Causes

Doctors aren't certain what starts the process that causes chronic lymphocytic leukemia. What's known is that something happens to cause changes (mutations) in the DNA of blood-producing cells. A cell's DNA contains the instructions that tell the cell what to do. The changes tell the blood cells to produce abnormal, ineffective lymphocytes.

Beyond being ineffective, these abnormal lymphocytes continue to live and multiply when healthy lymphocytes would die. The abnormal lymphocytes accumulate in the blood and certain organs, where they cause complications. They may crowd healthy cells out of the bone marrow and interfere with blood cell production.

Doctors and researchers are working to understand the exact mechanism that causes chronic lymphocytic leukemia.