A total of 835 hereditary thrombophilia tests - including those for factor V Leiden, prothrombin<sub>G20210A</sub>, deficiencies of protein S, protein C, and antithrombin, hyperhomocysteinemia, and plasminogen activator inhibitor-1 excess - were ordered in 220 patients. The gene discussed is SERPINE1; the disease is hyperhomocysteinemia.