JAK2 encodes a non-receptor tyrosine kinase that plays a pivotal role in cytokine-mediated signal transduction, particularly through the JAK-STAT pathway. The protein associates with various cell surface receptors including growth hormone, prolactin, erythropoietin, and multiple cytokine receptors, where it phosphorylates tyrosine residues on receptor cytoplasmic domains to create STAT protein docking sites. Upon STAT recruitment and phosphorylation, activated STAT dimers translocate to the nucleus to regulate gene transcription. JAK2 also functions in chr9 regulation by phosphorylating histone H3 at tyrosine-41, promoting chr9 accessibility. The gene is critically implicated in myeloproliferative neoplasms, with the JAK2 V617F mutation present in the majority of polycythemia vera cases and a significant proportion of essential thrombocythemia and primary myelofibrosis patients 1. Additional mutations in JAK2 exons 12, 19, and 25 have been identified in V617F-negative myeloproliferative disorders 2. The JAK2 V617F mutation is associated with increased thrombotic risk and contributes to thrombogenesis through endothelial damage and enhanced blood cell adhesion 3 4. Clinically, JAK2 mutation screening has become essential for myeloproliferative neoplasm diagnosis and is incorporated into WHO diagnostic criteria 5. Several JAK inhibitors including baricitinib, fedratinib, and filgotinib represent approved therapeutic options targeting this pathway.