Sequence homology between the β₂GPI peptide and P gingivalis and anti–P gingivalis immunoreactivity. (A) Sequence homology between β₂GPI peptide and P gingivalis. (B) Box-whisker plots of anti–P gingivalis IgG in patients with SLE and APS positive for anti-β₂GPI peptide IgG (A group), subjects with moderate chronic periodontitis (B group), and healthy subjects without periodontitis and autoimmune diseases (C group). Median, quartiles, range, and possibly extreme values are indicated. Statistical analysis was performed with the Mann-Whitney test. *P < .001 compared with the C group.