Clonal haematopoietic mutations linked to platelet traits and the risk of thrombosis or bleeding.

Platelets are key elements in thrombosis, particularly in atherosclerosis-associated arterial thrombosis (atherothrombosis), and haemostasis. Megakaryocytes in the bone marrow, differentiated from haematopoietic stem cells are generally considered as a uniform source of platelets. However, recent insights into the causes of malignancies, including essential thrombocytosis, indicate that not only inherited but also somatic mutations in haematopoietic cells are linked to quantitative or qualitative platelet abnormalities. In particular cases, these form the basis of thrombo-haemorrhagic complications regularly observed in patient groups. This has led to the concept of clonal haematopoiesis of indeterminate potential (CHIP), defined as somatic mutations caused by clonal expansion of mutant haematopoietic cells without evident disease. This concept also provides clues regarding the importance of platelet function in relation to cardiovascular disease. In this summative review, we present an overview of genes associated with clonal haematopoiesis and altered platelet production and/or functionality, like mutations in JAK2. We consider how reported CHIP genes can influence the risk of cardiovascular disease, by exploring the consequences for platelet function related to (athero)thrombosis, or the risk of bleeding. More insight into the functional consequences of the CHIP mutations may favour personalised risk assessment, not only with regard to malignancies but also in relation to thrombotic vascular disease.