NF1 and malignant peripheral nerve sheath tumor: The combination of PRC2 inactivation and oncogenic RAS pathway activation now has been observed in several contexts: NF1-associated malignant peripheral nerve sheath tumors (MPNST) (36–38), juvenile myelomonocytic leukemia (JMML) (39, 40), megakaryocytic AML of Down syndrome (41), and ETP-ALL (16).