The alpha-defensin test is in excellent accordance with the Musculoskeletal Infection Society (MSIS) criteria compared to other tests routinely used for the pre-/intraoperative diagnosis of PJI (culture, erythrocyte sedimentation rate [ESR], CRP level, synovial white cell count, and leukocyte-esterase test) (21, 22). The gene discussed is CRP; the disease is juvenile polyposis syndrome.