What you carry at this position in your DNA and what research says about it.
Heart Disease Risk: 6/10 evidence, 15 publications.
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Sample genotype (not yours): C/C
Typical Heart and Cholesterol Profile
Baseline levels of LDL cholesterol and blood clotting factors characterize this genetic profile. It carries a typical risk for coronary artery disease.
What this genotype means: Typical risk of coronary artery disease; Baseline LDL and total cholesterol levels; Typical blood clotting factor VIII activity.
Sample genotype (not yours): C/T
Slightly Elevated Heart and Cholesterol Risk
A single copy of the T allele is linked to slightly higher LDL cholesterol and a modest increase in coronary artery disease risk.
What this genotype means: Slightly increased risk of coronary artery disease; Slightly higher LDL and total cholesterol levels; Modestly elevated blood clotting factor VIII activity.
Sample genotype (not yours): T/T
Elevated Heart and Cholesterol Risk
Two copies of the T allele are associated with higher LDL cholesterol, elevated blood clotting factors, and an increased risk of coronary artery disease.
What this genotype means: Increased risk of coronary artery disease; Higher LDL and total cholesterol levels; Elevated blood clotting factor VIII activity.
Gene function and biological role
Gene Function: The ABO gene encodes a glycosyltransferase enzyme responsible for determining an individual's ABO blood group [1]. This enzyme works by adding specific sugar molecules to the surface of red blood cells and other tissues [1]. Beyond blood transfusions, the ABO gene plays a critical role in cardiovascular health, inflammation, and cell adhesion [2]. Variations in this gene can alter the clearance and levels of various circulating proteins, including clotting factors and adhesion molecules [2]. Consequently, the ABO locus is one of the most highly replicated regions in genome-wide studies of heart health and blood chemistry [3].
Variant Impact: The rs651007 variant is an intergenic genetic marker located near the ABO gene on chromosome 9. This specific change is strongly linked to the ABO A1 blood group subtype, which is characterized by highly active glycosyltransferase enzymes [1]. The variant acts as a major genetic regulator of several plasma proteins, most notably soluble E-selectin, which is a marker of blood vessel inflammation [1]. By influencing how these proteins are processed and cleared from the bloodstream, the variant impacts cardiovascular risk and lipid levels [3]. It is also associated with differences in blood clotting factors and systemic iron storage [4].
Key Insight: The rs651007 variant is a powerful genetic tag for the ABO A1 blood group subtype, which has over 30-fold higher enzyme activity than the A2 subtype. This single genetic change simultaneously influences blood clotting, cholesterol levels, and blood vessel inflammation.
Location: ABO. Chromosome 9 · 9q34.2 · 133.3 Mb
Estimated prevalence by population
Global 65.6%; European 61.1%; African 74.2%; East Asian 63.4%; South Asian 70.4%; Americas 68.7%; Ashkenazi 61.4%; Finnish 60.1%; Middle Eastern 63.9%; Amish 26.3%.
Estimated CC genotype frequency.
Global 30.6%; European 34.2%; African 23.9%; East Asian 32.4%; South Asian 27.0%; Americas 28.4%; Ashkenazi 33.9%; Finnish 34.8%; Middle Eastern 32.1%; Amish 50.0%.
Estimated CT genotype frequency.
Global 3.8%; European 4.8%; African 1.9%; East Asian 4.1%; South Asian 2.6%; Americas 2.9%; Ashkenazi 4.7%; Finnish 5.0%; Middle Eastern 4.0%; Amish 23.7%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Heart Disease
Coronary Artery Disease. Evidence: 6/10. Source: PMID 36474045. Typical Risk.
Lipids & Cholesterol
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Typical Levels.
Coagulation & Clotting
Clotting Factor Levels. Evidence: 4/10. Source: PMID 23381943. Typical Levels.
Blood Cell & Iron Traits
Iron Levels. Evidence: 5/10. Source: PMID 25352340. Slightly Increased.
Immunity & Inflammation
Inflammatory & Circulating Protein Markers
Soluble E-Selectin. Evidence: 6/10. Source: PMID 20147318. Increased.
Showing effects for C/T genotype
Coronary Artery Disease. Evidence: 6/10. Source: PMID 36474045. ~1.05x Risk.
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Slightly Increased.
Clotting Factor Levels. Evidence: 4/10. Source: PMID 23381943. Slightly Increased.
Iron Levels. Evidence: 5/10. Source: PMID 25352340. Typical Levels.
Soluble E-Selectin. Evidence: 6/10. Source: PMID 20147318. Slightly Decreased.
Showing effects for T/T genotype
Coronary Artery Disease. Evidence: 6/10. Source: PMID 36474045. ~1.1x Risk.
LDL Cholesterol. Evidence: 6/10. Source: PMID 29507422. Increased.
Clotting Factor Levels. Evidence: 4/10. Source: PMID 23381943. Increased.
Iron Levels. Evidence: 5/10. Source: PMID 25352340. Slightly Decreased.
Soluble E-Selectin. Evidence: 6/10. Source: PMID 20147318. Decreased.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Two copies of the C allele represent the most common genetic profile at this locus. This genotype is associated with typical levels of low-density lipoprotein (LDL) and total cholesterol, avoiding the genetic elevation seen with the T allele [1]. It is also linked to baseline levels of factor VIII, a key protein involved in blood clotting, which translates to a typical risk of developing coronary artery disease [2]. Additionally, this profile is associated with higher circulating levels of soluble E-selectin, a marker of endothelial activation [3]. While higher E-selectin is sometimes linked to inflammation, in this genetic context, it primarily reflects differences in protein clearance rather than active vascular damage [3]. Overall, this genotype represents a balanced cardiovascular baseline.
Typical risk of coronary artery disease; Baseline LDL and total cholesterol levels; Typical blood clotting factor VIII activity.
Sample genotype: CT (Heterozygous)
One copy of the T allele is associated with a slight increase in both low-density lipoprotein (LDL) and total cholesterol levels [1]. This genetic change also leads to a modest elevation in factor VIII, a protein that promotes blood clotting, which can slightly increase the likelihood of cardiovascular events [2]. Consequently, large-scale genetic studies have linked this genotype to a small but measurable increase in the risk of coronary artery disease [3]. On the other hand, carriers of the T allele tend to have lower circulating levels of soluble E-selectin, a protein involved in cell adhesion [4]. This reduction is thought to be driven by the high glycosyltransferase activity of the linked ABO A1 blood group subtype, which accelerates protein clearance [4]. Despite this lower inflammatory marker, the overall cardiovascular impact leans toward slightly elevated risk.
Slightly increased risk of coronary artery disease; Slightly higher LDL and total cholesterol levels; Modestly elevated blood clotting factor VIII activity.
Sample genotype: TT (Homozygous)
Double copies of the T allele are linked to the highest genetic elevation of LDL and total cholesterol at this locus [1]. This genotype is also associated with significantly higher levels of factor VIII, a key blood clotting protein, which can increase the risk of blood clots [2]. Together, these factors contribute to a moderately increased risk of developing coronary artery disease compared to those with the C/C genotype [3]. Interestingly, this profile is also associated with the lowest levels of soluble E-selectin, an adhesion molecule on blood vessel walls [4]. This occurs because the T allele is strongly linked to the ABO A1 blood group, which enhances the clearance of certain proteins from circulation [4]. However, the clinical benefits of lower E-selectin are outweighed by the elevated cholesterol and clotting factors, resulting in an overall higher cardiovascular risk profile.
Increased risk of coronary artery disease; Higher LDL and total cholesterol levels; Elevated blood clotting factor VIII activity.
Variants with shared genetic architecture
rs507666 · ABO Gene · Chr 9 · Heart Disease Risk
rs550057 · ABO Gene · Chr 9 · COVID-19 Severity
rs495828 · ABO Gene · Chr 9 · Blood Clot Risk
Connecting genetic risk to disease end points through the human blood plasma proteome.
Ischemic stroke is associated with the ABO locus: the EuroCLOT study.
A large electronic-health-record-based genome-wide study of serum lipids.
Content updated August 2026.
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