Germ-line PTPN11 mutations cause ∼50% of Noonan syndrome (NS), which is characterized by short stature, skeletal abnormalities, cardiac defects, learning disabilities, and a predisposition to hematologic abnormalities, particularly juvenile myelomonocytic leukemia (JMML) [2]. This evidence concerns the gene PTPN11 and juvenile myelomonocytic leukemia.