Activated Protein C Resistance in Ischemic Stroke Not Due to Factor V Arginine 506 →Glutamine Mutation

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Abstract
Background and Purpose Resistance to activated protein C (APC), a natural plasma anticoagulant, is the most common identifiable risk factor for venous thromboembolic disease. One point mutation in coagulation factor V that renders it APC-resistant is found in >90% of APC-resistant venous thrombosis patients. To determine the prevalence of APC resistance and of this factor V mutation in stroke, we screened a group of ischemic stroke patients. Methods Hispanic ischemic stroke patients were screened using two different activated partial thromboplastin time-based assays. One assay using neat patient plasma determined APC resistance, and the other assay using patient plasma diluted into factor V-deficient plasma determined APC-resistant factor V, including the Arg 506 →Gln mutation. Results were compared with those in 31 Hispanic control subjects of similar ages. Results Six of 63 (9.5%) stroke patients had APC resistance compared with none of 31 (0%) control subjects. No patient or control subject had APC-resistant factor V, ie, the factor V Arg 506 →Gln mutation. Conclusions In Hispanic patients with ischemic stroke, the incidence (approximately 10%) of APC resistance is not caused by the factor V Arg 506 →Gln mutation. APC resistance not caused by this factor V mutation may be a risk factor for ischemic stroke in this population.