Genetic Architecture of Lacunar Stroke
Background and Purpose—Lacunar strokes comprise ≈20% of all strokes. Despite this frequency, their pathogenesis is poorly understood. Previous genome-wide association studies in lacunar stroke have been disappointing, which may be because of phenotypic heterogeneity. Pathological and radiological studies suggest that there may be different pathologies underlying lacunar strokes. This has led to the suggestion of 2 subtypes: isolated lacunar infarcts and multiple lacunar infarcts and leukoaraiosis.
Methods—We performed genome-wide analyses in a magnetic resonance imaging–verified cohort of 1012 younger onset lacunar stroke cases and 964 controls. Using these data, we first estimated the heritability of lacunar stroke and its 2 hypothesized subtypes, and secondly, we determined whether this is enriched for regulatory regions in the genome, as defined by data from Encyclopedia of DNA Elements (ENCODE) and other sources. Finally, we determine the evidence for a polygenic contribution from rare variation to lacunar stroke and its subtypes.
Results—Our results indicate a substantial heritable component to magnetic resonance imaging–verified lacunar stroke (20%–25%) and its 2 subtypes (isolated lacunar infarct, 15%–18%; multiple lacunar infarcts/leukoaraiosis, 23%–28%). This heritable component is significantly enriched for sites affecting expression of genes. In addition, we show that the risk of the 2 subtypes of lacunar stroke in isolation, but not in combination, is associated with rare variation in the genome.
Conclusions—Lacunar stroke, when defined on magnetic resonance imaging, is a highly heritable complex disease. Much of this heritability arises from regions of the genome affecting gene regulation. Rare variation affects 2 subtypes of lacunar in isolation, suggesting that they may have distinct genetic susceptibility factors.
- genetic association studies
- magnetic resonance imaging
- polymorphism, single nucleotide
- stroke, lacunar
- Received March 24, 2015.
- Revision received June 16, 2015.
- Accepted June 19, 2015.
- © 2015 The Authors.
Stroke is published on behalf of the American Heart Association, Inc., by Wolters Kluwer. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited and is not used for commercial purposes.