Chronic myeloid leukaemia (CML) is characterised by the BCR-ABL fusion gene, which is a constitutively active cytoplasmic tyrosine kinase that activates numerous signal transduction pathways and contributes to leukaemogenesis (Druker et al, 2001). This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.