Chronic myeloid leukaemia is a type of cancer that affects the blood and bone marrow. In this condition the bone marrow produces too many granulocytes (white blood cells). 

In CML, most commonly a genetic abnormality called Philadelphia (Ph) Chromosome occurs in chromosome 22 in immature, not fully functioning myeloid cells (leukemic blast cells forming red blood cells) which in turn forms an abnormal fusion gene called BCR-ABL. The Ph-chromosome induces the production of an enzyme called tyrosine kinase which leads to CML. These blast cells grow and divide, crowd the bone marrow and interfere with the normal blood cell production. They eventually spill out of the bone marrow, entering the blood stream and circulate in the body. Since they are not fully mature, the cells won’t be able to fight infections effectively, hence recurrent infections and slow healing may be observed.  Compared to other subtypes of leukaemia, CML is progressing fairly slowly. For this reason, many people initially don’t have any symptoms. Over time a lack of red blood cells and platelets can lead to anaemia (causing tiredness, dizziness, paleness, shortness of breath), bleeding and/or bruising. Another symptom might be pain under the left-side ribs due to an enlarged spleen, excessive sweating or unintentional weight loss. CML can be categorized into three phases: the chronic phase, the accelerated phase and the blast phase. CML may affect people of any age, however more commonly adults older than 50 years of age, occurring more frequently in men than in women. Treatment options may involve targeted therapy using Tyrosine Kinase Inhibitors (TKI), chemotherapy, stem cell transplantation, surgery, etc.

Source: cancer.org; leukaemia.org; ESMO (2017)