What you carry at this position in your DNA and what research says about it.
Glaucoma Risk: 7/10 evidence, 23 publications.
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Sample genotype (not yours): T/T
Higher Risk of Glaucoma
This genotype is associated with an increased susceptibility to open-angle glaucoma and altered optic nerve structure. It is linked to a larger optic cup size and a thinner retinal nerve fiber layer.
What this genotype means: Increased risk of open-angle glaucoma; Larger optic nerve cup-to-disc ratio; Thinner retinal nerve fiber layer.
Sample genotype (not yours): C/C
Typical Glaucoma Risk
This genotype is associated with a lower risk of open-angle glaucoma. It is linked to a more robust optic nerve structure and a thicker retinal nerve fiber layer.
What this genotype means: Lower risk of open-angle glaucoma; Favorable optic nerve cup-to-disc ratio; Thicker retinal nerve fiber layer.
Sample genotype (not yours): T/C
Moderately Higher Risk of Glaucoma
Carrying one copy of the T allele is associated with a moderately increased risk of open-angle glaucoma. It is linked to intermediate changes in optic nerve structure.
What this genotype means: Moderately increased risk of open-angle glaucoma; Slightly larger optic nerve cup-to-disc ratio.
Gene function and biological role
Gene Function: The SIX6 gene plays a critical role in the early development of the eyes, particularly in the formation of the retina and the optic nerve. It is highly active during embryonic development, guiding the differentiation of retinal progenitor cells into retinal ganglion cells [1]. These ganglion cells are the essential neurons that transmit visual information from the eye to the brain. Proper expression of this gene is vital for maintaining a healthy number of these cells throughout life [2]. Disruptions in its function can lead to structural vulnerabilities in the optic nerve, making it more susceptible to degenerative damage.
Variant Impact: The variant rs10483727 is located in an intergenic regulatory region between the SIX1 and SIX6 genes on chromosome 14. This genetic change acts as an expression modulator, influencing how actively the neighboring SIX6 gene is transcribed during development [2]. The T allele is associated with altered optic nerve morphology, specifically a larger vertical cup-to-disc ratio, which is a key clinical marker for glaucoma susceptibility [3]. Conversely, the C allele is linked to a more robust retinal nerve fiber layer, offering relative protection against nerve degeneration.
Key Insight: This variant is one of the most strongly and widely replicated genetic markers for primary open-angle glaucoma, directly influencing the physical architecture of the optic nerve.
Location: SIX6. Chromosome 14 · 14q23.1 · 60.6 Mb
Estimated prevalence by population
Global 34.6%; European 15.6%; African 77.9%; East Asian 59.0%; South Asian 32.1%; Americas 16.6%; Ashkenazi 24.2%; Finnish 7.4%; Middle Eastern 40.5%; Amish 19.3%.
Estimated TT genotype frequency.
Global 39.5%; European 47.8%; African 20.8%; East Asian 35.6%; South Asian 49.1%; Americas 48.3%; Ashkenazi 50.0%; Finnish 39.6%; Middle Eastern 46.3%; Amish 49.3%.
Estimated TC genotype frequency.
Global 25.8%; European 36.6%; African 1.4%; East Asian 5.4%; South Asian 18.8%; Americas 35.2%; Ashkenazi 25.8%; Finnish 53.0%; Middle Eastern 13.2%; Amish 31.4%.
Estimated CC genotype frequency.
Showing effects for T/T genotype
Organ Systems
Vision & Eye Health
Glaucoma. Evidence: 7/10. Source: PMID 22419738. ~1.3x Higher Risk.
Optic Cup Size. Evidence: 8/10. Source: PMID 25631615. Larger Optic Cup.
Respiratory Health
Lung Function. Evidence: 8/10. Source: PMID 40374629. Slightly Higher.
Lifestyle, Fitness & Aging
Height & Body Size
Height. Evidence: 9/10. Source: PMID 36224396. Slightly Taller.
Muscle Strength & Power
Muscle Mass. Evidence: 8/10. Source: PMID 33097823. Slightly Higher.
Showing effects for C/C genotype
Glaucoma. Evidence: 7/10. Source: PMID 22419738. Typical Risk.
Optic Cup Size. Evidence: 8/10. Source: PMID 25631615. Typical Cup Size.
Lung Function. Evidence: 8/10. Source: PMID 40374629. Slightly Lower.
Height. Evidence: 9/10. Source: PMID 36224396. Slightly Shorter.
Muscle Mass. Evidence: 8/10. Source: PMID 33097823. Slightly Lower.
Showing effects for T/C genotype
Glaucoma. Evidence: 7/10. Source: PMID 22419738. Moderately Higher.
Optic Cup Size. Evidence: 8/10. Source: PMID 25631615. Slightly Larger.
Lung Function. Evidence: 8/10. Source: PMID 40374629. Typical.
Height. Evidence: 9/10. Source: PMID 36224396. Typical Height.
Muscle Mass. Evidence: 8/10. Source: PMID 33097823. Typical.
What this genotype means for the people who carry it
Sample genotype: TT (Homozygous)
Carrying two copies of the T allele is a well-established risk factor for primary open-angle glaucoma across multiple diverse populations [1]. Large-scale genomic studies show that this variant significantly influences the physical structure of the optic nerve, leading to an increased vertical cup-to-disc ratio [2]. This structural change often correlates with a thinner retinal nerve fiber layer, indicating fewer retinal ganglion cells to transmit visual signals [3]. Over time, this cellular vulnerability makes the optic nerve more sensitive to pressure-related or degenerative damage [4]. While this genetic marker elevates risk, it is not a direct diagnosis, and regular comprehensive eye exams remain the primary tool for monitoring optic nerve health.
Increased risk of open-angle glaucoma; Larger optic nerve cup-to-disc ratio; Thinner retinal nerve fiber layer.
Sample genotype: CC (Homozygous)
Carrying two copies of the protective C allele is associated with a significantly lower risk of developing primary open-angle glaucoma [1]. Individuals with this genotype typically present with a smaller vertical cup-to-disc ratio, which is clinically favorable [2]. This structural pattern is often accompanied by a thicker, more resilient retinal nerve fiber layer, providing better natural defense against nerve degeneration [3]. While this genetic profile is protective, standard age-related risks and other environmental factors still play a role in overall eye health [4]. Maintaining routine eye examinations is still recommended to monitor intraocular pressure and general vision.
Lower risk of open-angle glaucoma; Favorable optic nerve cup-to-disc ratio; Thicker retinal nerve fiber layer.
Sample genotype: TC (Heterozygous)
Having one copy of the T allele and one copy of the C allele puts individuals at an intermediate risk level for developing primary open-angle glaucoma [1]. Research indicates that heterozygous carriers exhibit a slightly larger vertical cup-to-disc ratio compared to those with the protective C/C genotype [2]. This structural variation reflects a mild reduction in the density of the retinal nerve fiber layer [3]. Because glaucoma is a complex condition influenced by both genetics and intraocular pressure, carrying a single risk allele contributes to overall susceptibility without guaranteeing disease onset [4]. Regular eye checkups, including optic nerve imaging and pressure measurements, are helpful for early detection.
Moderately increased risk of open-angle glaucoma; Slightly larger optic nerve cup-to-disc ratio.
Variants with shared genetic architecture
rs33912345 · SIX6 Gene · Chr 14 · Glaucoma Risk
rs2745572 · FOXC1 Gene · Chr 6 · Glaucoma Risk
rs1192415 · TGFBR3 Gene · Chr 1 · Glaucoma and Lung Risk
Content updated August 2026.
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