Polycythemia Vera, Myelofibrosis and Essential Thrombocythemia: Identification of PV, MF & ET Genes

Inclusion Criteria: 1. Patients with an elevated hemoglobin concentration (\>18 in males and \>16 in females) and who are suspected to have congenital or acquired primary polycythemia 2. Patients with a persistent thrombocytosis (\>400,000) that does not have an obvious secondary cause 3. Patients with a bone marrow biopsy that shows increased cellularity and fibrosis 4. Patients where there is clinical concern for primary myelofibrosis, such as anemia in combination with leukocytosis, thrombocytosis, splenomegaly and/or a leukoerythroblastic blood smear 5. Patients with thrombosis at unusual sites, such as Budd-Chiari syndrome, can have early PV before hemoglobin is elevated, these patients will also be included. Exclusion Criteria: 1. Subjects who have a known acquired cause of polycythemia (increased hemoglobin/hematocrit) such as people living in high altitudes (in excess of 14,000 feet), subjects with heart disease, left to right heart shunt, severe hypoxia or severe pulmonary disease will be excluded from this study. 2. Subjects with a known acquired cause of thrombocytosis. 3. Subjects will be excluded if they cannot demonstrate decision making capacity sufficient to agree or decline the blood drawing or use of their blood for the study.