FAM20C and periodontal disorder: It should be noted that mice younger than 12 months do not naturally develop periodontal diseases [37], and thus, the periodontal disease in the cKO mice must be attributed to the inactivation of Fam20C. The cKO mice also had inflammation in the dental pulp at 12 or 24 weeks, which might spread to the PDL via the apical foremen.