Compared to controls, MDD patients exhibited a set of genes significantly upregulated in the DLPFC: HDAC4, HDAC5, HDAC6, HDAC8, and DNMT3B (by 77, 38, 72, 43, and 49%, respectively; p < 0.05) (Fig. 1a). This evidence concerns the gene HDAC6 and major depressive disorder.