Leukemia is a form of cancer that begins in the stem cells in the bone marrow that make blood cells. Bone marrow is the material that fills the center of most bones, where blood cells are made. Leukemia is essentially a cancer of the blood in which cells do not form properly. Leukemia is found in blood cells and because blood cells do not have chromosomes or DNA, they cannot divide or reproduce like somatic cells do. Blood cells form in the bone marrow and when too many blood cells form in the human body, leukemia cancer develops. There are three different types of blood cells that grow out of control and are produced in the bone marrow: white blood cells [leukocytes], red blood cells [erythrocytes], and platelets. White blood cells are part of the immune system and help fight infections. They too help heal sores, wounds and cuts. Red blood cells contain hemoglobin, which carries oxygen and removes carbon dioxide to and from cells in different organs of the body. Platelets help punch holes in blood vessels and form clots just as blood vessels become corrupted or damaged (What is Leukemia? par. 4 and 5). When these bone marrow cells divide uncontrollably, they form more white blood cells than needed and thus, lead to leukemia cancer. Leukemia is sometimes developed by genetic predisposition. Family history studies involving twins have indicated that some people are at higher risk of developing leukemia due to one or more genes. (Silverstein 29) Additionally, Down syndrome is a genetic cause of leukemia cancer. Normally, each human cell contains 23 different pairs of chromosomes. Each chromosome carries genes, which are necessary for... middle of paper ......es Average cost of leukemia treatment?" How much does leukemia treatment cost on average? ChaCha Answers, February 9, 2011. Web , March 7, 2011. “Secondhand Smoke.” United States Government, June 14, 2007. Web, March 7, 2011. Simmons, Jack. “Leukemia Topic Overview” Web 2011. “Country Statistics for Leukemia. "Country statistics for leukemia 2011, January 26, 2011. Web. March 7, 2011. "What is leukemia?" .Web March 07.. 2011. .