Juvenile myelomonocytic leukemia: Abbreviated JMML. A rare cancer of the myeloid cells in the bone marrow, accounting for less than 1% of all childhood leukemia.
JMML is most common in children under four years of age, especially those with genetic disorders called neurofibromatosis 1 (NF1) and Noonan syndrome. Up to 14% of cases of JMML occur in children with NF1.
Few approaches other than hematopoietic stem cell transplantation have resulted in long-term survival for this disease. JMML was formerly called juvenile chronic myelogenous leukemia (juvenile chronic myeloid leukemia, juvenile CML or JCML).