FAMILIAL CEREBROVASCULAR ACCIDENTS DUE TO CONCOMITANT HYPERHOMOCYSTEINEMIA AND PROTEIN-C DEFICIENCY TYPE-1

Background and Purpose: Hyperhomocysteinemia and protein C deficiency are risk factors for thromboembolism. Hyperhomocysteinemia has been re ported to inhibit the expression of thrombomodulin and to inactivate b oth thrombomodulin and protein C irreversibly, leading to decreased pr otein C activity. Case Description: In a 16-year-old girl, who develop ed a sinus sagittalis thrombosis, and in her father, who experienced a transient ischemic attack, both hyperhomocysteinemia and protein C de ficiency type 1 were present. Protein C deficiency alone was found in one of the two sisters, who was without any clinical vascular history. Conclusions: In this family with independently inherited hyperhomocys teinemia and protein C deficiency, clinical cerebrovascular disease oc curred only in those members with a combination of both risk factors, suggesting a synergistic interaction between these thrombogenic risk f actors.