FAMILIAL THROMBOPHILIA AND ACTIVATED PROTEIN-C RESISTANCE - THROMBOTIC RISK IN PREGNANCY

An abnormal anticoagulant response in vitro to activated protein C (aP C) has been proposed as an aetiological factor in familial thrombophil ia. It is postulated that this phenomenon is due to an inherited molec ular defect of factor V resulting in poor inactivation by aPC. We cond ucted a family study when the proband presented in her second pregnanc y with superficial phlebitis, a history of deep venous thrombosis and a family history of venous thromboembolic disease. No abnormality of a ntithrombin activity, protein C activity or deficiency of protein S we re demonstrated in the family members tested. The probandhad aPC ratio s below the laboratory range on three consecutive occasions. In additi on, her mother, who had a history of recurrent DVTs and a pulmonary em bolus, and also an asymptomatic nulliparous sister, both had aPC resis tance ratios below the laboratory range on consecutive samples. Furthe r information about the combined risk of aPC resistance and pregnancy is needed before guidance on the management of affected women can be f ormulated.