According to a new meta-analysis, gene variants associated with a person’s blood type may be linked to their risk of stroke before age 60. The study included all available data from genetic studies that included young adult ischemic stroke, which is caused by a blockage of blood flow to the brain. The meta-analysis was published recently in Neurology, the medical journal of the American Academy of Neurology.
“Non-O blood types have previously been linked to a risk of early stroke, but the findings of our meta-analysis showed a stronger link between these blood types with early stroke compared to late stroke, and in linking risk mostly to blood type A,” said study author Braxton D. Mitchell, PhD, MPH, of University of Maryland School of Medicine in Baltimore. “Specifically, our meta-analysis suggests that gene variants tied to blood types A and O represent nearly all of those genetically linked with early stroke. People with these gene variants may be more likely to develop blood clots, which can lead to stroke.”
48 studies on genetics and ischemic stroke from North America, Europe, and Asia were reviewed in the meta-analysis. 16,927 people with stroke and 576,353 people who did not have a stroke were included in the studies. Of those with stroke, 5,825 people had early onset stroke and 9,269 people had late onset stroke. Early onset stroke was defined as an ischemic stroke occurring before age 60 and late-onset stroke was older than 60 years old.
In order to identify genetic variants associated with stroke, scientists looked across all the chromosomes. They discovered a link between early onset stroke and the area of the chromosome that includes the gene that determines A, AB, B, or O blood type.
After dividing the participants into A, AB, B, and O blood types. they recompiled the data and compared the prevalence of those blood types in people with early stroke, late stroke, and people who did not have a stroke.
In the analysis, researchers discovered that people with early stroke were more likely to have blood type A and less likely to have blood type O compared to people with late stroke and people without stroke. Compared to controls, both early and late stroke were also more likely to have blood type B.
Next, they focused on people of European ancestry comparing 5,825 people with early stroke to 29,320 people who did not have a stroke. There, the meta-analysis found that 48% of people with early stroke had blood type A compared to 45% of people with late stroke and 44% of people without stroke. They also calculated that 35% of people with early stroke had blood type O compared to 39% of those with late stroke and 41% of people without stroke.
After adjusting for various factors including sex, the scientists found that those who had blood type A had a 16% higher risk of having an early stroke than people with other blood types. On the other hand, those who had blood type O had a 12% lower risk of having a stroke than people with other blood types.
“This work deepens our understanding of early onset stroke development and changes,” said Jennifer Juhl Majersik, MD, MS, of the University of Utah and Fellow of the American Academy of Neurology, who wrote an editorial accompanying the study. “Future research is needed to help develop a more precise understanding of how stroke develops. This could lead to targeted preventative treatments for early-onset stroke, which could result in less disability during people’s most productive years.”
Although 35% of the participants were of non-European ancestry, a limitation of the study was the limited amount of diversity among participants.
For more on this research, see Blood Type May Predict Your Risk of Having a Stroke Before Age 60.
Reference: “Contribution of Common Genetic Variants to Risk of Early Onset Ischemic Stroke” by Thomas Jaworek, Huichun Xu, Brady J Gaynor, John W. Cole, Kristiina Rannikmae, Tara M Stanne, Liisa Tomppo, Vida Abedi, Philippe Amouyel, Nicole D Armstrong, John Attia, Steven Bell, Oscar R Benavente, Giorgio B Boncoraglio, Adam Butterworth, for the Cervical Artery Dissections and Ischemic Stroke Patients (CADSIP) Consortium, Jara Carcel-Marquez, Zhengming Chen, Michael Chong, Carlos Cruchaga, Mary Cushman, John Danesh, Stephanie Debette, David J Duggan, Jon Peter Durda, Gunnar Engstrom, Chris Enzinger, Jessica D Faul, Natalie S Fecteau, Israel Fernandez-Cadenas, Christian Gieger, Anne-Katrin Giese, Raji P Grewal, Ulrike Grittner, Aki S Havulinna, Laura Heitsch, Marc C Hochberg, Elizabeth Holliday, Jie Hu, Andreea Ilinca, for the INVENT Consortium, Marguerite R Irvin, Rebecca D Jackson, Mina A. Jacob, Raquel Rabionet Janssen, Jordi Jimenez-Conde, Julie A Johnson, Yoichiro Kamatani, Sharon L Kardia, Masaru Koido, Michiaki Kubo, Leslie Lange, Jin-Moo Lee, Robin Lemmens, Christopher R Levi, Jiang Li, Liming Li, Kuang Lin, Haley Lopez, Sothear Luke, Jane Maguire, Patrick F McArdle, Caitrin W. McDonough, James F Meschia, Tiina Metso, Martina Muller-Nurasyid, Timothy D O’Connor, Martin O’Donnell, Leema R Peddareddygari, Joanna Pera, James A Perry, Annette Peters, Jukka Putaala, Debashree Ray, Kathryn Rexrode, Marta Ribases, Jonathan Rosand, Peter M Rothwell, Tatjana Rundek, Kathleen A Ryan, Ralph L. Sacco, Veikko Salomaa, Cristina Sanchez-Mora, Reinhold Schmidt, Pankaj Sharma, Agnieszka Slowik, Jennifer A Smith, Nicholas L Smith, Sylvia Wassertheil-Smoller, Martin Soederholm, O. C Stine, Daniel Strbian, Cathie L Sudlow, Turgut Tatlisumak, Chikashi Terao, Vincent Thijs, Nuria P Torres-Aguila, David-Alexandre Tregouet, Anil M. Tuladhar, Jan H Veldink, Robin G Walters, David R Weir, Daniel Woo, Bradford B Worrall, Charles C Hong, Owen Ross, Ramin Zand, Frank-Erik de Leeuw, Arne G Lindgren, Guillaume Pare, Christopher D. Anderson, Hugh S Markus, Christina Jern, Rainer Malik, Martin Dichgans, Braxton D Mitchell, Steven J Kittner, the Early Onset Stroke Genetics Consortium of the International Stroke Genetics Consortium (ISGC), 31 August 2022, Neurology.
The study was supported by the National Institutes of Health and the Department of Veterans Affairs.