NRAS Mutation Is the Sole Recurrent Somatic Mutation in Large Congenital Melanocytic Nevi

• Published in: Journal of investigative dermatology Vol. 134; no. 4; pp. 1067 - 1074
• Main Authors: Charbel, Christelle, Fontaine, Romain H., Malouf, Gabriel G., Picard, Arnaud, Kadlub, Natacha, El-Murr, Nizar, How-Kit, Alexandre, Su, Xiaoping, Coulomb-L'Hermine, Aurore, Tost, Jorg, Mourah, Samia, Aractingi, Selim, Guégan, Sarah
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.04.2014; Elsevier Limited; Nature Publishing Group
• Subjects: Cell Proliferation; Child; Child, Preschool; Dermatology; DNA Mutational Analysis; Exome; Female; Genes, ras; Genotype; GTP Phosphohydrolases - genetics; GTP Phosphohydrolases - metabolism; Human health and pathology; Humans; Infant; Life Sciences; Male; Melanocytes - cytology; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mutation; Nevus, Pigmented - congenital; Nevus, Pigmented - genetics; Phenotype; Polymerase Chain Reaction; Polymorphism, Single Nucleotide; Proto-Oncogene Proteins B-raf - genetics; Proto-Oncogene Proteins B-raf - metabolism; Risk
• ISSN: 0022-202X; 1523-1747; 1523-1747
• DOI: 10.1038/jid.2013.429

Congenital melanocytic nevus (CMN) is a particular melanocytic in utero proliferation characterized by an increased risk of melanoma transformation during infancy or adulthood. NRAS and BRAF mutations have consistently been reported in CMN samples, but until recently results have been contradictory. We therefore studied a series of large and giant CMNs and compared them with small and medium CMNs using Sanger sequencing, pyrosequencing, high-resolution melting analysis, and mutation enrichment by an enhanced version of ice-COLD-PCR. Large–giant CMNs displayed NRAS mutations in 94.7% of cases (18/19). At that point, the role of additional mutations in CMN pathogenesis had to be investigated. We therefore performed exome sequencing on five specimens of large–giant nevi. The results showed that NRAS mutation was the sole recurrent somatic event found in such melanocytic proliferations. The genetic profile of small–medium CMNs was significantly different, with 70% of cases bearing NRAS mutations and 30% showing BRAF mutations. These findings strongly suggest that NRAS mutations are sufficient to drive melanocytic benign proliferations in utero.