The results showed that among these hub genes, KDM6B, CUX2, NAAA, and PHKB showed markedly higher expression in the blood of MDD patients (Figure 7A), whereas NFYA, GTF2H1, CRK, CCNG2, ACER3, and SLC4A2 exhibited significantly lower expression (Figure 7B), which was consistent with the changes in the expression of these hub genes in the prefrontal cortex of MDD patients. Here, CCNG2 is linked to major depressive disorder.