The influence of genetics on intracranial aneurysms

It’s important to understand the factors that can put brain health at risk. Research has shown that both environmental and genetic factors can increase the risk of an intracranial aneurysm, a weakened area in a blood vessel in the brain that causes it to dilate or bulge. In most cases, it occurs in the area of the brain called the cerebrum or telencephalon, which corresponds to the area we usually know as the cerebrum, and is called a cerebral aneurysm [1].

If the intracranial aneurysm ruptures or tears it can cause bleeding in the brain, which is known as a hemorrhagic stroke. When that rupture occurs in the space between the brain and the thin tissues lining it, the particular stroke is called a subarachnoid hemorrhage [2].

Worldwide, an intracranial aneurysm ruptures every 18 minutes and is usually fatal in approximately 40% of cases [3]. However, the vast majority of intracranial aneurysms never rupture, nor do they create health problems or symptoms. Many people have an intracranial aneurysm and will never notice it. Indeed, they are often detected almost by chance [2].

Intracranial aneurysms can be classified into saccular and fusiform aneurysms. The vast majority belong to the first type and are characterized by generating a balloon-shaped protrusion on one side of the blood vessel, with a rounded bottom and a small neck where it communicates with the artery that originates it. In English literature, these saccular aneurysms are called “berry aneurysms” or berry aneurysms [4]. On the other hand, fusiform aneurysm shows a bulge on all sides of the blood vessel, shaped like a spindle.

Symptoms of intracranial aneurysm

Symptoms of intracranial aneurysms vary depending on whether or not they rupture and how large they are. Most aneurysms that rupture are small and do not cause specific symptoms. In some cases, unruptured aneurysms are detected because as they grow they press on nearby nerves, causing symptoms related to those nerves [5].

<h3>Intact aneurysms</h3>

Intracranial aneurysms that have not ruptured do not usually cause symptoms, unless, as we mentioned, because of their size they come to press on nearby brain tissues and nerves. In this case the most characteristic symptoms would be the following:

• Pain in the upper or back part of the eye.
• Blurred vision.
• Dilation of the pupil.
• Numbness of one side of the face.
• Drooping eyelid.
• Constant headache.

Ruptured aneurysms

When an intracranial aneurysm ruptures, the first symptom that usually occurs is an intense headache that appears suddenly. But there are also a number of other symptoms that have been reported by people who have suffered a ruptured aneurysm in the brain. All of them appear suddenly and we can find those detailed below:

• • Stiffness in the neck.

• Nausea and vomiting.

• Drowsiness or loss of consciousness.
• Pain in the upper and back part of the eye.
• Changes in vision: blurred or double vision.
• Trouble walking or dizziness.
• Sensitivity to light.
• Confusion.
• Seizures.

Fissured aneurysm

Intracranial aneurysms may also leak a little blood, but do not rupture. In these cases the most representative symptom is a headache that comes on suddenly and very intensely, just as in the case of ruptured intracranial aneurysms. In many of the cases in which a leak occurs the aneurysm eventually ruptures.

Genetics and intracranial aneurysm

Numerous studies have concluded that there’s a direct relationship between genetics and intracranial aneurysm, so family history is considered a risk factor. 

The idea that genetics plays a role in the development of aneurysms has led to the creation of research models that examine different genes that could be related to the development of this pathology. To carry out these analyses, association studies are used that evaluate the correlation between the presence of aneurysms and a specific allele, comparing it with individuals without this condition, called GWAS studies (genome-wide association studies) [6].

One of these risk alleles identified in scientific studies is located near the SOX17 gene. This gene is necessary for the formation of endothelial cells, such as those that line the inner area of blood vessels and have direct contact with blood [7]. But in addition to this gene, there are others implicated in an increased risk of intracranial aneurysm.

At 24Genetics we perform genetic tests to detect the probability that you are prone to develop an intracranial aneurysm. With our health test we will analyze your DNA and determine whether the genes involved with a higher risk of suffering this type of aneurysm are present in it or not. In this way, you will know your predisposition to suffer from an intracranial aneurysm, among many other diseases. For more detailed information, click here and access an example of the report generated by our genetic health test.

Bibliography

[1] MedlinePlus in English [Internet]. Amit M. Shelat, DO, FACP, FAAN, Attending Neurologist and Assistant Professor of Clinical Neurology, Renaissance School of Medicine at Stony Brook University, Stony Brook, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. Translation and localization by: DrTango, Inc. – Aneurysm in the brain [reviewed Feb. 2022; accessed Feb. 2023] Available from: https://medlineplus.gov/spanish/ency/article/001414.htm#:~:text=The%20aneurysm%20is%20one%20zone,and%20it%20is%20called%20cerebral%20aneurysm.

[2] Cerebral aneurysm – Mayo Clinic staff [reviewed Jun. 2022; accessed Feb. 2023] Available at: https://www.mayoclinic.org/es-es/diseases-conditions/brain-aneurysm/symptoms-causes/syc-20361483

[3] Cerebral Aneurysms: Know the Reality and Treatment Options – Baptist Health South Florida [accessed Feb. 2023] Available at: https://baptisthealth.net/es/baptist-health-news/brain-aneurysms-know-the-facts-and-treatment-options#:~:text=Every%2018%20minutes%20it%20breaks,type%20of%20permanent%20neurolic%20C3%B3gica%20disability%20permanent.

[4] Ruptured saccular aneurysm of the middle cerebral artery with subarachnoid hemorrhage – Berenice Medina-Espinoza, Gaspar-Alberto Motta-Ramírez, Cristóbal Zavala-Ruiz, Alejandro Gutiérrez-Toxqui, Karina Ortiz-Contreras – Acta Médica Grupo Ángeles. Volume 10, No. 2 [published Apr-Jun 2012; accessed Feb. 2023] Available from: https://www.medigraphic.com/pdfs/actmed/am-2012/am122g.pdf

[5] What are the symptoms of a cerebral aneurysm? – University of Illinois Hospital & Health Sciences System [accessed Feb. 2023] Available from: https://hospital.uillinois.edu/es/primary-and-specialty-care/neurolog%C3%ADa-y-neurocirug%C3%ADa/condiciones-neurologicas-que-tratamos/aneurisma-cerebral/cuales-son-los-sintomas-de-un-aneurisma-cerebral

[6] Intracranial aneurysms: molecular and genetic aspects related to their origin and development – Guerrero-Muñiz Salvador, Zárate-Méndez Antonio Maximiano, Pérez Razo Juan Carlos, Chima-Galán María del Carmen, García-Ortiz Liliana, Gutiérrez-Salinas José – Revista Mexicana de Neurociencia 10(6): 453-458 [published Nov-Dec. 2009; accessed Feb. 2023] Available in: https://www.medigraphic.com/pdfs/revmexneu/rmn-2009/rmn096h.pdf

[7] Large study identifies new genetic risk factors for brain aneurysm – Howard Hughes Medical Institute [published Nov. 2008; accessed Feb. 2023] Available at: https://www.hhmi.org/news/extenso-estudio-identifica-nuevos-factores-gen-ticos-de-riesgo-de-aneurisma-cerebral