Genome-wide screen for stroke: Pilot testing in the siblings with ischemic stroke study (SWISS)

Background: The results of cohort and twins studies suggest that stroke risk has a genetic component. To prepare for a multicenter linkage study of sibling pairs, we conducted a pilot study in a small number of subjects. Methods: At 3 centers, we tested a strategy for collecting sibling pairs concordant and discordant for ischemic stroke. Local investigators enrolled probands and obtained family histories. Primary proband inclusion criteria were age 18 to 80 years, ischemic stroke within 180 days, and proband report of at least 1 living sibling with a history of stroke. A central office verified sibling concordance by a medical record review and sibling discordance by a structured telephone interview. Results: Nine consecutive probands (median age, 74 years; age range, 57 to 79 years; male, 67%) were enrolled. Requests for medical records forms were sent to 10 potentially concordant siblings; signed forms were returned by 10 siblings (100%). Ten potentially discordant siblings were contacted by telephone; 9 (90%) agreed to a structured telephone interview. For 6 probands (67%), we verified concordance in at least 1 sibling. For all probands, discordance was verified in at least 1 sibling. None of the potentially concordant siblings lived in the same city as the related proband; 6 (67%) lived in the same state. Conclusion: Our procedure for enrolling siblings was widely accepted by nonpatient family members. The Siblings With Ischemic Stroke Study (SWISS) can enroll sibling pairs with ischemic stroke even when siblings are geographically dispersed.