Fluorescence in situ hybridization and molecular characterization of the translocation confirmed a BCR-JAK2 fusion and helped delineate the breakpoints upstream of exon 1 of minor cluster region of BCR gene and likely intron 18 of the JAK2 gene, resulting in an in-frame transcript This case provides convincing support, along with two previous case-reports, for a role for activation of the Janus kinase 2 in evolution of myeloproliferative disease. Here, JAK2 is linked to myeloproliferative disorder.