Additionally, complement receptor 2 (CR2, Epstein–Barr virus receptor, CD21), POU domain class 2-associating factor 1 (POU2AF1), and TNFRSF17 [B-cell maturation antigen (BCMA); tumor necrosis factor receptor superfamily member 17] were increased in aged periodontitis approximately10-fold compared with healthy adult tissues. Here, CR2 is linked to periodontitis.