Somatic SHP2 mutations mainly occur in several types of hematologic malignancies, including ~10% myelodysplastic syndromes, ~5% juvenile acute myeloid leukemia, ~7% B-cell acute lymphoblastic leukemia, and particularly ~35% juvenile myelomonocytic leukemia (JMML) (3, 5–7). Here, PTPN11 is linked to juvenile myelomonocytic leukemia.