An aneurysm occurs when the wall of a blood vessel weakens and balloons outward, making the blood vessel abnormally large. The larger the vessel becomes, the greater the risk of rupture — a serious emergency. Often there are no symptoms of an aneurysm until a rupture occurs. Brain (also known as intracranial) aneurysms are relatively common; up to 5% of people are thought to have one. Only a small fraction of these will ever rupture, however.
Several genetic variations have been associated with increased risk for brain aneurysms. The research group that found many of the first SNPs now reports new results from a larger study, comprising more than 15,000 Europeans and almost 5,000 Japanese people. The study, published online this week in the journal Nature Genetics, implicates three new areas of the genome in brain aneurysms.
“When combined with traditional risk factors such as gender, blood pressure and smoking, these findings form the basis of future work aimed at preclinical identification of individuals who are at high risk of intracranial aneurysm formation and rupture,” the authors write.
(The three new variants are detailed in the table at the end of this post. 23andMe customers can see their data for seven previously reported SNPs, several of which were replicated in this new study, in the Brain Aneurysm Research Report).
Many of the variations associated with increased risk for brain aneurysm are in or near genes involved in cell replication and differentiation. The researchers suggest that perhaps part of what causes an aneurysm is disruption of the normal cell proliferation process, or a change in the balance between stem cells and more specialized cell types.
It’s known that siblings of people with brain aneurysms are at fourfold increase for the condition. Based on this fact and the effect sizes of the SNPs identified or confirmed in this study, the researchers think that their findings explain between three and five percent of the familial risk of brain aneurysm. This means that there is still a lot to learn about both genetic and non-genetic risk factors for the condition.
(Increase in odds per copy compared to two copies non-risk version)
The effect of the risk versions was very similar for Europeans and Japanese people. The numbers in this table reflect the overall odds ratios calculated by the researchers that apply to both populations.
SNPwatch gives you the latest news about research linking various traits and conditions to individual genetic variations. These studies are exciting because they offer a glimpse into how genetics may affect our bodies and health; but in most cases, more work is needed before this research can provide information of value to individuals. For that reason it is important to remember that like all information we provide, the studies we describe in SNPwatch are for research and educational purposes only. SNPwatch is not intended to be a substitute for professional medical advice; you should always seek the advice of your physician or other appropriate healthcare professional with any questions you may have regarding diagnosis, cure, treatment or prevention of any disease or other medical condition.