From the Research
Retinal vein thrombosis with normal platelet count and hematocrit still warrants JAK2 mutation testing, as it may identify an underlying myeloproliferative neoplasm (MPN) in its early stages. This is based on the understanding that JAK2 mutations can be present before overt hematological abnormalities develop, and testing for these mutations can help identify patients at risk of thrombotic events 1. The pathophysiology involves JAK2 mutations causing increased cellular proliferation and a prothrombotic state through multiple mechanisms, including increased blood viscosity and platelet activation, which can precipitate thrombosis even before blood counts become abnormal.
Some key points to consider in this context include:
- The prevalence of JAK2 mutations in patients with myeloproliferative neoplasms, with approximately 80% of patients expressing myeloproliferative neoplasm driver mutations (JAK2, CALR, MPL) 1
- The association between JAK2 mutations and thrombotic events, with JAK2 mutations being an independent risk factor for thrombotic events 2
- The importance of early detection of JAK2 mutations in preventing future thrombotic events and guiding appropriate treatment strategies 3
However, it's also important to note that the prevalence of JAK2 mutations in patients with nonsplanchnic venous thrombosis in the absence of MPN is relatively low, and some studies have suggested that mutation screening may not be warranted as part of the hypercoagulable work-up in these cases 4. Nevertheless, in the context of retinal vein thrombosis, which is considered an unusual site thrombosis, testing for JAK2 mutations is still recommended to identify underlying MPN and guide management. A positive JAK2 mutation would significantly alter management, potentially leading to cytoreductive therapy, anticoagulation, and specialized hematology follow-up 1.