If at least two of your close family members have had a brain aneurysm, genetic testing may help identify if you’re at risk.

A brain aneurysm is a bulge in one of your brain’s blood vessels. The flow of blood may lead to pressure on a thin, weakened vessel wall, causing an aneurysm to form and become larger.

Brain aneurysms that haven’t ruptured (burst) usually have no symptoms. But unruptured brain aneurysms can sometimes cause symptoms, such as headaches, double vision, or a droopy eyelid.

A ruptured aneurysm may cause blood to flow between your brain and skull. This type of stroke is called a subarachnoid hemorrhage, and it can lead to brain damage, coma, and death.

About 1 in 50 people in the United States have an unruptured brain aneurysm, also called a cerebral or intracranial aneurysm. Every year, about 30,000 people in the United States experience a ruptured brain aneurysm.

Brain aneurysm diagnoses may occur at any age but are more common between the ages of 35 and 60 years. They occur more often in females than males. Among other risk factors are smoking, high blood pressure, and a family history of brain aneurysms.

Genetic testing may help determine if you’re at high risk of having an aneurysm. If you’re at high risk, a doctor may recommend further testing to see if you have an aneurysm and suggest treatments to lower your risk of a rupture.

Some studies suggest that genetic testing may benefit people with two or more first-degree relatives who’ve had a brain aneurysm, as it could help determine whether they carry risk factors such as a specific genetic mutation or syndrome.

A large 2020 study of over 10,000 people with brain aneurysms suggests that 17 genetic variants or mutations can affect the functioning of the inner lining of blood vessels in the brain, which could lead to aneurysms.

Other research suggests that having one of these genetic mutations may put you at higher risk of multiple aneurysms, rupture, and worse outcomes after a rupture.

If you test positive for a high risk of brain aneurysms, you might need periodic screening with brain imaging.

Genetic testing may also indicate if you’re at risk of developing aneurysms in other parts of your body, such as an abdominal aortic aneurysm.

Genetic conditions linked to brain aneurysms

According to some research, the following are some of the genetic conditions that may be linked to changes in blood vessels in the brain, leading to aneurysms:

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If any of your close family members have had brain aneurysms, a doctor may first refer you to a genetic counselor.

A genetic counselor will provide you with details about the pros and cons of genetic testing so that you can make an informed decision about whether to proceed.

If you decide to go ahead with genetic testing, a healthcare professional may take a blood, hair, or skin sample or swab the inside of your cheek for a cell sample.

They’ll then send the sample to a laboratory for analysis for specific genetic mutations.

Genetic testing has little physical risk, but it does have other risks you should consider. Those include the following:

  • Discovering that you have a genetic risk of a brain aneurysm may cause you to have anxiety or depression.
  • It may also lead to stress among your family members, knowing that they may also be at risk.
  • Although there are laws prohibiting it, you may experience genetic discrimination if your health insurance provider or employer treats you differently based on the test results.

Some recent research suggests that the predictive value of genetic testing for brain aneurysms is modest, and further studies are needed to improve the prediction of genetic risk.

Experts generally only recommend genetic testing if at least two close family members — such as your parent, sibling, or child — have had a brain aneurysm.

A doctor may also recommend genetic testing or preventive screening tests if you have a genetic condition linked to brain aneurysms. Some researchers recommend screening every 5 years.

Below are answers to some frequently asked questions about genetics and brain aneurysms.

If my parent had a brain aneurysm, will I have one?

For people with at least two close family members — such as a parent, sibling, or child — who’ve had a brain aneurysm, the risk of a brain aneurysm is two to three times higher than people whose first-degree relatives haven’t had one. The risk is higher if a sibling has had a brain aneurysm.

If you smoke or have high blood pressure, you could also be at higher risk.

Are there warning signs days before an aneurysm?

Small, unruptured brain aneurysms usually cause no symptoms. However, seek immediate medical attention if you experience a sudden, extremely severe headache. This could indicate that an aneurysm has ruptured or is leaking blood and may soon rupture.

The Brain Aneurysm Foundation recommends you call 911 or your local emergency services rather than have someone take you to the hospital. First responders may need to perform lifesaving procedures in an emergency vehicle.

The following symptoms may also occur if a brain aneurysm presses on nerves in your brain:

What percentage of brain aneurysms are hereditary?

According to a 2021 study, about 10% of brain aneurysms happen in people with relatives who’ve also had the condition.

Genetic testing is a noninvasive way to identify whether you have a specific genetic mutation or syndrome that could lead to a brain aneurysm. If the result is positive, you can take steps to reduce the possibility of an aneurysm rupturing.

Because of the emotional and other nonphysical risks involved, experts generally only recommend genetic testing for people whose parents, siblings, or children have had a brain aneurysm or for people with a genetic condition linked to brain aneurysms.