Somatic pathogenic variants in genes of the RAS/MAPK signaling pathway, in turn, are causative for RASopathies such as Noonan syndrome (BRAF, MAP2K1, PTPN11, or RAF1 variants), Costello syndrome (HRAS variants) as well as other Noonan-like syndromes [26]. Here, PTPN11 is linked to Noonan syndrome.