All patients diagnosed or followed in Brest University Hospital for Philadelphia negative myeloproliferative neoplasms will be included in this observational study. Myeloproliferative neoplasms recorded included: polycythemia vera, essential Thrombocythemia and Primary Myelofibrosis. This is a not interventional study. Alive patients need to sign a non-opposition consent form. Patients will be followed until last news (death, change of reference centre...).