Women with the Factor V Leiden (FVL) gene mutation who had been prescribed oestrogen had more than double the risk of blood clotting compared to women who did not have this mutation. And almost 20% of the women who carry FVL, were prescribed oestrogen and had two medical conditions suffered a blood clot. The presence of the FVL gene made a substantial difference to risk, with only around 5% of women taking oestrogen and having two conditions suffering a clotting event.
The study also found that a woman with obesity, high blood pressure, high cholesterol, and kidney disease – which is not uncommon in a clinical setting – had an 8 times greater chance of blood clotting compared to a woman with none of these conditions. This amounted to roughly one in every six women with the four conditions in the study suffering a blood clot. Three medical conditions meant a five times greater chance of blood clotting, and two medical conditions meant a two times greater chance.
One in three women who had the FVL gene mutation and three of the medical conditions examined also suffered a blood clotting event.
The researchers examined the health data of 20,048 British-Bangladeshi and British-Pakistani women from the Genes & Health project, a large community-based genetics study. While oestrogen use, FVL, and common medical conditions are all known risk factors of blood clots, studies have not looked at the combined risk of these factors together on blood clot prevalence.
Women are commonly prescribed oestrogen, both through oral contraception containing the hormone and as part of hormone replacement therapy to replace the oestrogen that their body stops making during menopause.
Dr Emma Magavern, lead author from Queen Mary University of London, said: “Many women will take oestrogen at some point in their lifetime. Overall, this is very safe and there are far more positives to taking it than negatives when it’s prescribed. But these women may not be aware of the combined risk of their genetics and overall health and how it affects their risk of developing a blood clot, which could be life-threatening for some individuals.
“It’s important that women have all the information they need to make an informed choice. While our results are important for women everywhere, they are especially relevant for South Asian women with multiple existing health conditions.”
Professor Sir Mark Caulfield, from Queen Mary University of London, said: “Our study gives a more complete picture of blood clotting in Bangladeshi and Pakistani communities who have previously been underrepresented in research.
“Genetic testing of the FVL gene mutation could give a clearer sense of someone’s personalised risk of this potentially fatal complication if they were prescribed oestrogen.”
This work was funded by the National Institute for Health and Care Research Barts Biomedical Research Centre and Barts Charity.
Genes & Health is core-funded by Wellcome, the Medical Research Council, Higher Education Funding Council for England Catalyst, Barts Charity, and Health Data Research UK. Queen Mary’s Genes & Health group are trying to reduce health inequalities by analysing the genetic information of 100,000 Bangladeshi and Pakistani people to improve health outcomes locally and globally.
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Notes to editors
Research paper: Factor V Leiden, estrogen, and multimorbidity association with venous thromboembolism in a British-South Asian cohort. Emma F. Magavern, Damian Smedley, Mark J. Caulfield. iScience.
For a copy of the paper or to speak with one of the study authors, please contact Laurence Leong in the Queen Mary press office (l.leong@qmul.ac.uk)
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Throughout our history, we’ve fostered social justice and improved lives through academic excellence. And we continue to live and breathe this spirit today, not because it’s simply ‘the right thing to do’ but for what it helps us achieve and the intellectual brilliance it delivers.
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We continue to embrace diversity of thought and opinion in everything we do, in the belief that when views collide, disciplines interact, and perspectives intersect, truly original thought takes form.
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The mission of the National Institute for Health and Care Research (NIHR) is to improve the health and wealth of the nation through research. We do this by:
Funding high quality, timely research that benefits the NHS, public health and social care;
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As East London’s oldest healthcare charity, we’ve been at the forefront of advancing healthcare for hundreds of years. The hospitals we support provide excellent care to their patients. Yet too many people’s lives in East London are affected by ill health. At Barts Charity we have East London in our hearts and we want healthier, longer lives for everyone in our community.
As the dedicated charity for Barts Health NHS Trust, we support St Bartholomew’s, Whipps Cross, Newham, Royal London, and Mile End hospitals, as well as the Faculty of Medicine and Dentistry at Queen Mary University of London. We also support researchers at the School of Health & Psychological Sciences at City, University of London. Visit https://www.bartscharity.org.uk
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