ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive: Introduction: Chronic myelogenous leukaemia (CML) is a myeloproliferative disorder characterised by t(9:22) (q34:q11) reciprocal translocation, resulting in the expression of chimeric Bcr–Abl oncoprotein with constitutive tyrosine kinase activity.