Table 2.
Noonan syndrome and other RASopathies
| Gene | % of Patients | Comments |
|---|---|---|
| PTPN11 | 50% | Also causes NSML |
| SOS1 | 10–15% | High prevalence of ectodermal abnormalities |
| RAF1 | 5% | HCM in > 80%; also causes NSML |
| RIT1 | 5% | High incidence of congenital heart disease; HCM in 70% |
| KRAS | 2% | Also associated with CFC syndrome |
| BRAF | 1–2% | Usually seen in CFC syndrome |
| NRAS | <1% | |
| A2ML1 | unknown | candidate |
| LZTR1 | unknown | candidate |
| RASA2 | unknown | candidate |
| SOS2 | unknown | candidate; ectodermal defects |
| RRAS | candidate; Noonan like syndrome | |
| HRAS | Costello syndrome; activating mutations | |
| MAP2K1 | 2% | CFC syndrome |
| MAP2K2 | CFC syndrome | |
| SHOC2 | 2% | Noonan-like syndrome |
| CBL | Noonan-like syndrome |