In addition to the above 2 hub DEPs, there is no direct evidence from previous studies for the remaining hub DPEs (TMED5, HLA-DPA1, CD79A, ADPGK, TBXAS1 and PLCH1) correlating closely with periodontitis, OCN had been reported that it is involved in the physiological or pathological process of periodontitis. This evidence concerns the gene ADPGK and periodontitis.