PTPN11 and Noonan syndrome: Mutations in PTPN11 in human patients cause aberrant signaling of SHP2, resulting in multiple rare hereditary diseases, including Noonan Syndrome (NS), Noonan Syndrome with Multiple Lentigines (NSML), Juvenile Myelomonocytic Leukemia (JMML) and Metachondromatosis (MC).