PTPN11 and juvenile myelomonocytic leukemia: Somatic Shp2 mutations are found in ∼35 % of patients with sporadic juvenile myelomonocytic leukemia (JMML), a clonal pediatric myeloproliferative disorder (MPD) featuring the amplified expansion and tissue infiltration of myeloid cells, along with macrocytic anemia and persisting fetal hemoglobinemia [157, 158].