Acknowledgments / The Authors

Abstract

The online version of this article has a supplementary appendix. BackgroundThe MPL Ser505Asn mutation has been reported to be a cause of hereditary thrombocythemia. Recently, we detected this mutation in a large proportion of children with familial thrombocythemia, suggesting that in Italy the incidence of MPL Ser505Asn mutation could be underestimated. Design and MethodsWe extended the search for this mutation to all patients with essential thrombocythemia who had a positive family history for thrombocytosis or essential thrombocythemia. We identified eight Italian families positive for the MPL Ser505Asn mutation. Clinical and hematologic data were available for members of seven families, including 21 patients with a proven mutation and 20 relatives with thrombocytosis. ResultsFifteen major thrombotic episodes, nine of which were fatal, were recorded among 41 patients. The thrombotic manifestation was stroke in four cases, myocardial infarction in seven cases, fetal loss in two cases, deep vein thrombosis of the leg in one case and Budd Chiari syndrome in one case. Almost all patients over 20 years old had splenomegaly and bone marrow fibrosis, while these were rarely observed in patients under 20 years old, suggesting that these manifestations are associated with aging. Finally, the life expectancy of family members with thrombocytosis was significantly shorter than that of members without thrombocytosis (P=0.003). ConclusionsPatients with familial thrombocytosis caused by a MPL Ser505Asn mutation have a high risk of thrombosis and, with aging, develop splenomegaly and bone marrow fibrosis, significantly affecting their life expectancy.Key words: MPL Ser505Asn , hereditary thrombocytosis, splenomegaly, bone marrow fibrosis. Giona F, Torti L, Cenci T, Ricerca BM, Rumi C, Nunes V, Foà R, Leone G, Martini M, and Larocca LM. Hereditary thrombocytosis caused by MPL Ser505Asn is associated with a high thrombotic risk, splenomegaly and progression to bone marrow fibrosis. Haematologica. 2010; 95:65-70. doi:10.3324/haematol.2009 Hereditary thrombocytosis caused by MPL Ser505Asn is associated with a high thrombotic risk, splenomegaly and progression to bone marrow fibrosis