FLT1 rs61818925: Retinal Microvasculature and Retinal Health
The rs61818925 single nucleotide polymorphism is an intronic genetic variant located within the FLT1 gene, also recognized as VEGFR1. Large-scale ophthalmic genetic studies have linked this locus to subtle differences in retinal vascular caliber—the measurable width of the tiny blood vessels behind the eye—and complex vascular susceptibility traits such as diabetic retinopathy. However, because its individual statistical contribution is modest, current scientific evidence for predicting clinical eye disease from this single marker remains limited.
What each genotype means
Typical retinal vessel caliber
You carry two copies of the common C allele for this variant in the FLT1 gene. Research suggests this genotype is associated with baseline retinal vascular diameter and standard susceptibility to microvascular complications such as diabetic retinopathy. Because evidence linking this locus to vascular changes is limited, lifestyle and routine medical screenings remain the primary determinants of eye health.
Carried by approximately 65% to 75% of individuals across European and East Asian populations.
Slightly altered retinal caliber
You carry one copy of the T minor allele at the rs61818925 locus. Some association studies suggest that this variant may modestly influence retinal blood vessel caliber and vascular signaling mediated by FLT1 (VEGFR1). However, the evidence remains limited, and carrying this allele does not diagnose or guarantee the development of diabetic retinopathy or related vascular conditions.
Carried by roughly 25% to 30% of individuals in European and East Asian ancestries.
Altered retinal vascular caliber
You carry two copies of the less common T allele in the FLT1 gene. Published genome-wide research has tentatively associated this genotype with subtle shifts in retinal microvascular caliber and potential alterations in angiogenic pathway sensitivity. Current scientific evidence is preliminary and limited, meaning this genotype should be interpreted as a slight statistical variation rather than a clinical indicator.
Carried by approximately 2% to 4% of individuals in European and East Asian populations.
Genomic Context and the Biology of FLT1
The rs61818925 polymorphism is situated on chromosome 13 within the non-coding intronic region of the FLT1 gene. FLT1 encodes fms-related receptor tyrosine kinase 1, an essential cell-surface receptor commonly called vascular endothelial growth factor receptor 1 (VEGFR1). This receptor serves as an integral regulator within the vascular endothelial growth factor (VEGF) signaling pathway, which orchestrates angiogenesis (new blood vessel formation) and controls the permeability and structural maintenance of the body's microvasculature. In delicate structures such as the human retina, precise VEGF signaling is paramount to ensure proper oxygenation without triggering pathological vessel leakage, excessive vessel branching, or fragile neovascular proliferation.
Associated Traits: Vascular Caliber and Diabetic Retinopathy
Genome-wide association studies (GWAS) measuring structural parameters of the human fundus have identified genetic signals near FLT1 in connection with retinal vascular caliber—specifically variations in arteriolar and venular diameter. Because systemic vascular states, metabolic dysfunction, and aging frequently manifest early in the retinal microcirculation, investigators have examined whether variations like rs61818925 influence susceptibility to microvascular complications, including diabetic retinopathy. In individuals living with diabetes, altered vascular signaling can impair retinal capillary integrity, potentially leading to swelling, ischemia, and vision-threatening neovascularization. While statistically significant cohort-level associations have been documented, the evidence strength is currently classified as limited because the effect size of the single variant is minor and heavily modulated by systemic health factors.
Ancestry and Population Distribution
The frequency of the rs61818925 minor allele varies across global biogeographical groups. Genomic reference sets like gnomAD and population cohorts demonstrate a minor allele frequency typically between 0.15 and 0.20 among populations of European and East Asian descent, indicating that roughly 30% to 35% of individuals in these groups carry at least one copy of the minor allele. Allele distributions may differ across African, South Asian, and Latin American ancestries, emphasizing the importance of diverse cohort representation in ophthalmic genetics. Because this variant is common in healthy populations, its presence is consistent with standard biological variation rather than a damaging Mendelian mutation.
Interpreting Results: Clinical Context and Limitations
Having a specific genotype at rs61818925 does not diagnose an eye disorder, nor does it guarantee the development or prevention of diabetic retinopathy. Retinopathy and retinal vascular caliber are complex, multifactorial traits driven predominantly by glycemic control, blood pressure, duration of diabetes, lipid levels, and broader lifestyle and genetic determinants. Genetic testing for non-coding variants in FLT1 cannot replace routine clinical care. For anyone concerned about retinal microvascular health—particularly individuals diagnosed with diabetes—regular comprehensive dilated eye examinations performed by an optometrist or ophthalmologist remain the essential standard of preventive medicine.
How common is this variant?
The minor allele occurs at a frequency of approximately 0.15 to 0.20 in European and East Asian ancestral populations, making heterozygous and homozygous minor genotypes common in the general population.
Frequently asked questions
Does having the rs61818925 variant mean I will develop diabetic retinopathy?
No. The rs61818925 variant is only associated with small statistical differences in population studies and is not a causal mutation. Diabetic retinopathy is primarily driven by clinical and metabolic factors, including blood sugar regulation, blood pressure, and diabetes duration.
What is retinal vascular caliber, and why is it studied?
Retinal vascular caliber refers to the microscopic diameter of the small arteries and veins that supply blood to the retina. Researchers study these dimensions using retinal photographs because microvascular narrowing or widening can serve as a sensitive early biomarker of systemic cardiovascular and metabolic health.
How does the FLT1 gene influence eye blood vessels?
FLT1 encodes VEGFR1, a primary receptor for vascular endothelial growth factors that regulate blood vessel formation, tone, and permeability. Variations within or near the gene may subtly influence how local blood vessels maintain their structure and adapt to environmental stressors like high blood sugar.
Can I use my rs61818925 genotype to guide eye treatments or medications?
No. There are no clinical guidelines or pharmacogenomic dosing protocols linked to rs61818925. Any medical management of diabetic eye disease or anti-VEGF therapy must be determined by qualified eye care specialists based on physical examination and diagnostic imaging.
Sources & further reading
Educational information only, last refreshed 9/14/2026. Not medical advice — these associations describe population statistics, not individual predictions.
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