The tyrosine kinase Syk plays a critical role in signalling by integrin αIIbβ3 and GPVI [8,9] and an inhibitor of Syk, fostamatinib, is clinically used for the treatment of patients with refractory immune thrombocytopenia (ITP) without increasing the risk of bleeding despite the marked reduction in platelet count in this patient group [10]. This evidence concerns the gene SYK and autoimmune thrombocytopenic purpura.