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Ann Hematol (2008) 87:413415 DOI 10.1007/s00277-007-0409-0
LETTER TO THE EDITOR
MPL 515 and JAK2 mutation analysis in MDS presenting with a platelet count of more than 500109/l
E. Zipperer & M. Wulfert & U. Germing & R. Haas &
N. Gattermann
Received: 2 August 2007 /Accepted: 1 November 2007 /Published online: 27 November 2007 # Springer-Verlag 2007
Dear Editor,The detection of the activating mutation V617F in the Janus kinase 2 (JAK2) has shed new light on the pathogenesis of myeloproliferative diseases. Recently, it was shown that the thrombopoietin receptor MPL can also carry mutations (MPL W515L or MPL W515K) in patients with essential thrombocythemia (ET) and idiopathic myelofibrosis (IMF) [1]. The frequency of MPL W515K/L was reported to be 1% in ET and 5% in IMF [2]. Some patients harbor coexisting JAK2 V617F and MPL W515K/L mutations [2]. Jak2 V617F is present in more than 90% of patients with polycythemia vera (PV) and about 50% of patients with ET and IMF, but is rarely detectable in MDS [3]. There are two exceptions: Ingram et al. [4] showed that Jak2 V617F identifies a subgroup of 5q patients with a proliferative bone marrow.
Another exception is refractory anemia with ringed sideroblasts associated with marked thrombocytosis (RARS-T). This disorder has been classified as myelodys-plastic/myeloproliferative syndrome, unclassifiable by the WHO. The diagnosis requires at least 15% ringed side-roblasts in the bone marrow and a platelet count of at least 600109/l in the peripheral blood. About 60% of patients with RARS-T carry the JAK2 V617F mutation [510]. We
wondered whether RARS-T may also be associated with MPL mutations. Because Shaw et al. proposed to lower the diagnostic platelet threshold for RARS-T to 500109/l [11], we included in our analysis patients with RARS who presented with a platelet count between 500109/l and 600109/l at diagnosis.
Because thrombocytosis is a rather uncommon feature suggesting a myeloproliferative component in the disease pathology, we sought to determine the frequency of Jak2 V617F and MPL W515L/K in MDS patients with a platelet count of at least 500109/l. In the Duesseldorf MDS Registry, material for mutation analysis was available for18 RA, 4 CMML, 8 RAEB, and 2 RAEB-T patients with a platelet count of at least 500109/l, 4 RARS patients with platelets between 500109/l and...