PTPN11 and Noonan syndrome with multiple lentigines: PTPN11 has been identified as a causative gene of Noonan Syndrome (NS), Noonan Syndrome with Multiple Lentigines (NSML, formerly known as Leopard Syndrome), Juvenile Myelomonocytic Leukemia (JMML), and Metachondromatosis (MC), all of which are clustered as different RASopathies due to sharing of alterations in the RAS/MAPK signaling pathway (Yang and Neel, 2013; Huang et al., 2014; Tajan et al., 2015; Liao and Mehta, 2019; Shen et al., 2020b; Dong et al., 2021).