A recent retrospective study by Cies et al. in children demonstrated that a PCT value of ≥1 ng/mL predicted having a serious bacterial infection (OR = 1.18, 95% CI 1.07–1.49) and exhibited a PPV of 28%, a NPV of 93%, a sensitivity of 70%, and a specificity of 68% [13]. The gene discussed is CALCA; the disease is bacterial infectious disease.