Always confident about his health, this man, who worked as a technician and whose name is not revealed, was shocked when doctors diagnosed him with a rare type of stroke, cerebral venous thrombosis, caused by a blood clot in the brain’s venous sinuses which blocks blood drainage and increases pressure, potentially leading to brain swelling, bleeding or infarction.
Unusual headaches and nausea had led him to the hospital a few months earlier.
Typically, stroke-causing blood clots form in the arteries as a result of vascular aging, driven by lifestyle and underlying conditions.
But in this case, with a clot forming in the brain’s venous system in someone so young, Dr Phan Truc of the hematology–genetics unit for rare diseases at Vinmec Central Park International General Hospital said the cause and mechanism needed to be identified.
Reviewing the family’s medical history revealed a crucial detail: the patient’s father had also suffered a stroke at age 50 though he had had no cardiovascular risk factors.
Advanced genetic testing solved the puzzle: The father had a gene mutation that impaired Protein S function, making the body prone to clot formation.
The son had inherited this mutation and, from his mother, also carried an MTHFR variant that elevated homocysteine levels in the blood, a compound linked to vascular damage.
The combination of these two genetic factors created a “perfect storm,” causing vessel blockage at a very young age, Truc said.
The patient was diagnosed with genetically driven stroke, prescribed lifelong anticoagulants, and will require close monitoring as aging weakens blood vessels and raises the risk of blockage.
But this is not an isolated case.
Truc has seen many stroke patients whose genes were the real culprit and not high blood pressure or atherosclerosis.
A person’s blood pressure is measured. Illustration photo by Unsplash
One 55-year-old woman was admitted with ischemic stroke, and initial tests only showed a mild increase in platelets – an easily overlooked sign.
Deeper genetic screening revealed the JAK2 V617F mutation, characteristic of chronic myeloproliferative disorders, which increases both the number and activity of platelets, leading to clots.
These cases illustrate how genetic factors can silently persist for years without symptoms, waiting for the right conditions to cause a major vascular event.
In fact, the link between genes and stroke is well established. A meta-analysis published in the journal Stroke, a peer-reviewed medical journal published monthly by Lippincott Williams & Wilkins on behalf of the American Heart Association, found about 15% of stroke patients had a family history of the disease.
Research has identified multiple genes as being involved.
For example, a 2016 study by Boston University in the U.S. identified the FOXF2 gene as raising the risk of stroke due to small vessel disease.
Other genes such as NINJ2 and WNK1 play a role in blood pressure regulation and brain recovery.
But Hoang Tien Trong Nghia, head of the neurology department at Military Hospital 175, warned against blaming genetics for every family history of stroke, pointing out that sometimes family members simply share the same unhealthy environment and lifestyle including high salt intake, lack of exercise, smoking, obesity, all leading risk factors.
Determining a genetic predisposition requires screening, he said.
Truc said genetic testing not only helps identify causes after a stroke occurs, but also enables prevention for those at high risk.
Detecting abnormalities such as Protein S, MTHFR, JAK2, or other clotting-related genes allows doctors to personalize treatment, select drugs that match the disease mechanism, and uncover hidden hematological disorders that routine check-ups could miss, he said.
It also helps guide long-term prevention strategies through lifestyle changes and close monitoring, he said.
He advised those with relatives who suffered a stroke at a young age or from unclear causes, those with early thrombosis or those with moderate to high cardiovascular risk due to hypertension, dyslipidemia, obesity, or diabetes to consider genetic screening.
While genetic factors cannot be changed, a person could lower the risk through a healthy diet with less salt, limited saturated fat and more vegetables and fruits, at least 150 minutes of exercise per week, maintaining a BMI of 18.5–24.9, and adhering to treatment of underlying conditions.