Brief Summary: The mandate of this MPN registry is to collect clinical information, including molecular results, from consenting patients with a variety of MPNs at different time points during the course of their disease.

Detailed Description: The myeloproliferative neoplasms (MPNs) are a group of rare hematological malignancies in which the bone marrow cells that produce the body's blood cells develop and function abnormally. Despite the gains that have already been made in understanding and treatment of MPNs there is much that can still be learned. This registry will establish a clinical annotation database would help to better understand this group of diseases and to more effectively assign individual patients to the optimal therapy and so, improve their outcomes. This project will provide new insights on the molecular profiling of patients with MPN. It will be used as future resource for observational studies related to MPN. The registry involves the collection of clinical information from patients with diagnosis of MPN at different time points during the course of their disease. The clinical data is collected following written informed consent from the Hematologic Malignancy tissue bank (UHN REB 01-0573C). Data collected includes: a range of clinical measures, disease-associated factors, details of treatment and its results, complications during treatment, molecular and cytogenetic data, symptom assessment and survival outcome (up to 10 years). Data will be collected prospectively and retrospectively, in both cases after obtaining written informed consent as per the study standard operating procedure (SOP).