Genetic analysis of desmoplastic melanoma

Desmoplastic melanoma is an infrequent variant of melanoma with sarcomatous histology, distinct clinical behavior, and unknown pathogenesis. We performed low-coverage genome and high-coverage exome sequencing of 20 desmoplastic melanomas, followed by targeted sequencing of 293 genes to validate candidate genes. A high mutation burden (median 62 mutations/Mb) ranked desmoplastic melanoma among the most highly mutated cancers. Mutation patterns strongly implicate UV-radiation as the dominant mutagen, indicating a superficially located cell of origin. Novel alterations included recurrent promoter mutations of NF-kappa B inhibitor epsilon, NFKBIE (IkB epsilon) in 14.5% of samples. Commonly mutated oncogenes in melanomas, in particular BRAF(V600E) and NRAS(Q61K/R), were absent. Instead, other genetic alterations known to activate the MAPK and PI3K signaling cascades were identified in 73% of samples, affecting NF1, CBL, ERBB2, MAP2K1, MAP3K1, BRAF, EGFR, PTPN11, MET... (for more see dbGaP study page.)