**2.9 The first described as a clonal hematological disease in leukemia**

Cells from bone marrow or peripheral blood of a patient with CML show excessive proliferation from one or multiple lineages and different maturation stages due to the partial blocking of differentiation.

CML was first identified as a clonal hematological malignancy from pluripotent bone marrow stem cells [23, 24]. Such finding increased our understanding of the stages of disease mechanism and helps in the diagnosis, differential diagnosis, and treatment.
