What you carry at this position in your DNA and what research says about it.
LDL Cholesterol Levels: 10/10 evidence, 20 publications.
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Sample genotype (not yours): T/T
Lower LDL Cholesterol and Heart Risk
Two copies of the protective T allele are linked to significantly lower LDL cholesterol and a reduced risk of heart disease. This genetic profile supports highly efficient lipid clearance from the bloodstream.
What this genotype means: Significantly lower LDL and total cholesterol levels; Reduced risk of coronary artery disease; Lower carotid artery wall thickness.
Sample genotype (not yours): C/C
Typical LDL Cholesterol and Heart Risk
Two copies of the common C allele represent the standard population baseline for LDL cholesterol and cardiovascular risk. This genotype does not carry the protective lipid-lowering effects of the T allele.
What this genotype means: Typical population baseline for LDL and total cholesterol; Standard risk of coronary artery disease; Typical carotid artery wall thickness.
Sample genotype (not yours): T/C
Slightly Lower LDL and Heart Risk
Carrying one copy of the protective T allele is associated with slightly lower LDL cholesterol and a modest reduction in cardiovascular risk. This provides a mild natural advantage for arterial health.
What this genotype means: Slightly lower LDL and total cholesterol; Modestly reduced risk of coronary artery disease; Slightly lower carotid artery thickness.
Gene function and biological role
Gene Function: The APOB gene provides instructions for making apolipoprotein B, a primary structural protein essential for packaging and transporting lipids through the bloodstream. This protein exists in two main forms, with the full-length version being a critical component of very-low-density lipoprotein and low-density lipoprotein particles [1]. Apolipoprotein B acts as a key ligand that binds to LDL receptors on cell surfaces, allowing cells to absorb and clear cholesterol from circulation [2]. When this clearance process is less efficient, cholesterol-rich particles can accumulate in the blood vessels, contributing to plaque buildup [3]. Consequently, genetic variations within or near this gene are among the most well-studied determinants of inherited lipid levels and cardiovascular risk [4].
Variant Impact: The rs515135 variant is an intergenic genetic marker located near the APOB gene on chromosome 2. Although it does not directly alter the amino acid sequence of the apolipoprotein B protein, it acts as a regulatory modifier influencing how the gene is expressed. The common C allele is consistently associated with higher circulating levels of LDL cholesterol and total cholesterol across diverse populations [5]. Conversely, the less common T allele is associated with reduced expression or altered regulation that leads to lower circulating lipid levels [6]. Because of this direct impact on lipid transport, this variant is strongly linked to long-term arterial health and the risk of developing coronary artery disease [7].
Key Insight: Carrying even a single copy of the minor T allele acts as a natural shield that lowers LDL cholesterol and reduces the risk of plaque buildup in the arteries.
Location: APOB. Chromosome 2 · 2p24.1 · 21.1 Mb
Estimated prevalence by population
Global 8.9%; European 3.4%; African 22.8%; East Asian 0.9%; South Asian 2.0%; Americas 4.4%; Ashkenazi 10.6%; Finnish 3.6%; Middle Eastern 3.5%; Amish 0.9%.
Estimated TT genotype frequency.
Global 35.6%; European 30.2%; African 49.9%; East Asian 17.1%; South Asian 24.2%; Americas 33.1%; Ashkenazi 44.0%; Finnish 30.7%; Middle Eastern 30.4%; Amish 16.9%.
Estimated TC genotype frequency.
Global 55.5%; European 66.3%; African 27.3%; East Asian 82.0%; South Asian 73.9%; Americas 62.6%; Ashkenazi 45.4%; Finnish 65.7%; Middle Eastern 66.1%; Amish 82.2%.
Estimated CC genotype frequency.
Showing effects for T/T genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
LDL Cholesterol. Evidence: 10/10. Source: PMID 19060906. Lower LDL.
Total Cholesterol. Evidence: 10/10. Source: PMID 29507422. Lower Cholesterol.
Triglycerides. Evidence: 6/10. Source: PMID 29507422. Lower Triglycerides.
Heart Disease
Coronary Artery Disease. Evidence: 8/10. Source: PMID 29212778. Lower Risk.
Vascular Health & Aneurysm
Carotid Artery Thickness. Evidence: 8/10. Source: PMID 30510157. Lower Thickness.
Blood Cell & Iron Traits
Hemoglobin Levels. Evidence: 6/10. Source: PMID 32888494. Slightly Higher.
Showing effects for C/C genotype
LDL Cholesterol. Evidence: 10/10. Source: PMID 19060906. Typical LDL.
Total Cholesterol. Evidence: 10/10. Source: PMID 29507422. Typical Cholesterol.
Triglycerides. Evidence: 6/10. Source: PMID 29507422. Typical Levels.
Coronary Artery Disease. Evidence: 8/10. Source: PMID 29212778. Typical Risk.
Carotid Artery Thickness. Evidence: 8/10. Source: PMID 30510157. Typical Thickness.
Hemoglobin Levels. Evidence: 6/10. Source: PMID 32888494. Typical.
Showing effects for T/C genotype
LDL Cholesterol. Evidence: 10/10. Source: PMID 19060906. Slightly Lower LDL.
Total Cholesterol. Evidence: 10/10. Source: PMID 29507422. Slightly Lower.
Triglycerides. Evidence: 6/10. Source: PMID 29507422. Slightly Lower.
Coronary Artery Disease. Evidence: 8/10. Source: PMID 29212778. Slightly Lower Risk.
Carotid Artery Thickness. Evidence: 8/10. Source: PMID 30510157. Slightly Lower.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Inheriting two copies of the protective T allele is associated with a highly favorable cardiovascular profile. Large-scale genome-wide association studies show that this genotype is linked to significantly lower levels of low-density lipoprotein cholesterol and total cholesterol [1]. By naturally maintaining lower circulating lipid levels, this genetic profile helps limit the accumulation of plaque in the blood vessels over time [2]. Consequently, individuals with this genotype tend to have lower carotid artery intima-media thickness, which is a key marker of arterial health [3]. Research also demonstrates a corresponding reduction in the lifetime risk of developing coronary artery disease [4]. While genetics provide a strong protective baseline, maintaining a heart-healthy diet and active lifestyle remains important for long-term wellness.
Significantly lower LDL and total cholesterol levels; Reduced risk of coronary artery disease; Lower carotid artery wall thickness.
Sample genotype: CC (Homozygous)
Carrying two copies of the common C allele represents the typical genetic baseline for lipid levels and cardiovascular risk in most populations. This genotype is associated with standard levels of circulating LDL cholesterol, total cholesterol, and triglycerides [1]. Because it lacks the protective, lipid-lowering T allele, individuals with this profile do not receive a genetic shield against arterial plaque accumulation [2]. Consequently, carotid artery thickness and the risk of coronary artery disease align with standard population averages [3].
Typical population baseline for LDL and total cholesterol; Standard risk of coronary artery disease; Typical carotid artery wall thickness.
Sample genotype: TC (Heterozygous)
Having one copy of the protective T allele and one copy of the common C allele provides a moderate cardiovascular benefit. This heterozygous profile is associated with slightly lower circulating levels of LDL cholesterol, total cholesterol, and triglycerides compared to the population average [1]. Because lipid levels are slightly reduced, there is a corresponding modest reduction in the risk of plaque buildup within the arterial walls [2]. Studies tracking carotid artery thickness show that carriers of this genotype generally maintain healthier blood vessel walls over time [3]. This genetic advantage also translates to a slightly lower risk of coronary artery events [4]. Standard cardiovascular wellness practices, such as routine lipid screenings and a balanced diet, help maximize this inherited advantage.
Slightly lower LDL and total cholesterol; Modestly reduced risk of coronary artery disease; Slightly lower carotid artery thickness.
Variants with shared genetic architecture
rs1042034 · APOB Gene · Chr 2 · Cholesterol and Lipids
rs1367117 · APOB Gene · Chr 2 · Cholesterol Levels
rs4665710 · APOB Gene · Chr 2 · Blood Lipid Levels
Common variants at 30 loci contribute to polygenic dyslipidemia.
Genetic variants influencing circulating lipid levels and risk of coronary artery disease.
Genetic analyses of diverse populations improves discovery for complex traits.
The impact of low-frequency and rare variants on lipid levels.
A large electronic-health-record-based genome-wide study of serum lipids.
Content updated August 2026.
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