The study cohort included 44 patients with total knee/hip arthroplasty (16 with PJI, 8 with low-grade PJI with low α-defensin/CRP levels, 20 with osteolysis/aseptic loosening) and 64 controls with osteoarthritis with/without infection (OA-INF/OA: 28/36). The gene discussed is CRP; the disease is osteoarthritis.