Thrombophilic abnormalities, either inherited (antithrombin, protein C, or protein S deficiency, with mutations in the FVL, FII, or MTHFR genes) or acquired (antiphospholipid antibodies) should be investigated in patients with CVT, as well as those with hyperhomocysteinemia [1]. Here, PROS1 is linked to hyperinsulinemic hypoglycemia, familial, 4.