Chronic Myeloid Leukaemia (CML)
A single acquired fusion gene, BCR-ABL1 from the Philadelphia chromosome, creates a constitutively active tyrosine kinase that drives myeloid overproduction with preserved maturation, so the blood fills with maturing granulocytes and the spleen enlarges, usually indolently until it is controlled by a targeted inhibitor.
Definition
Chronic myeloid leukaemia is a myeloid neoplasm defined by the BCR::ABL1 fusion, usually produced by the Philadelphia chromosome. Chronic phase retains granulocyte maturation and is managed with long-term molecularly monitored TKI therapy.
First principles
One fusion kinase drives the whole disease
CML is driven by the Philadelphia chromosome rearrangement that creates the BCR::ABL1 fusion tyrosine kinase. This explains the disease biology and the effectiveness of BCR::ABL1-directed TKI therapy.
This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.

