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Retinoblastoma Survivor
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Juvenile Myelomonocytic Leukemia (JMML)

Treatment offers hope for a cure

Juvenile myelomonocytic leukemia, or JMML, is a cancer of the blood. It occurs when too many immature white blood cells, called “myelocytes” and “monocytes,” are made in the bone marrow. They eventually crowd out the healthy, normal cells that belong in the bone marrow.
Quick facts

  • JMML is a very rare disease, accounting for less than 1% of all childhood leukemias.
  • Children with the genetic condition neurofibromatosis type 1 (NF1) have an increased risk of developing JMML.
  • Most cases of JMML are diagnosed in infants and toddlers.
  • The best course of treatment for JMML is a blood or bone marrow transplant (BMT), also known as a stem cell transplant.


Common symptoms for JMML include:

  • Fever for no known reason.
  • Feeling very tired.
  • Weight loss.
  • Easy bruising or bleeding.
  • Infections such as bronchitis or tonsillitis.
  • Skin rash.
  • Painless swelling of lymph nodes in the neck, underarm, stomach, or groin.
  • Pain or a feeling of fullness below the ribs.


If a child has symptoms of JMML, the doctor will perform tests on the blood and bone marrow to gather more information.

  • Blood test: A sample of the child’s blood is drawn and a complete blood count (CBC) is performed to analyze the elements of the blood.
  • Bone marrow aspiration and biopsy: For this procedure, the child will be sedated and given a numbing shot in the hip area. A hollow needle is then inserted into the back of the hipbone. Samples are taken of blood, bone marrow, and bone, and examined under a microscope for signs of cancer.

The chance of recovery for JMML is influenced by factors including:

  • The age of the child at diagnosis.
  • The number of platelets in the blood.
  • The amount of a certain type of hemoglobin in red blood cells.


Treatment options for JMML patients are limited. The only treatment known to cure JMML is a BMT, also known as a stem cell transplant.

  • Replacing diseased bone marrow with healthy marrow through blood and marrow transplantation is a technique pioneered at the University of Minnesota. In 1968, the very first successful human blood and marrow transplant was performed here, and physicians here have since done more than 3,000 transplants.
  • Through this technique, diseased marrow is killed with high doses of chemotherapy, and sometimes with radiation as well. Along with the diseased marrow, normal cells end up being destroyed. To replace them, healthy marrow or stem cells are then taken from a donor whose tissues match the patient’s tissues. This donated marrow is transplanted through a needle in a vein. Marrow cells then seek the right places in the bones to restore missing marrow.
  • As many as 50% of patients who are treated with a blood and marrow transplant will have a recurrence of the JMML, usually within the first few months. A second blood and marrow transplant may be performed.
  • As part of treatment, a patient might also want to enroll in a clinical trial. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Leading the way to a cure

Researchers in the University of Minnesota Pediatric Leukemia Program work to provide treatment programs that will improve survival rates for high-risk or relapsed patients with leukemia. Children’s Cancer Research Fund’s relationship with the University’s Masonic Cancer Center supports this work by providing resources to help with pilot studies and support for clinical trials.

For more information on our work with leukemia, visit our Leukemia Research page.

This information is displayed with permission of the University of Minnesota Cancer Center. For more information about this disease or to review active clinical trials, please visit the website of the Cancer Center.

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