CML-Chronic Myeloid Leukemia: CML can be a fatal disease if it goes untreated, however recent breakthroughs in treatment have been very successful. CML is caused by a genetic change that occurs in your body with a switch in chromosome 9 and 22, this is called the Philadelphia Chromosome. This causes a buildup of a certain protein. Imatinib (gleevec) is a medication to prevent buildup of this protein.