Previous investigations in febrile neutropenic patients have reported controversial results regarding the performance of PCT for the initial assessment of the etiology of fever by distinguishing bacteremia due to pathogens other than CNS from non-bacteremic infections, and systemic from localized infections or FUO [9], [10], [11], [12], [24], [25], [26], [27], [28], [29], [30].In the present study, the low PCT values observed at the time of onset of fever in severe documented infections do not support the use of PCT for the decision to start or withhold prompt empirical antibacterial therapy. The gene discussed is CALCA; the disease is bacterial infectious disease with sepsis.