ABSTRACT
Answer 7 CML is a clonal myeloproliferative bone marrow stem cell disorder in which there is an increase in the number of neutrophils and their precursors in the bone marrow and peripheral blood (the stem cell also generates cells of the erythroid and megakaryocyte series). If a bone marrow stem cell acquires the Philadelphia chromosome, the greatly enhanced tyrosine kinase activity of the bcr-abl fusion protein provides an excessive drive to the cell to divide. However, at this stage, there is no blockage to the maturation pathways of the daughter cells, so CML features an excess of mature forms (compared with acute myeloid leukaemia (AML) and acute lymphoblastic leukaemia (ALL) in which significant maturation is not encountered).
