In patients with an intermediate level of risk (10–20%), the indication of prophylaxis with G-CSF must be individualized depending on the characteristics that increase the risk of FN (age > 65 years, liver or kidney dysfunction, widespread bone marrow involvement, recent extensive surgery, persistent neutropenia, or prior episodes of FN) [II, A] [2, 11, 45, 46]. The gene discussed is CSF3; the disease is neutropenia.