Genome‐wide studies demonstrated that 60% of all B‐cell precursor acute lymphoblastic leukemia (B‐ALL) cases carry genetic alterations in genes coding for regulators of B cell development, with the most commonly affected transcription factor genes being PAX5, EBF1, and IKZF1 (Ikaros) (Kuiper et al, 2007; Mullighan et al, 2007, 2008). Here, PAX5 is linked to acute lymphoblastic leukemia.