Absence of BRAF-V600E in the human cell lines BONNA-12, ESKOL, HAIR-M, and HC-1 questions their origin from hairy cell leukemia

To the editor: Hairy cell leukemia (HCL) shows distinct clinicopathologic, immunophenotypic, and gene expression features.[1][1][⇓][2]–[3][3] We previously identified the BRAF -V600E mutation as the disease-defining genetic event in HCL.[4][4] This mutation is present in virtually all cases of