Characteristics and clinical correlates of MPL 515W>L/K mutation in essential thrombocythemia

Alessandro M. Vannucchi, Elisabetta Antonioli, Paola Guglielmelli, Alessandro Panerazzi, Vittoria Guerini, Giovanni Barosi, Marco Ruggeri, Giorgina Specchia, Francesco Lo-Coco, Federica Delaini, Laura Villani, Silvia Finotto, Emanuele Ammatuna, Renato Alterini, Valentina Carrai, Gloria Capaccioli, Simonetta Di Lollo, Vincenzo Liso, Alessandro Rambaldi, Alberto BosiTiziano Barbui

Research output: Contribution to journalArticlepeer-review


Among 994 patients with essential thrombocythemia (ET) who were genotyped for the MPLW515L/K mutation, 30 patients carrying the mutation were identified (3.0%), 8 of whom also displayed the J4K2V671F mutation. MPLW515L/K patients presented lower hemoglobin levels and higher platelet counts than did wild type (wt) MPL; these differences were highly significant compared with MPLwt/J4K2V617F-positive patients. Reduced hemoglobin and increased platelet levels were preferentially associated with the W515L and W515K alleles, respectively. MPL mutation was a significant risk factor for microvessel disturbances, suggesting platelet hyperreactivity associated with constitutively active MPL; arterial thromboses were increased only in comparison to MPLwt/JAK2wt patients. MPLW515L/K patients presented reduced total and erythroid bone marrow cellular ity, whereas the numbers of megakaryocytes, megakaryocytic clusters, and small-sized megakaryocytes were all significantly increased. These data indicate that MPLW515L/K mutations do not define a distinct phenotype in ET, although some differences depended on the JAK2V617F mutational status of the counterpart.

Original languageEnglish
Pages (from-to)844-847
Number of pages4
Issue number3
Publication statusPublished - Aug 1 2008

ASJC Scopus subject areas

  • Hematology
  • Biochemistry
  • Cell Biology
  • Immunology


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