What you carry at this position in your DNA and what research says about it.
Blood Clot and Stroke Risk: 10/10 evidence, 17 publications.
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Sample genotype (not yours): G/G
Typical Blood Clotting and Stroke Risk
Typical cardiovascular risk characterizes the common genetic profile. The body produces fully functional enzymes that maintain a healthy balance between forming and dissolving blood clots.
What this genotype means: Typical blood clotting activity; Baseline risk for carotid stenosis; Typical risk for venous thromboembolism.
Sample genotype (not yours): A/A
Significantly Elevated Risk for Blood Clots and Stroke
Significantly higher risk of blood clots, stroke, and carotid stenosis occurs with two copies of the Marburg I variant. This rare profile leads to a substantial reduction in clot-dissolving enzyme activity.
What this genotype means: Severely reduced clot-dissolving enzyme activity; Highly elevated risk of deep vein thrombosis; Significantly increased risk of carotid stenosis and stroke.
Sample genotype (not yours): G/A
Elevated Risk for Blood Clots and Stroke
Elevated risk of blood clots, carotid stenosis, and stroke is associated with the Marburg I variant. A single copy of the altered allele reduces the activity of a key enzyme responsible for breaking down clots.
What this genotype means: Reduced factor VII-activating protease activity; Increased risk of deep vein thrombosis; Elevated risk of carotid artery narrowing.
Gene function and biological role
Gene Function: The HABP2 gene encodes hyaluronan-binding protein 2, also known as factor VII-activating protease (FSAP) [1]. This protein is a serine protease circulating in the blood that plays a critical role in both blood coagulation and the breakdown of clots (fibrinolysis) [1]. It acts as an initiator of the coagulation cascade by activating factor VII, while also facilitating clot dissolution by activating pro-urokinase [1]. Beyond its role in clotting, HABP2 is involved in inflammatory responses, tissue remodeling, and cell migration [2]. It has also been studied for its potential role as a tumor suppressor in certain tissues [2].
Variant Impact: A single-nucleotide substitution in the HABP2 gene defines the Marburg I polymorphism [3]. This genetic change replaces the amino acid glycine with glutamate at position 534 of the protein (p.Gly534Glu) [3]. This alteration significantly reduces the enzymatic activity of the factor VII-activating protease, impairing its ability to break down blood clots [3] [4]. Consequently, individuals carrying this variant have a higher tendency to form persistent blood clots [4]. The variant is also studied for its potential impact on cellular growth and tumor suppression [2].
Key Insight: The Marburg I variant reduces the body's natural ability to dissolve blood clots, leading to a higher risk of deep vein thrombosis and stroke.
Location: HABP2. Chromosome 10 · 10q25.3 · 113.6 Mb
Estimated prevalence by population
Global 95.5%; European 92.6%; African 98.7%; East Asian > 99.9%; South Asian 98.1%; Americas 96.5%; Ashkenazi 97.7%; Finnish 94.7%; Middle Eastern 98.6%; Amish 98.7%.
Estimated GG genotype frequency.
Global 4.5%; European 7.2%; African 1.3%; East Asian < 0.1%; South Asian 1.9%; Americas 3.4%; Ashkenazi 2.3%; Finnish 5.2%; Middle Eastern 1.4%; Amish 1.3%.
Estimated GA genotype frequency.
Global 0.1%; European 0.1%; African < 0.1%; East Asian < 0.1%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi < 0.1%; Finnish 0.1%; Middle Eastern < 0.1%; Amish < 0.1%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Cardiovascular & Metabolic
Vascular Health & Aneurysm
Carotid Stenosis. Evidence: 3/10. Source: PMID 12578864. Typical Risk.
Coagulation & Clotting
Venous Thromboembolism. Evidence: 3/10. Source: PMID 22421107. Typical Risk.
Stroke
Stroke. Evidence: 3/10. Source: PMID 12578864. Typical Risk.
Blood Cell & Iron Traits
Eosinophil Count. Evidence: 10/10. Source: PMID 27863252. Slightly Higher.
Cancer & Oncology
Thyroid & Endocrine Cancers
Thyroid Cancer. Evidence: 3/10. Source: PMID 26691890. Typical Risk.
Immunity & Inflammation
Inflammatory & Circulating Protein Markers
Interferon Gamma Levels. Evidence: 9/10. Source: PMID 29875488. Typical.
Showing effects for A/A genotype
Carotid Stenosis. Evidence: 3/10. Source: PMID 12578864. ~6x Increased Risk.
Venous Thromboembolism. Evidence: 3/10. Source: PMID 22421107. ~3.5x-6x Risk.
Stroke. Evidence: 3/10. Source: PMID 12578864. Highly Elevated Risk.
Eosinophil Count. Evidence: 10/10. Source: PMID 27863252. Slightly Lower.
Thyroid Cancer. Evidence: 3/10. Source: PMID 26691890. Possibly Elevated.
Interferon Gamma Levels. Evidence: 9/10. Source: PMID 29875488. Higher Levels.
Showing effects for G/A genotype
Carotid Stenosis. Evidence: 3/10. Source: PMID 12578864. ~2x Increased Risk.
Venous Thromboembolism. Evidence: 3/10. Source: PMID 22421107. ~2x Increased Risk.
Stroke. Evidence: 3/10. Source: PMID 12578864. Increased Risk.
Eosinophil Count. Evidence: 10/10. Source: PMID 27863252. Typical.
Interferon Gamma Levels. Evidence: 9/10. Source: PMID 29875488. Slightly Higher.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Production of fully active factor VII-activating protease (FSAP) occurs when two copies of the G allele are present [1]. This enzyme efficiently balances blood clot formation and dissolution, maintaining typical cardiovascular health [1]. Studies show that the elevated risk of carotid stenosis or deep vein thrombosis associated with the Marburg I variant is absent here [2] [3]. Furthermore, typical risks for clinical stroke and all-cause mortality are maintained [3]. While other lifestyle and genetic factors still influence cardiovascular health, this specific genetic marker does not add risk.
Typical blood clotting activity; Baseline risk for carotid stenosis; Typical risk for venous thromboembolism.
Sample genotype: AA (Homozygous)
A highly pronounced reduction in factor VII-activating protease activity occurs when two copies of the A allele are present [1]. This severe impairment in the body's clot-dissolving mechanism significantly increases the risk of venous thromboembolism and recurrent clotting events [2]. Research indicates a substantial increase in the risk of carotid stenosis, which can severely restrict blood flow to the brain and lead to clinical stroke [1]. The risk of stroke and associated cardiovascular mortality is notably higher compared to non-carriers [1]. Additionally, some studies have explored a link to familial thyroid cancer due to the loss of the protein's tumor-suppressive function, though this association remains debated in the scientific community [3].
Severely reduced clot-dissolving enzyme activity; Highly elevated risk of deep vein thrombosis; Significantly increased risk of carotid stenosis and stroke.
Sample genotype: GA (Heterozygous)
Presence of a single A allele characterizes the Marburg I variant [1]. This genetic change reduces the activity of the factor VII-activating protease, which impairs the body's natural ability to dissolve blood clots [1]. Clinical studies have linked this carrier status to an approximately twofold higher risk of venous thromboembolism and deep vein thrombosis [2]. It is also associated with an increased risk of carotid stenosis, which is the narrowing of the main arteries supplying blood to the brain [1]. Some research has also investigated a potential link to familial nonmedullary thyroid cancer, though subsequent studies suggest this connection is controversial and may not be causal [3].
Reduced factor VII-activating protease activity; Increased risk of deep vein thrombosis; Elevated risk of carotid artery narrowing.
Variants with shared genetic architecture
rs10886430 · GRK5 Gene · Chr 10 · Blood Clot Risk
rs12445050 · PLCG2 Gene · Chr 16 · Blood Clot Risk
rs2066865 · FGG Gene · Chr 4 · Blood Clot Risk
The HABP2 G534E variant is an unlikely cause of familial non-medullary thyroid cancer.
Content updated August 2026.
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