Advances in understanding the pathogenesis of familial thrombocythaemia.

Familial thrombocytosis can be divided into two broad categories. The first includes inherited syndromes that affect only the megakaryocytic lineage with Mendelian inheritance, high penetrance and polyclonal haematopoiesis. The second category includes inherited predisposition to true Philadelphia-negative myeloproliferative neoplasms (MPN) and is characterized by low penetrance, clonal haematopoiesis and presence of somatic mutations such as JAK2 V617F. It must be underlined that these two categories represent two well separate entities, with different patterns of proliferation and different transmission modalities. This review will focus on the molecular pathogenesis of hereditary thrombocytosis, underlining those clinical pictures that are specifically associated with mutations in the genes of thrombopoietin or in its receptor. Moreover, we propose an approach for the diagnosis and therapy of these syndromes.