The current work (1) reports on the findings of an initial standard thrombophilia screening that included Factor V Leiden mutation, Prothrombin G20210A mutation, protein C and protein S deficiencies, antithrombin III deficiency, and antiphospholipid syndrome; and (2) explores the value of advanced molecular genetic analysis in patients with CVT without conclusive results in a basic thrombophilia screening. Here, PROS1 is linked to Rare hereditary thrombophilia.