 brain tissue samples by microarray. The technical explanation is that RNA-seq can quantify a wider range of gene expression levels when compared to microarray. Although only about 78% of differentially expressed genes identified by microarray overlapped with those identified by RNA-seq even in the same set of RNA samples [51], a high correlation between these two platforms was observed in highly expressed genes that had less degradation or were more tolerant of degradation due to a larger number of transcripts [52]. The biological explanation for the inconsistent findings from Set 1 and Set 2 samples is that (1) brain tissues from the same brain region for RNA-seq and microarray were from different cohorts and they might not be dissected from the exactly same location and thus the brain tissue cell types could be slightly different, and (2) Set 1 samples consisted of both males and females while Set 1 samples were all males. Therefore, the
