Brain aneurysms can be fatal
Genetic differences which may make people more vulnerable to potentially lethal strokes have been discovered by scientists.
Swellings in the brain's blood vessels called aneurysms can lie undetected up until the moment they rupture.
The international team compared the genes of 10,000 aneurysm patients and healthy volunteers, picking out clues.
The results, published in the journal Nature Genetics, could lead to an "early warning".
An aneurysm is a weakening and swelling of an artery, and can happen in both the brain and other parts of the body.
In the brain it can be a dangerous condition - producing a stroke either by simply bursting, or by producing large clots which break off and block blood vessels elsewhere in the brain.
The latest research was led by academics at Yale University in the US, and involved 2,000 patients with known intracranial aneurysms from Finland, the Netherlands and Japan, alongside 8,000 apparently healthy volunteers.
Scanning the genomes of these individuals uncovered three areas of their chromosomes in which gene variations could be linked to increased risk.
People with three of these variants had a tripled risk of aneurysm.
Professor Murat Gunel, who led the team, said that the discovery might not just help the development of screening tests, but also reveal the cause of the weaknesses which cause aneurysms, and perhaps point to ways of correcting the problem.
One of the variants found, for example, involves the gene SOX17, which is known to play a crucial role in the early development and repair of the cells which make up the walls of arteries.
He said: "Until now we have not had an effective means of identifying the majority of individuals at risk of developing this deadly problem.
"These genetic findings provide a starting point for changing that equation."
Andrea Lane from the Stroke Association, said that the role of genes in aneurysm was likely to be small.
She said: "The study does demonstrate some common genetic features in certain chromosomes and does contribute to our limited understanding on the genetic contribution to the disease.
"However, the main issues which cause aneurysms to continue to worsen are related to our lifestyle choices, for example smoking and drinking, and the genetic influence remains small in comparison."