JAK2 (Janus Kinase 2) is a tyrosine kinase. A mutation in JAK2 may be associated with thrombosis and/or certain myeloproliferative disorders.


Mutation in JAK2: JAK2(V617F)


Myeloproliferative disorders associated with JAK2(V617F) include Philadelphia chromosome-negative essential thrombocythemia and polycythemia vera.


Sites of thrombosis associated with JAK2(V617F):

(1) hepatic vein, resulting in the Budd-Chiari syndrome

(2) portal vein

(3) splanchnic vein

(4) mesenteric vein

(5) cerebral sinus or vein

(6) other deep vein thrombosis


A patient with unexplained thrombosis should be screened for JAK2 mutations. A patient without evidence of myeloproliferative disease should be monitored for evolution into one.


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