What you carry at this position in your DNA and what research says about it.
Heart Disease Risk: 10/10 evidence, 35 publications.
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Sample genotype (not yours): A/A
Significantly Higher Risk of Heart Disease and Elevated Cholesterol
Inheriting two copies of the A allele, which tags the A1 blood group, is linked to elevated LDL and total cholesterol. This genetic profile is associated with the highest risk of coronary artery disease among the genotypes.
What this genotype means: Significantly higher LDL and total cholesterol; Elevated risk of coronary artery disease; Lower levels of inflammatory marker ICAM-1.
Sample genotype (not yours): A/G
Increased Risk of Heart Disease and Elevated Cholesterol
Carrying one copy of the A allele is associated with moderately elevated total and LDL cholesterol levels. This intermediate profile carries an increased risk of coronary artery disease compared to the typical baseline.
What this genotype means: Moderately elevated LDL and total cholesterol; Increased risk of coronary artery disease; Intermediate levels of inflammatory marker ICAM-1.
Sample genotype (not yours): G/G
Typical Heart Disease Risk and Favorable Cholesterol Levels
Two copies of the G allele, which typically correspond to the O blood group, are linked to lower total and LDL cholesterol. This profile is associated with a lower risk of coronary artery disease.
What this genotype means: Favorable LDL and total cholesterol levels; Lower risk of coronary artery disease; Higher levels of inflammatory marker ICAM-1.
Gene function and biological role
Gene Function: The ABO gene encodes glycosyltransferases that determine an individual's ABO blood group by modifying cell-surface antigens [1]. Beyond blood typing, these enzymes influence the clearance of key clotting factors and adhesion molecules in the bloodstream [2]. Consequently, variations in this gene are strongly linked to cardiovascular health and inflammatory processes [2]. Research shows that ABO activity also affects circulating lipid levels, including total and LDL cholesterol [3].
Variant Impact: Located in an intron of the ABO gene, rs507666 acts as a highly accurate genetic marker for the A1 blood group subtype [2]. This specific nucleotide change alters how the body regulates several circulating proteins, including cell adhesion molecules like ICAM-1 [2]. The presence of the A allele at this locus is associated with higher levels of total and LDL cholesterol [3]. Furthermore, this genetic variant has been identified as a key risk factor for coronary artery disease in multiple large-scale studies [4].
Key Insight: This variant acts as a genetic proxy for the A1 blood group, linking blood type directly to cholesterol levels and heart disease risk.
Location: ABO. Chromosome 9 · 9q34.2 · 133.3 Mb
Estimated prevalence by population
Global 3.0%; European 3.8%; African 1.1%; East Asian 4.2%; South Asian 2.4%; Americas 2.3%; Ashkenazi 4.5%; Finnish 4.4%; Middle Eastern 3.6%; Amish 19.7%.
Estimated AA genotype frequency.
Global 27.6%; European 31.5%; African 19.0%; East Asian 32.5%; South Asian 26.2%; Americas 25.8%; Ashkenazi 33.3%; Finnish 33.1%; Middle Eastern 30.8%; Amish 49.4%.
Estimated AG genotype frequency.
Global 69.4%; European 64.7%; African 79.9%; East Asian 63.4%; South Asian 71.4%; Americas 71.9%; Ashkenazi 62.3%; Finnish 62.5%; Middle Eastern 65.5%; Amish 30.9%.
Estimated GG genotype frequency.
Showing effects for A/A genotype
Cardiovascular & Metabolic
Heart Disease
Coronary Artery Disease. Evidence: 8/10. Source: PMID 28714975. Highest Risk.
Lipids & Cholesterol
LDL Cholesterol. Evidence: 10/10. Source: PMID 24386095. +0.15 mmol/L.
Total Cholesterol. Evidence: 10/10. Source: PMID 24386095. Elevated Levels.
Immunity & Inflammation
Inflammatory & Circulating Protein Markers
Soluble ICAM-1 Levels. Evidence: 8/10. Source: PMID 18604267. Lower Levels.
Allergy & Hypersensitivity
Allergic Rhinitis. Evidence: 6/10. Source: PMID 31361310. ~1.1x Risk.
Endocrine & Reproductive
Female Reproductive Health & Fertility
Endometriosis. Evidence: 7/10. Source: PMID 36914876. ~1.1x Risk.
Showing effects for A/G genotype
Coronary Artery Disease. Evidence: 8/10. Source: PMID 28714975. Increased Risk.
LDL Cholesterol. Evidence: 10/10. Source: PMID 24386095. +0.07 mmol/L.
Total Cholesterol. Evidence: 10/10. Source: PMID 24386095. Moderately Elevated.
Soluble ICAM-1 Levels. Evidence: 8/10. Source: PMID 18604267. Typical Levels.
Allergic Rhinitis. Evidence: 6/10. Source: PMID 31361310. ~1.05x Risk.
Endometriosis. Evidence: 7/10. Source: PMID 36914876. ~1.05x Risk.
Showing effects for G/G genotype
Coronary Artery Disease. Evidence: 8/10. Source: PMID 28714975. Lower Risk.
LDL Cholesterol. Evidence: 10/10. Source: PMID 24386095. Typical Levels.
Total Cholesterol. Evidence: 10/10. Source: PMID 24386095. Typical Levels.
Soluble ICAM-1 Levels. Evidence: 8/10. Source: PMID 18604267. Higher Levels.
Allergic Rhinitis. Evidence: 6/10. Source: PMID 31361310. Typical Risk.
Endometriosis. Evidence: 7/10. Source: PMID 36914876. Typical Risk.
What this genotype means for the people who carry it
Sample genotype: AA (Homozygous)
A double dose of the A allele at this locus serves as a strong genetic marker for the A1 blood group subtype [1]. Large-scale genomic studies consistently link this profile to significantly elevated levels of both total and LDL cholesterol [2]. These elevated lipids directly contribute to a higher risk of developing coronary artery disease over time [3]. Interestingly, while cardiovascular risks are elevated, this genotype is associated with lower circulating levels of the inflammatory adhesion molecule ICAM-1 [1]. The biological mechanism is thought to involve how ABO glycosyltransferases affect the clearance of vascular proteins [1]. Individuals with this genetic makeup may also have a slightly increased susceptibility to inflammatory conditions like endometriosis and allergic rhinitis [4] [5]. Managing cardiovascular health through standard lifestyle and medical approaches is particularly relevant for this group.
Significantly higher LDL and total cholesterol; Elevated risk of coronary artery disease; Lower levels of inflammatory marker ICAM-1.
Sample genotype: AG (Heterozygous)
Possessing one copy of the A allele and one copy of the G allele represents a heterozygous state that typically correlates with a non-O blood group [1]. Clinical data show that this genotype leads to moderately higher levels of total and LDL cholesterol compared to the G/G baseline [2]. This lipid elevation translates to an increased risk of coronary artery disease [3]. On the inflammatory front, this profile results in intermediate levels of soluble ICAM-1, balancing the opposing effects of the A and G alleles [1]. The underlying biology relates to the partial activity of the A1-specific glycosyltransferase enzyme [1]. Slight increases in the risk of endometriosis and allergic rhinitis are also observed with this genetic pattern [4] [5]. Standard cardiovascular prevention strategies remain highly beneficial for individuals with this profile.
Moderately elevated LDL and total cholesterol; Increased risk of coronary artery disease; Intermediate levels of inflammatory marker ICAM-1.
Sample genotype: GG (Homozygous)
Two copies of the G allele at this position generally align with the O blood group, which is widely recognized for its cardiovascular advantages [1]. Multiple genome-wide association studies show that this genotype is linked to lower levels of total and LDL cholesterol [2]. Consequently, this genetic profile carries a significantly lower risk of coronary artery disease compared to those carrying the A allele [3]. However, this genotype is also associated with higher circulating levels of the inflammatory marker ICAM-1 [4]. Despite the higher ICAM-1 levels, the overall cardiovascular profile remains highly favorable due to the lipid-lowering effect [2]. The risk for other conditions, such as endometriosis and allergic rhinitis, is also lower in this group [5] [6]. Maintaining a healthy lifestyle helps preserve this natural cardiovascular advantage.
Favorable LDL and total cholesterol levels; Lower risk of coronary artery disease; Higher levels of inflammatory marker ICAM-1.
Variants with shared genetic architecture
rs550057 · ABO Gene · Chr 9 · COVID-19 Severity
rs495828 · ABO Gene · Chr 9 · Blood Clot Risk
rs505922 · ABO Gene · Chr 9 · Blood Type Disease Risk
The genetic basis of endometriosis and comorbidity with other pain and inflammatory conditions.
Content updated August 2026.
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