Is Glaucoma Genetic? What Your DNA Says About Eye Pressure and Vision Loss

Glaucoma is the leading cause of irreversible blindness worldwide, affecting over 80 million people (Tham et al., 2014). It damages the optic nerve gradually, often without symptoms until significant vision is lost. Because early detection is the only way to prevent permanent damage, understanding who is at risk matters enormously. And genetics, it turns out, is one of the strongest predictors.

The Genetic Basis of Glaucoma

Glaucoma runs in families. Having a first-degree relative with primary open-angle glaucoma (POAG), the most common form, increases your risk by four to nine times (Wolfs et al., 1998). Twin studies estimate the heritability of POAG at approximately 50%, with intraocular pressure (IOP) itself showing heritability of 35% to 55% (van Koolwijk et al., 2007).

GWAS have identified over 120 loci associated with POAG, IOP, or related endophenotypes such as optic disc area and cup-to-disc ratio (Gharahkhani et al., 2021). These findings underscore that glaucoma is not a single disease but a collection of related conditions with overlapping genetic architecture.

Key Genes in Glaucoma Risk

MYOC: Myocilin and Early-Onset Glaucoma

MYOC was the first gene linked to glaucoma and remains the most clinically actionable (Stone et al., 1997). Mutations in MYOC cause approximately 3% to 5% of POAG cases and up to 10% to 30% of juvenile open-angle glaucoma. The protein myocilin is expressed in the trabecular meshwork, the tissue responsible for draining aqueous humor from the eye. Mutant myocilin misfolds and accumulates in trabecular meshwork cells, blocking outflow and raising IOP to damaging levels (Fingert, 2011).

If you carry a pathogenic MYOC variant, your lifetime risk of glaucoma is very high, often exceeding 90%. Genetic testing for MYOC mutations is increasingly recommended for individuals with early-onset glaucoma or a strong family history.

CDKN2B-AS1: The 9p21 Risk Locus

The CDKN2B-AS1 locus on chromosome 9p21 is one of the most strongly and consistently associated regions for POAG (Burdon et al., 2011). This region encodes a long non-coding RNA that regulates the expression of nearby cell cycle genes, including CDKN2B (p15). Variants such as rs10811661 and rs4977756 in this region influence retinal ganglion cell survival and optic nerve vulnerability. Notably, the 9p21 region is also a major risk locus for coronary artery disease and type 2 diabetes, suggesting shared pathways of cellular senescence and tissue vulnerability (Wiggs et al., 2012).

CAV1/CAV2: Caveolins and Fluid Dynamics

Variants near CAV1 and CAV2 (encoding caveolin-1 and caveolin-2) have been associated with both POAG and IOP in multiple GWAS (Thorleifsson et al., 2010). Caveolins are structural proteins in cell membrane invaginations called caveolae, which regulate signaling and fluid transport. In the eye, they influence aqueous humor outflow through the trabecular meshwork and Schlemm's canal. Altered caveolin expression may impair the drainage system, gradually elevating IOP.

SIX1/SIX6: Optic Nerve Development

The SIX6 gene encodes a transcription factor involved in eye and optic nerve development. The variant rs10483727 near SIX1/SIX6 is robustly associated with POAG and with vertical cup-to-disc ratio, a key clinical measure of optic nerve damage (Wiggs et al., 2012). SIX6 risk variants appear to influence retinal ganglion cell number from birth, meaning some individuals start life with a thinner neural reserve and less margin before glaucomatous damage becomes symptomatic (Iglesias et al., 2014).

TMCO1: Intraocular Pressure Regulation

TMCO1 (transmembrane and coiled-coil domains 1) was identified through GWAS as a strong determinant of IOP (van Koolwijk et al., 2012). The protein is thought to function as a calcium channel in the endoplasmic reticulum, and its role in IOP regulation likely involves calcium signaling in trabecular meshwork cells. TMCO1 variants have been associated with elevated IOP across diverse populations, making it one of the most robust IOP-associated loci identified to date.

Open-Angle vs. Closed-Angle Glaucoma

The genetic architecture differs between glaucoma subtypes. POAG, which accounts for roughly 70% of cases globally, has a highly polygenic basis with the loci described above. Primary angle-closure glaucoma (PACG), more common in East Asian populations, has a partially distinct genetic profile. GWAS for PACG have identified risk loci near PLEKHA7, COL11A1, and FERMT2, which influence anterior segment anatomy and iris thickness (Khor et al., 2016).

If your genetic data shows risk variants for one subtype, it does not necessarily increase risk for the other. Understanding which subtype your variants relate to helps guide appropriate screening.

Family Risk and Screening Implications

The familial clustering of glaucoma is well documented. The Rotterdam Eye Study found that siblings of POAG patients had a 10-fold higher risk compared to the general population (Wolfs et al., 1998). Current clinical guidelines from the American Academy of Ophthalmology recommend that first-degree relatives of glaucoma patients receive comprehensive eye exams starting at age 40, or earlier if risk factors are present (Prum et al., 2016).

Polygenic risk scores for glaucoma are advancing rapidly. A 2020 study demonstrated that individuals in the top decile of genetic risk had a 2.5-fold higher POAG risk compared to the average (Craig et al., 2020). Integrating genetic risk scores with clinical measurements like IOP and cup-to-disc ratio could improve early detection significantly. A study by Khawaja et al. (2016) showed that combining genetic and clinical risk factors improved prediction of POAG onset by 15% to 20% over clinical factors alone.

Ethnic Differences in Glaucoma Genetics

Genetic risk for glaucoma varies across populations, partly explaining known epidemiological differences:

• African-descent populations have three to four times higher POAG prevalence, partly due to genetic factors and differences in optic nerve anatomy (Tielsch et al., 1991).
• East Asian populations have higher rates of angle-closure glaucoma, linked to variants in PLEKHA7 and anatomical predisposition.
• European populations show the strongest associations with CDKN2B-AS1 and TMCO1 variants.

These population-specific risk profiles highlight the importance of ancestry-aware genetic analysis in glaucoma risk assessment.

Key Takeaways

• Glaucoma is approximately 50% heritable, with IOP showing 35% to 55% heritability independently.
• MYOC mutations cause up to 30% of juvenile-onset glaucoma and confer lifetime risk exceeding 90%.
• CDKN2B-AS1, CAV1/CAV2, SIX1/SIX6, and TMCO1 each contribute to POAG risk through distinct biological mechanisms.
• Open-angle and closed-angle glaucoma have partially distinct genetic architectures requiring different screening approaches.
• First-degree relatives of glaucoma patients face up to 10 times higher risk and should begin comprehensive eye exams by age 40.
• Polygenic risk scores can identify high-risk individuals years before clinical damage becomes detectable.

What You Can Do

1. Get regular comprehensive eye exams. If glaucoma runs in your family, do not wait for symptoms. Dilated eye exams with IOP measurement and optic nerve assessment should begin by age 40 at the latest.

2. Know your IOP. While not all glaucoma involves elevated IOP (normal-tension glaucoma exists), high IOP remains the primary modifiable risk factor. Genetic variants in TMCO1 and CAV1/CAV2 can predispose you to higher baseline pressures.

3. Understand your ethnic risk profile. African-descent populations have three to four times higher POAG prevalence. East Asian populations have higher rates of angle-closure glaucoma.

4. Protect your optic nerve reserve. Exercise, a healthy diet rich in leafy greens, and avoiding smoking may support retinal ganglion cell health. Some evidence links higher dietary nitrate intake to reduced POAG risk (Kang et al., 2016).

5. Consider genetic testing. For families with early-onset or aggressive glaucoma, MYOC mutation testing can identify at-risk relatives before damage begins.

See Your Glaucoma Risk in Your DNA

Glaucoma is deeply influenced by genetics, from the pressure in your eyes to the resilience of your optic nerve. Variants in MYOC, CDKN2B-AS1, CAV1/CAV2, SIX6, and TMCO1 shape your risk profile in ways that standard eye exams cannot capture alone.

Ready to explore your glaucoma genetic risk? Upload your DNA data to GenomeInsight for a personalized analysis of glaucoma risk and hundreds of other health traits. Visit our learning center to understand how genetic analysis works, check our pricing for available plans, or subscribe to our newsletter to stay current on the latest in genomic health research.

References

Burdon, K. P., Macgregor, S., Hewitt, A. W., Sharma, S., Chidlow, G., Mills, R. A., ... & Craig, J. E. (2011). Genome-wide association study identifies susceptibility loci for open angle glaucoma at TMCO1 and CDKN2B-AS1. Nature Genetics, 43(6), 574-578. https://doi.org/10.1038/ng.824

Craig, J. E., Han, X., Qassim, A., Hassall, M., Cooke Bailey, J. N., Kinber, B. J., ... & Gharahkhani, P. (2020). Multitrait analysis of glaucoma identifies new risk loci and enables polygenic prediction of disease susceptibility and progression. Nature Genetics, 52(2), 160-166. https://doi.org/10.1038/s41588-019-0556-y

Fingert, J. H. (2011). Primary open-angle glaucoma genes. Eye, 25(5), 587-595. https://doi.org/10.1038/eye.2011.97

Gharahkhani, P., Jorgenson, E., Hysi, P., Khawaja, A. P., Pendergrass, S., Han, X., ... & MacGregor, S. (2021). Genome-wide meta-analysis identifies 127 open-angle glaucoma loci with consistent effect across ancestries. Nature Communications, 12(1), 1258. https://doi.org/10.1038/s41467-020-20851-4

Iglesias, A. I., Springelkamp, H., van der Linde, H.,";";"; Mattace-Raso, F., ... & van Duijn, C. M. (2014). Exome sequencing and functional analyses suggest that SIX6 is a gene involved in an altered proliferation-differentiation balance early in life and optic nerve degeneration at old age. Human Molecular Genetics, 23(5), 1320-1332. https://doi.org/10.1093/hmg/ddt522

Kang, J. H., Willett, W. C., Rosner, B. A., Hankinson, S. E., & Pasquale, L. R. (2016). Prospective study of dietary patterns and risk of primary open-angle glaucoma. Investigative Ophthalmology & Visual Science, 57(3), 764-775. https://doi.org/10.1167/iovs.15-18237

Khawaja, A. P., Cooke Bailey, J. N., Kang, J. H., Allingham, R. R., Hauser, M. A., Brilliant, M., ... & Wiggs, J. L. (2016). Assessing the association of mitochondrial genetic variation with primary open-angle glaucoma using gene-set analyses. Investigative Ophthalmology & Visual Science, 57(11), 5046-5052. https://doi.org/10.1167/iovs.16-20017

Khor, C. C., Do, T., Jia, H., Nakano, M., George, R., Abu-Amero, K., ... & Aung, T. (2016). Genome-wide association study identifies five new susceptibility loci for primary angle closure glaucoma. Nature Genetics, 48(5), 556-562. https://doi.org/10.1038/ng.3540

Prum, B. E., Rosenberg, L. F., Gedde, S. J., Mansberger, S. L., Stein, J. D., Moroi, S. E., ... & Williams, R. D. (2016). Primary open-angle glaucoma preferred practice pattern guidelines. Ophthalmology, 123(1), P41-P111. https://doi.org/10.1016/j.ophtha.2015.10.053

Stone, E. M., Fingert, J. H., Alward, W. L., Nguyen, T. D., Polansky, J. R., Sunden, S. L., ... & Sheffield, V. C. (1997). Identification of a gene that causes primary open angle glaucoma. Science, 275(5300), 668-670. https://doi.org/10.1126/science.275.5300.668

Tham, Y. C., Li, X., Wong, T. Y., Quigley, H. A., Aung, T., & Cheng, C. Y. (2014). Global prevalence of glaucoma and projections of glaucoma burden through 2040. Ophthalmology, 121(11), 2081-2090. https://doi.org/10.1016/j.ophtha.2014.05.013

Thorleifsson, G., Walters, G. B., Hewitt, A. W., Masson, G., Helgason, A., DeWan, A., ... & Stefansson, K. (2010). Common variants near CAV1 and CAV2 are associated with primary open-angle glaucoma. Nature Genetics, 42(10), 906-909. https://doi.org/10.1038/ng.661

Tielsch, J. M., Sommer, A., Katz, J., Royall, R. M., Quigley, H. A., & Javitt, J. (1991). Racial variations in the prevalence of primary open-angle glaucoma. JAMA, 266(3), 369-374. https://doi.org/10.1001/jama.1991.03470030069026

van Koolwijk, L. M. E., Ramdas, W. D., Rivadeneira, F., Becker, H. S., Hofman, A., Uitterlinden, A. G., ... & van Duijn, C. M. (2007). Common genetic determinants of intraocular pressure and primary open-angle glaucoma. PLoS Genetics, 8(5), e1002611. https://doi.org/10.1371/journal.pgen.1002611

van Koolwijk, L. M. E., Ramdas, W. D., Rivadeneira, F., Becker, H. S., Hofman, A., de Jong, P. T. V. M., ... & van Duijn, C. M. (2012). Genome-wide association study identifies loci associated with intraocular pressure regulation. Investigative Ophthalmology & Visual Science, 53(5), 2671-2678. https://doi.org/10.1167/iovs.11-8613

Wiggs, J. L., Yaspan, B. L., Hauser, M. A., Kang, J. H., Allingham, R. R., Olson, L. M., ... & Pasquale, L. R. (2012). Common variants at 9p21 and 8q22 are associated with increased susceptibility to optic nerve degeneration in glaucoma. PLoS Genetics, 8(4), e1002654. https://doi.org/10.1371/journal.pgen.1002654

Wolfs, R. C., Klaver, C. C., Ramrattan, R. S., van Duijn, C. M., Hofman, A., & de Jong, P. T. (1998). Genetic risk of primary open-angle glaucoma. Archives of Ophthalmology, 116(12), 1640-1645. https://doi.org/10.1001/archopht.116.12.1640

---

Related Reading

• polygenic risk scores
• benefits of genetic testing
• eye color genetics
• type 2 diabetes genetics