A stroke is a serious life-threatening medical condition that happens when the blood supply to part of the brain is cut off. Stroke remains a leading cause of death in the UK so researchers are actively trying to understand the risk factors that contribute to it. A new study has shed light on a previously unknown risk factor for an uncommon type of stroke: cerebral venous thrombosis (CVT).
CVT is a blood clot of a cerebral vein in the brain, accounting for less than one percent of all stroke cases worldwide.
New research from a consortium led by Royal Holloway, University of London, has identified the first genetic link for CVT.
Although numerous risk factors have previously been reported as contributors to adult CVT, its genetic basis has not been well understood.
In this study, researchers were able to identify the first chromosomal region to strongly associate with a genetic susceptibility to CVT: the ABO gene – a gene that determines individual blood group status.
To investigate the association, 882 Europeans diagnosed with CVT (and a control group of 1205 individuals of similar demographics without CVT) took part in the genome study.
By identifying an area of the human genome that strongly correlates with CVT, researchers found that this region more than doubles the likelihood of CVT: a risk greater than any previously identified genetic risk marker.
Researchers were also able to demonstrate that those with an AB blood group faced a 5.6 times increased risk of CVT, compared with those from blood group O.
Professor Pankaj Sharma, Director of the Institute of Cardiovascular Research at Royal Holloway, University of London, said: “CVT is a form of stroke which affects young people, especially women.
Our work, 10 years in the making, brings together a global international collaboration that has identified a risk factor, as simple as someone’s blood group, and presents a major step forward in predicting and understanding the mechanism of this disease.
“Needless to say, CVT has entered the public domain following its association with the AstraZeneca COVID-19 vaccine.
“Whether an individual’s blood group status affects their risk of developing CVT following the vaccine remains to be seen.”
Other CVT risk factors
According to an article published in the British Medical Journal (BMJ), another important risk factor for CVT are oestrogen-containing oral contraceptives.
The main stroke symptoms can be remembered with the word FAST:
- Face – the face may have dropped on one side, the person may not be able to smile, or their mouth or eye may have drooped.
- Arms – the person may not be able to lift both arms and keep them there because of weakness or numbness in one arm
- Speech – their speech may be slurred or garbled, or the person may not be able to talk at all despite appearing to be awake; they may also have problems understanding what you’re saying to them
- Time – it’s time to dial 999 immediately if you notice any of these signs or symptoms.
- It’s important for everyone to be aware of these signs and symptoms, particularly if you live with or care for a person who is in a high-risk group.
Symptoms in the FAST test identify most strokes, but occasionally a stroke can cause different symptoms.
Other signs and symptoms may include:
- Complete paralysis of one side of the body
- Sudden loss or blurring of vision
- Difficulty understanding what others are saying
- Problems with balance and coordination
- Difficulty swallowing (dysphagia)
- A sudden and very severe headache resulting in a blinding pain unlike anything experienced before
- Loss of consciousness.