Deletion of IKZF1 results in monoallelic, expression of dominant-negative form, or loss of expression of IKAROS. Deletion of PAX5 and CDKN2A/B, together with loss of IKFZ1 in lymphoid but not myeloid blast phase of CML indicates that these genes play important role in the transformation of CML to lymphoid blast phase of CML [32]. The gene discussed is CDKN2A; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.