The clinical significance of serum PCT in discriminating between bacterial infections and nonbacterial infections, such as systemic inflammatory response syndrome (SIRS), has been compared with that of other markers including endotoxin, β-D-glucan, interleukin (IL)-6, C-reactive protein (CRP), and white blood cell (WBC) count [2–6]. The gene discussed is CALCA; the disease is bacterial infectious disease.