RAS pathway influences the number of melanocytic nevi in cardiofaciocutaneous and Costello syndromes

Abstract

To the Editor: The number of melanocytic nevi is one of the strongest risk factors for melanoma,1 yet the reasons for the interpersonal variability in this number are largely unknown. Both nevi and melanoma show somatic mutations in the RAS pathway components, most commonly in BRAF.2 Germline mutations in these same genes cause a group of developmental syndromes termed RASopathies,3 some of which characteristically display melanocytic nevi.4 However, the effects of germline RAS pathway mutations on the number of nevi are poorly understood.