JAK1 and acute lymphoblastic leukemia: Activating mutations encoding cytokine receptors and mediating the RAS signal transduction system (NRAS, KRAS, FLT3, and JAK1), inactivating mutations encoding transcription factors (GATA3, ETV6, and RUNX1) and histone repair (EZH2 and EP300) during hematopoietic stem cell development are common in ETP-ALL/LBL patients [5, 6, 13].