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- Larsson, Susanna C., et al.
(author)
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Homocysteine and small vessel stroke : A mendelian randomization analysis
- 2019
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In: Annals of Neurology. - : Wiley. - 0364-5134 .- 1531-8249. ; 85:4, s. 495-501
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Journal article (peer-reviewed)abstract
- Objective Trials of B vitamin therapy to lower blood total homocysteine (tHcy) levels for prevention of stroke are inconclusive. Secondary analyses of trial data and epidemiological studies suggest that tHcy levels may be particularly associated with small vessel stroke (SVS). We assessed whether circulating tHcy and B vitamin levels are selectively associated with SVS, but not other stroke subtypes, using Mendelian randomization.MethodsWe used summary statistics data for single-nucleotide polymorphisms (SNPs) associated with tHcy (n = 18), folate (n = 3), vitamin B-6 (n = 1), and vitamin B-12 (n = 14) levels, and the corresponding data for stroke from the MEGASTROKE consortium (n = 16,952 subtyped ischemic stroke cases and 404,630 noncases).ResultsGenetically predicted tHcy was associated with SVS, with an odds ratio of 1.34 (95% confidence interval [CI], 1.13-1.58; p = 6.7 x 10(-4)) per 1 standard deviation (SD) increase in genetically predicted tHcy levels, but was not associated with large artery or cardioembolic stroke. The association was mainly driven by SNPs at or near the MTHFR and MUT genes. The odds ratios of SVS per 1 SD increase in genetically predicted folate and vitamin B-6 levels were 0.49 (95% CI, 0.34-0.71; p = 1.3 x 10(-4)) and 0.70 (95% CI, 0.52-0.94; p = 0.02), respectively. Genetically higher vitamin B-12 levels were not associated with any stroke subtype.Interpretation These findings suggest that any effect of homocysteine-lowering treatment in preventing stroke will be confined to the SVS subtype. Whether genetic variants at or near the MTHFR and MUT genes influence SVS risk through pathways other than homocysteine levels and downstream effects require further investigation. Ann Neurol 2019;85:495-501
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| 2. |
- Larsson, Susanna C., et al.
(author)
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Smoking and stroke : A mendelian randomization study
- 2019
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In: Annals of Neurology. - : John Wiley & Sons. - 0364-5134 .- 1531-8249. ; 86:3, s. 468-471
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Journal article (peer-reviewed)abstract
- We used the Mendelian randomization design to explore the potential causal association of smoking with ischemic stroke and intracerebral hemorrhage using summary statistics data for 34,217 ischemic stroke cases and 404,630 noncases, and 1,545 cases of intracerebral hemorrhage and 1,481 noncases. Genetic predisposition to smoking initiation (ever smoking regularly), based on up to 372 single-nucleotide polymorphisms, was statistically significantly positively associated with any ischemic stroke, large artery stroke, and small vessel stroke but not cardioembolic stroke or intracerebral hemorrhage. This study provides genetic support for a causal association of smoking with ischemic stroke, particularly large artery and small vessel stroke. ANN NEUROL 2019;86:468-471
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