CRLF2 and acute lymphoblastic leukemia: Deletions of IKZF1 and BTG1 occurred at higher incidences than seen in B‐other ALL at 23% and 2%, respectively.21 Deletions of IKZF1 (71% vs. 33% P < .001) and BTG1 (31% vs. 9%, P = .004) were more frequent in IGH‐CRLF2 than P2RY8‐CRLF2 patients, respectively (Figure 1B).