Rapid detection and quantitation of BRAF mutations in hairy cell leukemia using a sensitive pyrosequencing assay.

BRAF protooncogene is an important mediator of cell proliferation and survival signals. BRAF p.V600E mutation was recently described as a molecular marker of hairy cell leukemia (HCL). We developed and validated a pyrosequencing-based approach that covers BRAF mutational hotspots in exons 11 (codon 468) and 15 (codons 595 to 600). The assay detects BRAF mutations at an analytical sensitivity of 5%. We screened 16 unenriched archived bone marrow aspirate samples from patients with a diagnosis of HCL (n = 12) and hairy cell leukemia-variant (HCL-v) (n = 4) using pyrosequencing. BRAF p.V600E mutation was present in all HCL cases and absent in all HCL-v. Our data support the recent finding that BRAF p.V600E mutation is universally present in HCL. Moreover, our pyrosequencing-based assay provides a convenient, rapid, sensitive, and quantitative tool for the detection of BRAF p.V600E mutations in HCL for clinical diagnostic testing.