Noonan Syndrome

**Semantic type:** Congenital Abnormality|Disease or Syndrome

**Definition:** A genetic syndrome caused by mutations in the PTPN11 gene (over 50% of the cases) or less frequently mutations in the SOS1, RAF1, or KRAS genes. It is characterized by short stature, webbed neck, hypertelorism, low-set ears, deafness, and thrombocytopenia or abnormal platelet function.

**Synonyms:** - Noonan syndrome - Noonan's Syndrome