40 new genetic markers for glaucoma found

Australian researchers have identified 40 new genetic markers that increase a person’s risk of developing glaucoma — the leading cause of irreversible blindness worldwide.

As explained by Associate Professor Stuart MacGregor from the QIMR Berghofer Medical Research Institute, a person’s risk of developing glaucoma — which damages the optic nerve and leads to a gradual loss of peripheral vision — increases with age. The good news is that the high intraocular pressure commonly associated with glaucoma can be treated with drugs and even surgery, so although there is currently no cure, early detection through screening can halt or significantly slow the disease’s progression.

With this in mind, Associate Professor MacGregor collaborated with institutions across Australia and New Zealand on a genome-wide study of more than 134,000 people, using the genetic information of participants from the UK Biobank and the International Glaucoma Genetic Consortium. Together, the researchers found 101 genetic markers that influence intraocular pressure — the fluid pressure in a person’s eye.

Associate Professor MacGregor said the study, published in the journal Nature Genetics, showed 40 of the new genetic markers influencing eye pressure also increased a person’s risk of glaucoma. He said individuals with a large number of the genetic markers had an almost six-fold increased risk of developing glaucoma compared to someone who had fewer genetic variants.

“The discovery of these previously unknown genetic markers for glaucoma will be important for improving our ability to test for and predict a person’s risk of the disease,” Associate Professor MacGregor said.

“If we can identify who is most at risk of developing glaucoma at the earliest opportunity, we can make sure those individuals receive the preventative treatment they need to stop them from going blind as they age.

“Early treatment is vital because once a person experiences vision loss, it is impossible to reverse.”

Professor Jamie Craig, Director of the Flinders Centre for Ophthalmology, Eye and Vision Research, said the findings dramatically increase the current understanding of which genes caused glaucoma and high eye pressure.

“We expect far-reaching consequences in terms of predicting who will develop glaucoma in the population, and exciting possibilities to develop better ways to treat this disease, which is a leading cause of blindness worldwide,” he said.

“We have used DNA from thousands of patients with glaucoma to understand how these new genetic discoveries about eye pressure influence the risk of an individual developing severe vision loss from glaucoma.

“We are getting much better at predicting these outcomes in patients and this will help us find people at risk and get them on sight-saving treatment early in the course of the disease.”

Associate Professor MacGregor said while the findings increased the number of known genetic markers underpinning intraocular pressure by more than 90, the most surprising finding was the sheer number of those variants that were associated with developing glaucoma.

“There is natural variation in eye pressure from person to person, and having high eye pressure doesn’t necessarily damage your vision,” he said.

“So for the 101 genetic markers we identified, although they are a risk factor, their presence in your genetic coding doesn’t necessarily mean you will develop glaucoma.

“However, we were able to show 53 of the genetic markers do directly increase your risk of developing glaucoma and particularly increase the risk of developing advanced glaucoma, the type that tends to cause blindness.”

Image credit: ©iStockphoto.com/Brian Jackson