STAT1 activation in association with JAK2 exon 12 mutations

JAK2 exon 12 mutations are associated with more marked and isolated erythrocytosis than JAK2V617F. We analysed expression profiles of JAK2exon 12-mutant and wild-type erythroid colonies from patients with polycythemia vera (PV). Exon 12 mutations were associated with interferon- target gene upregulation, STAT1 activation and additional gene expression changes that were quantitatively and qualitatively similar to those in JAK2V617F-heterozygous cells from essential thrombocythemia (ET) patients. These results demonstrate that JAK2 exon 12-mutated PV does not reflect attenuated STAT1 signalling, and that transcriptional consequences of JAK2 mutations are remarkably similar in JAK2 exon 12-mutated PV and JAK2V617F -positive ET