Chronic myeloid leukemia (also called chronic myelogenous leukemia or CML) is a form of leukemia (blood cancer) that develops in the bone marrow, the soft, spongy center of long bones. CML affects a subtype of white blood cell called a “myeloblast.” Normal myoblasts grow, divide and mature into white blood cells capable of fighting infections. This process is controlled by the body through complex signaling networks. In a child with CML, the bone marrow makes abnormal myeloblasts that don’t respond to these normal signals and therefore produce large amounts of abnormal white blood cells in an uncontrolled manner. These abnormal cells do not fight infections, and instead spill into the blood in large numbers, causing a variety of serious problems.
CML is very rare in children. Approximately 150 children in the U.S. are diagnosed with CML each year.