JAK2 and deep vein thrombosis: JAK2 mutation sometimes can be falsely negative initially and in a case report of a 40-year-old patient with a positive family history of deep venous thrombosis (DVT), she developed thrombosis of the inferior vena cava extending to the suprahepatic veins and pulmonary arteries, although she tested negative for JAK 2 mutation initially but tested positive later [2].