[Juvenile myelomonocytic leukemias]

Area of Science:

• Pediatric Hematology Oncology
• Molecular Genetics
• Cancer Biology

Background:

• Juvenile myelomonocytic leukemias (JMML) are rare, severe stem cell neoplasms affecting infants.
• They are characterized by RAS pathway dysregulation due to specific gene mutations.
• JMML often present with multisystemic infiltration and can transform into acute myeloid leukemia.

Purpose of the Study:

• To highlight the diagnostic challenges and genetic underpinnings of JMML.
• To emphasize the importance of genetic typing in JMML diagnosis and management.
• To discuss the current understanding of JMML prognosis and treatment limitations.

Main Methods:

• Review of clinical and genetic features of JMML.
• Analysis of diagnostic criteria, including blood smear and in vitro progenitor growth.
• Incorporation of genetic mutation analysis in diagnostic workup.

Main Results:

• Mutations in RAS pathway genes (NRAS, KRAS, PTPN11, NF1, CBL) are found in over 90% of JMML cases.
• Splenomegaly, monocytosis, and abnormal basophils are key clinical findings.
• Poor prognostic factors include age over two years, low platelet count, and high fetal hemoglobin.

Conclusions:

• JMML diagnosis is complex due to clinical heterogeneity, necessitating genetic analysis.
• Bone marrow transplantation is the only curative option, but relapse rates are significant.
• Further research is needed for improved prognosis prediction and targeted therapies for JMML.