JAK2V617F homozygosity arises commonly and recurrently in PV and ET, but PV is characterized by expansion of a dominant homozygous subclone.
Subclones homozygous for JAK2V617F are more common in polycythemia vera (PV) than essential thrombocythemia (ET), but their prevalence and significance remain unclear. The JAK2 mutation status of 6495 BFU-E, grown in low erythropoietin conditions, was determined in 77 patients with PV or ET. Homozygous-mutant colonies were common in patients with JAK2V617F-positive PV and were surprisingly prevalent in JAK2V617F-positive ET and JAK2 exon 12-mutated PV. Using microsatellite PCR to map loss-of-heterozygosity breakpoints within individual colonies, we demonstrate that recurrent acquisition of JAK2V617F homozygosity occurs frequently in both PV and ET. PV was distinguished from ET by expansion of a dominant homozygous subclone, the selective advantage of which is likely to reflect additional genetic or epigenetic lesions. Our results suggest a model in which development of a dominant JAK2V617F-homzygous subclone drives erythrocytosis in many PV patients, with alternative mechanisms operating in those with small or undetectable homozygous-mutant clones.
Cambridge Institute for Medical Research and Department of Haematology, University of Cambridge, Cambridge, United Kingdom.
Anna L
AL
Godfrey
Edwin
E
Chen
Francesca
F
Pagano
Christina A
CA
Ortmann
Yvonne
Y
Silber
Beatriz
B
Bellosillo
Paola
P
Guglielmelli
Claire N
CN
Harrison
John T
JT
Reilly
Frank
F
Stegelmann
Fontanet
F
Bijou
Eric
E
Lippert
Mary F
MF
McMullin
Jean-Michel
JM
Boiron
Konstanze
K
Döhner
Alessandro M
AM
Vannucchi
Carlos
C
Besses
Peter J
PJ
Campbell
Anthony R
AR
Green
D005799:Genes, Dominant; D006579:Heterozygote; D006720:Homozygote; D006801:Humans; D053614:Janus Kinase 2 / Q000235:genetics*; D018895:Microsatellite Repeats; D009154:Mutation / Q000235:genetics*; D011086:Polycythemia / Q000235:genetics / Q000473:pathology*; D011087:Polycythemia Vera / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011379:Prognosis; D012008:Recurrence; D013920:Thrombocythemia, Essential / Q000235:genetics*
D053614:Janus Kinase 2