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MYOC gene


Normal Function

The MYOC gene provides instructions for producing a protein called myocilin. Myocilin is found in certain structures of the eye, called the trabecular meshwork and the ciliary body, that regulate the pressure within the eye (intraocular pressure). Myocilin's function is not well understood, but it may help to control the intraocular pressure through its action in the muscle tissue of the ciliary body.

Researchers believe that myocilin functions together with other proteins in the eye as part of the extracellular matrix, which is an intricate lattice that forms in the space between cells and provides structural support. Myocilin may interact with a number of other proteins that also function in the extracellular matrix.

Health Conditions Related to Genetic Changes

Early-onset glaucoma

Approximately 10 percent to 33 percent of people with juvenile open-angle glaucoma have variants (also called mutations) in the MYOC gene. People with this condition experience increased pressure within the eye before the age of 40. MYOC gene variants have also been detected in some people with primary congenital glaucoma. More than 100 MYOC gene variants have been identified.

Variants in the MYOC gene may alter the myocilin protein so that its interactions with other proteins are impeded. Defective myocilin that does not get incorporated in the extracellular matrix remains inside the cell. The defective protein may damage  the cell, causing insufficient flow or fluid from the eye, resulting in increased intraocular pressure and causing the signs and symptoms of early-onset glaucoma.

More About This Health Condition

Other disorders

A small percentage (3 to 5 percent) of individuals with late-onset primary open-angle glaucoma (POAG), the most common adult form of glaucoma, have variants in the MYOC gene. 

Other Names for This Gene

  • GLC1A
  • GPOA
  • JOAG
  • JOAG1
  • myocilin, trabecular meshwork inducible glucocorticoid response
  • TIGR
  • trabecular meshwork-induced glucocorticoid response protein

Additional Information & Resources

Tests Listed in the Genetic Testing Registry

Scientific Articles on PubMed

Catalog of Genes and Diseases from OMIM

Gene and Variant Databases


  • Bayat B, Yazdani S, Alavi A, Chiani M, Chitsazian F, Tusi BK, Suri F, Narooie-Nejhad M, Sanati MH, Elahi E. Contributions of MYOC and CYP1B1 mutations to JOAG. Mol Vis. 2008 Mar 13;14:508-17. Citation on PubMed or Free article on PubMed Central
  • Chen Y, Jiang D, Yu L, Katz B, Zhang K, Wan B, Sun X. CYP1B1 and MYOC mutations in 116 Chinese patients with primary congenital glaucoma. Arch Ophthalmol. 2008 Oct;126(10):1443-7. doi: 10.1001/archopht.126.10.1443. Citation on PubMed
  • Kaur K, Reddy AB, Mukhopadhyay A, Mandal AK, Hasnain SE, Ray K, Thomas R, Balasubramanian D, Chakrabarti S. Myocilin gene implicated in primary congenital glaucoma. Clin Genet. 2005 Apr;67(4):335-40. doi: 10.1111/j.1399-0004.2005.00411.x. Citation on PubMed
  • Polansky JR. Current perspectives on the TIGR/MYOC gene (Myocilin) and glaucoma. Ophthalmol Clin North Am. 2003 Dec;16(4):515-27, v-vi. doi: 10.1016/s0896-1549(03)00068-3. Citation on PubMed
  • Scelsi HF, Barlow BM, Saccuzzo EG, Lieberman RL. Common and rare myocilin variants: Predicting glaucoma pathogenicity based on genetics, clinical, and laboratory misfolding data. Hum Mutat. 2021 Aug;42(8):903-946. doi: 10.1002/humu.24238. Epub 2021 Jun 24. Citation on PubMed

The information on this site should not be used as a substitute for professional medical care or advice. Contact a health care provider if you have questions about your health.