Interestingly, osteoclasts derived from Atp6i+/− mutant mice still maintain about 40% bone resorption activity (Fig. 1C, D), however Atp6i haploinsufficiency dramatically protected mice from bone loss in vivo in the P. gingivalis W50-stimulated periodontitis model (Fig. 4C, D). This evidence concerns the gene TCIRG1 and periodontitis.