PTPN11 and precursor B-cell acute lymphoblastic leukemia: Importantly, germline and somatic mutations (heterozygous) in Ptpn11 (encoding Shp2) have been identified in the developmental disorder Noonan syndrome (50%) [15], juvenile myelomonocytic leukemia (JMML) (35%) [16], [17], myelodysplastic syndrome (10%), B cell acute lymphocytic leukemia (7%), acute myeloid leukemia (4%) [18], [19], and sporadic solid tumors [20].