Routine primary prophylaxis with granulocyte‐colony stimulating factors (G‐CSF) is not usually recommended, but its administration could be considered as secondary prophylaxis at the first occurrence of G4 neutropenia with a duration of more than 7 days, febrile neutropenia, or G3–4 neutropenia that has delayed dosing by 2 or 3 weeks for recovery to ≤ G1.38 The gene discussed is CSF3; the disease is Decreased total neutrophil count.