Abstract 95: Associations of Ischemic Stroke With Known Stroke Susceptibility Loci Vary by Age

Abstract

Objective: The goal of this study was to test whether the strength of association of stroke-associated genetic variants differs by age of stroke onset. Background: In the MEGASTROKE GWAS study, 55 variants were robustly associated with ischemic stroke in predominantly older populations. Yet limited research has been carried out to date to understand how these genetic associations are modified by age, which could provide clues to the underlying biological mechanisms of these associations. Methods: Analyses were based on 16,000 stroke cases of European ancestry identified from the Stroke Genetics Network (SiGN) and Early Onset Ischemic Stroke Consortium and 24,838 stroke-free controls. We tested if the associations of each variant with stroke differed by age using two complementary approaches. First, we used a case-control logistic regression model testing for the associations of stroke with variant, age, and a variant*age interaction term and second, we used a case-only approach, testing for an association of variant with age of stroke onset. All analyses were adjusted for sex and population structure. Results: We identified six variants whose associations were significantly modified by age (p ≤ 0.001) by either analysis; 5 variants by the case-control analysis and 4 variants by the case-only analysis. Among these were 2 variants at the ABO locus that have been previously shown to be more strongly associated with early compared to late onset stroke, tagging blood groups A and O, respectively, and a variant in WNT2B that has previously been associated with early, but not late, onset ischemic stroke in a small case-control study. Conclusions: Six out of 55 variants previously associated with ischemic stroke in large GWAS studies show differential effects by age, with the stroke risk allele more strongly associated with early onset stroke for 5 variants or more strongly associated with older onset stroke (1 variant). Future work is needed to understand the reasons for this age dependency. Disclosures: None. Study Supported By: R01NS100178, R01NS105150, R01NS114045