What you carry at this position in your DNA and what research says about it.
Cholesterol and Heart Risk: 9/10 evidence, 8 publications.
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Sample genotype (not yours): G/G
Lower Cholesterol and Reduced Heart Disease Risk
This genotype is associated with naturally lower levels of LDL and total cholesterol. It is linked to a significantly reduced risk of cardiovascular disease, though it may slightly increase the likelihood of developing gallstones.
What this genotype means: Lower LDL and total cholesterol levels; Reduced risk of cardiovascular disease; Slightly increased risk of gallstones.
Sample genotype (not yours): G/T
Typical Cholesterol Levels and Average Heart Risk
This genotype is associated with typical cholesterol absorption and average cardiovascular risk. It represents an intermediate state between the protective G/G genotype and the higher-risk T/T genotype.
What this genotype means: Typical LDL and total cholesterol levels; Average risk of cardiovascular disease; Typical risk of gallstones.
Sample genotype (not yours): T/T
Higher Cholesterol and Elevated Heart Disease Risk
This genotype is associated with increased cholesterol absorption and higher circulating lipid levels. It is linked to an elevated risk of cardiovascular disease, but a slightly lower risk of gallstones.
What this genotype means: Elevated LDL and total cholesterol levels; Increased risk of cardiovascular disease; Slightly lower risk of gallstones.
Gene function and biological role
Gene Function: The NPC1L1 gene encodes the Niemann-Pick C1-like 1 protein, which plays a critical role in cholesterol absorption [1]. This protein is primarily active in the small intestine, where it absorbs dietary and biliary cholesterol, and in the liver, where it reabsorbs cholesterol from bile [1]. By regulating how much cholesterol enters the bloodstream, NPC1L1 is a major determinant of circulating lipid levels [2]. It is also the direct molecular target of ezetimibe, a widely prescribed cholesterol-lowering medication [1]. Genetic variations that reduce NPC1L1 activity naturally mimic the effects of this drug, lowering blood cholesterol levels [2].
Variant Impact: The rs41279633 variant is located in the 5 prime untranslated region of the NPC1L1 gene, where it influences gene expression and protein production [1]. The G allele is associated with lower expression of the transporter, leading to reduced cholesterol absorption in the intestines and liver [1]. This reduction in transporter activity results in lower circulating levels of LDL and total cholesterol [3]. Conversely, the T allele increases transporter activity, leading to higher absorption of dietary cholesterol and elevated blood lipid levels [3]. Because of these effects on cholesterol transport, this variant is a key genetic marker for cardiovascular risk and response to cholesterol-lowering therapies [1].
Key Insight: This variant naturally mimics the mechanism of the cholesterol-lowering drug ezetimibe, meaning some people naturally absorb less cholesterol from their diet.
Location: NPC1L1. Chromosome 7 · 7p13 · 44.5 Mb
Estimated prevalence by population
Global 78.9%; European 70.1%; African 94.0%; East Asian 95.8%; South Asian 82.4%; Americas 85.4%; Ashkenazi 68.7%; Finnish 60.7%; Middle Eastern 75.8%; Amish 76.6%.
Estimated GG genotype frequency.
Global 19.3%; European 27.2%; African 5.9%; East Asian 4.1%; South Asian 16.7%; Americas 14.0%; Ashkenazi 28.4%; Finnish 34.4%; Middle Eastern 22.5%; Amish 21.9%.
Estimated GT genotype frequency.
Global 1.7%; European 2.6%; African 0.1%; East Asian < 0.1%; South Asian 0.8%; Americas 0.6%; Ashkenazi 2.9%; Finnish 4.9%; Middle Eastern 1.7%; Amish 1.6%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Cardiovascular & Metabolic
Lipids & Cholesterol
LDL Cholesterol. Evidence: 9/10. Source: PMID 25961943. Lower LDL.
Total Cholesterol. Evidence: 9/10. Source: PMID 29507422. Lower Cholesterol.
VLDL Cholesterol. Evidence: 9/10. Source: PMID 38448586. Lower VLDL.
Organ Systems
Digestive & Gut Disorders
Gallstones. Evidence: 6/10. Source: PMID 33339817. Slightly Higher Risk.
Showing effects for G/T genotype
LDL Cholesterol. Evidence: 9/10. Source: PMID 25961943. Typical LDL.
Total Cholesterol. Evidence: 9/10. Source: PMID 29507422. Typical.
VLDL Cholesterol. Evidence: 9/10. Source: PMID 38448586. Typical.
Gallstones. Evidence: 6/10. Source: PMID 33339817. Typical Risk.
Showing effects for T/T genotype
LDL Cholesterol. Evidence: 9/10. Source: PMID 25961943. Higher LDL.
Total Cholesterol. Evidence: 9/10. Source: PMID 29507422. Higher Cholesterol.
VLDL Cholesterol. Evidence: 9/10. Source: PMID 38448586. Higher VLDL.
Gallstones. Evidence: 6/10. Source: PMID 33339817. Slightly Lower Risk.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Having two copies of the G allele results in reduced activity of the NPC1L1 cholesterol transporter [1]. This naturally mimics the action of the cholesterol-lowering drug ezetimibe, leading to decreased absorption of dietary and biliary cholesterol [1]. As a result, individuals with this genotype tend to have lower circulating levels of LDL and total cholesterol [2]. This lifelong reduction in cholesterol levels translates to a significantly lower risk of ischemic vascular disease and heart attacks [1]. However, because less cholesterol is reabsorbed from the bile back into the liver, the concentration of cholesterol in the gallbladder increases, which can slightly elevate the risk of forming gallstones [1]. Overall, this genotype provides a strong protective effect against cardiovascular events [1].
Lower LDL and total cholesterol levels; Reduced risk of cardiovascular disease; Slightly increased risk of gallstones.
Sample genotype: GT (Heterozygous)
Carrying one copy of the G allele and one copy of the T allele results in typical levels of NPC1L1 transporter activity [1]. Cholesterol absorption in the intestines and liver is generally within the average range for the population [1]. Consequently, circulating levels of LDL and total cholesterol, as well as overall cardiovascular risk, are typical [2]. While this genotype does not confer the strong cardiovascular protection seen with the G/G genotype, it also avoids the elevated heart disease risks associated with the T/T genotype [1]. The risk of developing cholesterol-related gallstones is also intermediate and typical [1]. Maintaining a balanced diet and regular exercise remains highly effective for managing lipid levels with this genetic profile [2].
Typical LDL and total cholesterol levels; Average risk of cardiovascular disease; Typical risk of gallstones.
Sample genotype: TT (Homozygous)
Having two copies of the T allele leads to increased activity of the NPC1L1 transporter, promoting higher absorption of cholesterol from both diet and bile [1]. This increased absorption results in elevated circulating levels of LDL and total cholesterol [2]. Over a lifetime, these higher lipid levels contribute to an increased risk of plaque buildup in the arteries and ischemic vascular disease [1]. Interestingly, because more cholesterol is actively reabsorbed from the bile back into the liver, the concentration of cholesterol in the gallbladder is reduced, which slightly lowers the risk of developing gallstones [1]. Individuals with this genotype may show a more pronounced response to cholesterol-lowering strategies, particularly those targeting absorption like ezetimibe [1]. Monitoring lipid profiles and focusing on dietary cholesterol management are particularly relevant for this group [2].
Elevated LDL and total cholesterol levels; Increased risk of cardiovascular disease; Slightly lower risk of gallstones.
Variants with shared genetic architecture
rs2072183 · NPC1L1 Gene · Chr 7 · Cholesterol and Heart Risk
rs17725246 · NPC1L1 Gene · Chr 7 · Cholesterol Levels
rs2073547 · NPC1L1 Gene · Chr 7 · Cholesterol Levels
A genetic map of human metabolism across the allele frequency spectrum.
A large electronic-health-record-based genome-wide study of serum lipids.
Content updated August 2026.
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