Test Details: Chronic Myeloid Leukaemia (CML) accounts for 15-20% of the diagnosed cases of leukaemia in adults. CML is usually diagnosed in its chronic phase when treatment is very effective for most patients. Majority of CML are caused by the BCR-ABL1 fusion gene. The identification of different BCR-ABL gene fusion is useful in diagnosis of the disease and monitoring Minimal Residual Disease (MRD) status. Isochromosome 17q is the most frequent genetic abnormality observed during progression of CML and plays a presumably important pathogenic role. In patients receiving TKI (Imatinib) therapy, cytogenetic analysis is still relevant especially in case of cytopenia. Signs of dysplasia with del7 clonal chromosomal abnormalities/Ph negative cells should be considered as a red signal and a switch to alternative treatment be discussed. Trisomy 8 in Ph+ CML patients is frequently observed as a secondary chromosome change and is one of the non-random abnormalities associated with the blastic phase of the disease.