First, LMO2 ectopic activation caused by retroviral insertion in the CD34+ HSCs of X‐SCID patients specifically triggered T‐ALL development, but no other hematopoietic tumors (Hacein‐Bey‐Abina et al, 2008; Howe et al, 2008), although it is considered that LMO2 expression in BM progenitors is not relevant per se (Ruggero et al, 2016). This evidence concerns the gene LMO2 and acute lymphoblastic leukemia.