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What Causes Chronic Myeloid Leukemia (CML)?

• To understand what causes most cases of CML, you need to know about your cells. Every cell in your body has the same DNA—the genetic material you inherited from your parents. DNA makes up your chromosomes, and contains genes that control the activity of the cell
• Each time a cell divides, its DNA is copied into the new cells. Errors can occur during the duplication that affect the genes and may lead to the creation of cancer cells instead of normal cells
• Chronic myeloid leukemia (CML) occurs when pieces of two different chromosomes break off and attach to each other

• The new chromosome is called the Philadelphia-positive chromosome or Ph+ chromosome
• The Philadelphia-positive (Ph+) chromosome contains an abnormal gene called the bcr-abl gene
• This gene produces the BCR-ABL protein, which causes your body to make too many abnormal white blood cells
• Ordinarily, the body is able to tightly control the number of new white blood cells
• In chronic myeloid leukemia (CML), BCR-ABL acts like a switch stuck in the "on" position, signaling white blood cells to continuously grow
• There is no known reason for the genetic changes that cause chronic myeloid leukemia (CML)

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