What you carry at this position in your DNA and what research says about it.
Cholesterol and Heart Risk: 10/10 evidence, 127 publications.
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Sample genotype (not yours): C/C
Typical Cholesterol and Heart Risk
This genotype is the most common and represents the baseline for lipid clearance. It is associated with typical levels of LDL cholesterol and standard cardiovascular and cognitive risk profiles.
What this genotype means: Typical LDL cholesterol levels; Baseline risk for Alzheimer's disease; Standard response to statin therapy.
Sample genotype (not yours): C/T
Lower LDL Cholesterol and Heart Risk
Carrying one copy of the T allele typically lowers LDL cholesterol levels. This genotype is associated with a reduced risk of both coronary artery disease and Alzheimer's disease.
What this genotype means: Lower circulating LDL cholesterol; Reduced risk of late-onset Alzheimer's disease; Slightly higher triglyceride levels.
Sample genotype (not yours): T/T
Very Low LDL but High Triglyceride Risk
Two copies of the T allele lead to the lowest LDL cholesterol and Alzheimer's risk. However, it also significantly increases the risk of high triglycerides and a rare lipid clearance disorder.
What this genotype means: Significantly lower LDL cholesterol; Elevated risk of high triglycerides; Increased susceptibility to Type III hyperlipoproteinemia.
Gene function and biological role
Gene Function: The APOE gene provides instructions for making apolipoprotein E, a crucial protein involved in lipid metabolism [1]. This protein acts as a vehicle to package and transport cholesterol and other fats through the bloodstream [1]. It is produced primarily by the liver and by cells in the central nervous system [2]. In the brain, apolipoprotein E plays a vital role in clearing cellular debris and regulating beta-amyloid proteins [3]. Variations in this gene significantly influence an individual's susceptibility to cardiovascular disease and cognitive decline [4].
Variant Impact: This variant, rs7412, is a missense mutation in the APOE gene that changes the amino acid arginine to cysteine at position 176 [5]. This single amino acid substitution alters the structure of the apolipoprotein E protein, reducing its binding affinity for low-density lipoprotein receptors [6]. As a result, the clearance of fat particles from the blood is modified, typically leading to lower levels of circulating LDL cholesterol [7]. This specific genetic change is the defining marker for the protective ApoE2 isoform [2]. However, in rare cases, it can also lead to a lipid clearance disorder when inherited in two copies [8].
Key Insight: While the T allele generally protects against heart disease and Alzheimer's, having two copies can paradoxically trigger a rare lipid clearance disorder called Type III hyperlipoproteinemia.
Location: APOE. Chromosome 19 · 19q13.32 · 44.9 Mb
Estimated prevalence by population
Global 85.1%; European 84.8%; African 80.2%; East Asian 84.6%; South Asian 92.7%; Americas 91.8%; Ashkenazi 86.6%; Finnish 91.8%; Middle Eastern 90.6%; Amish 97.6%.
Estimated CC genotype frequency.
Global 14.2%; European 14.6%; African 18.7%; East Asian 14.7%; South Asian 7.2%; Americas 8.0%; Ashkenazi 12.9%; Finnish 8.0%; Middle Eastern 9.1%; Amish 2.4%.
Estimated CT genotype frequency.
Global 0.7%; European 0.6%; African 1.1%; East Asian 0.6%; South Asian 0.1%; Americas 0.2%; Ashkenazi 0.5%; Finnish 0.2%; Middle Eastern 0.2%; Amish < 0.1%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
LDL Cholesterol. Evidence: 10/10. Source: PMID 34887591. Typical.
Triglycerides. Evidence: 10/10. Source: PMID 29507422. Typical.
Heart Disease
Coronary Artery Disease. Evidence: 10/10. Source: PMID 36474045. Typical Risk.
Neurology & Mental Health
Neurodegenerative Diseases
Alzheimer's Disease. Evidence: 10/10. Source: PMID 39023044. Typical Risk.
Pharmacogenomics
Lipid-Lowering Drug Response
Statin Response. Evidence: 10/10. Source: PMID 20031551. Reduced Efficacy.
Organ Systems
Digestive & Gut Disorders
Gallstones. Evidence: 10/10. Source: PMID 34651315. Typical Risk.
Showing effects for C/T genotype
LDL Cholesterol. Evidence: 10/10. Source: PMID 34887591. Lowered.
Triglycerides. Evidence: 10/10. Source: PMID 29507422. Slightly Elevated.
Coronary Artery Disease. Evidence: 10/10. Source: PMID 36474045. Lowered Risk.
Alzheimer's Disease. Evidence: 10/10. Source: PMID 39023044. Lowered Risk.
Statin Response. Evidence: 10/10. Source: PMID 20031551. Typical Response.
Gallstones. Evidence: 10/10. Source: PMID 34651315. Slightly Higher Risk.
Showing effects for T/T genotype
LDL Cholesterol. Evidence: 10/10. Source: PMID 34887591. Significantly Lowered.
Triglycerides. Evidence: 10/10. Source: PMID 29507422. Elevated Risk.
Coronary Artery Disease. Evidence: 10/10. Source: PMID 36474045. Variable Risk.
Alzheimer's Disease. Evidence: 10/10. Source: PMID 39023044. Lowest Risk.
Gallstones. Evidence: 10/10. Source: PMID 34651315. Higher Risk.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Having two copies of the C allele is the most common genetic profile globally [1]. This genotype typically results in standard levels of apolipoprotein E, which efficiently clears most fat particles but maintains baseline levels of circulating LDL cholesterol [2]. Because it lacks the protective T allele, it does not convey the reduced risk of Alzheimer's disease or coronary artery disease seen in carriers of the minor allele [3]. However, it also avoids the elevated triglyceride levels and the risk of rare lipid disorders associated with the homozygous minor genotype [4]. Individuals with this genotype generally show a standard response to common cholesterol-lowering statin medications [5].
Typical LDL cholesterol levels; Baseline risk for Alzheimer's disease; Standard response to statin therapy.
Sample genotype: CT (Heterozygous)
Inheriting one copy of the T allele produces the ApoE2 protein isoform alongside the common ApoE3 isoform [1]. This combination reduces the overall levels of low-density lipoprotein (LDL) cholesterol in the bloodstream [2]. Consequently, individuals with this genotype enjoy a naturally lower risk of developing coronary artery disease [3]. Furthermore, the ApoE2 isoform is highly efficient at clearing amyloid plaques in the brain, leading to a significantly reduced risk of late-onset Alzheimer's disease [4]. On the other hand, this genotype can slightly increase circulating triglyceride levels [5]. It may also influence how the body responds to certain medications, such as greater sensitivity to warfarin or variable responses to statins [6]. Overall, this profile is highly favorable for cardiovascular and cognitive longevity [7].
Lower circulating LDL cholesterol; Reduced risk of late-onset Alzheimer's disease; Slightly higher triglyceride levels.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele means only the ApoE2 protein isoform is produced [1]. This results in exceptionally low levels of circulating LDL cholesterol and the lowest genetic risk for late-onset Alzheimer's disease [2]. However, the ApoE2 protein has a severely reduced binding affinity for lipoprotein receptors, which can impair the clearance of other fat particles [3]. This impairment often leads to significantly elevated triglyceride levels [4]. In some individuals, particularly when combined with factors like obesity or diabetes, this can trigger a rare condition called Type III hyperlipoproteinemia [5]. This disorder causes fatty deposits to build up in blood vessels, paradoxically increasing the risk of premature cardiovascular disease despite low LDL [6].
Significantly lower LDL cholesterol; Elevated risk of high triglycerides; Increased susceptibility to Type III hyperlipoproteinemia.
Variants with shared genetic architecture
rs429358 · APOE Gene · Chr 19 · Alzheimer's Disease Risk
rs769449 · APOE Gene · Chr 19 · Alzheimer's Disease Risk
rs449647 · APOE Gene · Chr 19 · Alzheimer Risk and ApoE Levels
Genome-wide characterization of circulating metabolic biomarkers.
Genotyping and sequence analysis of apolipoprotein E isoforms.
Diversity and scale: Genetic architecture of 2068 traits in the VA Million Veteran Program.
Isolation and characterisation of a variant allele of the gene for human apolipoprotein E.
The power of genetic diversity in genome-wide association studies of lipids.
Genome-wide meta-analysis identifies ancestry-specific loci for Alzheimer's disease.
Polymorphisms in the apolipoprotein A5 (APOA5) gene and type III hyperlipidemia.
A large electronic-health-record-based genome-wide study of serum lipids.
Content updated August 2026.
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