Incidence of BRAF p.Val600Glu and p.Val600Lys mutations in a consecutive series of 183 metastatic melanoma patients from a high incidence region

Aim: Approximately 40-60% of melanomas from Caucasian populations carry activating mutations in the BRAF oncogene, with the most common being the p.Val600Glu (V600E) hotspot mutation in exon 15. The aim of the present study was to investigate the frequency of the less common p.Val600Lys (V600K) mutation in metastatic melanoma from a high incidence region. Method: Dideoxy sequencing and fluorescent single strand conformation analysis were used to screen for mutations in exon 15 of BRAF in 183 cases of metastatic melanoma. Results: The overall incidence of BRAF mutation (89/183, 49%) was very similar to other large studies of Caucasian populations. However, the frequency of the p.Val600Lys mutation was higher than in most other studies and comprised almost one-third of all BRAF mutations in our cohort (27/89, 30%). Conclusion: BRAF p.Val600Lys mutations were present at a relatively high frequency in this cohort of metastatic melanoma patients (27/183, 15%). Assays used to screen for BRAF mutations in the clinic should be robust enough to detect the p.Val600Lys mutation, as this may have therapeutic implications.