What causes Chronic Myelocytic Leukemia?

CML is almost always associated with a gene mutation. The gene is in a chromosome called the Philadelphia chromosome. This mutation occurs during life. It is not passed from parent to child. In most cases, the cause of the mutation is not known. Studies show that exposure to large doses of radiation is associated with development of CML. This size of the dose would be found in survivors of nuclear accidents or of the atomic bomb blasts. However, most patients with the condition have not been exposed to radiation.