Most forms of leukemia occur in the white blood cells. These abnormal cells reproduce in large quantities and look and perform differently than normal cells. Right now the causes of leukemia are unknown. Some studies have shown that exposure to high-energy radiation increases chances of contracting leukemia. Such radiation was produced in the atomic bombing of Japan during World War II. There is also enough energy in nuclear plants so strict safety precautions are taken. Some research shows that exposure to electric magnetic fields, such as power lines and electric appliances, is a possible risk factor. More studies are needed to prove this link. Some genetic conditions, such as Down’s syndrome, are also believed to increase the risk factor. Exposure to some chemicals is also suspected to be a risk factor. There are many symptoms of leukemia. The symptoms of leukemia are the same for all the different types of leukemia. The acute types of leukemia, ALL and AML, symptoms are seen more quickly than in the chronic types of leukemia, CLL and CML, where symptoms do not necessarily appear right away. The symptoms are flu symptom, weakness, fatigue, constant infections, easily bleed and bruise, loss of weight and appetite, swollen lymph nodes, liver or spleen, paleness, bone or joint pain, excess sweating, swollen or bleeding gums, nosebleeds and other hemorrhages, and red spots called petechiae located underneath the skin.