What you carry at this position in your DNA and what research says about it.
Macular Degeneration Risk: 10/10 evidence, 61 publications.
You're viewing every possible genotype for this variant.
None of these is your result. Use the genotype toggle to compare them, then sign up and upload your DNA to see which one is yours.
Sample genotype (not yours): G/G
Typical Macular Degeneration Risk
Carrying two copies of the common G allele is associated with typical complement system activity and a standard baseline risk of developing age-related macular degeneration.
What this genotype means: Typical complement system regulation; Baseline risk for age-related macular degeneration.
Sample genotype (not yours): C/C
Significantly Higher Macular Degeneration Risk
Carrying two copies of the C allele is associated with a significantly elevated risk of developing advanced age-related macular degeneration.
What this genotype means: Increased complement system activation; Significantly elevated risk of advanced macular degeneration.
Sample genotype (not yours): G/C
Increased Macular Degeneration Risk
Carrying one copy of the C allele is linked to a moderately higher risk of developing age-related macular degeneration.
What this genotype means: Altered complement system activity; Moderately increased risk of macular degeneration.
Gene function and biological role
Gene Function: Complement C3 encodes the central protein of the complement system, a crucial part of the innate immune response [1]. This system helps clear pathogens and cellular debris, but its overactivation can lead to chronic inflammatory tissue damage [2]. The C3 protein is cleaved into active fragments that coordinate inflammatory cascades and cell lysis [3]. Genetic variations in this gene are heavily implicated in susceptibility to inflammatory and degenerative diseases, particularly in the eye [2].
Variant Impact: The rs2230199 variant is a missense mutation in the C3 gene that changes the amino acid at position 102 from arginine to glycine [1]. This change alters the electrophoretic mobility of the C3 protein, historically distinguishing the fast and slow allotypes [4]. The glycine-encoding C allele is associated with increased complement activation and inflammatory deposition [3]. This functional alteration directly influences susceptibility to age-related macular degeneration by promoting chronic inflammation in retinal tissues [5].
Key Insight: This variant historically defined the fast and slow allotypes of the complement C3 protein, which were discovered decades before their genetic link to macular degeneration was established.
Location: C3. Chromosome 19 · 19p13.3 · 6.7 Mb
Estimated prevalence by population
Global 74.2%; European 62.7%; African 90.8%; East Asian 99.8%; South Asian 76.5%; Americas 78.6%; Ashkenazi 62.8%; Finnish 67.0%; Middle Eastern 67.2%; Amish 87.5%.
Estimated GG genotype frequency.
Global 23.2%; European 33.0%; African 9.0%; East Asian 0.2%; South Asian 22.0%; Americas 20.2%; Ashkenazi 32.9%; Finnish 29.7%; Middle Eastern 29.6%; Amish 12.1%.
Estimated GC genotype frequency.
Global 2.6%; European 4.3%; African 0.2%; East Asian < 0.1%; South Asian 1.6%; Americas 1.3%; Ashkenazi 4.3%; Finnish 3.3%; Middle Eastern 3.3%; Amish 0.4%.
Estimated CC genotype frequency.
Showing effects for G/G genotype
Organ Systems
Vision & Eye Health
Macular Degeneration. Evidence: 10/10. Source: PMID 25688879. Typical Risk.
Dry Macular Degeneration. Evidence: 10/10. Source: PMID 22705344. Typical Risk.
Wet Macular Degeneration. Evidence: 10/10. Source: PMID 22705344. Typical Risk.
Retinopathy. Evidence: 8/10. Source: PMID 39024449. Typical Risk.
Immunity & Inflammation
Inflammatory & Circulating Protein Markers
Complement C3d Levels. Evidence: 6/10. Source: PMID 34814699. Typical Levels.
Showing effects for C/C genotype
Macular Degeneration. Evidence: 10/10. Source: PMID 25688879. ~2.5x Increased Risk.
Dry Macular Degeneration. Evidence: 10/10. Source: PMID 22705344. ~1.8x Increased Risk.
Wet Macular Degeneration. Evidence: 10/10. Source: PMID 22705344. ~1.6x Increased Risk.
Retinopathy. Evidence: 8/10. Source: PMID 39024449. Increased Risk.
Complement C3d Levels. Evidence: 6/10. Source: PMID 34814699. Increased Levels.
Showing effects for G/C genotype
Macular Degeneration. Evidence: 10/10. Source: PMID 25688879. ~1.6x Increased Risk.
Dry Macular Degeneration. Evidence: 10/10. Source: PMID 22705344. Increased Risk.
Wet Macular Degeneration. Evidence: 10/10. Source: PMID 22705344. Increased Risk.
Complement C3d Levels. Evidence: 6/10. Source: PMID 34814699. Slightly Increased.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Arginine at position 102 represents the ancestral form of the complement C3 protein, which plays a critical role in the body's innate immune response [1]. Having two copies of this G allele is associated with normal regulation of the complement cascade, preventing the overactivation that can damage retinal tissues over time [2]. Large-scale genetic studies consistently show that this genotype does not elevate the risk for either dry or wet forms of macular degeneration [3]. Consequently, individuals with this profile exhibit baseline susceptibility to age-related vision loss [4].
Typical complement system regulation; Baseline risk for age-related macular degeneration.
Sample genotype: CC (Homozygous)
Two copies of the C allele result in complement C3 proteins entirely consisting of the glycine-102 variant [1]. This complete substitution is strongly linked to hyperactivation of the complement system, which promotes inflammatory damage and deposit formation beneath the retina [2]. Research demonstrates that this genotype carries a 2.5-fold or greater risk of developing age-related macular degeneration compared to the common genotype [3]. The risk is pronounced for advanced stages of the disease, including geographic atrophy and choroidal neovascularization [4].
Increased complement system activation; Significantly elevated risk of advanced macular degeneration.
Sample genotype: GC (Heterozygous)
A single copy of the C allele alters the complement C3 protein by substituting glycine for arginine at position 102 [1]. This structural change is thought to increase the stability or activity of the complement system, leading to low-grade, chronic inflammation in the retina [2]. Clinical data indicates that heterozygotes face approximately a 1.6-fold increased risk of developing age-related macular degeneration [3]. This elevated risk applies to both dry geographic atrophy and wet neovascular subtypes of the disease [4].
Altered complement system activity; Moderately increased risk of macular degeneration.
Variants with shared genetic architecture
rs1047286 · C3 Gene · Chr 19 · Macular Degeneration Risk
rs10737680 · CFH Gene · Chr 1 · Macular Degeneration Risk
rs34882957 · C9 Gene · Chr 5 · Macular Degeneration Risk
Molecular basis of polymorphisms of human complement component C3.
Variation in complement factor 3 is associated with risk of age-related macular degeneration.
Complement C3 variant and the risk of age-related macular degeneration.
Content updated September 2026.
ReadYourDNA provides educational interpretation of DNA data you already have. It is not diagnostic, not a substitute for professional medical advice, diagnosis, or treatment, and is not intended to diagnose, treat, cure, or prevent any disease. Talk to a clinician before acting on any result.
Raw DNA Data Reports for 23andMe & AncestryDNA · About ReadYourDNA · FAQ · Methodology & Science · Pricing · Support and complaints · Legal & Contact · Health Traits · Pharmacogenomics · Carrier Status · Variant Explorer · The Human Karyotype · Privacy Policy · Terms of Service · Accessibility · Consumer Health Data Privacy · Your Privacy Choices · Editorial Standards · Your Data, Checkable · Sample Report · ReadYourDNA and Promethease compared · What is inside a 23andMe raw data file · What is inside an AncestryDNA raw data file · What a chatbot can and cannot do with your raw DNA file · Where a raw DNA file can still be uploaded in 2026
Written, maintained and operated by Martin Pechhacker, sole proprietor, Vienna, Austria. Trade register GISA 40064420. support@readyourdna.com