Both variant and IGHV4-34-expressing hairy cell leukemia lack the BRAF V600E mutation.
Recently, the BRAF V600E mutation was reported in all cases of hairy cell leukemia (HCL) but not in other peripheral B-cell neoplasms. We wished to confirm these results and assess BRAF status in well-characterized cases of HCL associated with poor prognosis, including the immunophenotypically defined HCL variant (HCLv) and HCL expressing the IGHV4-34 immunoglobulin rearrangement. Fifty-three classic HCL (HCLc) and 16 HCLv cases were analyzed for BRAF, including 5 HCLc and 8 HCLv expressing IGHV4-34. BRAF was mutated in 42 (79%) HCLc, but wild-type in 11 (21%) HCLc and 16 (100%) HCLv. All 13 IGHV4-34(+) HCLs were wild-type. IGHV gene usage in the 11 HCLc BRAF wild-type cases included 5 IGHV4-34, 5 other, and 1 unknown. Our results suggest that HCLv and IGHV4-34(+) HCLs have a different pathogenesis than HCLc and that a significant minority of other HCLc are also wild-type for BRAF V600.
Laboratory of Pathology, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA.
Liqiang
L
Xi
Evgeny
E
Arons
Winnifred
W
Navarro
Katherine R
KR
Calvo
Maryalice
M
Stetler-Stevenson
Mark
M
Raffeld
Robert J
RJ
Kreitman
D019943:Amino Acid Substitution; D015870:Gene Expression; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007135:Immunoglobulin Variable Region / Q000235:genetics*; D007943:Leukemia, Hairy Cell / Q000235:genetics*; D009154:Mutation; D048493:Proto-Oncogene Proteins B-raf / Q000235:genetics*
D007143:Immunoglobulin Heavy Chains; D007135:Immunoglobulin Variable Region; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf