Gene variant linked to common type of stroke

A genetic variant has been linked to an increased risk of a common type of stroke. Researchers identified an alteration in a gene called HDAC9 that is more common in people who have had an ischaemic stroke than in those who have not. The study also replicated variants previously associated with subtypes of ischaemic strokes.

Ischaemic strokes account for 80 percent of stroke cases, and occur when the blood flow to a part of the brain is blocked. This case-control study, published in Nature Genetics, found that the genetic variant was associated with an increased risk of a subtype of ischaemic stroke called a 'large vessel stroke'. This is where blood flow to the brain is blocked in one or more arteries.

Professor Peter Donnelly, director of the Wellcome Trust Centre for Human Genetics at the University of Oxford, who co-led the study, says: 'This is really fascinating, and if it holds up more generally, will move us closer to personalised medicine, where treatments and preventions can be tailored more precisely to individual patients'.

Overall, the international team of researchers examined genetic variants in around 10,000 people who had had an ischaemic stroke and around 40,000 healthy people. People can carry two copies of the variant, and the team estimates that each copy of the variant carried is associated with around a 42 percent increase in the odds of a large vessel stroke.

Although this study was thorough and well designed, it can only point to an association between a particular genetic variant and strokes. Further research is needed in order to establish whether the variants identified play a casual role in strokes, or if they lie close to other genetic variants that have this effect.

'This discovery identifies a completely new mechanism for causing stroke. The next step is to determine in more detail the relationship between HDAC9 and stroke and see whether we can develop new treatments that reduce the risk of stroke', says Professor Hugh Markus, from St George's, University of London, who co-led the study. 'Interestingly, there are already drugs available which inhibit the HDAC9 protein. However, it is important that we understand the mechanism involved before trialling the effects of these drugs on stroke'.

Strokes are one of the top two leading causes of death worldwide and a major cause of disability in developing countries.

Dr Peter Coleman, deputy director of research at The Stroke Association described the study as 'ground breaking'. 'Over a third of strokes are caused by a blockage in one of the large blood vessels supplying blood to the brain... Further study is needed, but this research could potentially lead to new methods of screening and prevention for large vessel stroke, and ultimately, new methods of treatment'.