Half of all cases (20/40, 50.0%) received granulocyte colony-stimulating factor (G-CSF) or granulocyte-macrophage colony-stimulating factor (GM-CSF) therapy, primarily for agranulocytosis (17 cases), followed by neutropenia (2 cases) and bicytopenia (1 case). The gene discussed is CSF2; the disease is Decreased total neutrophil count.