BCR and chronic myelogenous leukemia, BCR-ABL1 positive: Typical CML begins with the t(9;22)(q34;q11) translocation, which can cause the fusion of the proto‐oncogene ABL fragment on chromosome 9 with the BCR gene fragment on chromosome 22,1 resulting in the fusion gene, BCR::ABL1, which encodes a large number of abnormal tyrosine kinases that promote disease development.