PROS1 and thrombophilia: We also demonstrated that family history is an independent risk factor for occurrence of VTE and could therefore be added to a prior VTE history to diagnose clinical thrombophilia that is not necessarily related to carrying a known inheritable risk factor.[15] Although antithrombin, protein C, and protein S[8,22,23] are important risk factors in Chinese patients, investigators have found no preponderant mutation.[24,25] Many mutations in the genes encoding these factors can cause deficiency; the activities of the corresponding proteins serve as surrogates for assessing genetic defects.