Where your DNA places you among other people, and the studies behind it.
Not tailored to your result, and not medical advice
Work Toward a Healthy Weight: Genetic evidence points to excess weight as a cause of venous clots, not just a correlate. A Mendelian randomisation study using 95 BMI-associated variants in 7,507 VTE cases and 52,632 controls estimated an odds ratio of 1.59 for VTE per standard deviation increase in BMI, with sensitivity analyses showing no sign of directional pleiotropy. Body weight is one of the few VTE risk factors that everyday eating and activity choices can actually shift. Human Genetics (PMC)
Move During Long Journeys: Clot risk rises with journey length, with the effect appearing above roughly 4 hours of travel. A review of travel-associated VTE reported a pooled relative risk of about 2.0 (95% CI 1.5 to 2.7) in travellers, and about 26% higher risk for every additional 2 hours of air travel. The pattern fits immobility as the driver: sitting without moving cut lower-limb blood flow by almost 40% in one study, and window seats carried roughly twice the risk of aisle seats. Walking the cabin or carriage when it is safe, flexing the calves and feet while seated, and keeping fluids up all work against that stasis. Wilderness & Environmental Medicine (PMC)
Quit Or Avoid Smoking: A meta-analysis of 32 studies covering nearly 4 million people and more than 35,000 events found VTE risk 23% higher in current smokers (RR 1.23, 95% CI 1.14 to 1.33) and 10% higher in former smokers (RR 1.10, 95% CI 1.03 to 1.17) than in never smokers. Risk rose by about 10% for every additional ten cigarettes smoked per day. The authors attributed roughly 8.7% of VTE events in these populations to ever having smoked. The smaller excess among former smokers is consistent with risk falling after quitting, although observational data alone cannot prove that. PLoS Medicine (PMC)
Stay Active, Expect Modest Gains: The honest summary is that exercise looks mildly protective here and the data are inconsistent. A meta-analysis of prospective cohorts found VTE risk 13% lower in the most active compared with the least active groups (RR 0.87, 95% CI 0.79 to 0.95), but heterogeneity between studies was high (I-squared 73%), no clear dose-response emerged, and the prediction interval spanned values on both sides of no effect. Regular activity is worth doing for many well-established reasons, but clot prevention is a weaker claim than it is for weight or smoking. European Journal of Epidemiology (PMC)
Know The Warning Signs: Deep vein thrombosis typically shows up as a swollen, tender leg that is painful to the touch. A clot that reaches the lungs tends to cause shortness of breath and pain on breathing. NHLBI notes that symptoms vary between people and that VTE sometimes produces nothing noticeable until a serious complication develops, and it advises contacting a healthcare provider right away if you think you have symptoms. These are signs worth getting looked at promptly rather than waiting to see whether they settle. NHLBI (NIH)
How much of this is genetic?
Genetics explains 60% of why people differ in this trait. The rest is environment, daily habits and chance.
Heritability estimate: Souto et al. 2000, Am J Hum Genet
Background and further reading
Venous thromboembolism (VTE) is the umbrella term for two related conditions: deep vein thrombosis (DVT), a clot that usually forms in the deep veins of the leg or pelvis, and pulmonary embolism (PE), which occurs when part of a clot breaks off and lodges in the arteries of the lungs. VTE is common, affecting on the order of 1 to 2 people per 1,000 each year, with incidence rising sharply with age. Symptoms of DVT include leg swelling, pain, warmth, and redness; PE can cause sudden shortness of breath, chest pain, and a rapid heartbeat, and can be life-threatening. Most cases are treatable with anticoagulant (blood-thinning) medication.
Genetic Basis: VTE is strongly heritable, with twin and family studies estimating that roughly half to 60% of the variation in risk is genetic. Unlike many polygenic traits, a substantial share of VTE risk is carried by a few relatively common variants of large effect. Factor V Leiden (the F5 rs6025 variant) impairs the shutdown of clotting factor V, and the prothrombin G20210A variant (F2 rs1799963) increases prothrombin levels; both meaningfully raise clot risk. Non-O ABO blood group (which raises von Willebrand factor and factor VIII levels) is another major common contributor, alongside variants in FGG (fibrinogen), F11 (factor XI), and the natural anticoagulant genes. Rare high-impact deficiencies of antithrombin (SERPINC1), protein C (PROC), and protein S (PROS1) cause the strongest inherited thrombophilias but are individually uncommon.
Environmental & Acquired Factors: Genetics sets a baseline, but most clots occur when an inherited tendency meets an acquired trigger. Major provoking factors include surgery (especially orthopedic), prolonged immobility, hospitalization, major trauma, and active cancer. Hormonal exposures matter: estrogen-containing oral contraceptives, hormone-replacement therapy, and pregnancy or the weeks after delivery all increase risk, and this risk is amplified in people who also carry factor V Leiden or prothrombin variants. Obesity, advancing age, smoking, and long-distance travel with prolonged sitting are additional contributors. Because these factors are modifiable or time-limited, awareness of genetic predisposition is most useful for informing prevention around high-risk situations.
The published research behind your score, and the variants it draws on.
13 published scores from 7 studies
The venous thromboembolism score combines 13 polygenic scores drawn from 7 published studies.
Heit JA. Epidemiology of venous thromboembolism. Nature Reviews Cardiology (2015)
These traits are influenced by some of the same genes and variants as this one
Nephrolithiasis: The formation of kidney stones, strongly shaped by diet and fluid intake.
Lean Body Mass: The fat-free portion of your body: mostly muscle, bone, organs, and water.
Content updated August 2026.
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