Factor V Leiden and Ischemic Stroke Risk: The Genetics of Early Onset Stroke (GEOS) Study

Background: Factor V Leiden (FVL) has been associated with ischemic stroke in children but not in adults. Although the FVL mutation is associated with increased risk for venous thrombosis, its association with ischemic stroke in young adults remains uncertain. Therefore, we examined the association between FVL and ischemic stroke in participants of the Genetics of Early Onset Stroke (GEOS) study. Methods: A population-based case control study identified 354 women and 476 men 15 to 49 years of age with first-ever ischemic stroke and 907 controls. Participant-specific data included vascular risk factors, FVL genotype and, for cases, the ischemic stroke subtype by modified Trial of ORG 10172 in Acute Stroke criteria. Logistic regression was used to calculate odds ratios for the entire population and for subgroups stratified by risk factors and ischemic stroke subtype. Results: The frequency of the FVL mutation was similar between ischemic stroke patients (3.6%; 95% confidence interval [CI] 2.5%-5.1%) and nonstroke controls (3.8%; 95% CI 2.7%-5.2%). This frequency did not change significantly when cases were restricted to patients with stroke of undetermined etiology (4.1%; 95% CI 2.6%-6.4%). Conclusions: Among young adults, we found no evidence for an association between FVL and either all ischemic stroke or the subgroup with stroke of undetermined etiology.