Genetic variant ups risk of common type stroke

London (CNST): Scientists have now identified a genetic variant that increases the risk of a common type of stroke.
This is one of the few genetic variants to date to be associated with risk of stroke and the discovery opens up new possibilities for
treatment.
Several different mechanisms underlie strokes. One of the most common types is when blood flow is impaired because of a blockage to one or
more of the large arteries supplying blood to the brain - large artery
ischemic stroke. This accounts for over a third of all strokes.
Researchers from St George's, University of London and Oxford
University, working with scientists from Europe, America and Australia,
in one of the largest genetic studies of stroke to date, compared the
genetic make-up of 10,000 people who had suffered from a stroke with
40,000 healthy individuals.
The researchers discovered an alteration in a gene called HDAC9,
which affects a person's risk of large artery ischemic stroke. This
variant occurs on about 10 per cent of human chromosomes.
Those people who carry two copies of the variant (one inherited from
each parent) have nearly twice the risk for this type of stroke compared to those with no copies of the variant.
The protein produced by HDAC9 is already known to play a role in the
formation of muscle tissue and heart development. However, the exact
mechanism by which the genetic variant increases the risk of stroke is
not yet known.
A better understanding of the mechanism could lead to new drugs to
treat or prevent stroke; however, the researchers stress that this is
still some way off.
"This discovery identifies a completely new mechanism for causing
stroke," Professor Hugh Markus, from St George's, University of London,
who co-led the study, said.
"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.
"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."
The researchers went on to show that the new variant does not have
the same effect on the risk of other types of stroke, which include
bleeding in the brain (haemorrhagic stroke).
"Our study shows that the different subtypes of stroke could involve
quite different genetic mechanisms," Professor Peter Donnelly, Director
of the Wellcome Trust Centre for Human Genetics in the University of
Oxford, who co-led the study, said.
"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."
According to Dr Peter Coleman, Deputy Director of Research at The
Stroke Association, who funded collection of some of the samples used in this study, over a third of strokes are caused due to a blockage in one of the large blood vessels supplying blood to the brain (large artery
stroke).
"Findings from this ground breaking study appear to show a genetic
link which may affect a person's risk of large vessel stroke," Dr
Coleman said.
"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," Dr Coleman added.

IANS

The study has been recently published online in Nature Genetics. (ANI)