Gene Variants Linked to Increased Risk of Leg Blood Clots

Recent research has unveiled three gene variants that significantly elevate the risk of developing venous blood clots in the legs, with an increase of up to 180%. This discovery comes from a study conducted by a research team at Lund University, published in the journal Research and Practice in Thrombosis and Haemostasis.

Blood clots can occur in both arteries and veins, but the causes and implications vary. In Sweden, nearly half of venous thrombosis cases have a genetic basis. The newly identified gene variants are crucial in understanding the hereditary risks associated with this condition.

Unlike arterial clots that can lead to heart attacks or strokes due to plaque rupture, venous clots usually form in the legs when blood flow stagnates. This can activate the body's coagulation system, leading to clot formation that can obstruct circulation. A serious complication can arise if these clots dislodge and travel to the lungs, causing pulmonary embolism--a potentially fatal condition.

According to specialists, venous thrombosis is a leading cause of mortality worldwide, often overshadowed by the more recognized risks of arterial clots. In Sweden alone, over 10,000 annual cases of venous thromboembolism are reported, with incidence rates on the rise due to various factors, including an aging population. Approximately 10% of individuals aged 80 and older experience a blood clot at some point in their lives, with increased risks linked to obesity and height.

The mechanics behind blood flow in the veins involve the muscles acting against gravity, making prolonged inactivity detrimental. Valves in the veins prevent blood from flowing backward, and damage to these valves can heighten the risk of clot formation. Tall individuals are particularly vulnerable due to the longer distances blood must travel back to the heart.

While arterial health is influenced by factors such as high blood pressure and cholesterol levels, venous clots are less affected by these issues. Instead, obesity plays a significant role in venous circulation, compounded by lower activity levels often seen in overweight individuals. Dietary habits also contribute, with studies suggesting that ultra-processed foods may correlate with a higher risk of clots, whereas diets rich in healthy, plant-based foods might reduce risk.

Certain situations present heightened risks for venous clot formation; these include prolonged periods of immobility, such as during long flights or bed rest, as well as surgical procedures that may damage blood vessel walls. Additionally, the physiological changes during pregnancy can increase clotting factors, necessitating careful monitoring and preventive measures.

The research team identified three gene variants--ABO, F8, and VWF--via data from the Malmö Kost Cancer study, which encompassed 30,000 residents. These variants, when present in multiple copies, significantly raise the likelihood of venous thrombosis, mirroring the impact of the well-known Factor V Leiden mutation. Notably, the prevalence of these gene variants is not limited to specific ethnic groups, making them relevant across diverse populations.

The next steps for researchers include examining how the number of genetic risk factors influences the duration and type of anticoagulant treatment required following a clot. This personalized approach to treatment based on genetic risk assessments is anticipated to become increasingly important in clinical practice.