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It is estimated that intracranial aneurysms can be found in 2-3% of the adult population.

Most of these never rupture, are without symptoms, and are never diagnosed.

Genetic factors play a recognized, albeit not yet fully known role, in their development.

Genetic factors play a recognized role in the development of brain aneurysms – deCODEme analyzes your DNA and interprets your genetic risk.

A bulging, weak area develops in the wall of a brain artery

When a weak area of an artery supplying the brain with blood expands or bulges, it is called an intracranial aneurysm (also known as a brain aneurysm). The feared complication of this type of aneurysm is rupture of the weakened vessel wall, causing bleeding in the area between the brain and the surrounding arachnoid membrane (called a subarachnoid hemorrhage). This is a medical emergency that may result in brain damage or death. Prior to rupture, most intracranial aneurysms are without symptoms, but may in some cases cause severe headaches, double vision, seizures, or vomiting.

Most brain aneurysms are without symptoms and never diagnosed

It is estimated that intracranial aneurysms can be found in 2-3% of the adult population. Most of these never rupture, are without symptoms, and are never diagnosed. The estimated incidence of ruptured intracranial aneurysms ranges from two to 22 cases per 100,000 individuals per year. Up to half of those who experience a rupture of intracranial aneurysms and the consequential subarachnoid hemorrhage die and a third of survivors suffer moderate to severe disability.

Genetic factors play a recognized role

Genetic factors play a recognized, albeit not yet fully known role, in the development of intracranial aneurysms. About one in every 10 patients with a subarachnoid hemorrhage has a family history of intracranial aneurysms and those who have a family history are usually younger at the time of diagnosis and more commonly have multiple and large aneurysms. Scientists at deCODE genetics and others, have identified three common genetic variants that associate with increased risk of intracranial aneurysm; two on chromosome 8 and one on chromosome 9.

deCODEme can calculate your genetic risk for intracranial aneurysm

The deCODEme Complete Scan identifies the three variants and provides an interpretation of the risk of developing this type of aneurysm for individuals of European ancestry. For East Asians, the deCODEme Genetic Scans can only provide risk calculations for the variant on chromosome 9. At the present time no risk data are available for people of other ethnicities for the variants listed above.

The variant on chromosome 9 also increases the risk of Heart Attack in individuals of both European and Asian ancestry and increases the risk of Abdominal Aortic Aneurysm in individuals of European descent. At the present time, risk of intracranial aneurysms conferred by this genetic variant on individuals of ethnicities other than European, is not available.

Risk factors

• Age and gender. Intracranial aneurysms can occur in all age groups but are most commonly detected in individuals between the ages of 40 and 60. The average age of a ruptured or bleeding intracranial aneurysm is 50 years of age.
• Hypertension. High blood pressure increases the risk of intracranial aneurysms and of their bleeding.
• Other. Smoking, alcohol abuse, and cocaine use have been associated with intracranial aneurysms. Rare causes include infections, connective tissue disorders and trauma.
• Ethnicity. Studies have indicated that subarachnoid hemorrhage is less common in individuals of European descent than in African-Americans, Asians and Hispanics.
• Genetics. Autosomal dominant polycystic kidney disease and various other rare hereditary conditions, are associated with intracranial aneurysms. Additionally, about 10% of patients diagnosed with an intracranial aneurysm, have a first-degree family member also with the condition. A family history of intracranial aneurysms has been found to be equally common among individuals of European descent, African-Americans and Hispanics.

Treatment depends on size and location of the aneurysm

Intracranial aneurysms can be treated with either open surgery or minimally invasive endovascular methods (the aneurysm is treated through thin plastic tubes or catheters inserted in a groin artery). Ruptured aneurysms are generally treated immediately to prevent further tears and bleeding. Whether treatment is recommended for asymptomatic and incidentally diagnosed aneurysms depends on the size and location of the lesion.

Screening is only recommended for high-risk individuals

Screening has been recommended for patients with autosomal dominant polycystic kidney disease and for those who have two immediate relatives with intracranial aneurysms (although the latter indication remains controversial).

More information

You can learn more about intracranial aneurysms by talking to your doctor and visiting these websites:

• The Aneurysm and AVF Foundation
• American Heart Association
• American Academy of Family Physicians
• Mount Sinai Medical Center – Patient Information
• Mayo Clinic on Intracranial Aneurysms

This content was last reviewed on February 08, 2010.

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