From the Guidelines
Retinal vein thrombosis with normal platelet count and hematocrit still warrants JAK2 mutation testing, as approximately 20-25% of patients with splanchnic vein thrombosis (including retinal vein thrombosis) who have normal blood counts may test positive for the JAK2 V617F mutation. This mutation is commonly associated with myeloproliferative neoplasms (MPNs) like polycythemia vera, essential thrombocythemia, and primary myelofibrosis, but can be present before abnormal blood counts develop 1. Testing for JAK2 mutations is recommended in unusual thrombotic events like retinal vein thrombosis, even with normal blood parameters, as early detection of an underlying MPN can significantly impact management.
Some key points to consider in the management of retinal vein thrombosis with normal platelet count and hematocrit include:
- The presence of JAK2 mutation increases thrombotic risk regardless of blood count values, as it causes increased cellular adhesion, platelet activation, and a prothrombotic state through multiple inflammatory pathways, explaining why thrombosis can occur even before blood counts become abnormal 1.
- If JAK2 mutation is detected, patients typically require hematology referral for consideration of cytoreductive therapy (such as hydroxyurea), anticoagulation, and possibly low-dose aspirin, as outlined in the NCCN guidelines for myeloproliferative neoplasms 1.
- The revised International Prognostic Score of Thrombosis for ET (IPSET-Thrombosis) is preferred for the risk stratification of ET, which can help guide management decisions 1.
Overall, the detection of JAK2 mutation in patients with retinal vein thrombosis and normal blood counts can have significant implications for management and outcomes, and testing for this mutation is recommended in these cases.
From the Research
Retinal Vein Thrombosis and JAK2 Mutation
- Retinal vein thrombosis is a type of blood clot that forms in the veins of the retina, and it can be associated with various conditions, including myeloproliferative neoplasms (MPNs) 2, 3.
- The JAK2 mutation is a genetic abnormality that is commonly found in MPNs, such as essential thrombocythemia and polycythemia vera 2, 3.
- Studies have shown that the JAK2 mutation can increase the risk of thrombosis, including retinal vein thrombosis 4, 5.
Normal Platelet Count and Hematocrit
- A normal platelet count and hematocrit do not necessarily rule out the possibility of a JAK2 mutation or an underlying MPN 4, 6.
- In some cases, patients with MPNs may have normal blood counts, including platelet count and hematocrit, despite having a JAK2 mutation 4.
Chances of Positive JAK2 Mutation
- The chances of a positive JAK2 mutation in patients with retinal vein thrombosis and normal platelet count and hematocrit are not well established 2, 3.
- However, studies suggest that the JAK2 mutation can be found in a significant proportion of patients with MPNs, even in those with normal blood counts 4, 5.
- Screening for the JAK2 mutation may be considered in patients with retinal vein thrombosis, especially if there are other signs or symptoms suggestive of an underlying MPN 4, 5.