Keywords: CALMs, café au lait macules; Legius syndrome; MAPK, mitogen-activated protein kinase; NF1, neurofibromatosis type 1; Noonan syndrome; PTPN11, protein tyrosine phosphatase nonreceptor type 11; RAF1, rapidly accelerated fibrosarcoma-1; RAS, rat sarcoma family of protooncogenes; RASopathy; SPRED1, sprouty-related, EVH1 domain containing protein 1; neurofibromatosis; nevus anemicus; α1-AR, α1-adrenergic receptors.