BCR and acute lymphoblastic leukemia: CRLF2 rearrangements and overexpression are commonly determined in the BCR‐ABL1‐like B‐ALL subtype, but not in B‐ALL patients with recurrent gene fusions, who are not screened for CRLF2 abnormalities [10, 12, 13, 14, 15, 16, 17, 18, 19].