What you carry at this position in your DNA and what research says about it.
Coronary Heart Disease Risk: 10/10 evidence, 28 publications.
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Sample genotype (not yours): G/G
Typical Coronary and Immune Health
Typical risk of coronary events and standard immune cell counts are expected. Standard progression rates are observed for viral infections.
What this genotype means: Typical risk of cardiovascular events; Standard retinal immune cell function.
Sample genotype (not yours): A/A
Lower Coronary Risk but Higher Macular and Immune Risks
Two copies of the variant allele lower coronary risk but are linked to faster HIV progression and higher macular degeneration risk.
What this genotype means: Significantly lower risk of coronary artery disease; Increased risk of age-related macular degeneration; Faster progression of HIV infection if exposed.
Sample genotype (not yours): G/A
Lower Risk of Coronary Events
A single copy of the variant allele is linked to a reduced risk of acute coronary events. Immune function and macular health remain largely typical.
What this genotype means: Reduced risk of acute coronary events; Largely typical immune and retinal health.
Gene function and biological role
Gene Function: The CX3CR1 gene encodes the fractalkine receptor, a specialized protein found on the surface of immune cells like monocytes, microglia, and killer T cells [1]. This receptor plays a vital role in guiding immune cells to sites of inflammation and injury throughout the body [1]. By binding to its unique partner molecule, fractalkine, the receptor helps regulate cellular adhesion, migration, and survival [2]. Proper functioning of this pathway is crucial for maintaining cardiovascular health, protecting the retina, and mounting effective immune responses against viral pathogens [1] [2].
Variant Impact: The rs3732378 variant represents a missense mutation in the CX3CR1 gene, resulting in the replacement of the amino acid threonine with methionine at position 280 of the receptor protein [1]. This structural change, often referred to as p.Thr280Met or T280M, alters the receptor's binding pocket and reduces its overall signaling efficiency [3]. Because the receptor is less active, immune cells do not adhere as strongly to blood vessel walls, which can influence inflammatory processes [1]. This reduction in cellular adhesion and migration has downstream effects on blood cell counts, cardiovascular plaque formation, and retinal health [1] [3].
Key Insight: The same genetic variant that helps protect your blood vessels from plaque buildup can also make it harder for immune cells to protect your eyes and fight off certain viral infections.
Location: CX3CR1. Chromosome 3 · 3p22.2 · 39.3 Mb
Estimated prevalence by population
Global 77.7%; European 68.7%; African 93.5%; East Asian 95.0%; South Asian 80.2%; Americas 75.2%; Ashkenazi 67.6%; Finnish 69.5%; Middle Eastern 80.5%; Amish 88.3%.
Estimated GG genotype frequency.
Global 20.5%; European 28.4%; African 6.4%; East Asian 4.9%; South Asian 18.7%; Americas 23.0%; Ashkenazi 29.3%; Finnish 27.8%; Middle Eastern 18.4%; Amish 11.3%.
Estimated GA genotype frequency.
Global 1.9%; European 2.9%; African 0.1%; East Asian 0.1%; South Asian 1.1%; Americas 1.8%; Ashkenazi 3.2%; Finnish 2.8%; Middle Eastern 1.1%; Amish 0.4%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Cardiovascular & Metabolic
Heart Disease
Coronary Artery Disease. Evidence: 3/10. Source: PMID 11264153. Typical Risk.
Blood Cell & Iron Traits
Monocyte Count. Evidence: 10/10. Source: PMID 32888494. Typical.
Organ Systems
Vision & Eye Health
Macular Degeneration. Evidence: 3/10. Source: PMID 24287500. Typical Risk.
Immunity & Inflammation
Infection Susceptibility & Resistance
HIV Progression Rate. Evidence: 3/10. Source: PMID 10731151. Typical Rate.
Endocrine & Reproductive
Hormone Levels & Endocrine Regulation
Hypothyroidism. Evidence: 8/10. Source: PMID 41238958. Typical Risk.
Showing effects for A/A genotype
Coronary Artery Disease. Evidence: 3/10. Source: PMID 11264153. Lower Risk.
Monocyte Count. Evidence: 10/10. Source: PMID 32888494. Higher.
Macular Degeneration. Evidence: 3/10. Source: PMID 24287500. Increased Risk.
HIV Progression Rate. Evidence: 3/10. Source: PMID 10731151. Faster Progression.
Hypothyroidism. Evidence: 8/10. Source: PMID 41238958. Slightly Higher Risk.
Showing effects for G/A genotype
Monocyte Count. Evidence: 10/10. Source: PMID 32888494. Slightly Higher.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Carrying two copies of the standard G allele results in a fully functional CX3CR1 receptor that exhibits typical binding to its partner molecule, fractalkine [1]. This standard receptor activity ensures normal immune cell migration and adhesion to blood vessel walls during inflammatory responses [1]. Consequently, cardiovascular risk remains at the typical baseline level for the general population [1]. Retinal microglia cells also function normally, maintaining standard protection against age-related macular degeneration [2]. In the event of viral exposure, such as HIV, the standard receptor allows for typical disease progression rates rather than accelerated progression [3]. Blood cell measurements, including monocyte and white blood cell counts, generally fall within standard reference ranges [4]. Overall, this genotype represents the most common genetic baseline across global populations.
Typical risk of cardiovascular events; Standard retinal immune cell function.
Sample genotype: AA (Homozygous)
Carrying two copies of the A allele significantly reduces the signaling efficiency and binding capacity of the CX3CR1 receptor [1]. This pronounced reduction in receptor activity prevents immune cells from adhering strongly to blood vessel walls, which provides a strong protective effect against coronary artery disease and acute cardiac events [1]. However, this same lack of immune cell mobility has negative consequences in other tissues. In the eye, impaired immune cell function is linked to an increased risk of developing age-related macular degeneration [2]. In the context of viral infections, particularly HIV, the altered receptor is associated with a faster progression to advanced disease stages [3]. Additionally, this genotype is linked to slightly higher baseline monocyte counts and a minor increase in the risk of developing hypothyroidism [4] [5]. Managing overall cardiovascular risk factors remains beneficial, while regular eye exams can help monitor retinal health.
Significantly lower risk of coronary artery disease; Increased risk of age-related macular degeneration; Faster progression of HIV infection if exposed.
Sample genotype: GA (Heterozygous)
Carrying one copy of the A allele produces a mixture of standard and altered CX3CR1 receptors, leading to a mild reduction in overall receptor signaling [1]. This slight decrease in receptor activity reduces the stickiness of immune cells, making them less likely to accumulate on blood vessel walls [1]. As a result, clinical studies have observed a protective effect, showing a reduced risk of acute coronary events and slower progression of plaque buildup [1]. Most other health markers, including retinal health and susceptibility to macular degeneration, remain close to typical baseline levels [2]. Immune system responses to viral infections also appear largely unaffected in single-copy carriers [3]. Standard blood cell counts are generally maintained, though minor variations in monocyte levels may occur [4]. This heterozygous state offers a favorable balance by providing cardiovascular benefits without significant immune drawbacks.
Reduced risk of acute coronary events; Largely typical immune and retinal health.
Variants with shared genetic architecture
rs3732379 · CX3CR1 Gene · Chr 3 · Macular Degeneration Risk
rs1042663 · C2 Gene · Chr 6 · Macular Degeneration Risk
rs10096633 · LPL Gene · Chr 8 · Triglycerides and Heart Health
Fractalkine receptor/ligand genetic variants and carotid intima-media thickness.
The Polygenic and Monogenic Basis of Blood Traits and Diseases.
Genome-wide association study and polygenic risk prediction of hypothyroidism.
Content updated August 2026.
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