Chronic Myelogenous Leukemia

Chronic myelogenous leukemia (CML) is a slow-growing bone marrow cancer resulting in too many white blood cells. The disease is also sometimes called chronic myeloid, chronic granulocytic or chronic myelocytic leukemia. CML is a relatively common form of leukemia, but overall it is a relatively uncommon type of cancer. In the United States, more than 20,000 people have CML and about 4,600 new cases are diagnosed each year. Most cases of CML appear in adults, but about 2-4% of CML patients are children.

CML is caused by a change in the genetic code of some of the cells in the bone marrow. In these cells, part of chromosome 9 switches places with a part of chromosome 22, a process called chromosomal translocation. This creates an abnormal chromosome called the Philadelphia chromosome. The rearranged Philadelphia chromosome signals the marrow to overproduce white blood cells. Doctors do not know what causes the Philadelphia chromosome to appear.