What you carry at this position in your DNA and what research says about it.
Glaucoma Risk: 10/10 evidence, 15 publications.
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Sample genotype (not yours): G/G
Typical Glaucoma Risk
No copies of the glaucoma-associated variant were detected. This genotype is associated with typical intraocular pressure and baseline risk for open-angle glaucoma.
What this genotype means: Typical intraocular pressure; Baseline glaucoma risk.
Sample genotype (not yours): A/A
Very High Glaucoma Risk
Two copies of the pathogenic variant were detected, which is extremely rare and associated with a very high risk of severe, early-onset glaucoma.
What this genotype means: Severely elevated intraocular pressure; Very high risk of early-onset glaucoma.
Sample genotype (not yours): G/A
Significantly Increased Glaucoma Risk
One copy of the pathogenic variant was detected, which significantly raises the risk of developing primary open-angle glaucoma.
What this genotype means: Elevated intraocular pressure; Significantly higher risk of open-angle glaucoma.
Gene function and biological role
Gene Function: The MYOC gene encodes myocilin, a glycoprotein highly expressed in the trabecular meshwork of the eye [1]. This tissue regulates the outflow of aqueous humor, which maintains healthy pressure inside the eye [1]. Mutations in MYOC can cause the protein to misfold and accumulate inside cells rather than being secreted [2]. This accumulation leads to cellular stress and dysfunction in the trabecular meshwork, restricting fluid drainage [2]. Over time, the resulting pressure buildup can damage the optic nerve, leading to vision loss [1].
Variant Impact: A premature stop codon introduced by the p.Gln368Ter change results in a shortened, nonfunctional myocilin protein [1]. The truncated protein cannot be properly secreted and instead aggregates within trabecular meshwork cells [2]. This molecular bottleneck impairs the eye's natural fluid drainage system, elevating intraocular pressure [1]. It is the most common genetic risk factor for primary open-angle glaucoma in populations of European ancestry [1]. Although it significantly increases glaucoma risk, its penetrance is incomplete, meaning not everyone with the variant will develop the condition [3].
Key Insight: Despite being a strong genetic risk factor, many carriers of this variant do not develop glaucoma until later in life, and some never do, highlighting the role of age and other genetic modifiers.
Location: MYOC. Chromosome 1 · 1q24.3 · 171.6 Mb
Estimated prevalence by population
Global 99.8%; European 99.7%; African 99.9%; East Asian 100.0%; South Asian > 99.9%; Americas 99.9%; Ashkenazi 100.0%; Finnish 99.6%; Middle Eastern 100.0%; Amish 100.0%.
Estimated GG genotype frequency.
Global 0.2%; European 0.3%; African 0.1%; East Asian 0.0%; South Asian < 0.1%; Americas 0.1%; Ashkenazi 0.0%; Finnish 0.4%; Middle Eastern 0.0%; Amish 0.0%.
Estimated GA genotype frequency.
Global < 0.1%; European < 0.1%; African < 0.1%; East Asian 0.0%; South Asian < 0.1%; Americas < 0.1%; Ashkenazi 0.0%; Finnish < 0.1%; Middle Eastern 0.0%; Amish 0.0%.
Estimated AA genotype frequency.
Showing effects for G/G genotype
Organ Systems
Vision & Eye Health
Open-Angle Glaucoma. Evidence: 10/10. Source: PMID 10815160. Typical Risk.
Intraocular Pressure. Evidence: 6/10. Source: PMID 36450729. Typical Pressure.
Glaucoma Surgery Risk. Evidence: 10/10. Source: PMID 39024449. Typical Risk.
Myocilin Secretion. Evidence: 10/10. Source: PMID 19023451. Normal Secretion.
Showing effects for A/A genotype
Open-Angle Glaucoma. Evidence: 10/10. Source: PMID 10815160. High Risk.
Intraocular Pressure. Evidence: 6/10. Source: PMID 36450729. High Pressure.
Glaucoma Surgery Risk. Evidence: 10/10. Source: PMID 39024449. High Risk.
Myocilin Secretion. Evidence: 10/10. Source: PMID 19023451. Severely Reduced.
Showing effects for G/A genotype
Open-Angle Glaucoma. Evidence: 10/10. Source: PMID 10815160. ~6.8x Increased Risk.
Intraocular Pressure. Evidence: 6/10. Source: PMID 36450729. Elevated Pressure.
Glaucoma Surgery Risk. Evidence: 10/10. Source: PMID 39024449. Increased Risk.
Myocilin Secretion. Evidence: 10/10. Source: PMID 19023451. Reduced Secretion.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
A typical genetic baseline is represented here, with two functional copies of the MYOC gene producing normal myocilin protein [1]. The protein is successfully secreted into the trabecular meshwork, supporting healthy fluid drainage and normal intraocular pressure [1]. Consequently, there is no elevated genetic risk for primary open-angle glaucoma from this specific variant [2]. Other genetic and environmental factors still influence overall eye health [2]. The absence of this high-risk variant is the most common finding across all global populations [3].
Typical intraocular pressure; Baseline glaucoma risk.
Sample genotype: AA (Homozygous)
Two copies of this nonsense variant mean that no functional myocilin protein is produced, leading to severe cellular stress in the eye's drainage pathways [1]. This complete lack of normal protein secretion severely impairs the outflow of aqueous humor, leading to highly elevated intraocular pressure [1]. This genotype is associated with a very high risk of developing severe, early-onset, or childhood glaucoma [2]. The risk of progressive optic nerve damage and vision loss is extremely high [3]. This genotype is extremely rare in the general population.
Severely elevated intraocular pressure; Very high risk of early-onset glaucoma.
Sample genotype: GA (Heterozygous)
A single copy of this nonsense variant leads to the production of a truncated, nonfunctional myocilin protein alongside the normal version [1]. This abnormal protein accumulates inside the cells of the eye's drainage system, causing cellular stress and reducing fluid outflow [1]. The resulting buildup of fluid increases intraocular pressure, which is a major driver of optic nerve damage [2]. Studies show that carriers have a significantly higher risk of developing primary open-angle glaucoma, with odds ratios often ranging from 4 to 8 times higher than non-carriers [3]. However, the condition is not guaranteed, as penetrance is incomplete and symptoms typically do not appear until later in adulthood [4].
Elevated intraocular pressure; Significantly higher risk of open-angle glaucoma.
Variants with shared genetic architecture
rs2472493 · ABCA1 Gene · Chr 9 · Glaucoma and Eye Pressure
rs9853115 · DGKG Gene · Chr 3 · Glaucoma Risk
rs4236601 · CAV1 Gene · Chr 7 · Glaucoma Risk
MYOC mutation frequency in primary open-angle glaucoma patients from Western Switzerland.
Age-dependent prevalence of mutations at the GLC1A locus in primary open-angle glaucoma.
Content updated September 2026.
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