Causes & symptoms

Updated March 18, 2026

What causes acute lymphoblastic leukemia?

Acute lymphoblastic leukemia occurs because of damage (mutations) in the genetic material (DNA) of a cell. The cause of most cases of acute lymphoblastic leukemia is unknown; however, certain risk factors may increase the risk of developing acute lymphoblastic leukemia. People with some rare genetic conditions, such as Down syndrome, Fanconi anemia, Bloom syndrome, and ataxia-telangiectasia have a higher chance of developing acute lymphoblastic leukemia (ALL). Some environmental factors are known to increase the likelihood of mutations, such as exposure to very high levels of radiation or high levels of a gas called radon. Patients with a weak immune system, or those who have received chemotherapy for a prior malignancy, may also have an increased risk of developing leukemia.

What are the symptoms of acute lymphoblastic leukemia?

The symptoms (a patient’s own experience) and signs (observed by a doctor) of acute lymphoblastic leukemia can be divided into four categories. As acute lymphoblastic leukemia affects the production of the three types of blood cells, each group produces different symptoms.

1. Low red blood cells (anemia) may cause:

• Fatigue.
• Shortness of breath during normal physical activities.
• Dizziness.
• Pale skin.

2. Low white blood cells (leukopenia) may cause:

• More frequent infections.
• Fever.

3. Symptoms of low platelets (thrombocytopenia) can be:

• Bruising easily.
• Minor cuts bleeding for longer than normal.
• More frequent and/or severe nosebleeds.
• Bleeding gums.
• Small red dots on the skin, called petechiae.
• In women, periods may be heavier or more frequent.

4. General symptoms may occur, including:

• Night sweats.
• Joint or bone discomfort.
• A feeling of fullness or pain just below the ribs.
• Unexplained weight loss.
• Loss of appetite.
• Coughing or painful breathing.
• Lumps in the neck, armpits, abdomen, or groin, caused by swollen glands known as lymph nodes.
• Enlarged liver or spleen.

Acute lymphoblastic leukemia is a rare disease, and other conditions can cause similar symptoms; therefore, if a patient notices any of the symptoms listed above, or a parent/carer notices them in their child, they should speak to their physician.