KRAS gene

I am looking for as much info as possible on the KRAS mutation. I hear this is the most severe and rarest form of Noonan’s, Affecting

I came across this site:

“Noonan syndrome is genetically heterogeneous. Mutations in PTPN11 have been detected in 50% of individuals clinically diagnosed with NS (Tartaglia, 2001, 2002). All mutations reported thus far are missense changes in the coding region with 76-90% clustering in exons 3, 8, and 13 (Tartaglia, 2005). Of the remaining individuals, mutations in RAF1, SOS1, and KRAS have been observed in 3-17%, 10%, and 1%, respectively (Pandit, 2007, Razzaque, 2007, Roberts, 2007, Tartaglia, 2007, Carta, 2006, and Schubbert, 2006). PTPN11, RAF1, and SOS1 mutations co-segregate with NS within families; however, variable expressivity has been observed. All KRAS mutations described to date have occurred de novo…”