Incidence of the BRAF V600E mutation in chronic lymphocytic leukaemia and prolymphocytic leukaemia.

The spectrum of underlying molecular abnormalities of clinically and biologically heterogeneous chronic lymphocytic leukaemia (CLL) and prolymphocytic leukaemia (PLL) has yet to be identified. While whole genome sequencing has identified several genes implicated in the pathogenesis and progression of CLL, the molecular lesions in a substantial proportion of patients remain to be elucidated. The incidence of the BRAF V600E mutation, widely implicated in solid tumours and other B-cell malignancies, was sought in a cohort of patients with CLL and related disorders. One CLL patient and one patient with B-prolymphocytic leukaemia (PLL) were found to harbour this mutation. Although present at a low frequency, the finding of BRAF V600E has biological and clinical implications for CLL and PLL.