Clinical neurogenetics: stroke

Stroke and the risk of gastrointestinal disorders: A Mendelian randomization study

Background

The issue of whether a stroke is causally related to gastrointestinal disorders was still not satisfactorily understood. Therefore, we investigated if there is a connection between stroke and the most prevalent gastrointestinal disorders, including peptic ulcer disease (PUD), gastroesophageal reflux disease (GERD), irritable bowel syndrome (IBS), and inflammatory bowel disease (IBD).

Methods

We applied two-sample Mendelian randomization to investigate relationships with gastrointestinal disorders. We obtained genome-wide association study (GWAS) summary data of any stroke, ischemic stroke, and its subtypes from the MEGASTROKE consortium. From the International Stroke Genetics Consortium (ISGC) meta-analysis, we acquired GWAS summary information on intracerebral hemorrhage (ICH), including all ICH, deep ICH, and lobar ICH. Several sensitivity studies were performed to identify heterogeneity and pleiotropy, while inverse-variance weighted (IVW) was utilized as the most dominant estimate.

Results

No evidence for an effect of genetic predisposition to ischemic stroke and its subtypes on gastrointestinal disorders were found in IVW. The complications of deep ICH are a higher risk for PUD and GERD. Meanwhile, lobar ICH has a higher risk of complications for PUD.

Conclusion

This study provides proof of the presence of a brain-gut axis. Among the complications of ICH, PUD and GERD were more common and associated with the site of hemorrhage.

Genetic Predisposition to Severe COVID-19 Might Increase the Risk of Stroke: A Two-Sample Mendelian Randomization Study

Aims: The causal relationship between COVID-19 infection and stroke has not yet been fully established. This study aimed to explore this causality using two-sample Mendelian randomization (MR).

Materials and Methods: Genetic variants associated with COVID-19 infection and stroke were both obtained from genome-wide association study (GWAS) summary data. The single nucleotide polymorphisms (SNPs) were selected as instrumental variables. The standard inverse variance weighted (IVW) was primarily used to assess this causality. Finally, sensitivity analysis was performed to evaluate the reliability and stability.

Results: The results showed that being hospitalized due to COVID-19 had a positive effect on stroke [OR = 1.05; 95% CI= (1.01, 1.10); p = 2.34 × 10⁻⁵] and ischemic stroke [OR = 1.06; 95% CI= (1.02, 1.11); p = 2.28 × 10⁻⁶] analyzed by inverse variance weighted. Moreover, the results revealed that severe respiratory symptoms due to COVID-19 had a positive effect on stroke [OR = 1.04; 95% CI= (1.00, 1.06); p = 0.04] and that the causal effect of severe respiratory symptoms due to COVID-19 on ischemic stroke estimated by IVW suggested a positive effect [OR = 1.06; 95% CI= (1.02, 1.09); p = 0.0068], too.

Conclusion: In summary, this study showed that severe COVID-19 might increase the risk of stroke, thus much more attention should be paid to patients with severe COVID-19.

The Dutch String-of-Pearls Stroke Study: protocol of a large prospective multicenter genetic cohort study

BACKGROUND

In the last couple of years, genome-wide association studies have largely altered the scope in genetic research in diseases in which both environmental and genetic risk factors contribute to the disease. To date, the genetic risk loci identified in stroke have lagged behind those in other complex diseases, possibly because of the heterogeneity of stroke phenotypes. Sufficiently large cohorts with well-defined and detailed phenotyping of stroke patients are needed to identify additional genetic risk loci.

DESIGN

The String-of-Pearls Institute is a unique partnership between all eight University Medical Centers in the Netherlands. It was established in 2007 by the Netherlands Federation of University Medical Centers, and it conducts a large prospective cohort study in which comprehensive clinical data, detailed phenotyping of stroke, imaging data, and biomaterials are collected in a large cohort of stroke patients.

AIMS

The study aims (1) to collect a sufficiently large prospective cohort of stroke patients, with well-defined phenotypes; (2) to collect blood samples and DNA in a standardized infrastructure, allowing for storing and analyzing the samples in a uniform way; (3) to investigate associations between genetic risk loci and stroke; (4) to create possibilities to perform epidemiological studies in a well-defined hospital-based cohort of stroke patients; and (5) to allow for pooling data with other large ongoing genetic stroke studies.