Analysis of all MPN patients showed a significant decrease in basal CD62P expression in platelets from patients with CALR compared with that from patients with JAK2V617F mutation, and subanalysis in patients with ET showed a significant decrease in basal GpIIbIIIa expression and a significant decrease in Gp1b internalization after activation. The gene discussed is SELP; the disease is myeloproliferative disorder.