<prompt> Which of the following is not compatible with a diagnosis of juvenile myelomonocytic leukemia -Peripheral blood monocytosis, more than 1 x 109LIncreased hemoglobin F levels for agePresence of bcrabl fusion geneGM-CSF hypersensitivity of myeloid progenitors in vitro  <response>: Ans. is c i.e., Presence of bcrabl fusion geneJuvenile myelomonocvtic leukemia JMML o Juvenile myelomonocytic leukemia JMML is a rare but distinct form of childhood leukemia, formerly called juvenile chronic myeloid leukemia Juvenile CML.Most of the patients are less than 2 years of age.In contrast to adult CML, the cells in JMML do not contain Philadelphia chromosome and do not express bcrabl fusion gene.Clinical featureso Children frequently present with complains of malaise, bleeding, or fever, often with localized infection.o Less common presentations include pulmonary symptoms cough, wheezing, abdominal discomfo distension, weight loss, splenomegaly, hepatomegaly, lymphadenopathy and eczematous skin rash.o Xanthoma and cafe - au - lait spots are often associated with JMML and JMML has been associated with neurofibromatosis type I in 11 of the cases.Laboratory findingso Peripheral blood -- Monocytosis 1000 1, mild leukocytosis, thrombocytopenia, elevated fetal hemoglobin, elevated nuramidase, normal to diminished leukocyte alkaline phosphatase.o Bone marrow -- Hypercellularity with predominance of granulocytes at all stages of maturation, monocytosis, reduced megakaryocytes, increased blast count but not to the level seen in acute leukemia.Chromosomal alteration :- monosomy 7 -7q in 25 of the cases.o A distinctive characteristic of JMML leukemic cells is their spontaneous proliferation in vitro due to their hypersensitivity to GM- CSF. 