Atypical BCR-ABL1 transcripts are detected in less than 5% of patients diagnosed with chronic myeloid leukaemia (CML), of which e19a2 is the most frequently observed, with breakpoints in the micro breakpoint cluster region (μ-BCR) and coding for the p230 BCR-ABL1 protein. p230CML is associated with various clinical presentations and courses with variable responses to first-line imatinib.
Chronic myeloid leukemia (CML) with the e19a2 transcript coding for p230 is typically associated with a benign clinical course unless accompanied at presentation with additional chromosomal abnormalities.
The P190, P210, and P230 forms of the BCR/ABL oncogene induce a similar chronic myeloid leukemia-like syndrome in mice but have different lymphoid leukemogenic activity.