• unable to obtain any viable homozygotes, with the stage of prenatal lethality not specified

• median survival is 146 days

• all develop a myeloproliferative neoplasm

• these myeloproliferative neoplasms can be transplanted by transfer of either unfractionated bone marrow cells or LSK cells but not by transfer of MEP or granulocyte/macrophage progenitor cells

• however, acute leukemia is not detected

• despite the increase in megakaryocyte numbers no increases in platelet counts are detected (J:160883)

• expansion of the megakaryocytic/erythroid progenitor (MEP) population

• disproportional increase in the number of erythroid progenitors relative to other myeloid progenitor

• increase in the number of erythroid precursors in the bone marrow and spleen

• marked erythroid hyperplasia in the splenic red pulp

• prominent splenic extramedullary hematopoiesis

• megakaryocytes with atypical nuclear features and prominent emperipolesis are present in the bone marrow

• mild hyperplasia in the splenic red pulp

• overall effacement of the normal architecture

• marked erythroid and mild megakaryocytic hyperplasia in the splenic red pulp

• MEPs show EPO hypersensitivity

• gene set enrichment analysis indicates that hematopoietic differentiation in the LSK compartment is altered

• overall effacement of the normal architecture

• marked erythroid and mild megakaryocytic hyperplasia in the splenic red pulp