BTG1 and chronic myelogenous leukemia, BCR-ABL1 positive: Evidence shows that there are characteristics exclusive to specific leukemias, including deletion of BTG1 in B-cell leukemia, loss of IKZF1 with monosomy 7 in AML, and deletions involving IGH, TCR, IKZF1, and CDKN2A/B in CML-AP/CP.