ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: However, although most patients with CML are diagnosed with the e13a2 or e14a2 <i>BCR::ABL1</i> fusion transcripts, about 5% of them carry rare <i>BCR::ABL1</i> fusion transcripts, such as e19a2, e8a2, e13a3, e14a3, e1a3, and e6a2.