An overview of Juvenile Myelomonocytic Leukemia (JMML) based on the latest research...
- Juvenile Myelomonocytic Leukemia (JMML) is a serious chronic leukemia (cancer of the blood) that affects children mostly aged 4 and under.
- The average age of patients at diagnosis is 2 years old.
- The World Health Organization has included JMML in the category of Myelodysplastic and Myeloproliferative disorders.
- The name JMML now encompasses all diagnoses formerly referred to as Juvenile Chronic Myeloid Leukemia (JCML), Chronic Myelomonocytic Leukemia of Infancy, and Infantile Monosomy 7 Syndrome.
- JMML accounts for 1-2% of childhood leukemias each year; in the United States, an estimated 25-50 new cases are diagnosed each year, which also equates to about 3 cases per million children.
- There is no known environmental cause for JMML.
- Since about 10% of patients are diagnosed before 3 months of age, it is thought that JMML is a congenital condition in these infants.
- About 80% of JMML patients have some sort of genetic abnormality in their leukemia cells that can be identified with laboratory testing. This includes:
- 15-20% of patients with neurofibromatosis 1 (NF1)
- 25% of patients with mutations in one of the RAS family of oncogenes (only in their leukemia cells)
- another 35% of patients with a mutation in a gene called PTPN11 (again, only in their leukemia cells).
If you need help with some of the medical terms included in these pages, please use the NIH Medical Glossary
Page created: 12 May 2005 by Fred Dini
Last reviewed: Aug 2005 by Mignon Loh, MD