Noonan syndrome is a condition that affects many areas of the body. It is characterized by mildly unusual facial features, short stature, heart defects, bleeding problems, skeletal malformations, and many other signs and symptoms. Noonan syndrome occurs in approximately 1 in 1,000 to 2,500 people.
Inherited in an autosomal dominant manner, mutations in multiple genes can cause Noonan syndrome. Mutations in the PTPN11 gene cause about half of all cases. SOS1 gene mutations cause an additional 10 to 15 percent, and RAF1 and RIT1 genes each account for about 5 percent of cases. Mutations in other genes each account for a small number of cases. The cause of Noonan syndrome in 15 to 20 percent of people with this disorder is unknown.
In SNPedia, the mutations judged by a ClinVar expert panel to be pathogenic and likely pathogenic have been annotated as leading to Noonan syndrome.