About Chronic Myelogenous Leukemia (CML)
In chronic myelogenous leukemia (CML), the other major form of myeloid leukemia, too many bone marrow stem cells develop into a type of white blood cell called granulocytes. Some of these bone marrow stem cells never become mature white blood cells. These immature cells are called blasts. Over time, the granulocytes and blasts crowd out the red blood cells and platelets in the bone marrow. CML is rare in children. The hallmark of CML is the presence of what is known as the Philadelphia chromosome, an abnormal chromosome containing an oncogene (cancer-causing gene). The course of this disease is much slower than with AML (hence the description “chronic.”) However, patients with advanced CML may experience what is known as a “blast crisis,” which resembles AML clinically, where there is a large and sudden proliferation of blasts. CML is also particularly responsive to a relatively new drug therapy called Gleevec.