What you carry at this position in your DNA and what research says about it.
Cholesterol and Lipid Levels: 10/10 evidence, 33 publications.
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Sample genotype (not yours): C/C
Higher HDL but Elevated Total Cholesterol
This genotype is associated with higher levels of beneficial HDL cholesterol. However, it also links to elevated total cholesterol, LDL, and triglycerides, creating a complex lipid profile.
What this genotype means: Higher HDL cholesterol; Elevated total and LDL cholesterol; Increased risk of macular degeneration.
Sample genotype (not yours): C/T
Typical Cholesterol and Lipid Profile
This genotype represents a balanced genetic influence, resulting in typical levels of HDL, LDL, and total cholesterol. Most lipid markers remain near the population average.
What this genotype means: Typical HDL and LDL cholesterol levels; Average triglyceride levels; Standard baseline risk for macular degeneration.
Sample genotype (not yours): T/T
Lower HDL but Favorable Total Cholesterol and Triglycerides
This genotype is linked to lower levels of beneficial HDL cholesterol. However, it offers a protective benefit by lowering total cholesterol, LDL, triglycerides, and the risk of macular degeneration.
What this genotype means: Lower HDL cholesterol; Reduced total and LDL cholesterol; Lower risk of macular degeneration.
Gene function and biological role
Gene Function: The ABCA1 gene encodes the ATP-binding cassette transporter A1, a crucial protein that regulates cellular cholesterol export. It acts as a cellular gatekeeper, facilitating the transfer of excess cholesterol and phospholipids to apolipoprotein A-I to form high-density lipoprotein, commonly known as HDL or good cholesterol. Proper functioning of this transporter is essential for preventing cholesterol accumulation in tissues and blood vessels. Variations in this gene can significantly alter lipid transport efficiency, directly impacting circulating blood lipid profiles. Beyond cardiovascular health, ABCA1-mediated lipid transport in the retina plays an important role in maintaining eye health.
Variant Impact: The rs1883025 variant is an intron variant located within the ABCA1 gene that influences how lipid levels are regulated in the body. This genetic change affects the expression or splicing of the transporter, leading to altered levels of circulating HDL and other blood lipids. The C allele is associated with increased levels of HDL cholesterol, which is generally considered protective for heart health. However, this same allele also correlates with higher total cholesterol, LDL, and triglycerides. Conversely, the T allele leads to lower HDL but offers a benefit by lowering other lipid markers and reducing the risk of age-related macular degeneration.
Key Insight: The same genetic variant that raises beneficial HDL cholesterol also increases total cholesterol, LDL, and triglycerides, demonstrating a complex trade-off in cardiovascular lipid markers.
Location: ABCA1. Chromosome 9 · 9q31.1 · 104.9 Mb
Estimated prevalence by population
Global 52.5%; European 55.6%; African 44.5%; East Asian 57.5%; South Asian 39.6%; Americas 52.2%; Ashkenazi 57.2%; Finnish 66.9%; Middle Eastern 46.3%; Amish 53.0%.
Estimated CC genotype frequency.
Global 39.6%; European 37.9%; African 44.4%; East Asian 36.6%; South Asian 46.7%; Americas 40.1%; Ashkenazi 36.9%; Finnish 29.7%; Middle Eastern 43.5%; Amish 39.6%.
Estimated CT genotype frequency.
Global 7.9%; European 6.5%; African 11.1%; East Asian 5.8%; South Asian 13.7%; Americas 7.7%; Ashkenazi 5.9%; Finnish 3.3%; Middle Eastern 10.2%; Amish 7.4%.
Estimated TT genotype frequency.
Showing effects for C/C genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
HDL Cholesterol. Evidence: 10/10. Source: PMID 20686565. Higher HDL.
Total Cholesterol. Evidence: 10/10. Source: PMID 20686565. Higher Cholesterol.
Triglycerides. Evidence: 9/10. Source: PMID 29507422. Higher Triglycerides.
LDL Cholesterol. Evidence: 10/10. Source: PMID 29507422. Higher LDL.
Obesity & Body Composition
Waist-to-Hip Ratio. Evidence: 7/10. Source: PMID 30595370. Higher Ratio.
Organ Systems
Vision & Eye Health
Macular Degeneration. Evidence: 4/10. Source: PMID 24223199. Higher Risk.
Showing effects for C/T genotype
HDL Cholesterol. Evidence: 10/10. Source: PMID 20686565. Typical HDL.
Total Cholesterol. Evidence: 10/10. Source: PMID 20686565. Typical Cholesterol.
Triglycerides. Evidence: 9/10. Source: PMID 29507422. Typical Levels.
LDL Cholesterol. Evidence: 10/10. Source: PMID 29507422. Typical LDL.
Waist-to-Hip Ratio. Evidence: 7/10. Source: PMID 30595370. Typical Ratio.
Macular Degeneration. Evidence: 4/10. Source: PMID 24223199. Typical Risk.
Showing effects for T/T genotype
HDL Cholesterol. Evidence: 10/10. Source: PMID 20686565. Lower HDL.
Total Cholesterol. Evidence: 10/10. Source: PMID 20686565. Lower Cholesterol.
Triglycerides. Evidence: 9/10. Source: PMID 29507422. Lower Triglycerides.
LDL Cholesterol. Evidence: 10/10. Source: PMID 29507422. Lower LDL.
Waist-to-Hip Ratio. Evidence: 7/10. Source: PMID 30595370. Lower Ratio.
Macular Degeneration. Evidence: 4/10. Source: PMID 24223199. Lower Risk.
What this genotype means for the people who carry it
Sample genotype: CC (Homozygous)
Carrying two copies of the C allele promotes higher levels of high-density lipoprotein (HDL) cholesterol, which helps clear cholesterol from the bloodstream. Large-scale genetic studies show that this genotype increases HDL by about 0.08 standard deviations per allele. However, this lipid-clearing efficiency comes with a trade-off, as it also correlates with higher total cholesterol and LDL levels. Triglycerides and VLDL levels are also typically elevated in individuals with this profile. Furthermore, the higher circulating HDL levels associated with this genotype have been linked to an increased risk of age-related macular degeneration. This dual effect means that while some cardiovascular markers are favorable, others may require closer attention through diet and lifestyle. Regular cardiovascular screening and maintaining an active lifestyle can help optimize this complex lipid balance.
Higher HDL cholesterol; Elevated total and LDL cholesterol; Increased risk of macular degeneration.
Sample genotype: CT (Heterozygous)
Carrying one C allele and one T allele results in an intermediate lipid profile that closely mirrors the general population average. The opposing genetic forces of the C allele (which raises HDL and total cholesterol) and the T allele (which lowers them) balance each other out. Consequently, there is no strong genetic push toward either exceptionally high or low cholesterol levels. Risk factors for lipid-related conditions, such as metabolic syndrome or high cholesterol, remain at baseline levels. Similarly, the risk of developing age-related macular degeneration is typical, without the elevated risk of the C/C genotype or the protective effect of the T/T genotype. Standard dietary habits and regular exercise are generally sufficient to maintain healthy lipid levels for individuals with this genetic background. This genotype provides a stable, baseline foundation for cardiovascular and metabolic health.
Typical HDL and LDL cholesterol levels; Average triglyceride levels; Standard baseline risk for macular degeneration.
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele is associated with reduced levels of HDL cholesterol, which is often referred to as a risk factor for cardiovascular issues. However, this genetic profile also provides significant metabolic advantages by lowering total cholesterol, LDL, and triglycerides. These lower levels of circulating bad lipids can help reduce overall cardiovascular burden. Additionally, the lower HDL levels associated with this genotype are linked to a reduced risk of developing age-related macular degeneration. Research also suggests that the cardiovascular risks of lower HDL in this genotype may be mitigated by a high-protein diet. Therefore, while the low HDL number on a standard blood test might seem concerning, the overall lipid profile has several protective elements. Focus should remain on maintaining a healthy diet and regular physical activity to support overall metabolic wellness.
Lower HDL cholesterol; Reduced total and LDL cholesterol; Lower risk of macular degeneration.
Variants with shared genetic architecture
rs1800978 · ABCA1 Gene · Chr 9 · Heart and Lipid Health
rs2066718 · ABCA1 Gene · Chr 9 · Cholesterol and Heart Health
rs2472493 · ABCA1 Gene · Chr 9 · Glaucoma and Eye Pressure
Content updated August 2026.
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