[Rasopathies: developmental disorders that predispose to cancer and skin manifestations].

Proteins belonging to the RAS/mitogen activated protein kinase (MAPK) pathway play key roles in cell proliferation, differentiation, survival, and death. For more than 30 years now we have known that 30% of human cancers carry somatic mutations in genes encoding proteins from this pathway. Whereas somatic mutations have a high malignant potential, germline mutations are linked to developmental abnormalities that are often poorly clinically differentiated, although each is dependent upon the specific gene affected. Thus, all patients share varying degrees of mental retardation or learning difficulties, heart disease, facial dysmorphism, skin anomalies, and, in some cases, predisposition to cancer. These syndromes, known as rasopathies, include Noonan syndrome, Costello syndrome, neurofibromatosis-1, LEOPARD syndrome, cardiofaciocutaneous syndrome, and Legius syndrome. Recognizing the skin manifestations of rasopathies can facilitate diagnosis of these syndromes.