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Glaucoma affects 3% of the population over 40 years of age and untreated, causes loss of peripheral (side) vision and eventual blindness.
Anyone can develop glaucoma, however, if you have an immediate family member with glaucoma, you are at a much higher risk than the rest of the population.
Since 1994, the Glaucoma Inheritance Study in Tasmania (GIST) has been working with families and individuals with glaucoma to help find the genes that cause glaucoma so that we can:
• Understand the disease better
• Predict those at risk of developing glaucoma, so that early detection and treatment reduces the risk of blindness
• Develop new treatments for glaucoma
Since starting the Glaucoma Inheritance Study in Tasmania (GIST) over 25 years ago, we have published over 150 papers describing major scientific discoveries relating to the genes that cause glaucoma.
In some families, we have been able to identify a specific glaucoma gene. Family members can then be tested if they carry the same specific glaucoma gene as their affected relative and help minimise blindness by regularly having their eyes examined.
Myocilin (MYOC), was the first gene associated with glaucoma and it was through our research that we were able to identify these genetic changes. To date (year 2020) we have identified over 100 genes that each contribute a small effect to the risk of developing glaucoma. This work has been part of the International Glaucoma Genetics Consortium (IGGC) with the Australian team members as leading contributors.
In some cases, glaucoma can be influenced by several gene changes, as well as environmental factors. Therefore, glaucoma is referred to as a “complex” or “polygenic eye disease”. With the latest genetic discoveries, a new genetic risk scoring system has recently been developed for certain diseases.
This system is called a polygenic risk score (PRS)1. This can help determine whether people are at high or low risk of developing glaucoma. High risk individuals could access treatment early to help stop vision loss.
We are continuing to test additional patients and families to find other glaucoma gene changes and improve the accuracy of the PRS. We are also retesting the original families we studied in the 1990s. We will continue to analyse all the glaucoma patients who were enrolled in the GIST in the last 25 years.
The opportunity to have this testing performed by a US-based laboratory owned by the company Regeneron has arisen. As part of ongoing research, these results will be combined with that of other international research groups to better understand genetic risk factors for glaucoma.
The ultimate aim is to identify potential new treatments for glaucoma. If you have any questions about this testing contact us at the details below.
We will be recontacting family members who were unaffected by glaucoma when they were seen as part of our research in the 1990s to find out whether they have since developed glaucoma. For the first time anywhere in the world, this will help us determine how useful the PRS can be in screening for glaucoma.
If we check the accuracy of the PRS, then this offers the possibility of widespread genetic testing for glaucoma, not only for relatives of people with glaucoma, but also for the general population.
One impact of the GIST is that visual field testing for glaucoma has increased in Tasmania.2 The PRS will allow us to ensure that those at highest risk for glaucoma continue to undergo regular eye examinations, while individuals at lower risk are screened less often, conserving healthcare resources and saving clinician and patient time.
People who wish to learn more about the outcomes of the last 25 years of the GIST can read the attached articles.
We will be contacting many GIST participants again over the next 2 years and hope to be able to provide everyone with updates on their genetic test results.
For further information or any specific questions, contact us (03) 6226 4731 or by email at alex.hewitt@utas.edu.au or david.mackey@utas.edu.au
References:
1. Craig JE, Han X, Qassim A, et al. Multitrait analysis of glaucoma identifies new risk loci and enables polygenic prediction of disease susceptibility and progression. Nat Genet 2020; https://doi.org/10/1038.s41588-019-0556-y.
2. Mackey DM, Craig JE, Hewitt AW. Seeing the impact of the Glaucoma Tasmania after 25 years (letter). Clin Experiment Ophthalmol 2019;47:677-9.
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