In patients with congenital neutropenia (CN), steady state granulopoiesis driven by lymphoid enhancer-binding factor (LEF-1) and C/EBPα is almost abrogated [32], and treatment of these patients with G-CSF triggered C/EBPβ-dependent emergency granulopoiesis, which resembled the C/EBPα-independent and C/EBPβ-dependent ‘emergency’ granulopoiesis previously observed in a mouse model. This evidence concerns the gene CSF3 and severe congenital neutropenia.