Primary myelofibrosis (PMF) is a hematological cancer characterized by abnormal proliferation and differentiation of hematopoietic progenitors, variable degrees of bone marrow fibrosis, cytopenias, elevated blood CD34-positive stem and progenitor hematopoietic cells, splenomegaly, and risk of transformation to a blast phase. This evidence concerns the gene CD34 and Splenomegaly.