Signs and symptoms of acute lymphocytic leukemia may include:

• Bleeding from the gums
• Bone pain
• Fever
• Frequent infections
• Frequent or severe nosebleeds
• Lumps caused by swollen lymph nodes in and around the neck, underarm, abdomen or groin
• Pale skin
• Shortness of breath
• Weakness, fatigue or a general decrease in energy

Acute lymphocytic leukemia occurs when a bone marrow cell develops errors in its DNA. The errors tell the cell to continue growing and dividing, when a healthy cell would normally stop dividing and eventually die. When this happens, blood cell production becomes abnormal. The bone marrow produces immature cells that develop into leukemic white blood cells called lymphoblasts. These abnormal cells are unable to function properly, and they can build up and crowd out healthy cells.

It's not clear what causes the DNA mutations that can lead to acute lymphocytic leukemia. But doctors have found that most cases of acute lymphocytic leukemia aren't inherited.

Factors that may increase the risk of acute lymphocytic leukemia include:

• Previous cancer treatment. Children and adults who've had certain types of chemotherapy and radiation therapy for other kinds of cancer may have an increased risk of developing acute lymphocytic leukemia.
• Exposure to radiation. People exposed to very high levels of radiation, such as survivors of a nuclear reactor accident, have an increased risk of developing acute lymphocytic leukemia.
• Genetic disorders. Certain genetic disorders, such as Down syndrome, are associated with an increased risk of acute lymphocytic leukemia.
• Having a brother or sister with ALL. People who have a sibling, including a twin, with acute lymphocytic leukemia have an increased risk of ALL.