We aim to (i) identify common genetic variation that predisposes to chronic myeloproliferative neoplasms (a type of blood cancer) and (ii) understand the relationship between age-related clonal haematopoiesis and the development of a myeloproliferative phenotype. This study will improve our understanding of genetic factors that contribute to the onset and severity of myeloproliferative neoplasms. We anticipate that our findings will improve methods to diagnose and stage these disorders, thus providing a framework for more personalised management. We will perform a genome wide association study by comparing genetic variation in patients with chronic myeloproliferative neoplasms (cases) and the Biobank population (controls). In addition we will analyse the Biobank population for evidence of somatically acquired clonal abnormalities, and relate this information to constitutional genetic factors as well as any available information on blood counts.