Juvenile Myelomonocytic Leukemia

Also known as: JMML, juvenile chronic myeloid leukemia, chronic myelomonocytic leukemia of infancy, infantile monosomy 7 syndrome.

What is juvenile myelomonocytic leukemia?

JMML is a rare, serious chronic form of cancer of the blood in children (frequently boys), aged less than 4 years. On average it affects children around 2 years of age.

What causes juvenile myelomonocytic leukemia?

It appears that though the causes are unknown, sporadic or inherited genetic changes in a particular cell in the bone marrow (stem cell), gives rise to a blood type called an immature monocyte which increases uncontrollably in the bone marrow, eventually preventing the bone marrow producing the other blood cell types (red blood cells, white blood cells and platelets).

Children with Noonan syndrome or neurofibromatosis type 1, are at increased risk of developing JMML.

What are the symptoms of juvenile myelomonocytic leukemia?

Symptoms of JMML can include fever, pale skin (anemia), frequent infections, bruising and abnormal bleeding, a swollen abdomen due to a large spleen and liver, swollen lymph nodes, bone and joint pain, and cough/difficulty breathing.

What are juvenile myelomonocytic leukemia care options?

Chemotherapy and radiation may be used before stem cell transplantation of the bone marrow, the only cure for JMML.

Reviewed by: Jack Wolfsdorf, MD, FAAP

This page was last updated on: 9/16/2025 12:15:39 PM

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Neurofibromatosis Neurofibromatosis (NF) is a medical term that refers to a group of three unique but related disorders of the nervous system: NF1, NF2 and schwannomatosis.
Noonan Syndrome Noonan syndrome is a genetic disorder characterized by features such as heart defects, short stature, unique facial features and other physical abnormalities.
Radiation Therapy Radiation therapy is a common form of cancer treatment. It refers to exposing the body to beams of radiation that are used to kill cancer cells and prevent them from coming back.
Complete Blood Count A complete blood count is a common blood test that’s often taken during physicals or other medical checkups. It provides an evaluation of overall health, and also checks for certain disorders such as infection, anemia, leukemia, immune system disorders and other diseases.
Flow Cytometry Flow cytometry is a cutting edge medical test that uses a technique known as immunophenotyping. This technique is used to diagnose leukemias, lymphomas and immune system disorders.
Chemotherapy Chemotherapy is a common form of cancer treatment. It refers to drugs that are often used to kill cancer cells and prevent them from coming back.