SFMS is a mosaic RASopathy caused by postzygotic somatic activating variants in the proto-oncogenes HRAS, KRAS, and NRAS that act as small GTPases in the RAS/mitogen-activated protein kinase (MAPK) pathway, which promote variable organ manifestations and proliferative potential [8- 12]. The gene discussed is HRAS; the disease is RASopathy.