We performed follow-up chart review of clinical features of probands with LOF variants in the most frequently mutated syndromic genes in our cohort—CHD7 and KMT2D, and known GOF mutations in BRAF, PTPN11, RAF1, RIT1, SHOC2, and SOS1 (and LOFs in LZTR1) causing Noonan syndrome and related RASopathies. This evidence concerns the gene SOS1 and Noonan syndrome.