Detection of the BRAF V600E mutation in melanocytic lesions using the ligase detection reaction

Background: BRAF is a member of the RAF kinase family, and it promotes signaling through the RAS-MAP kinase signal transduction cascade. Research has shown that a majority of melanomas and nevi exhibit an activating V600E (T1799A) mutation in BRAF exon 15. Additional studies of BRAF have demonstrated that the T1799A mutation is absent in uveal melanomas and Spitz nevi. Methods: The ligase detection reaction (LDR) is a sensitive technique that can identify specific DNA mutations occurring at very low frequency within heterogeneous clinical samples, and it has previously been used to analyze mutations in paraffin-embedded tissue specimens. Results: The LDR can readily detect mutations in DNA extracted from non-microdissected paraffin-embedded sections of common nevi, dysplastic nevi, and melanomas. In addition, this method demonstrated the absence of the V600E (T1799A) mutation within Spitz nevi. Conclusion: The LDR is a highly sensitive and specific test for detecting mutations in formalin-fixed tissue. The LDR can be easily adapted to detect any mutation associated with a cutaneous disorder. The absence of the BRAF V600E mutation in Spitz's nevi may serve as a molecular signature to distinguish these lesions from common nevi, dysplastic nevi, and some types of malignant melanoma.