PTPN11 and RASopathy: PTPN11 is the first discovered and the most frequently mutated genes of the RASopathies, a clinically defined group of overlapping syndromes caused by germline mutations in genes of components and regulators of the RAS/MAPK pathway including neurofibromatosis type 1, Noonan (NS) and Noonan with multiple lentigines, Costello, cardio‐facio‐cutaneous, and Legius syndromes.8