Like the WHO-HAEM4R, the ICC recognizes an accelerated phase of CML (CML-AP), but this has been simplified from WHO-HAEM4R CML-AP definition to now only include cases with 10–19% blasts, ≥20% blood basophils, and/or presence of certain specific clonal cytogenetic aberrations in addition to the defining BCR::ABL1 rearrangement. This evidence concerns the gene BCR and chronic myelogenous leukemia, BCR-ABL1 positive.