Normal weight subjects with periodontitis had, compared to normal weight healthy subjects, higher levels of MCP-1 (pg/ml; mean (95% CI): 426 (376–476) versus 328 (274–382), P = 0.006, Fig 1D) and CRP (mg/l; mean (95% CI): 0.67 (0.39–2.84) versus 0.30 (0.17–0.51) mg/l, P = 0.019, Fig 1E). The gene discussed is CCL2; the disease is periodontitis.