No matter your age or your postcode, it’s likely you or someone you know has been touched by the devastating impact of stroke. It is the leading cause of adult disability in Australia and the second leading cause of death globally.
An international research consortium studying more than half a million individuals from around the world has identified 22 new genetic risk factors for stroke, casting fresh light on why strokes happen and how they might be better prevented or treated.
The research findings show shared genetic influences with multiple related vascular conditions, especially blood pressure, but also coronary artery disease, deep vein thrombosis, pulmonary embolism and others.
The MEGASTROKE project is the largest genetic study on stroke and contains analysis of DNA samples from 520,000 European, North and South American, Asian, African and Australian participants, of whom 67,000 had suffered a stroke. The results are published online in the journal Nature Genetics.
“Although stroke can occur at any age, we know it is more likely as one gets older. We also know that stroke is not one disease but a complex combination of many related diseases, and no single genetic variant is responsible for stroke risk,” says study co-author Professor Jane Maguire, from the UTS Faculty of Health.
“Reducing the burden of this disease is increasingly urgent as our population ages but because the causes remain poorly understood, the development of new treatments and preventive strategies is challenging.”
The research team says its large-scale collaboration spanning all continents and cultures has been a game changer in studying the genetics of a complex common disease such as stroke.
Stroke happens when there are changes in blood vessels including large and small arteries, the heart and veins. The most common type of stroke is caused by a blood clot (ischaemic stroke) while the most catastrophic is caused by a bleed (haemorrhagic stroke).
The scope and depth of the MEGASTROKE data has given researchers first insights into the specific genes, molecular pathways and cell and tissue types through which the newly identified genetic risk factors cause stroke. The study shows some genetic risk factors contribute to specific mechanisms and others to stroke susceptibility at large. Researchers have also found previously unknown genetic links between ischaemic and haemorrhagic stroke.
Of the 32 genetic variants – or 149 genes – reported in the study, 11 risk factors are in biological areas not previously thought to contribute to stroke. Sixteen genes are known drug targets in the management of other diseases or conditions.
“This surprise finding is the most clinically translatable aspect of our study and opens the door to investigating completely new targets for stroke prevention and management and increases our understanding of the biology of a stroke,” says Professor Maguire, whose work on stroke genetics began with her PhD.
“We now have the very real possibility that existing drugs can be repurposed more quickly for use in stroke prevention and management.
“More than half a million subjects have gone into this study and it has involved collaboration from many dedicated and passionate researchers around the world. It’s taken 10 years but things are really starting to pick up speed now.”
WHAT IS MEGASTROKE?
The study was conducted by members of MEGASTROKE, a large-scale international collaboration launched by the International Stroke Genetics Consortium, a multi-disciplinary collaborative of experts in stroke genetics who have been working together for the past 10 years. MEGASTROKE members include research groups from Germany, France, the UK, Japan, USA, Iceland, Spain, Switzerland, Italy, Belgium, the Netherlands, Denmark, Sweden, Norway, Finland, Estonia, Poland, Singapore, Australia and Canada.
The study received financial support from multiple sources, including in Australia from the National Health and Medical Research Council (NHMRC).
Multi-ancestry genome-wide association study of 520,000 subjects identifies 32 loci associated with stroke and stroke subtypes (2018). Rainer Malik, Ganesh Chauhan, Matthew Traylor, Muralidharan Sargurupremraj et al. Nature Genetics. http://dx.doi.org/10.1038/s41588-018-0058-3