CCNG2 and major depressive disorder: This finding suggests that some hub DEGs, including KDM6B, CUX2, NAAA, PHKB, NFYA, GTF2H1, CRK, CCNG2, ACER3, and SLC4A2, may be potential biomarkers for the diagnosis of MDD, and a larger sample size and more rigorous experimental design are needed for verification in the future.