Leukemia and the Causes
Leukemia is a form of cancer that affect the blood cells. There are different types of blood cells, including platelets, white blood cells, and red blood cells. In most cases, leukemia affects the white blood cells, which play an important role in the immune systems. They can protect the body from foreign invaders, such as abnormal cells, fungi, viruses, bacteria, and other substances. When the disease occurs, these cells may divide uncontrollably and dominate normal ones. 
The exact causes of leukemia have not fully understood. Scientists believe that it may occur from a combination of environmental and genetic factors. These factors may lead to certain mutations in the DNA of blood cells. Normally, the DNA contains information to instruction how cells grow and die. When mutations happen, these blood cells are instructed to multiply uncontrollably. Overtime, these cancerous cells may crowd own healthy ones in the bone marrow.