CFH rs3916966: Understanding Your Genetic Risk for AMD
The rs3916966 variant is a common genetic marker located within the CFH gene, which plays a critical role in regulating the body's immune system. Research has established that this variant is associated with an increased risk of developing age-related macular degeneration (AMD), a condition that affects central vision in older adults.
What each genotype means
Typical macular degeneration risk
You carry two copies of the common C allele at rs3916966 in the CFH gene. In published genome-wide and candidate gene evaluations, this genotype is considered the baseline reference profile and is not associated with elevated genetic risk for age-related macular degeneration. Evidence evaluating this specific non-coding marker independently is limited, and overall eye health depends significantly on lifestyle factors, age, and major complement pathway risk variants.
Carried by approximately 38% to 40% of individuals of European ancestry, and common across many global populations.
Slightly altered risk profile
You carry one copy of the T allele and one copy of the C allele at rs3916966. Some association studies have evaluated the T allele as a tagging or minor variant within the CFH locus for risk of age-related macular degeneration, but independent clinical evidence remains limited and mixed. This genotype alone does not cause vision loss and represents only a minor statistical variation among many contributing genetic and environmental factors.
Carried by approximately 45% to 48% of individuals of European ancestry.
Modest risk-associated profile
You carry two copies of the minor T allele at rs3916966 in the CFH locus. While early association studies assessed this variant for potential links to age-related macular degeneration, direct evidence demonstrating an independent causal impact remains limited, as much of the statistical signal in CFH is driven by other primary variants such as Y402H. Having this genotype does not mean you will develop macular degeneration, and regular comprehensive eye examinations remain the standard way to monitor macular health.
Carried by approximately 14% to 16% of individuals of European ancestry.
What is rs3916966?
The rs3916966 variant is a single-nucleotide polymorphism (SNP) situated within an intron of the complement factor H (CFH) gene on chromosome 1. Because this variant is located in a noncoding region, it does not directly alter the structure of the protein produced by the gene. Instead, it serves as a genetic marker that is often inherited alongside other functional changes within the CFH gene. These linked variations are collectively involved in how the body manages the complement system, a part of the innate immune response. Scientists use this SNP to track specific genetic patterns that have been statistically linked to eye health outcomes in large population studies.
The Role of the CFH Gene
The CFH gene provides the blueprint for the complement factor H protein. This protein acts as a vital regulator of the alternative complement pathway, which is a component of the immune system that helps clear pathogens and cellular debris. By controlling this pathway, complement factor H prevents the immune system from accidentally damaging healthy tissues. When the function of this protein is impaired or altered by genetic variations, it can lead to chronic, low-level inflammation. In the context of the eye, this inflammation is thought to contribute to the formation of drusen—small yellow deposits under the retina—which are a hallmark of age-related macular degeneration.
Research and Evidence Strength
The association between variants in the CFH gene and age-related macular degeneration is well-documented in scientific literature. Multiple genome-wide association studies have identified that common variants in this region significantly influence the risk of developing AMD. While rs3916966 is a recognized marker, it is important to note that genetic risk is complex and multifactorial. The evidence for this specific variant is considered strong in the context of its linkage to functional polymorphisms that affect complement regulation. However, having a risk-associated genotype does not guarantee that an individual will develop the condition. AMD is influenced by a combination of genetic factors, environmental exposures, and lifestyle choices, such as smoking and diet.
What You Can Do With This Information
Understanding your genetic predisposition can be a useful tool for personal health awareness, but it should not be used to diagnose or predict medical outcomes. If you are concerned about your vision or have a family history of macular degeneration, the most important step is to consult with an eye care professional, such as an ophthalmologist or optometrist. They can provide comprehensive eye exams and discuss personalized screening schedules based on your overall health profile. Because AMD risk is also heavily influenced by non-genetic factors, maintaining a healthy lifestyle—including regular exercise, a balanced diet rich in leafy greens, and avoiding smoking—is generally recommended for supporting long-term eye health.
How common is this variant?
The rs3916966 variant is common in populations of European descent, where it has been extensively studied in the context of age-related macular degeneration.
Frequently asked questions
Does having the rs3916966 variant mean I will get AMD?
No. Genetic variants only indicate a statistical increase in risk. Many people with this variant never develop AMD, and many people without it do.
Can I change my genetic risk for AMD?
You cannot change your DNA, but you can manage modifiable risk factors. Lifestyle choices like not smoking and eating a healthy diet are known to support eye health.
Should I get tested for this SNP?
Genetic testing for AMD is generally not recommended for the general population. Discuss your concerns with an eye doctor who can assess your actual clinical risk.
What is the link between CFH and the immune system?
The CFH gene produces a protein that prevents the immune system from overreacting. When this regulation is disrupted, it can lead to inflammation in the eye.
Sources & further reading
Educational information only, last refreshed 10/18/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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This regulatory variant in the CFH locus is linked to complement system dysregulation and is a recognized genetic risk factor for age-related macular degeneration.
This variant in the complement factor H gene is associated with altered regulation of the alternative complement pathway and increased susceptibility to age-related macular degeneration.
Intronic single nucleotide variant in the CFH region associated with susceptibility to age-related macular degeneration (AMD).
Common variant in the CFH locus strongly associated with risk of age-related macular degeneration (AMD).
Intronic marker in CFH forming critical susceptibility haplotypes for choroidal neovascularization and macular atrophy.
Intergenic/intronic variant within the CFH cluster contributing to phenotypic variation in retinal complement activation.