What you carry at this position in your DNA and what research says about it.
Cholesterol Levels: 6/10 evidence, 20 publications.
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Sample genotype (not yours): G/G
Higher Cholesterol and Blood Sugar Risk
This genotype is associated with elevated LDL cholesterol, higher average blood sugar levels, and an increased risk of hemorrhoids.
What this genotype means: Higher LDL cholesterol; Elevated HbA1c levels; Increased risk of hemorrhoids.
Sample genotype (not yours): G/T
Typical Cholesterol and Blood Sugar Levels
This genotype represents a balanced genetic profile with typical cholesterol, blood sugar, and cardiovascular risk markers.
What this genotype means: Typical lipid profile; Average blood sugar levels; Typical glaucoma and hemorrhoids risk.
Sample genotype (not yours): T/T
Favorable Cholesterol and Blood Sugar Levels
This genotype is linked to lower LDL cholesterol, lower average blood sugar, and a reduced risk of hemorrhoids.
What this genotype means: Lower LDL cholesterol; Favorable HbA1c levels; Reduced risk of hemorrhoids.
Gene function and biological role
Gene Function: The ABO gene encodes the glycosyltransferase enzymes responsible for determining an individual's ABO blood group by modifying antigens on red blood cells and other tissues [1]. Beyond its role in blood typing, the ABO gene is a major pleiotropic locus that influences a wide array of cardiovascular, metabolic, and hematological traits [2]. Variations in this gene affect the levels of circulating proteins, cell adhesion molecules, and lipids, thereby modulating the risk for cardiovascular diseases [3]. It also plays a role in inflammatory responses and susceptibility to certain infectious diseases, such as malaria [4].
Variant Impact: The rs8176746 variant is a single nucleotide polymorphism in the ABO gene that alters the amino acid sequence of the transferase enzyme, specifically determining the galactose specificity that distinguishes the B antigen from other blood group antigens [1]. Carrying the T allele at this locus is a primary genetic driver of the B blood group antigen. This molecular change not only alters red blood cell surface markers but also significantly impacts systemic levels of lipids, glycemic markers, and cell adhesion proteins [2]. Consequently, this single genetic letter change acts as a major pivot point for multiple metabolic and cardiovascular biomarkers [2].
Key Insight: This single genetic variant determines whether you carry the B blood group antigen while simultaneously acting as a major genetic regulator of your lifetime LDL cholesterol and blood sugar levels.
Location: ABO. Chromosome 9 · 9q34.2 · 133.3 Mb
Origin Story: The distribution of ABO gene variants has been heavily shaped by natural selection, as different blood groups provided survival advantages against historical infectious diseases like malaria and cholera.
Estimated prevalence by population
Global 78.6%; European 84.7%; African 70.8%; East Asian 67.2%; South Asian 55.4%; Americas 85.8%; Ashkenazi 75.0%; Finnish 74.7%; Middle Eastern 84.3%; Amish 84.8%.
Estimated GG genotype frequency.
Global 19.9%; European 14.6%; African 26.6%; East Asian 29.5%; South Asian 38.1%; Americas 13.7%; Ashkenazi 23.2%; Finnish 23.5%; Middle Eastern 15.0%; Amish 14.5%.
Estimated GT genotype frequency.
Global 1.5%; European 0.6%; African 2.5%; East Asian 3.2%; South Asian 6.6%; Americas 0.5%; Ashkenazi 1.8%; Finnish 1.8%; Middle Eastern 0.7%; Amish 0.6%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
LDL Cholesterol. Evidence: 6/10. Source: PMID 33462484. Higher LDL.
Diabetes & Glycemic Traits
HbA1c. Evidence: 6/10. Source: PMID 33462484. Higher HbA1c.
Blood Cell & Iron Traits
Platelet Count. Evidence: 8/10. Source: PMID 32888494. Higher Platelets.
Hemoglobin Levels. Evidence: 8/10. Source: PMID 20139978. Lower Hemoglobin.
Organ Systems
Digestive & Gut Disorders
Hemorrhoids. Evidence: 6/10. Source: PMID 39024449. Increased Risk.
Vision & Eye Health
Glaucoma. Evidence: 6/10. Source: PMID 39024449. Reduced Risk.
Showing effects for G/T genotype
LDL Cholesterol. Evidence: 6/10. Source: PMID 33462484. Typical LDL.
HbA1c. Evidence: 6/10. Source: PMID 33462484. Typical HbA1c.
Platelet Count. Evidence: 8/10. Source: PMID 32888494. Typical Platelets.
Hemoglobin Levels. Evidence: 8/10. Source: PMID 20139978. Typical Hemoglobin.
Hemorrhoids. Evidence: 6/10. Source: PMID 39024449. Typical Risk.
Glaucoma. Evidence: 6/10. Source: PMID 39024449. Typical Risk.
Showing effects for T/T genotype
LDL Cholesterol. Evidence: 6/10. Source: PMID 33462484. Lower LDL.
HbA1c. Evidence: 6/10. Source: PMID 33462484. Lower HbA1c.
Platelet Count. Evidence: 8/10. Source: PMID 32888494. Lower Platelets.
Hemoglobin Levels. Evidence: 8/10. Source: PMID 20139978. Higher Hemoglobin.
Hemorrhoids. Evidence: 6/10. Source: PMID 39024449. Reduced Risk.
Glaucoma. Evidence: 6/10. Source: PMID 39024449. Increased Risk.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Carrying two copies of the G allele is highly common and correlates with non-B blood groups, such as group A or O. Large-scale genetic studies show that this genotype is linked to higher levels of total cholesterol, LDL cholesterol, and apolipoprotein B, which are key markers for cardiovascular health [1]. It is also associated with slightly higher HbA1c levels, indicating higher average blood sugar over time [1]. Additionally, individuals with this genotype have a higher statistical risk of developing hemorrhoids [2]. On the positive side, this genetic profile is associated with a lower risk of developing open-angle glaucoma [2].
Higher LDL cholesterol; Elevated HbA1c levels; Increased risk of hemorrhoids.
Sample genotype: GT (Heterozygous)
Carrying one G allele and one T allele is directly associated with expressing the B blood group antigen, often resulting in blood type B or AB. Because this is a heterozygous state, it generally results in intermediate or typical levels of key metabolic biomarkers [1]. Your genetic predisposition for LDL cholesterol, total cholesterol, and apolipoprotein B sits at a baseline average [1]. Similarly, average blood sugar levels as measured by HbA1c are typical [1]. The risks for downstream conditions like hemorrhoids and open-angle glaucoma are also near the population average [2].
Typical lipid profile; Average blood sugar levels; Typical glaucoma and hemorrhoids risk.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele is strongly associated with blood group B. Large population studies demonstrate that this genotype is highly favorable for metabolic health, showing a link to lower total cholesterol, LDL cholesterol, and apolipoprotein B levels [1]. It is also associated with lower HbA1c, suggesting naturally better blood sugar regulation over time [1]. Furthermore, individuals with this genotype have a lower risk of developing hemorrhoids [2]. However, this profile is associated with a higher risk of open-angle glaucoma, which is an important health consideration to discuss with an eye care professional [2].
Lower LDL cholesterol; Favorable HbA1c levels; Reduced risk of hemorrhoids.
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
DNA-based methods in the immunohematology reference laboratory.
Genetics of 35 blood and urine biomarkers in the UK Biobank.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Content updated August 2026.
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